This prospectus relates to the proposed resale or other disposition by the selling stockholders identified herein (the “Selling Stockholders”) of up to (i) 3,563,247 shares (the “Private Placement Common Shares”) of our common stock, par value $0.0001 per share (“Common Stock”), and (ii) 2,937,903 shares of Common Stock (the “Private Placement Conversion Shares”) issuable upon the conversion of 2,937,903 shares (the “Private Placement Preferred Shares”) of Series B Non-Voting Convertible Preferred Stock, par value $0.0001 (the “Series B Preferred Stock”). Subject to receiving the requisite stockholder approval and certain beneficial ownership limitations set by each Selling Stockholder, each share of Series B Preferred Stock will automatically convert upon the requisite stockholder approval into one share of Common Stock. The shares of Common Stock registered by the registration statement of which this prospectus forms a part are referred to herein as the “Resale Shares.”

The Private Placement Common Shares and the Private Placement Preferred Shares were issued and sold to certain institutional and accredited investors in a private placement (the “Private Placement”), which closed on July 3, 2024. We are not selling any Resale Shares under this prospectus and will not receive any of the proceeds from the sale or other disposition of Resale Shares by the Selling Stockholders.

The Selling Stockholders may sell the Resale Shares on any national securities exchange or quotation service on which the securities may be listed or quoted at the time of sale, on the over-the-counter market, in one or more transactions otherwise than on these exchanges or systems, such as privately negotiated transactions, or using a combination of these methods, and at fixed prices, at prevailing market prices at the time of the sale, at varying prices determined at the time of sale, or at negotiated prices. See the disclosure under the heading “Plan of Distribution” elsewhere in this prospectus for more information about how the Selling Stockholders may sell or otherwise dispose of their Resale Shares hereunder.

The Selling Stockholders may sell any, all or none of the securities offered by this prospectus and we do not know when or in what amount the Selling Stockholders may sell their Resale Shares hereunder following the effective date of the registration statement of which this prospectus forms a part.

You should carefully read this prospectus and any applicable prospectus supplement before you invest in any of the securities being offered.

Our Common Stock is traded on The Nasdaq Global Market under the symbol “RNAC.” On July 31, 2024, the last reported sale price for our Common Stock was $16.16 per share.

An investment in our securities involves a high degree of risk. You should carefully consider the information under the heading “Risk Factors” beginning on page 7 of this prospectus and any applicable prospectus supplement.

We are a “smaller reporting company” as defined by Rule 12b-2 of the Exchange Act and are subject to reduced public company reporting requirements.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is    , 2024

This prospectus is part of a registration statement that we filed with the SEC using a “shelf” registration process. Under this shelf registration process, the Selling Stockholders may, from time to time, sell the securities described in this prospectus in one or more offerings.

This prospectus contains information that you should consider when making your investment decision. Neither we nor the Selling Stockholders have authorized anyone to provide you with information that is different from or in addition to the information contained in this prospectus or in any applicable prospectus supplement or in any related free writing prospectus prepared by or on behalf of us or to which we have referred you. Accordingly, neither we nor any Selling Stockholder takes any responsibility for, or can provide any assurance as to the reliability of, any information that others may give. The Selling Stockholders are offering to sell, and seeking offers to buy, our securities only in jurisdictions where it is lawful to do so. This prospectus and any accompanying prospectus supplement do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in any accompanying prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus, any prospectus supplement and any related free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

We may also provide a prospectus supplement or post-effective amendment to the registration statement to add information to, or update or change information contained in, this prospectus. You should read this prospectus and any applicable prospectus supplement or post-effective amendment to the registration statement together with the additional information to which we refer you in the section of this prospectus titled “Where You Can Find More Information.”

In this prospectus, unless the context otherwise requires, the terms “Cartesian,” the “Company,” “we,” “us,” and “our” refer to Cartesian Therapeutics, Inc., a Delaware corporation, and its consolidated subsidiaries.

This prospectus contains trade names, trademarks and service marks of others, which are the property of their respective owners. Solely for convenience, trademarks and trade names referred to in this prospectus may appear without the ® or TM symbols.

This prospectus contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These forward-looking statements involve a number of risks and uncertainties. We caution readers that any forward-looking statement is not a guarantee of future performance and that actual results could differ materially from those contained in the forward-looking statement. These statements are based on current expectations of future events.

In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential”, or “continue” or the negative of these terms or other similar expressions. The forward-looking statements in this prospectus are only predictions. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the date of this prospectus and are subject to a number of important factors that could cause actual results to differ materially from those in the forward-looking statements, including the factors described under the sections in this prospectus titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” as well as the following:

Moreover, we operate in an evolving environment. New risks and uncertainties may emerge from time to time, and it is not possible for management to predict all risk and uncertainties.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based on information available to us as of the date of this prospectus. While we believe that such information provides a reasonable basis for these statements, such information may be limited or incomplete. Our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all relevant information. These statements are inherently uncertain, and investors are cautioned not to unduly rely on these statements.

All subsequent written or oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to release publicly any revisions to these forward-looking statements to reflect events or circumstances after the date of this prospectus or to reflect the occurrence of unanticipated events, except as may be required under applicable U.S. securities laws. If we do update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

Our mRNA approach to develop product candidates for the treatment of autoimmune diseases is an unproven approach. Our most advanced product candidate, Descartes-08 is in Phase 2 clinical development. We have not demonstrated the ability to successfully complete any Phase 3 or other pivotal clinical trials, obtain regulatory approvals, manufacture a commercial product, or arrange for a third party to do so on our behalf, or conduct other sales and marketing activities necessary for successful product commercialization. We may have problems identifying new product candidates and applying our technologies to other areas. Even if we are successful in identifying new product candidates, they may not be suitable for clinical development, including as a result of manufacturing difficulties, harmful side effects, limited efficacy or other characteristics that indicate that they are unlikely to be products that will receive marketing approval and achieve market acceptance. The success of our product candidates will depend on several factors, including the following:

Our failure to successfully execute on of any of the foregoing for any reason would effectively prevent or delay approval of our lead and other product candidates.

Clinical development is expensive, time consuming and involves significant risk. It is impossible to predict when or if any of our product candidates will prove effective and safe in humans or will receive regulatory approval, and the risk of failure through the development process is high. Before obtaining marketing approval from regulatory authorities for the sale of any product candidate, we must complete manufacturing and preclinical development and then conduct extensive clinical trials to demonstrate the safety and efficacy of our product candidates in humans. Manufacturing cell therapies, particularly those modified with mRNA, is a new field.

Preclinical development is costly and inherently uncertain. Early preclinical results may not be predictive of future results, however, if our technology proves to be ineffective or unsafe as a result of, among other things, adverse side effects, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the clinical development and commercialization of our product candidates.

Before obtaining marketing approval from regulatory authorities for the sale of our product candidates, we must conduct extensive clinical trials to demonstrate the safety and efficacy of the product candidate for its intended indications. Clinical testing is expensive, difficult to design and implement, can take many years to complete and its outcome is inherently uncertain. A failed clinical trial can occur at any stage of testing. Moreover, the outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. Moreover, we may not be able to complete, or may be required to deviate from the current clinical trial protocol for a variety of reasons.

Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in clinical trials after achieving positive results in preclinical development or early-stage clinical trials, and we cannot be certain that we will not face similar setbacks. Serious adverse events (“SAEs”), caused by, or other unexpected properties of, any product candidates that we may choose to develop could cause us, an institutional review board or regulatory authority to interrupt, delay or halt clinical trials of one or more of such product candidates and could result in a more restrictive label or the delay or denial of marketing approval by the FDA or comparable non-U.S. regulatory authorities. If any product candidate that we may choose to develop is associated with SAEs or other unexpected properties, we may need to abandon development or limit development of that product candidate to certain uses or subpopulations in which those undesirable characteristics would be expected to be less prevalent, less severe or more tolerable from a risk-benefit perspective. Moreover, preclinical and clinical data is often susceptible to varying interpretations and analyses, and many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials nonetheless failed to obtain FDA or other regulatory authority approval. If we fail to produce positive results in clinical trials of our product candidates, the development timeline and regulatory approval and commercialization prospects for our product candidates, and, correspondingly, our business and financial prospects, would be negatively impacted.

In addition, we cannot be certain as to what type and how many clinical trials the FDA will require us to conduct before we may gain regulatory approval to market any of our product candidates in the United States or other countries, if any. Prior to approving a new therapeutic product, the FDA generally requires that safety and efficacy be demonstrated in two adequate and well-controlled clinical trials.

We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval for, or commercialize, our product candidates, including:

If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, or if we are forced to delay or abandon certain clinical trials or other testing in order to conserve capital resources, we may:

We could also encounter delays if a clinical trial is suspended or terminated. Authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA or comparable foreign regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial. In addition, changes in regulatory requirements and policies may occur, and we may need to amend clinical trial protocols to comply with these changes. Amendments may require us to resubmit our clinical trial protocols to institutional review boards (“IRBs”), for reexamination, which may impact the costs, timing or successful completion of a clinical trial.

Our product development costs will increase if we experience delays in clinical testing or in obtaining marketing approvals. We do not know whether any of our preclinical studies or clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Significant preclinical or clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring products to market before we do, potentially impairing our ability to successfully commercialize our product candidates and harming our business and results of operations.

We may not be able to initiate or continue clinical trials for our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or similar regulatory authorities outside the United States. In addition, from time to time our competitors have ongoing clinical trials for product candidates that treat the same indications as our product candidates, and patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ product candidates. Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays and could require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our product candidates, which could cause the value of our Common Stock to decline and limit our ability to obtain additional financing.

Opening trial sites outside the United States may involve additional regulatory, administrative and financial burdens, including compliance with foreign and local requirements relating to regulatory submission and clinical trial practices. Although the FDA may accept data from clinical trials conducted outside the United States, acceptance of these data is subject to certain conditions imposed by the FDA. For example, the clinical trial must be well designed and conducted and performed by qualified investigators in accordance with good clinical practices (“GCPs”), and the FDA must be able to validate the data from the trial through an onsite inspection, if necessary. Generally, the patient population for any clinical trials conducted outside the United States must be representative of the population for which we intend to seek approval in the United States. In addition, while these clinical trials are subject to the applicable local laws, FDA acceptance of the data will be dependent upon its determination that the trials also complied with all applicable U.S. laws and regulations. Nonetheless, there can be no assurance that the FDA will accept data from trials conducted outside the United States. If the FDA does not accept the data from any trial that we conduct outside the United States, it would likely result in the need for additional clinical trials, which would be costly and time-consuming and delay or permanently halt our development of any applicable product candidates.

Additional risks inherent in conducting international clinical trials include:

There exist several designations that we can apply for from the FDA and other regulators that would provide us with various combinations of the potential for expedited regulatory review, certain financial incentives as well as the potential for post-approval exclusivity for a period of time. These designations include but are not limited to orphan drug designation, breakthrough therapy designation, accelerated approval, fast track status and priority review for our product candidates. For example, Descartes-08 has been granted orphan drug designation and Regenerative Medicine Advanced Therapy (“RMAT”) designation by the FDA for the treatment of MG. We expect to seek one or more of these designations for our other current and future product candidates. There can be no assurance that any of our other product candidates will qualify for any of these designations. There can also be no assurance that any of our product candidates that do qualify for these designations will be granted such designations or that the FDA will not revoke a designation it grants at a later date, or that Congress will not change the law about a designation.

Further, there can be no assurance that any of our product candidates that are granted such designations, including Descartes-08, will ever benefit from such designations or that the FDA would not withdraw such designations once granted. Were we to receive a designation that promised a period of market exclusivity, such as orphan drug exclusivity, such exclusivity may not effectively protect the product from competition because different drugs can be approved for the same condition. In particular, the scope of exclusivity afforded for mRNA-modified cell therapy products may not be well defined. Further with respect to orphan drug status, even after an orphan drug is approved, the FDA can subsequently approve the same drug for the same condition if the FDA concludes that the later drug is clinically superior if it is shown to be safer, more effective or makes a major contribution to patient care.

From time to time, we may publish interim, top-line or preliminary data from our clinical studies, which is based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change following a full analyses of all data related to the particular trial. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, the top-line results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Preliminary or top-line data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. Interim data from clinical trials are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available.

Interim, top-line or preliminary data may not be representative of final data. If final data is not as positive as earlier interim, top-line or preliminary we have released, our business prospects would be significantly harmed.

In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and you or others may not agree with what we determine is the material or otherwise appropriate information to include in our disclosure. Any information we determine not to disclose may ultimately be deemed significant by you or others with respect to future decisions, conclusions, views, activities or otherwise regarding a particular product candidate or our business. As a result, preliminary and top-line data should not be relied upon in making an investment decision in our securities.

Undesirable side effects caused by our product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials, could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign authorities and could result in decreased market acceptance of any of

our product candidates, if approved. Results of our clinical trials could reveal a high and unacceptable severity and prevalence of side effects. In such an event, our trials could be suspended or terminated, and the FDA or comparable foreign regulatory authorities could order us to cease further development of or deny approval of our product candidates for any or all targeted indications.

In November 2023, the FDA issued a statement that it is investigating serious risk of T-cell malignancy following BCMA-directed or CD19-directed autologous CAR-T cell immunotherapies. While the FDA noted that it currently believes that the overall benefits of these products continue to outweigh their potential risks for their approved uses, the FDA stated that it is investigating the identified risk of T-cell malignancy with serious outcomes, including hospitalization and death, and is evaluating the need for regulatory action. Further, in January 2024, the FDA announced it would require a so-called “boxed warning” be added to the prescribing information for all six then-currently approved CAR-T therapies. A boxed warning is the strongest safety labeling the FDA may require. However, because all currently approved CAR T-cell immunotherapies are in oncology indications, there can be no assurance that FDA will reach the same risk-benefit analysis in other indications.

While we believe our mRNA-based CAR-T product candidates may have a differentiated toxicity profile than currently approved DNA-based CAR-T therapies, there can be no assurance that the FDA would not treat Descartes-08 or any of our other product candidates similar to approved DNA-based CAR-T therapies. The FDA’s investigation may impact the FDA’s review of product candidates that we are developing, or that we may seek to develop in the future, which may, among other things, result in additional regulatory scrutiny of our product candidates, delay the timing for receiving any regulatory approvals or impose additional post-approval requirements on any of our product candidates that receive regulatory approval.

Any drug-related side effects observed in our clinical trials could also affect patient enrollment in our clinical trials or the ability of any enrolled patients to complete such trials or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.

Additionally, if one or more of our product candidates receives marketing approval, and we or others later identify undesirable side effects caused by such products, a number of potentially significant negative consequences could result, including:

Any of these events could prevent us from achieving or maintaining market acceptance of a particular product candidate, if approved, and could significantly harm our business, results of operations and prospects.

We have growing manufacturing capabilities, and in order to continue to develop our current product candidates, apply for regulatory approvals and, if approved, commercialize future products, we will need to continue to develop, contract for, or otherwise arrange for any necessary external manufacturing capabilities.

We manufacture our product candidates internally. There are risks inherent in biological manufacturing and we may not meet our delivery time requirements or provide adequate amounts of material to meet our needs, and we may make errors in manufacturing, any of which could delay our clinical trials and result in additional expense to us.

Our autologous cell therapy product candidates, including Descartes-08, are made on a patient-by-patient basis, rendering their manufacture less predictable and requiring more demanding logistics.

We rely on one or more third-party laboratories to perform certain quality control tests. These laboratories could become unavailable, or provision of their services could be delayed.

Additionally, as we scale up our manufacturing, we may encounter further challenges. Furthermore, competition for supply from our manufacturers from other companies, a breach or violation by such manufacturers of their contractual or regulatory obligations or a dispute with such manufacturers would cause delays in our discovery and development efforts, as well as additional expense to us.

In developing manufacturing capabilities by building our own manufacturing facilities, we have incurred substantial expenditures, and expect to incur significant additional expenditures in the future. Also, we have had to, and will likely need to continue to recruit, hire, and train qualified employees to staff our facilities. If we are unable to manufacture sufficient quantities of material or if we encounter problems with our facilities in the future, we may also need to secure alternative suppliers, and such alternative suppliers may not be available, or we may be unable to enter into agreements with them on reasonable terms and in a timely manner. In addition, to the extent we or our partners rely on contract manufacturing organizations (“CMOs”), to supply our product candidates, any delays or disruptions in supply could have a material adverse impact on the research and development activities and potential commercialization of our or our partners’ product candidates.

The manufacturing process for any products that we may develop is subject to the FDA and foreign regulatory authority approval process and we will need to meet, or will need to contract with CMOs who can meet, all applicable FDA and foreign regulatory authority requirements on an ongoing basis. Our failure or the failure of any CMO to meet required regulatory authority requirements could result in the delayed submission of regulatory applications, or delays in receiving regulatory approval for any of our or our current or future collaborators’ product candidates.

To the extent that we have existing, or enter into future, manufacturing arrangements with third parties, we depend, and will depend in the future, on these third parties to perform their obligations in a timely manner and consistent with contractual and regulatory requirements, including those related to quality control and quality assurance. The failure of any CMO to perform its obligations as expected, or, to the extent we manufacture all or a portion of our product candidates ourselves, our failure to execute on our manufacturing requirements, could adversely affect our business in a number of ways, including:

We intend to explore licenses and other strategic collaborations with pharmaceutical and biotechnology companies for development and potential commercialization of therapeutic products. However, we face significant competition in seeking appropriate collaborators. If we fail to enter into collaborations and do not have sufficient funds or expertise to undertake the necessary development and commercialization activities, we

may not be able to further develop our product candidates or bring them to market or continue to develop our programs, and our business may be materially and adversely affected.

We rely, and expect to continue to rely, on third parties, such as CROs, clinical data management organizations, medical institutions and clinical investigators, to conduct and manage our clinical trials, including our ongoing Phase 2 clinical trials of Descartes-08. We also expect to rely on other third parties to store and distribute drug supplies for our clinical trials.

While we rely on these third parties for research and development activities, we remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial. Moreover, the FDA requires us to comply with GCP regulations, for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, safety and welfare of trial participants are protected. Other countries’ regulatory agencies also have requirements for clinical trials. If we or any of our CROs or third-party contractors fail to comply with applicable GCPs, the data generated in our clinical trials may be deemed unreliable and the FDA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. In addition, our clinical trials must be conducted with product produced under cGMP regulations. Our failure to comply with these regulations may require us to repeat clinical trials, which would delay the regulatory approval process. We also are required to register ongoing clinical trials and post the results of completed clinical trials on a government-sponsored database, www.ClinicalTrials.gov, within specified timeframes. Failure to do so can result in fines, adverse publicity, and civil and criminal sanctions.

Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. If these third parties do not successfully carry out their contractual duties, do not comply with confidentiality obligations, do not meet expected deadlines, experience work stoppages, terminate their agreements with us or need to be replaced, or do not conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we may need to enter into new arrangements with alternative third parties, which could be difficult, costly or impossible, and our clinical trials may be extended, delayed or terminated, or may need to be repeated. If any of the foregoing occur, we may not be able to obtain, or may be delayed in obtaining, marketing approvals for our product candidates or in commercializing our product candidates.

If any of our product candidates receives marketing approval, it may nonetheless fail to gain sufficient market acceptance by physicians, patients, third-party payors and others in the medical community. If our product candidates do not achieve an adequate level of acceptance, we may not generate significant product revenues and we may not become profitable. The degree of market acceptance of our product candidates, if approved for commercial sale, will depend on several factors, including:

We do not have a sales or marketing infrastructure and have no experience in the sale, marketing or distribution of pharmaceutical products. To achieve commercial success for any product candidate for which we obtain marketing approval, we will need to establish a sales and marketing organization or make arrangements with third parties to perform sales and marketing functions and we may not be successful in doing so. We expect to build a focused sales and marketing infrastructure to market or co-promote our product candidates in the United States and potentially elsewhere, if and when they are approved. There are risks involved with establishing our own sales, marketing and distribution capabilities. For example, recruiting and training a sales force is expensive and time-consuming and could delay any product launch. This may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

The development and commercialization of new drug and biologic products and technologies is highly competitive and is characterized by rapid and substantial technological development and product innovations. We are aware that pharmaceutical and biotechnology companies, offer or are pursuing the development of pharmaceutical products or technologies that may address one or more indications that our product candidates target, as well as smaller, early-stage companies, that offer or are pursuing the development of pharmaceutical products or technologies that may address one or more indications that our product candidates target. We face competition with respect to our current product candidates and will face competition with respect to any product candidates that we may seek to develop or commercialize in the future, from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide.

Many of the companies against which we are competing or against which we may compete in the future have significantly greater financial resources, established presence in the market and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and reimbursement for product candidates and in marketing approved products than we do.

These third parties compete with us in recruiting and retaining qualified scientific, sales and marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market, especially for any competitor developing a cell therapy product that will likely share our same regulatory approval requirements. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of generic or biosimilar products.

The Biologics Price Competition and Innovation Act of 2009 (the “BPCIA”), was enacted as part of the Affordable Care Act to establish an abbreviated pathway for the approval of biosimilar and interchangeable biological products. The regulatory pathway establishes legal authority for the FDA to review and approve biosimilar biologics, including the possible designation of a biosimilar as “interchangeable” based on its

similarity to an approved biologic. Under the BPCIA, an application for a biosimilar product cannot be approved by the FDA until 12 years after the reference product was approved under a biologics license application (“BLA”). The law is still being interpreted and implemented by the FDA, and as a result, its ultimate impact, implementation, and meaning are subject to uncertainty. However, any such processes could have a material adverse effect on the future commercial prospects for our biological products.

We believe that any product candidate approved in the United States as a biological product under a BLA should qualify for the 12-year period of exclusivity. However, there is a risk that this exclusivity could be shortened due to Congressional action or otherwise, or that the FDA will not consider the subject product candidates to be reference products for competing products, potentially creating the opportunity for generic competition sooner than anticipated. Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of the reference products in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

Significant uncertainty exists as to the coverage and reimbursement status of any product candidates for which we obtain regulatory approval, especially novel products like our cell therapy product candidates, and may be particularly difficult because of the higher prices associated with such product candidates. Our ability to commercialize any product candidates successfully will depend, in part, on the extent to which coverage and adequate reimbursement for these products and related treatments will be available from government health administration authorities, private health insurers and other organizations. Government authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels.

Obtaining and maintaining adequate reimbursement for our products may be difficult. We cannot be certain if we will obtain an adequate level of reimbursement for our products by third-party payors. Even if we do obtain adequate levels of reimbursement, third-party payors, such as government or private healthcare insurers, carefully review and question the coverage of, and challenge the prices charged for, products. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. Third-party payors often require that pharmaceutical companies provide them with predetermined discounts from list prices and are challenging the prices charged for products. We may also be required to conduct expensive pharmacoeconomic studies to justify coverage and reimbursement or the level of reimbursement relative to other therapies. Some third-party payors may require pre-approval of coverage for new and innovative therapies, such as our product candidates, before they will provide reimbursement. If coverage and reimbursement are not available or reimbursement is available only to limited levels, we may not be able to successfully commercialize any product candidate for which we obtain marketing approval.

There may be significant delays in obtaining reimbursement for newly approved products, and coverage may be more limited than the purposes for which the product is approved by the FDA or similar regulatory authorities outside of the United States. Moreover, eligibility for reimbursement does not imply that a product will be paid for in all cases or at a rate that covers our costs, including research, development, manufacture, sale and distribution. Interim reimbursement levels for new products, if applicable, may also not be sufficient to cover our costs and may not be made permanent. Reimbursement rates may vary according to the use of the product and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost products and may be incorporated into existing payments for other services. Net prices for products may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of products from countries where they may be sold at lower prices than in the United States. Our inability to promptly obtain coverage and adequate reimbursement rates from both government-funded and private payors for any approved products that we develop could have a material adverse effect on our operating results, our ability to raise capital needed to commercialize products and our overall financial condition.

The regulations that govern marketing approvals, pricing, coverage and reimbursement for new products vary widely from country to country. Current and future legislation may significantly change the approval requirements in ways that could involve additional costs and cause delays in obtaining approvals. Some countries require approval of the sale price of a product before it can be marketed. In many countries, the pricing review

period begins after marketing or product licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control, including possible price reductions, even after initial approval is granted. As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, and negatively impact the revenues we are able to generate from the sale of the product in that country. Adverse pricing limitations may hinder our ability to recoup our investment in one or more product candidates, even if our product candidates obtain marketing approval. There can be no assurance that our product candidates, if they are approved for sale in the United States or in other countries, will be considered medically necessary for a specific indication or cost-effective, or that coverage or an adequate level of reimbursement will be available.

Moreover, there is heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed bills designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. There can be no assurance that our product candidates, will not be subject to heightened governmental scrutiny, unfavorable regulatory inquiry or action, or Congressional inquiry.

We face an inherent risk of product liability exposure related to the testing of our product candidates in clinical trials and will face an even greater risk if we commercially sell any products that we may develop. If we cannot successfully defend ourselves against claims that our product candidates or products caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

We maintain general liability, product liability and umbrella liability insurance. Our existing insurance coverage may not fully cover potential liabilities that we may incur. We may need to increase our insurance coverage as we expand our clinical trials or if we commence commercialization of our product candidates. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise. A product liability claim or series of claims brought against us could cause our share price to decline and, if judgments exceed our insurance coverage, could adversely affect our results of operations and business, including preventing or limiting the commercialization of any product candidates we develop.

Arrangements with physicians, others who may be in a position to generate business for us, and customers may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that constrain the business or financial arrangements and relationships through which we market, sell and distribute any products for which we obtain marketing approval. Restrictions under applicable federal and state healthcare laws and regulations include the following:

Efforts to ensure that our business arrangements with third parties comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that our business practices, including our relationships with physicians and other healthcare providers, some of whom may recommend, purchase and/or prescribe our product candidates, if approved, may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other governmental laws and regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, imprisonment, exclusion of products from government funded healthcare programs, such as Medicare and Medicaid, disgorgement, contractual damages, reputational harm, diminished profits and the curtailment or restructuring of our operations. If any of the physicians or other healthcare providers or entities with whom we expect to do business is found to be not in compliance with applicable laws, they may be subject to criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs. The risk of our being found in violation of these laws is increased by the fact that many of them have not been fully interpreted by the regulatory authorities or the courts, and their provisions are open to a variety of interpretations.

In the United States and some foreign jurisdictions, there have been a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our product candidates, restrict or regulate post-approval activities and affect our ability to profitably sell any product candidates for which we obtain marketing approval.

For example, the Patient Protection and Affordable Care Act of 2010 (the “ACA”), is a sweeping law intended to broaden access to health insurance, reduce or constrain the growth of healthcare spending, enhance remedies against fraud and abuse, add new transparency requirements for the healthcare and health insurance industries, impose new taxes and fees on the health industry and impose additional health policy reforms.

Since its enactment, there have been judicial and Congressional challenges to certain aspects of the ACA. We cannot predict the ultimate content, timing or effect of any healthcare reform legislation or the impact of potential legislation on us.

We expect that the ACA, as well as other healthcare reform measures that may be adopted in the future, may result in additional reductions in Medicare and other healthcare funding, more rigorous coverage criteria, new payment methodologies and additional downward pressure on the price that we receive for any approved product. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability or commercialize our products.

The ability of the FDA to review and or approve new products can be affected by a variety of factors, including government budget and funding levels, statutory, regulatory, and policy changes, the FDA’s ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA’s

ability to perform routine functions. Average review times at the agency have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable. Disruptions at the FDA and other agencies may also slow the time necessary for new drugs and biologics to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. If a prolonged government shutdown occurs, or if global health concerns were to again prevent the FDA or other regulatory authorities from conducting their regular inspections, reviews, or other regulatory activities, it could significantly impact the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

We are subject to export control and import laws and regulations, including the U.S. Export Administration Regulations administered by the U.S. Commerce Department’s Bureau of Industry and Security, U.S. customs regulations, various economic and trade sanctions regulations including those administered or enforced by relevant government authorities, such as by the U.S. Treasury Department’s Office of Foreign Assets Control or the U.S. Department of State, the U.S. Foreign Corrupt Practices Act of 1977, as amended (the “FCPA”), the U.S. domestic bribery statute contained in 18 U.S.C. § 201, the U.S. Travel Act, the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism (“PATRIOT Act”), and other state and national anti-bribery and anti-money laundering laws in the countries in which we conduct activities. U.S. sanctions laws and regulations may govern or restrict our business and activities in certain countries and with certain persons. Anti-corruption laws are interpreted broadly and prohibit companies and their employees, agents, contractors and other partners from authorizing, promising, offering or providing, directly or indirectly, improper payments or anything else of value to recipients in the public or private sector. We may engage third parties for clinical trials outside of the United States, to sell our product candidates abroad once we enter a commercialization phase, and/or to obtain necessary permits, licenses, patent registrations, and other regulatory approvals. We have direct or indirect interactions with officials and employees of government agencies or government-affiliated hospitals, universities and other organizations. We can be held liable for the corrupt or other illegal activities of our employees, agents, contractors and other partners, even if we do not explicitly authorize or have actual knowledge of such activities. Our violations of the laws and regulations described above may result in substantial civil and criminal fines and penalties, imprisonment, the loss of export or import privileges, debarment, tax reassessments, breach of contract and fraud litigation, reputational harm and other consequences.

We and our contract manufacturers and other third parties with whom we do business are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including biological materials and chemicals. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury from these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations.

Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological, hazardous or radioactive materials.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or production efforts. The failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

Except for the year ended December 31, 2022, we have incurred significant operating losses since our inception. We incurred a net loss of $56.8 million and $21.7 million for the three months ended March 31, 2024 and 2023, respectively. As of March 31, 2024, we had an accumulated deficit of $671.5 million. To date, we have financed our operations primarily through public offerings and private placements of our securities, funding received from collaboration and license arrangements and a credit facility. We currently have no source of product revenue, and we do not expect to generate product revenue for the foreseeable future. Historically we devoted substantially all of our financial resources and efforts to developing our ImmTOR platform and following the closing of the Merger (the “Closing”), we expect to devote substantially all of our financial resources and efforts to developing our mRNA-based therapies for the treatment of autoimmune diseases, identifying potential product candidates and conducting preclinical studies and our clinical trials. We are in the early stages of clinical development of most of our product candidates. We expect to continue to incur significant expenses and operating losses for the foreseeable future. We expect that our expenses will increase substantially as we:

To become and remain profitable, we must succeed in developing and eventually commercializing products that generate significant revenue. This will require us to be successful in a range of challenging activities, including completing preclinical testing and clinical trials of our product candidates, discovering additional product candidates, obtaining regulatory approval and securing reimbursement for these product candidates, manufacturing, marketing and selling any products for which we may obtain regulatory approval, and establishing and managing our collaborations at various stages of a product candidate’s development. We are only in the preliminary stages of most of these activities. We may never succeed in these activities and, even if we do, may never generate revenues that are significant enough to achieve profitability.

Because of the numerous risks and uncertainties associated with pharmaceutical and biological product development, we are unable to accurately predict the timing or amount of increased expenses or when, or if, we will be able to achieve profitability. If we are required by the FDA or other regulatory authorities to perform

studies in addition to those currently expected, or if there are any delays in completing our clinical trials or the development of any of our product candidates, our expenses could increase and product revenue could be further delayed.

We may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to remain profitable would depress our value and could impair our ability to raise capital, expand our business, maintain our research and development efforts, diversify our product offerings or continue our operations.

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue research and development for other product candidates. Additionally, if we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product manufacturing, marketing, sales and distribution. Accordingly, we will need to obtain substantial additional funding to continue operations. If we are unable to raise capital when needed or on attractive terms, we could be forced to delay, reduce or eliminate our clinical trials, our other research and development programs or any future commercialization efforts.

We believe that our existing cash, cash equivalents and restricted cash as of March 31, 2024, combined with the net proceeds received subsequent to March 31, 2024 in connection with the Private Placement, will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months. We may pursue additional cash resources through public or private equity or debt financings, by establishing collaborations with other companies or through the monetization of potential royalty and/or milestone payments pursuant to our existing collaboration and license arrangements. Management’s expectations with respect to our ability to fund current and long-term planned operations are based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, we may need to seek additional strategic or financing opportunities sooner than would otherwise be expected. However, there is no guarantee that any of these strategic or financing opportunities will be executed on favorable terms, and some could be dilutive to existing stockholders. If we are unable to obtain additional funding on a timely basis, we may be forced to significantly curtail, delay, or discontinue one or more of our planned research or development programs or be unable to expand our operations, meet long-term obligations or otherwise capitalize on our commercialization of our product candidates. We have based this estimate on assumptions that may prove to be wrong, and we could use our capital resources sooner than we currently expect.

Our future capital requirements will depend on many factors, including:

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our product candidates. In addition, we cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. Market volatility resulting from the ongoing conflicts in Ukraine and the Middle East and current global macroeconomic conditions or other factors could also adversely impact our ability to access capital as and when needed. Moreover, the terms of any financing may adversely affect the holdings or the rights of our stockholders, and the issuance of additional securities, whether equity or debt, by us, or the possibility of such issuance, may cause the market price of our shares to decline. The sale of additional equity or convertible securities would dilute all of our stockholders. The incurrence of indebtedness could result in increased fixed payment obligations and we may be required to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. We could also be required to seek funds through arrangements with collaborators or others at an earlier stage than otherwise would be desirable and we may be required to relinquish rights to some of our technologies or product candidates or otherwise agree to terms unfavorable to us, any of which may have a material adverse effect on our business, operating results and prospects.

If we are unable to obtain funding on a timely basis, we may be required to significantly curtail, delay or discontinue one or more of our research or development programs, including our clinical trial programs, or the commercialization of any product candidates, or be unable to sustain or expand our operations or otherwise capitalize on our business opportunities, as desired, which could materially affect our business, financial condition and results of operations.

We have net operating loss carryforwards (“NOLs”), for federal and state income tax purposes that may be available to offset our future taxable income, if any. In general, under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the “Code”), a corporation that undergoes an “ownership change” is subject to limitations on its ability to use its pre-change NOLs to offset future taxable income. If the IRS, challenges our analysis that existing NOLs will not expire before utilization due to previous ownership changes, or if we undergo an ownership change, our ability to use our NOLs could be limited by Section 382 of the Code. Future changes in our stock ownership, some of which are outside of our control, could result in an ownership change under Sections 382 and 383 of the Code.

Furthermore, our ability to use NOLs of companies that we may acquire in the future may be subject to limitations. As a result, we may not be able to use a material portion of the NOLs reflected on our balance sheet, even if we attain profitability. Under current law, NOLs that arose before January 1, 2018 may be carried forward up to 20 years. NOLs that arose after 2017 may be used to offset at most 80% of our taxable income to the extent not offset by pre-2018 NOLs and such NOLs can be carried forward indefinitely. As a result, we may become required to pay federal income taxes in future years despite having generated losses for federal income tax purposes in prior years.

Our success depends in large part on our ability to obtain and maintain patent and other intellectual property protection in the United States and other countries with respect to our proprietary technology and products. We seek to protect our proprietary position by filing patent applications in the United States and abroad related to our novel technologies and product candidates. We also rely on trade secrets to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

The patent prosecution process is expensive and time-consuming, and we may not be able to file and prosecute all necessary or desirable patent applications at a reasonable cost, in a timely manner or in all jurisdictions. As we reach the statutory deadlines for deciding whether and where to initiate prosecution in specific foreign jurisdictions by filing national stage applications based on our Patent Cooperation Treaty (“PCT”), applications,

we will have to decide whether and where to pursue patent protection for the various inventions claimed in our patent portfolio, and we will only have the opportunity to obtain patents in those jurisdictions where we pursue protection. It is also possible that we will fail to identify patentable aspects of our research and development output before it is too late to obtain patent protection. It is possible that defects of form in the preparation or filing of our patents or patent applications may exist, or may arise in the future, such as, with respect to proper priority claims, inventorship, claim scope or patent term adjustments. If there are material defects in the form or preparation of our patents or patent applications, such patents or applications may be invalid and unenforceable. Moreover, our competitors may independently develop equivalent knowledge, methods and know-how. Any of these outcomes could impair our ability to prevent competition from third parties, which may have an adverse impact on our business. We also cannot guarantee that any of our patent searches or analyses, including but not limited to the identification of relevant patents, the scope of patent claims or the expiration of relevant patents, are complete and thorough, nor can we be certain that we have identified each and every patent and pending application in the United States and abroad that is relevant to or necessary for the commercialization of our product candidates in any jurisdiction.

In some circumstances, we may not have the right to control the preparation, filing and prosecution of patent applications, or to maintain the patents covering technology that we license from third parties. We may also require the cooperation of our licensors to enforce any licensed patent rights, and such cooperation may not be provided. Therefore, these patents and applications may not be prosecuted and enforced in a manner consistent with the best interests of our business. Moreover, we have obligations under our licenses, and any failure to satisfy those obligations could give our licensor the right to terminate the license. Termination of a necessary license could have a material adverse impact on our business.

Some of our patent licenses are non-exclusive. In those cases, a competitor could obtain a license to the same or similar technology from the licensor. We have at least one exclusive patent license that is restricted to a particular field of use. A competitor could obtain a license to a similar technology outside of that field of use.

We cannot provide any assurances that the issued patents we currently own, or any future patents, include claims with a scope sufficient to protect our product candidates or otherwise provide any competitive advantage.

Further, it is possible that a patent claim may provide coverage for some but not all parts of a product candidate or third-party product. These and other factors may provide opportunities for our competitors to design around our patents.

Moreover, other parties may have developed technologies that may be related or competitive to our approach, and may have filed or may file patent applications, and may have received or may receive patents that may overlap or conflict with our patent applications, either by claiming similar methods or by claiming subject matter that could dominate our patent position. In addition, it may be some time before we understand how the patent office reacts to our patent claims and whether they identify prior art of relevance that we have not already considered.

Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all. Therefore, we cannot know with certainty whether we were the first to make the inventions claimed in any owned patents or pending patent applications, or that we were the first to file for patent protection of such inventions, nor can we know whether those from whom we may license patents were the first to make the inventions claimed or were the first to file. For these and other reasons, the issuance, scope, validity, enforceability and commercial value of our patent rights are subject to a level of uncertainty. Our pending and future patent applications may not result in patents being issued that protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may diminish the value of our patents or narrow the scope of our patent protection.

We may be subject to a third-party preissuance submission of prior art to the U.S. Patent and Trademark Office (“USPTO”), or other patent office, or become involved in opposition, derivation, reexamination, inter partes review, post-grant review or interference proceedings challenging our patent rights or the patent rights of others. An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology or products and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize product

candidates without infringing third-party patent rights. In addition, if the breadth or strength of protection provided by our patents and patent applications is threatened, it could dissuade companies from collaborating with us to license, develop or commercialize current or future product candidates. Furthermore, an adverse decision in an interference proceeding can result in a third party receiving the patent right sought by us, which in turn could affect our ability to develop, market or otherwise commercialize our product candidates. The issuance, scope, validity, enforceability and commercial value of our patents are subject to a level of uncertainty.

The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions and has in recent years been the subject of much litigation. Due to legal standards relating to patentability, validity, enforceability and claim scope of patents covering biotechnological and pharmaceutical inventions, our ability to obtain, maintain and enforce patents is uncertain and involves complex legal and factual questions. Even if issued, a patent’s validity, inventorship, ownership or enforceability is not conclusive. Accordingly, rights under any existing patent or any patents we might obtain or license may not cover our product candidates, or may not provide us with sufficient protection for our product candidates to afford a commercial advantage against competitive products or processes, including those from branded and generic pharmaceutical companies.

In addition to the protection afforded by patents, we rely on trade secret protection and confidentiality agreements to protect proprietary know-how, information, or technology that is not covered by our patents. Although our agreements require all of our employees to assign their inventions to us, and we require all of our employees, consultants, advisors and any other third parties who have access to our trade secrets, proprietary know-how and other confidential information and technology to enter into appropriate confidentiality agreements, we cannot be certain that our trade secrets, proprietary know-how, and other confidential information and technology will not be subject to unauthorized disclosure or that our competitors will not otherwise gain access to or independently develop substantially equivalent trade secrets, proprietary know-how, and other information and technology. Furthermore, the laws of some foreign countries do not protect proprietary rights to the same extent or in the same manner as the laws of the United States. As a result, we may encounter significant problems in protecting and defending our intellectual property globally. If we are unable to prevent unauthorized disclosure of our intellectual property related to our product candidates and technology to third parties, we may not be able to establish or maintain a competitive advantage in our market, which could adversely affect our business and operations.

Any litigation to enforce or defend our patent rights, even if we were to prevail, could be costly and time-consuming and would divert the attention of our management and key personnel from our business operations. We may not prevail in any lawsuits that we initiate and the damages or other remedies awarded if we were to prevail may not be commercially meaningful. Even if we are successful, domestic or foreign litigation, or USPTO or foreign patent office proceedings, may result in substantial costs and distraction to our management. We may not be able, alone or with our licensors or potential collaborators, to prevent misappropriation of our proprietary rights, particularly in countries where the laws may not protect such rights as fully as in the United States. Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation or other proceedings, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation or other proceedings. In addition, during the course of this kind of litigation or proceedings, there could be public announcements of the results of hearings, motions or other interim proceedings or developments or public access to related documents. If investors perceive these results to be negative, the market price for our Common Stock could be adversely affected.

In addition to seeking patents for some of our technology and product candidates, we also rely on trade secrets, including unpatented know-how, technology and other proprietary information, to maintain our competitive position. We seek to protect these trade secrets, in part, by entering into non-disclosure and confidentiality agreements with parties who have access to them, such as our employees, corporate collaborators, outside scientific collaborators, contract manufacturers, consultants, advisors and other third parties. We also seek to enter into confidentiality and invention or patent assignment agreements with our employees, advisors and consultants. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. Our trade secrets may also be obtained by third parties by other means, such as breaches of our physical or

computer security systems. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside the United States are less willing or unwilling to protect trade secrets. Moreover, if any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them, or those to whom they communicate it, from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to, or independently developed by, a competitor, our competitive position would be harmed.

As is the case with other biotechnology companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biotechnology industry involves both technological and legal complexity, and is therefore costly, time-consuming and inherently uncertain. In addition, recent patent reform legislation could further increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents. The Leahy-Smith Act America Invents Act (the “Leahy-Smith Act”), included provisions that affect the way patent applications are prosecuted and may also affect patent litigation, including first-to-file provisions. A third party that files a patent application in the USPTO before us could therefore be awarded a patent covering an invention of ours even if we had made the invention before it was made by the third party. This requires us to be cognizant of the time from invention to filing of a patent application. Thus, for our U.S. patent applications containing a priority claim after March 16, 2013, the date such provisions became effective, there is a greater level of uncertainty in the patent law. Moreover, some of the patent applications in our portfolio will be subject to examination under the pre-Leahy-Smith Act law and regulations, while other patents applications in our portfolio will be subject to examination under the law and regulations, as amended by the Leahy-Smith Act. This introduces additional complexities into the prosecution and management of our portfolio.

In addition, the Leahy-Smith Act limits where a patentee may file a patent infringement suit and provides opportunities for third parties to challenge any issued patent in the USPTO. These provisions apply to all of our U.S. patents, even those issued before March 16, 2013. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in U.S. federal court necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a federal court action.

Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims because it may be easier for them to do so relative to challenging the patent in a federal court action. It is not clear what, if any, impact the Leahy-Smith Act will have on the operation of our business. However, the Leahy-Smith Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of which could have a material adverse effect on our business and financial condition.

In addition, recent U.S. Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. From time to time, the U.S. Supreme Court, other federal courts, the U.S. Congress or the USPTO may change the standards of patentability, and any such changes could have a negative impact on our business.

Depending on these and other decisions by the U.S. Congress, the federal courts and the USPTO, the laws and regulations governing patents could change or be interpreted in unpredictable ways that would weaken our ability to obtain new patents or to enforce any patents that may issue to us in the future. In addition, these events may adversely affect our ability to defend any patents that may issue in procedures in the USPTO or in courts.

Our commercial success depends upon our ability, and the ability of our collaborators, to develop, manufacture, market and sell our product candidates and use our proprietary technologies without infringing the proprietary rights of third parties. There is considerable intellectual property litigation in the biotechnology and

pharmaceutical industries. While no such litigation has been brought against us and we have not been held by any court to have infringed a third party’s intellectual property rights, we cannot guarantee that our technology, product candidates or use of our product candidates do not infringe third-party patents.

We are aware of numerous patents and pending applications owned by third parties, and we monitor patents and patent applications in the fields in which we are developing product candidates, both in the United States and elsewhere. However, we may have failed to identify relevant third-party patents or applications. For example, applications filed before November 29, 2000 and certain applications filed after that date that will not be filed outside the United States remain confidential until patents issue. Moreover, it is difficult for industry participants, including us, to identify all third-party patent rights that may be relevant to our product candidates and technologies because patent searching is imperfect due to differences in terminology among patents, incomplete databases and the difficulty in assessing the meaning of patent claims. We may fail to identify relevant patents or patent applications or may identify pending patent applications of potential interest but incorrectly predict the likelihood that such patent applications may issue with claims of relevance to our technology. In addition, we may be unaware of one or more issued patents that would be infringed by the manufacture, sale or use of a current or future product candidate, or we may incorrectly conclude that a third-party patent is invalid, unenforceable or not infringed by our activities. Additionally, pending patent applications that have been published can, subject to certain limitations, be later amended in a manner that could cover our technologies, our product candidates or the use of our product candidates.

The biotechnology and pharmaceutical industries are characterized by extensive litigation regarding patents and other intellectual property rights. Other parties may allege that our product candidates or the use of our technologies infringes patent claims or other intellectual property rights held by them or that we are employing their proprietary technology without authorization. We may become party to, or threatened with, future adversarial proceedings or litigation regarding intellectual property rights with respect to our product candidates and technology, including interference or derivation proceedings before the USPTO and similar bodies in other countries. Third parties may assert infringement claims against us based on existing intellectual property rights and intellectual property rights that may be granted in the future.

Patent and other types of intellectual property litigation can involve complex factual and legal questions, and their outcome is uncertain. If we are found, or believe there is a risk we may be found, to infringe a third party’s intellectual property rights, we could be required or may choose to obtain a license from such third party to continue developing and marketing our product candidates and technology. However, we may not be able to obtain any such license on commercially reasonable terms or at all. Even if we were able to obtain a license, it could be non-exclusive, thereby giving our competitors access to the same technologies licensed to us. We could be forced, including by court order, to cease commercializing the infringing technology or product. In addition, we could be found liable for monetary damages, including treble damages and attorneys’ fees if we are found to have willfully infringed a patent. A finding of infringement could prevent us from commercializing our product candidates or force us to cease some of our business operations, which could materially harm our business.

Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar negative impact on our business.

Even if we are successful in such proceedings, we may incur substantial costs and divert management time and attention in pursuing these proceedings, which could have a material adverse effect on us. Patent litigation is costly and time-consuming. We may not have sufficient resources to bring these actions to a successful conclusion. There could be public announcements of the results of hearings, motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our Common Stock.

Any of these risks coming to fruition could have a material adverse impact on our business.

Competitors may infringe our intellectual property, including our patents or the patents of our licensors. As a result, we may be required to file infringement claims to stop third-party infringement or unauthorized use. This can be expensive, particularly for a company of our size, and time-consuming. If we initiated legal proceedings against a third party to enforce a patent, if and when issued, covering one of our product candidates, the

defendant could counterclaim that the patent covering our product candidate is invalid and/or unenforceable. In patent litigation in the United States, defendant counterclaims alleging invalidity and/or unenforceability are commonplace. Grounds for a validity challenge include alleged failures to meet any of several statutory requirements, including lack of novelty, obviousness or non-enablement, or failure to claim patent-eligible subject matter. Grounds for unenforceability assertions include allegations that someone connected with the prosecution of the patent withheld relevant information from the USPTO, or made a misleading statement, during prosecution. Third parties may also raise similar claims before administrative bodies in the United States or abroad, even outside the context of litigation. Such mechanisms include re-examination, post-grant review, inter partes review, interference proceedings and equivalent proceedings in foreign jurisdictions, such as opposition proceedings. Such proceedings could result in revocation or amendment of our patents in such a way that they no longer cover our product candidates or competitive products. The outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to validity, for example, we cannot be certain that there is no invalidating prior art, of which we and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, we would lose at least part, and perhaps all, of the patent protection on our product candidates. Moreover, even if not found invalid or unenforceable, the claims of our patents could be construed narrowly or in a manner that does not cover the allegedly infringing technology in question. Such a loss of patent protection would have a material adverse impact on our business.

Patents have a limited lifespan. In the United States, the natural expiration of a patent is generally 20 years after its first effective non-provisional filing date. Although various extensions may be available, the life of a patent, and the protection it affords, is limited. Even if patents covering our product candidates, proprietary technologies and their uses are obtained, once the patent life has expired, we may be open to competition. In addition, although upon issuance in the United States a patent’s life can be increased based on certain delays caused by the USPTO, this increase can be reduced or eliminated based on certain delays caused by the patent applicant during patent prosecution. Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. If we do not have sufficient patent life to protect our product candidates, proprietary technologies and their uses, our business and results of operations will be adversely affected.

Periodic maintenance fees on any issued patent are due to be paid to the USPTO and foreign patent agencies in several stages over the lifetime of the patent and, in some jurisdictions, during the pendency of a patent application. The USPTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other similar provisions during the patent application process. While an inadvertent lapse can in many cases be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which noncompliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction.

Noncompliance events that could result in abandonment or lapse of a patent or patent application include, but are not limited to, failure to respond to official actions within prescribed time limits, non-payment of fees and failure to properly legalize and submit formal documents. In such an event, our competitors might be able to enter the market, which would have an adverse effect on our business.

We currently have rights to certain intellectual property, through licenses from third parties and under patents and patent applications that we own, to develop our product candidates. Because we may find that our programs require the use of proprietary rights held by third parties, the growth of our business may depend in part on our ability to acquire, in-license or use these proprietary rights. We may be unable to acquire or in-license compositions, methods of use, processes or other third-party intellectual property rights from third parties that we identify as necessary for our product candidates. The licensing and acquisition of third-party intellectual property rights is a competitive area, and a number of more established companies are also pursuing strategies to license

or acquire third-party intellectual property rights that we may consider attractive. These established companies may have a competitive advantage over us due to their size, financial resources and greater clinical development and commercialization capabilities. In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. We also may be unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return on our investment.

If we are unable to successfully obtain rights to required third-party intellectual property rights or maintain the existing intellectual property rights we have, we may have to abandon development of that program and our business and financial condition could suffer.

Many of our employees were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. We may also engage advisors and consultants who are concurrently employed at universities or other organizations or who perform services for other entities.

Although we try to ensure that our employees, advisors and consultants do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or our employees, advisors or consultants have used or disclosed intellectual property, including trade secrets or other proprietary information, of any such party’s former or current employer or in violation of an agreement with another party. Although we have no knowledge of any such claims being alleged to date, if such claims were to arise, litigation may be necessary to defend against any such claims.

In addition, while it is our policy to require our employees, consultants, advisors and contractors who may be involved in the development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who in fact develops intellectual property that we regard as our own. Our and their assignment agreements may not be self-executing or may be breached, and we may be forced to bring claims against third parties, or defend claims they may bring against us, to determine the ownership of what we regard as our intellectual property. Similarly, we may be subject to claims that an employee, advisor or consultant performed work for us that conflicts with that person’s obligations to a third party, such as an employer, and thus, that the third party has an ownership interest in the intellectual property arising out of work performed for us. Litigation may be necessary to defend against these claims.

Although we have no knowledge of any such claims being alleged to date, if such claims were to arise, litigation may be necessary to defend against any such claims.

If we fail in prosecuting or defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Even if we are successful in prosecuting or defending against such claims, litigation could result in substantial costs and be a distraction to management.

Filing, prosecuting and defending patents on product candidates in all countries and jurisdictions throughout the world would be prohibitively expensive, and our intellectual property rights in some countries outside the United States could be less extensive than in the United States, assuming that rights are obtained in the United States and assuming that rights are pursued outside the United States. In this regard, in addition to the United States, we also seek to protect our intellectual property rights in other countries. The statutory deadlines for pursuing patent protection in individual foreign jurisdictions are based on the priority date of each of our patent applications. For all of the patent families in our portfolio, including the families that may provide coverage for our lead product candidate, the relevant statutory deadlines have not yet expired. Therefore, for each of the patent families that we believe provide coverage for our lead product candidate, we will need to decide whether and where to pursue additional protection outside the United States. In addition, the laws of some foreign countries, do not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, for our existing patent rights outside the United States and any foreign patent rights we may decide to pursue in the future, we may not be able to obtain relevant claims and/or we may not be able to prevent third parties from practicing our inventions in all countries outside the United States, or from selling or importing products made using our inventions in and into the United States or other jurisdictions.

Competitors may use our technologies in jurisdictions where we do not pursue and obtain patent protection to develop their own products and further, may export otherwise infringing products to territories where we have patent protection, but enforcement is not as strong as in the United States. These products may compete with our product candidates and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing. Even if we pursue and obtain issued patents in particular jurisdictions, our patent claims or other intellectual property rights may not be effective or sufficient to prevent third parties from so competing.

Depending upon the timing, duration and specifics of FDA regulatory approval for our product candidates, one or more of our U.S. patents may be eligible for limited patent term restoration under the Drug Price Competition and Patent Term Restoration Act of 1984 (the “Hatch-Waxman Act”). The Hatch-Waxman Act permits a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. Patent term restorations, however, are limited to a maximum of five years and cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval by the FDA.

The application for patent term extension is subject to approval by the USPTO, in conjunction with the FDA. It takes at least six months to obtain approval of the application for patent term extension. We may not be granted an extension because of, for example, failing to apply within applicable deadlines, failing to apply prior to expiration of relevant patents or otherwise failing to satisfy applicable requirements. Moreover, the applicable time period or the scope of patent protection afforded could be less than we request. If we are unable to obtain patent term extension or restoration or the term of any such extension is less than we request, the period during which we will have the right to exclusively market our product will be shortened, our competitors may obtain earlier approval of competing products and our ability to generate revenues could be materially adversely affected.

We are highly dependent on Carsten Brunn, Ph.D., our President and Chief Executive Officer, as well as the other principal members of our management, scientific and clinical teams. Although we have entered into employment agreements or offer letters with Dr. Brunn and other executive officers, each of them may terminate their employment with us at any time. We do not maintain “key person” insurance for any of our executives or other employees.

Recruiting and retaining qualified scientific, clinical, manufacturing, technology and sales and marketing personnel will also be critical to our success. The loss of the services of our executive officers or other key employees could impede the achievement of our research, development and commercialization objectives and seriously harm our ability to successfully implement our business strategy. Furthermore, replacing executive officers and key employees may be difficult and may take an extended period of time because of the limited number of individuals in our industry with the breadth of skills and experience required to successfully develop, gain regulatory approval of and commercialize product candidates. Competition to hire from this limited pool is intense, and we may be unable to hire, train, retain or motivate these key personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy. Our consultants and advisors may be employed by employers other than us and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us. If we are unable to continue to attract and retain high quality personnel, our ability to pursue our growth strategy will be limited.

As a public company, we have incurred and expect to continue to incur significant legal, accounting and other expenses. If we are unable to maintain effective internal control over financial reporting, we may not have

adequate, accurate or timely financial information, and we may be unable to meet our reporting obligations as a public company or comply with the requirements of the SEC or Section 404 of the Sarbanes-Oxley Act of 2002. This could result in a restatement of our financial statements, the imposition of sanctions, including the inability of registered broker dealers to make a market in our Common Stock, or investigation by regulatory authorities. Any such action or other negative results caused by our inability to meet our reporting requirements or comply with legal and regulatory requirements or by disclosure of an accounting, reporting or control issue could adversely affect the trading price of our securities and our business. Material weaknesses in our internal control over financial reporting could also reduce our ability to obtain financing or could increase the cost of any financing we obtain. This could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

In connection with the audit of our consolidated financial statements as of and for the year ended December 31, 2023, we identified a material weakness in our internal control over financial reporting and concluded that our internal control over financial reporting was not effective as of December 31, 2023. There are no material accounting errors or omissions within the consolidated financial statements as a result of this material weakness. We concluded that we did not design and implement effective internal controls specifically related to the documentation of the assumptions supporting the valuation of the in-process intangible assets in connection with the Old Cartesian material business combination and the initial and ongoing contingent value right obligation issued at the time to legacy Selecta stockholders. This includes a lack of sufficient documentation to provide evidence of the associated management review controls.

In response to the identified material weakness above, we, with the oversight of the Audit Committee (the “Audit Committee”) of the Board of Directors (the “Board of Directors”), intend to take comprehensive actions to remediate the material weakness in internal control over financial reporting. We expect to re-evaluate the scope and level of precision for conducting and documenting the reviews over significant acquisitions and contingent value rights including the review of prospective financial information used in valuation reports produced by third-party specialists supporting the accounting for business combinations and contingent value rights. The remediation efforts are intended both to address the identified material weakness and to enhance our overall financial control environment.

This material weakness and any other failure to maintain effective internal control over financial reporting could result in a loss of confidence in the reliability of our financial statements which could have a negative impact on the trading price of our Common Stock and harm our ability to raise additional capital on acceptable terms or at all.

In addition to our U.S. operations, we maintain a wholly owned subsidiary in Russia, Selecta (RUS). However, we are in the process of winding down all remaining operations of this subsidiary. We may face risks associated with winding down the operations of our subsidiary in Russia, or with any international operations, including possible unfavorable regulatory, pricing and reimbursement, legal, political, tax and labor conditions, and risks associated with our compliance with evolving international sanctions, which could harm our business. We may also rely on collaborators to commercialize any approved product candidates outside of the United States. Doing business internationally involves a number of risks, including but not limited to:

Any of these factors could significantly harm our future international expansion and operations and, consequently, our results of operations.

Our internal computer systems and those of third parties on which we rely, including our CROs and other contractors and consultants, are vulnerable to damage from computer viruses, unauthorized access, natural disasters, terrorism, war and telecommunication and electrical failures. If such an event were to occur and cause interruptions in our operations, it could have a material adverse effect on our business operations, including a material disruption of our development programs. Unauthorized disclosure of sensitive or confidential patient or employee data, including personally identifiable information, whether through breach of computer systems, systems failure, employee negligence, fraud or misappropriation, or otherwise, or unauthorized access to or through our information systems and networks, whether by our employees or third parties, could result in negative publicity, legal liability and damage to our reputation. Unauthorized disclosure of personally identifiable information could also expose us to sanctions for violations of data privacy laws and regulations around the world. To the extent that any disruption or security breach resulted in a loss of or damage to our data or applications, or inappropriate disclosure of confidential or proprietary information, we could incur liability and the further development of our product candidates could be delayed. For example, the loss of or damage to clinical trial data, such as from completed or ongoing clinical trials, for any of our product candidates would likely result in delays in our marketing approval efforts and significantly increased costs in an effort to recover or reproduce the data.

We have previously been, and expect to remain, the target of cyber-attacks. As we become more dependent on information technologies to conduct our operations, cyber incidents, including deliberate attacks, such as

ransomware attacks, and attempts to gain unauthorized access to computer systems and networks, may increase in frequency and sophistication. These incidents pose a risk to the security of our systems and networks, the confidentiality and the availability and integrity of our data and these risks apply both to us, and to third parties on whose systems we rely for the conduct of our business. While we do not believe the effect of these incidents has historically been material to our results of operations, financial condition or prospects, cyber threats are persistent and constantly evolving. Such threats have increased in frequency, scope and potential impact in recent years, which increases the difficulty of detecting and successfully defending against them. As cyber threats continue to evolve, we may be required to incur additional expenses in order to enhance our protective measures or to remediate any information security vulnerability. There can be no assurance that we or our third-party providers will be successful in preventing cyber-attacks or mitigating their effects. Similarly, there can be no assurance that our collaborators, CROs, third-party logistics providers, distributors and other contractors and consultants will be successful in protecting our clinical and other data that is stored on their systems. Any cyber-attack or destruction or loss of data could have a material adverse effect on our business and prospects. In addition, we may suffer reputational harm or face litigation or adverse regulatory action as a result of cyber-attacks or destruction or loss of data and may incur significant additional expense to implement further data protection measures. It is also possible that unauthorized access to data may be obtained through inadequate use of security controls by our suppliers or other vendors.

Although we have general liability insurance coverage, our insurance may not cover all claims, continue to be available on reasonable terms or be sufficient in amount to cover one or more large claims. Additionally, the insurer may disclaim coverage as to any claim. The successful assertion of one or more large claims against us that exceed or are not covered by our insurance coverage or changes in our insurance policies, including premium increases or the imposition of large deductible or co-insurance requirements, could have a material adverse effect on our business, prospects, operating results and financial condition.

We may acquire other businesses, product candidates or technologies as well as pursue strategic alliances, joint ventures, technology licenses or investments in complementary businesses. We have not made any acquisitions to date, and our ability to do so successfully is unproven. Any of these transactions could be material to our financial condition and operating results and expose us to many risks, including:

Foreign acquisitions involve unique risks in addition to those mentioned above, including those related to integration of operations across different cultures and languages, currency risks and the particular economic, political and regulatory risks associated with specific countries.

Also, the expected benefit of any acquisition may not materialize. Future acquisitions or dispositions could result in potentially dilutive issuances of our equity securities, the incurrence of debt, contingent liabilities or amortization expenses or write-offs of goodwill, any of which could harm our financial condition. We cannot predict the number, timing or size of future joint ventures or acquisitions, or the effect that any such transactions might have on our operating results.

The trading price of our Common Stock is likely to be volatile and could be subject to wide fluctuations in response to various factors, some of which are beyond our control. The stock market in general and the market for smaller biopharmaceutical companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, you may not be able to sell your Common Stock at or above the price at which you purchased. The market price for our Common Stock may be influenced by many factors, including:

Our executive officers, directors and stockholders who own more than 5% of our outstanding Common Stock and their respective affiliates, in the aggregate, hold shares representing approximately 64.0% of our outstanding voting stock as of July 29, 2024, assuming the conversion of all outstanding shares of Series A Preferred Stock and Series B Preferred Stock into Common Stock, or 62.4%, assuming no conversion of outstanding shares of Series A Preferred Stock and Series B Preferred Stock into Common Stock. As a result, if these stockholders choose to act together, they would be able to control or significantly influence all matters submitted to our stockholders for approval, as well as our management and affairs. For example, these persons, if they choose to act together, would control or significantly influence the election of directors, the composition of our management and approval of any merger, consolidation or sale of all or substantially all of our assets.

Provisions in our restated certificate of incorporation, as amended (the “Charter”), and amended and restated by-laws (the “Bylaws”) may delay or prevent an acquisition or a change in management. These provisions include a prohibition on actions by written consent of our stockholders and the ability of our Board of Directors to issue preferred stock without stockholder approval. In addition, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law (the “DGCL”), which prohibits stockholders owning in excess of 15% of our outstanding voting stock from merging or combining with us.

Although we believe these provisions collectively will provide for an opportunity to receive higher bids by requiring potential acquirers to negotiate with our Board of Directors, they would apply even if the offer may be considered beneficial by some stockholders. In addition, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove then current management by making it more difficult for stockholders to replace members of the Board of Directors, which is responsible for appointing the members of management.

Furthermore, our Charter specifies that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for most legal actions involving claims brought against us by stockholders. We believe this provision benefits us by providing increased consistency in the application of Delaware law by chancellors particularly experienced in resolving corporate disputes, efficient administration of cases on a more expedited schedule relative to other forums and protection against the burdens of multi-forum litigation. However, the provision may have the effect of discouraging lawsuits against our directors, officers, employees and agents as it may limit any stockholder’s ability to bring a claim in a judicial forum that such stockholder finds favorable for disputes with us or our directors, officers, employees or agents.

In addition, the Certificate of Designation of Preferences, Rights and Limitations of Series A Non-Voting Convertible Preferred Stock (the “Series A Certificate of Designation”) may delay or prevent a change in control of our Company. At any time while at least 30% of the originally issued Series A Preferred Stock remains issued and outstanding, we may not consummate a Fundamental Transaction (as defined in the Series A Certificate of Designation) or any merger or consolidation of the Company with or into another entity or any stock sale to, or other business combination in which the stockholders of the Company immediately before such transaction do not hold at least a majority of the capital stock of the Company immediately after such transaction, without the affirmative vote of the holders of a majority of the then outstanding shares of the Series A Preferred Stock. This provision of the Series A Certificate of Designation may make it more difficult for us to enter into any of the aforementioned transactions.

In the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us because biopharmaceutical companies have experienced significant stock price volatility in recent years. Involvement in such litigation, could result in substantial costs and a diversion of management’s attention and resources, which could harm our business.

On February 21, 2024, Paul Wymer, a purported stockholder of our Company, filed an action against us and members of our Board of Directors in the U.S. District Court for the Southern District of New York, titled Wymer v. Cartesian Therapeutics, Inc., et al., No. 24-cv-01288. The complaint alleged that the defendants violated Sections 14(a) and 20(a) of the Exchange Act by failing to disclose purportedly material information to our stockholders in our Preliminary and Definitive Proxy Statements filed on January 31, 2024, and February 14, 2024, respectively, in connection with the solicitation of stockholder approval of a proposal to convert our Series A Preferred Stock into our Common Stock, subject to certain beneficial ownership limitations (the “Series A Conversion Proposal”). The complaint sought injunctive relief enjoining or rescinding the Merger, issuance of an amended proxy statement, and attorneys’ fees and costs. Additional similar lawsuits may be filed. This action was voluntarily dismissed on March 11, 2024.

On February 7, 2024, Justin Sloan, a purported stockholder of our Company, filed a putative class action on behalf of himself and similarly situated stockholders of the Company against our Company and members of our Board of Directors in the Court of Chancery of the State of Delaware, titled Sloan v. Barabe, et al., No. 2024-0105. The complaint alleged that the individual defendants breached their fiduciary duties by failing to disclose purportedly material information to our Company’s stockholders in our Preliminary Proxy Statement filed on January 31, 2024 in connection with the solicitation of stockholder approval of the Series A Conversion Proposal. The complaint seeks a temporary injunction against the stockholder vote on the Series A Conversion Proposal, compensatory damages, pre-and post-judgment interest, and attorneys’ fees and costs. At a telephonic hearing on February 28, 2024, the Court denied the Plaintiff’s motion to expedite the proceedings, rejecting Plaintiff’s argument that the lawsuit raised colorable disclosure claims warranting expedited treatment. Additional similar lawsuits may be filed. This action was subsequently dismissed on March 13, 2024.

On August 3, 2020, a stockholder of Selecta filed a stockholder derivative action, purportedly on behalf of Selecta and against certain current and former members of the Company’s Board of Directors, as well as one affiliated company owned by a current board member, in the Court of Chancery of the State of Delaware, namely Franchi v. Barabe, et al. The complaint alleged that the individual defendants breached their fiduciary duties and committed corporate waste when they authorized a private placement transaction, announced on December 19, 2019, at a price allegedly below fair value. The complaint further alleges that the four defendant directors who participated in the private placement were unjustly enriched in connection with the transaction. On September 25, 2020, the defendants filed a motion to dismiss the lawsuit. On November 6, 2020, the plaintiff filed an amended complaint, and the defendants filed a second motion to dismiss on January 8, 2021. On December 31, 2020, we received a litigation demand letter from two other putative stockholders relating to the same private placement transaction. On April 12, 2021, the Court of Chancery in the State of Delaware granted a motion to stay the litigation pending a review by a Special Committee appointed by the Company’s Board of Directors. While the litigation was stayed, the parties reached an agreement in principle to settle the matter, and on March 18, 2022, they submitted a Stipulation and Agreement of Settlement and other documentation to the Court for its approval of the settlement. On July 21, 2022, the Court held a settlement hearing, at which the settlement was approved. On August 1, 2022, the Court entered an Order and Final Judgment which dismissed the action, and all claims contained therein, with prejudice. We could receive other demands or be subject to other litigation. We intend to vigorously defend against any demands which we believe to be without merit.

There can be no assurance as to the outcome of any stockholder litigation. Unfavorable outcomes in class action litigation could require us to pay extensive damages, which could delay or prevent our ability to develop our product candidates and harm our operations.

We have incurred substantial expenses in connection with the Merger and the subsequent integration of Old Cartesian with Selecta. There are a large number of processes, policies, procedures, operations, technologies and systems that must be integrated, including purchasing, accounting and finance, sales, billing, payroll, research and development, marketing and benefits. Both we and Old Cartesian have incurred significant transaction expenses in connection with the drafting and negotiation of the Merger Agreement and significant severance expenses as a result of the Merger. While we and Old Cartesian have assumed that a certain level of expenses will be incurred, there are many factors beyond our control that could affect the total amount or the timing of the integration expenses. Moreover, many of the expenses that have been and will be incurred are, by their nature, difficult to estimate accurately. These integration expenses have resulted in our taking significant charges against earnings following the completion of the Merger, and the amount and timing of such charges are uncertain at present.

We are not selling any securities under this prospectus and we will not receive any proceeds from the sale of the Resale Shares covered hereby. The net proceeds from the sale of the Resale Shares offered by this prospectus will be received by the Selling Stockholders.

Subject to limited exceptions, the Selling Stockholders will pay any underwriting discounts and commissions and expenses incurred by the Selling Stockholders for brokerage, accounting, tax or legal services or any other expenses incurred by the Selling Stockholders in disposing of any of the Resale Shares. We will bear the costs, fees and expenses incurred in effecting the registration of the Resale Shares covered by this prospectus, including all registration and filing fees, listing fees of the Nasdaq Stock Market LLC (“Nasdaq”) and fees and expenses of our counsel and our independent registered public accounting firm.

You should read the following discussion of our financial condition and results of operations in conjunction with the consolidated financial statements and the related notes thereto and other financial information included elsewhere in this prospectus. This discussion contains forward-looking statements based upon current beliefs, plans and expectations related to future events and our future financial performance that involve risks, uncertainties and assumptions. Our actual results could differ materially from those discussed in these forward-looking statements as a result of various factors. Factors that could cause or contribute to these differences include, but are not limited to, those discussed below and elsewhere in this prospectus, particularly in the section titled “Risk Factors.” Please also see the section titled “Special Note Regarding Forward-Looking Statements.” As used in this prospectus, unless the context suggests otherwise, “we”, “us”, “our”, “the Company,” or “Cartesian” refers to Cartesian Therapeutics, Inc. and its subsidiaries.

We are a clinical-stage biotechnology company developing mRNA cell therapies for the treatment of autoimmune diseases. We leverage our proprietary technology and manufacturing platform to introduce one or more mRNA molecules into cells to enhance their function. Unlike DNA, mRNA degrades naturally over time without integrating into the cell’s genetic material. Therefore, our mRNA cell therapies are distinguished by their capacity to be dosed repeatedly like conventional drugs, administered in an outpatient setting, and given without pre-treatment chemotherapy required with many conventional cell therapies. In an open-label Phase 2 clinical trial in patients with MG, a chronic autoimmune disease that causes disabling muscle weakness and fatigue, we observed that our lead product candidate, Descartes-08, generated a deep and durable clinical benefit.

We are leveraging our proprietary technology and manufacturing platform, RNA Armory®, to develop mRNA cell therapies for autoimmune diseases across three modalities. Our mRNA CAR-T modality is a personalized approach that collects a patient’s T-cells and uses mRNA to introduce a CAR into the cell. The CAR redirects the T-cells to target and destroy pathogenic self-reactive cells. Our mRNA MSC modality is an allogeneic approach that introduces one or more mRNAs into donor-sourced mesenchymal stem cells, enabling them to produce proteins that target key pathways involved in autoimmunity. These cells are banked and are designed to be administered off-the-shelf to any patient. Our mRNA in situ modality is designed to deliver mRNA into a patient’s lymph node to generate CAR-T cells and other proteins that target autoimmunity.

On November 13, 2023, the Company (formerly known as Selecta Biosciences, Inc.) merged with the private Delaware corporation which, immediately prior to the Merger, was known as Old Cartesian, in accordance with the terms of the Merger Agreement. Pursuant to the Merger Agreement, First Merger Sub merged with and into Old Cartesian, pursuant to which Old Cartesian was the surviving corporation and became a wholly owned subsidiary of Selecta. Immediately following the First Merger, Old Cartesian merged with and into Second Merger Sub, pursuant to which Second Merger Sub was the surviving entity. In connection with the Second Merger, Old Cartesian changed its name to Cartesian Bio, LLC. In connection with the Merger and pursuant to the Merger Agreement, the Company changed its corporate name to Cartesian Therapeutics, Inc. See Note 3 of the accompanying notes to the unaudited consolidated financial statements appearing elsewhere in the registration statement of which this prospectus forms a part for additional information regarding the Merger.

To date, we have financed our operations primarily through public offerings and private placements of our securities, funding received from research grants, collaboration and license arrangements and a credit facility. We do not have any products approved for sale and have not generated any product sales.

Except for the year ended December 31, 2022, we have incurred significant operating losses since our inception. We incurred a net loss of $56.8 million and $21.7 million for the three months ended March 31, 2024 and 2023, respectively. As of March 31, 2024, we had an accumulated deficit of $671.5 million. We expect to continue to incur significant expenses and operating losses for the foreseeable future as we:

Until we can generate substantial product revenues, we expect to finance our cash needs through a combination of equity offerings, debt financings, and license and collaboration agreements. We may be unable to raise capital when needed or on reasonable terms, if at all, which would force us to delay, limit, reduce or terminate our product development or future commercialization efforts. We will need to generate significant revenues to achieve profitability, and we may never do so.

Concurrently with the closing of the Merger, we entered into a securities purchase agreement (the “November 2023 Securities Purchase Agreement”) pursuant to which we agreed to issue 149,330.115 shares of Series A Preferred Stock, in exchange for aggregate gross proceeds of $60.25 million (such transaction, the “November 2023 Private Placement”).

We believe that our existing cash, cash equivalents, and restricted cash as of March 31, 2024, together with proceeds from the Private Placement, will support development of Descartes-08 in MG, specifically supporting anticipated manufacturing costs associated with a Phase 3 clinical trial and early commercial activities in preparation for a potential launch. We have based this estimate on assumptions that may prove to be wrong, and we could use our capital resources sooner than we currently expect.

We intend to seek collaboration partners for the assets in the development programs that we are no longer actively advancing.

The consolidated financial information presented below includes the accounts of Cartesian Therapeutics, Inc. and our wholly owned subsidiaries, Selecta (RUS) LLC, a Russian limited liability company (“Selecta (RUS)”), and Selecta Biosciences Security Corporation, a Massachusetts securities corporation, and Cartesian Bio, LLC, a Delaware limited liability company, which is a variable interest entity for which we are the primary beneficiary. All intercompany accounts and transactions have been eliminated.

To date, we have not generated any revenue from product sales. Our revenue consists primarily of collaboration and license revenue, which includes amounts recognized related to upfront and milestone payments for research and development funding under collaboration and license agreements. We expect that any revenue we generate will fluctuate from quarter to quarter because of the timing and amounts of fees, research and development reimbursements and other payments from collaborators. We do not expect to generate revenue from product sales for at least the next several years. If we or our collaborators fail to complete the development of our product candidates in a timely manner or fail to obtain regulatory approval as needed, our ability to generate future revenue will be harmed, and will affect the results of our operations and financial position. For further description of the agreements underlying our collaboration and license revenue, see Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

Our research and development expenses consist of external research and development costs, which we track on a program-by-program basis and primarily include contract manufacturing organization related costs and fees paid to contract research organizations, and internal research and development costs, which are primarily compensation expenses for our research and development employees, lab supplies, analytical testing, allocated overhead costs and other related expenses. Our internal research and development costs are often devoted to expanding our programs and are not necessarily allocable to a specific target.

We expense research and development costs as incurred. Conducting a significant amount of research and development is central to our business model. Product candidates in clinical development generally have higher development costs than those in earlier stages of development, primarily due to the size, duration and cost of clinical trials. The successful development of our clinical and preclinical product candidates is highly uncertain. Clinical development timelines, the probability of success and development costs can differ materially from our expectations. For example, if the FDA or another regulatory authority were to require us to conduct clinical trials beyond those which we currently expect will be required for the completion of clinical development of a product candidate, or if we experience significant delays in enrollment in any of our clinical trials, we could be required to expend significant additional financial resources and time to complete any clinical development.

In June 2020, we and Swedish Orphan Biovitrum AB (“Sobi”), entered into a License and Development Agreement, which was amended in October 2023 (as so amended, the “Sobi License”). Pursuant to the Sobi License, clinical trial costs incurred to complete development of the product candidate SEL-212, including but not limited to costs incurred while conducting and completing the Phase 3 DISSOLVE trials for SEL-212, were reimbursed by Sobi. These costs, when reimbursed, were recognized as revenue consistent with the revenue recognition methodology disclosed in Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part. The reimbursable costs exclude any costs of additional development activities required that were related to the ImmTOR platform and were unrelated to SEL-212.

In January 2023, we and Audentes Therapeutics, Inc. (“Astellas”), entered into a License and Development Agreement (the “Astellas Agreement”). Pursuant to the Astellas Agreement, Astellas agreed to reimburse us for 25% of all budgeted costs incurred to complete the development of Xork, a bacterial IgG protease licensed from Genovis AB (publ.) (“Genovis”), for use in Pompe disease with an Astellas gene therapy investigational or authorized product. These costs, when reimbursed, will be recognized as revenue consistent with the revenue recognition methodology disclosed in Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part. In March 2024, we were notified by Astellas of its intention to terminate the Astellas Agreement, effective June 6, 2024.

General and administrative expenses consist primarily of salaries and related benefits, including stock-based compensation, related to our executive, finance, business development and support functions. Other general and administrative expenses include facility-related costs not otherwise allocated to research and development expenses, travel expenses for our general and administrative personnel and professional fees for auditing, tax and corporate legal services, including intellectual property-related legal services.

Investment income consists primarily of interest income earned on our cash, cash equivalents and marketable securities.

Interest expense consists of interest expense on amounts borrowed under our credit facilities.

Other income, net consists primarily of sublease income.

Common warrants classified as liabilities are remeasured quarterly at fair value, utilizing a Black-Scholes valuation methodology, with the change in fair value recognized as a component of earnings.

The CVR liability is remeasured quarterly at fair value, utilizing a Monte Carlo simulation, with the change in fair value recognized as a component of earnings.

The forward contract liability associated with the delayed issuance of the Series A Preferred Stock related to the November 2023 Private Placement is remeasured quarterly at fair value, utilizing the market price of our Common Stock, with the change in fair value recognized as a component of earnings.

The functional currency of Selecta (RUS) is the Russian ruble. In addition to holding cash denominated in Russian rubles, our Russian bank accounts also hold cash balances denominated in U.S. dollars to facilitate payments to be settled in U.S. dollars or other currencies. As of both March 31, 2024 and December 31, 2023, we maintained cash of $0.2 million in Russian bank accounts in denominations of both Russian rubles and U.S. dollars. The amounts denominated in U.S. dollars and used in transacting the day-to-day operations of our Russian subsidiary are subject to transaction gains and losses, which are reported as incurred.

During the three months ended March 31, 2024, we recognized $5.8 million of collaboration and license revenue, compared to $5.9 million for the three months ended March 31, 2023, a decrease of $0.1 million, or 2%. The decrease was primarily due to a decrease of revenue recognized under the Sobi License resulting from both the shipment of clinical supply and the reimbursement of costs incurred for the Phase 3 DISSOLVE clinical program offset by an increase in revenue recognized under the Astellas Agreement.

For the three months ended March 31, 2024, our research and development expenses were $9.7 million compared to $18.6 million for the three months ended March 31, 2023, a decrease of $8.9 million, or 48%. The decrease in cost primarily resulted from reductions in expenses incurred for preclinical and clinical programs due to the strategic reprioritization.

For the three months ended March 31, 2024, our general and administrative expenses were $9.5 million compared to $5.7 million for the three months ended March 31, 2023, an increase of $3.8 million, or 66%. The increase in cost was primarily the result of an increase in professional fees incurred in connection with the Merger.

Investment income for the three months ended March 31, 2024 was $1.2 million, compared to $1.3 million for the three months ended March 31, 2023. The decrease in investment income was due to decreased investment balance.

We recognized de minimis foreign currency fluctuations during each of the three months ended March 31, 2024 and 2023.

We recognized no interest expense for the three months ended March 31, 2024, compared to $0.8 million for the three months ended March 31, 2023, representing interest expense and amortization of the carrying costs of our credit facilities that were extinguished during the year ended December 31, 2023.

For the three months ended March 31, 2024, we recognized $1.0 million of income from the decrease in the fair value of warrant liabilities, compared to a $4.1 million charge from the increase in the fair value of warrant liabilities for the three months ended March 31, 2023, a decrease of $5.1 million, or 126%. Fair value of warrant liabilities was determined utilizing the Black-Scholes valuation methodology. The decrease in warrant value was primarily driven by a decrease in the per-share price of our Common Stock.

For the three months ended March 31, 2024, we recognized $39.3 million of expense associated with the increase in the fair value of the CVR liability. The fair value of the CVR liability as of March 31, 2024 was determined utilizing a Monte Carlo simulation model. The increase in the fair value of CVR liability was primarily driven by the passage of time since December 31, 2023. There was no CVR liability prior to the Merger and as such, no change in the fair value of the CVR liability is reflected in our unaudited consolidated financial statements for the three months ended March 31, 2023.

For the three months ended March 31, 2024, we recognized $6.9 million of expense associated with the increase in the fair value of Series A Preferred Stock forward contract liabilities. The increase in Series A Preferred Stock value was primarily driven by an increase in the per-share price of our Common Stock since December 31, 2023 through settlement. The remaining Series A Preferred Stock forward contract liability was settled during the three months ended March 31, 2024. There was no Series A Preferred Stock forward contract liability prior to the Merger and as such, no change in the fair value of the Series A Preferred Stock forward contract liability is reflected in our unaudited consolidated financial statements for the three months ended March 31, 2023.

During the three months ended March 31, 2024, we recognized other income, net of $0.5 million, compared to $0.3 million for the three months ended March 31, 2023, an increase of $0.2 million, or 99%. The increase was primarily driven by sublease income.

Net loss for the three months ended March 31, 2024 was $56.8 million as compared to net loss of $21.7 million for the three months ended March 31, 2023, a decrease of $35.1 million or 162%. The change was primarily due to expenses associated with the change in the fair value of the CVR liability and Series A Preferred Stock forward contract liability and increased general and administrative expenses, partially offset by decreased research and development expenses and income associated with the change in the fair value of the warrant liabilities.

During the year ended December 31, 2023, we recognized $26.0 million of collaboration and license revenue, compared to $110.8 million for the year ended December 31, 2022, a decrease of $84.8 million, or 77%. The decrease was primarily due to a decrease of revenue recognized under the Sobi License resulting from both the shipment of clinical supply and the reimbursement of costs incurred for the Phase 3 DISSOLVE clinical program partially offset by an increase for revenue recognized under the Astellas Agreement.

For the year ended December 31, 2023, our research and development expenses were $71.8 million, compared to $72.4 million for the year ended December 31, 2022, a decrease of $0.6 million, or 1%. The decrease in cost was primarily the result of reductions in expenses incurred for preclinical and clinical programs due to the strategic reprioritization partially offset by expenses incurred for stock compensation and personnel expenses.

During the year ended December 31, 2023, our general and administrative expenses were $40.6 million, compared to $23.9 million for the year ended December 31, 2022, an increase of $16.7 million, or 70%. The increase in costs was primarily the result of expenses incurred for stock compensation, personnel expenses, and professional fees incurred in connection with the Merger.

Investment income for the year ended December 31, 2023 was $5.0 million, compared to $2.1 million for the year ended December 31, 2022, an increase of $2.9 million, or 138%. The increase in investment income was due to increased investment balances and higher interest rates.

We recognized de minimis foreign currency translation adjustments during each of the years ended December 31, 2023 and 2022.

Interest expense for the year ended December 31, 2023 was $2.8 million compared to $3.0 million for the year ended December 31, 2022, a decrease of $0.2 million, or 7%. Interest expense for the year ended December 31, 2023 comprised interest expense and amortization of the carrying costs of our credit facilities and loss on extinguishment of debt.

For the year ended December 31, 2023, we recognized $12.7 million of income from the decrease in the fair value of warrant liabilities, compared to $20.9 million for the year ended December 31, 2022, a decrease of $8.2 million or 39.2%. Fair value of warrant liabilities was determined utilizing the Black-Scholes valuation methodology. The decrease in warrant value was primarily driven by a decrease in the per-share price of our Common Stock.

For the year ended December 31, 2023 we recognized $18.3 million of expense associated with the increase in the fair value of CVR liability. The fair value of the CVR liability was determined utilizing a discounted cash flow valuation methodology. The increase in CVR value was primarily driven by the decrease in interest rates from the Merger to December 31, 2023 and the corresponding impact on the discount rate used in our discounted cash flow valuation. There was no CVR liability prior to the Merger and as such no CVR liability is reflected in our consolidated financial statements as of or for any period prior to the year ended December 31, 2023.

For the year ended December 31, 2023 we recognized $149.6 million of expense associated with the increase in the fair value of Series A Preferred Stock forward contract liabilities. The increase in Series A Preferred Stock value was primarily driven by an increase in the per-share price of our Common Stock since the date of the Merger and November 2023 Private Placement. A portion of the Series A Preferred Stock forward contract liability was settled during the year ended December 31, 2023 and there was no such forward contract liability prior to the Merger. There was no Series A Preferred Stock forward contract liability prior to the Merger and as such no Series A Preferred Stock forward contract liability is reflected in our consolidated financial statements as of or for any period prior to the year ended December 31, 2023.

During the year ended December 31, 2023, we recognized other income, net of $0.7 million, compared to $0.3 million for the year ended December 31, 2022, an increase of $0.4 million, or 133%. The increase was primarily driven by sublease income.

During the year ended December 31, 2023, we recognized a current tax benefit of $19.0 million relating to the benefit of legacy Selecta tax attributes that reduced deferred tax liabilities during the year. For the year ended December 31, 2022, we recognized a $0.6 million benefit for penalty abatements received.

Net loss for the year ended December 31, 2023 was $219.7 million as compared to net income of $35.4 million for the year ended December 31, 2022, a decrease of $255.1 million, or 721%. The change was primarily due to decreased collaboration and license revenue and expenses associated with the change in fair value of the CVR liability and Series A Preferred Stock forward contract liability, and increased general and administrative expenses, partially offset by an increase in income tax benefit.

Except for net income of $35.4 million for the year ended December 31, 2022, we have incurred recurring net losses since our inception. We expect that we will continue to incur losses and that such losses will increase for the foreseeable future. We expect that our research and development and general and administrative expenses will continue to increase and, as a result, we will need additional capital to fund our operations, which we may raise through a combination of equity offerings, debt financings, third-party funding, potential royalty and/or milestone monetization transactions and other collaborations and strategic alliances.

As of March 31, 2024, our cash, cash equivalents, and restricted cash were $104.8 million, of which $1.4 million was restricted cash related to lease commitments and $0.2 million was held by our Russian subsidiary designated solely for use in its operations.

In addition to our existing cash equivalents, we from time to time have received and may receive in the future research and development funding pursuant to our collaboration and license agreements. Currently, funding from payments under our collaboration agreements represent our only source of committed external funds.

The liability associated with the contingent value rights agreement (“CVR Agreement”), entered into on December 6, 2023, will be settled solely through cash flow received under the Sobi License and any other Gross Proceeds (as such term is defined in the CVR Agreement) net of certain agreed deductions. Under the CVR Agreement, 100% of all milestone payments, royalties, and other amounts paid to us or our controlled entities under the Sobi License, and any other Gross Proceeds, in each case net of certain agreed deductions, will be distributed to holders of the CVRs. There is no contractual obligation for us to fund any amount related to the CVR liability.

In September 2023, we entered into a non-exclusive, sublicensable, worldwide, perpetual patent license agreement (the “Biogen Agreement”), with Biogen MA, Inc. (“Biogen”), to research, develop, make, use, offer, sell and import products or processes containing or using an engineering T-cell modified with an mRNA comprising, or encoding a protein comprising, certain sequences licensed under the Biogen Agreement for the prevention, treatment, palliation and management of autoimmune diseases and disorders, excluding cancers, neoplastic disorders, and paraneoplastic disorders. We are not obligated to pay Biogen any expenses, fees, or royalties. For further description of the Biogen Agreement, see Note 15 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

Effective September 2019, we entered into a nonexclusive, worldwide license agreement (the “NCI Agreement”), with the U.S. Department of Health and Human Services, represented by the National Cancer Institute of the National Institutes of Health (“NCI”). Under the NCI Agreement, we were granted a license under certain NCI patents and patent applications designated in the agreement, to make, use, sell, offer and import products and processes within the scope of the patents and applications licensed under the NCI Agreement when developing and manufacturing anti-BCMA CAR-T cell products for the treatment of MG, pemphigus vulgaris, and immune thrombocytopenic purpura according to methods designated in the NCI Agreement. In connection with our entry into the NCI Agreement, we paid to NCI a one-time $0.1 million license royalty payment. Under the NCI Agreement, we are further required to pay NCI a low five-digit annual royalty. We must also pay earned royalties on net sales in a low single-digit percentage and pay up to $0.8 million in benchmark royalties upon our achievement of designated benchmarks that are based on the commercial development plan agreed between the parties. For further description of the NCI Agreement, see Note 15 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

In October 2021, we and Ginkgo Bioworks Holdings, Inc. (“Ginkgo”), entered into a Collaboration and License Agreement (the “First Ginkgo Agreement”), and paid Ginkgo a $0.5 million one-time upfront payment. In June 2022, we paid $0.5 million and issued 29,761 shares of our Common Stock then-valued at $1.0 million to Ginkgo for the achievement of certain preclinical milestones under the First Ginkgo Agreement. In January 2022, we entered into a Collaboration and License Agreement (the “Second Ginkgo Agreement”), and paid Ginkgo a $1.5 million one-time upfront payment. In July 2023, we paid $1.0 million and issued 44,642 shares of our

Common Stock then-valued at $1.5 million to Ginkgo for the achievement of certain preclinical milestones under the Second Ginkgo Agreement. For further description of the First Ginkgo Agreement and the Second Ginkgo Agreement, see Note 15 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

Additionally, in October 2021, we entered into an Exclusive License Agreement with Genovis (the “Genovis Agreement”), and paid Genovis a $4.0 million one-time upfront payment. In February 2023, as a result of the sublicense of Xork to Astellas, we made a $4.0 million payment to Genovis. In March 2024, we informed Genovis of our intent to terminate the Genovis Agreement, effective September 13, 2024. For further description of the Genovis Agreement, see Note 15 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

On September 7, 2021, we entered into a Collaboration and License Agreement (the “Cyrus Agreement”), with Cyrus Biotechnology, Inc. (“Cyrus”), and purchased 2,326,934 shares of Cyrus’ Series B Preferred Stock, par value $0.0001 per share, at a purchase price of $0.8595 per share, for an aggregate purchase price of $2.0 million. In October 2023, we notified Cyrus of our termination of the Cyrus Agreement, effective December 29, 2023. For further description of the Cyrus Agreement, see Note 15 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

In January 2023, we entered into the Astellas Agreement with Astellas. Under this agreement, Astellas obtained the sole and exclusive right to commercialize Xork for use in Pompe disease in combination with an Astellas gene therapy investigational or authorized product, with a current focus on AT845. In connection with entry into this agreement, we received a $10 million upfront payment and are eligible to receive $340.0 million for certain additional development and commercial milestones plus royalties on any potential commercial sales where Xork is used as a pre-treatment for AT845. As a result of the sublicense of Xork to Astellas, we made a $4.0 million payment to Genovis in February 2023. In March 2024, we were notified by Astellas of their intention to terminate the Astellas Agreement, effective June 6, 2024. For further description of the Astellas Agreement, see Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

On October 1, 2021, we entered into a License Agreement (the “Takeda Agreement”), with Takeda Pharmaceuticals USA, Inc. (“Takeda”). We received a $3.0 million upfront payment and were entitled to receive up to $1.124 billion in future additional payments over the course of the partnership that were contingent on the achievement of development or commercial milestones or Takeda’s election to continue its activities at specified development stages. The Takeda Agreement was terminated effective July 25, 2023. For further description of the Takeda Agreement, see Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

In June 2020, we entered into the Sobi License. Sobi paid us a one-time, upfront payment of $75 million, and upon the closing of a private placement of our Common Stock to Sobi at a price of $138.468 per share, we received an additional $25 million from Sobi. We are eligible to receive $630 million in milestone payments upon the achievement of various development and regulatory milestones and sales thresholds for annual net sales of SEL-212, and tiered royalty payments ranging from the low double digits on the lowest sales tier to the high teens on the highest sales tier. Sobi has agreed to fund the Phase 3 clinical program of SEL-212, which commenced in September 2020. In July 2022, we received $10.0 million for the completion of the enrollment of the DISSOLVE II trial. Proceeds from milestone payments and royalties on sales of SEL-212, if any, are required to be distributed, net of certain agreed deductions, to holders of the CVRs. For further description of the Sobi License, see Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

Additionally, in June 2020, we and Sarepta Therapeutics, Inc. (“Sarepta”), entered into a Research License and Option Agreement (the “Sarepta Agreement”). Sarepta paid us a $2.0 million upfront payment upon closing and $3.0 million for the achievement of certain pre-clinical milestones in June 2021. In August 2022, we received a payment of $2.0 million in exchange for a nine-month extension to Sarepta’s options to both Duchenne muscular dystrophy and certain limb-girdle muscular dystrophies and a payment of $4.0 million for the achievement of certain non-clinical milestones. In March 2023, we were notified by Sarepta that Sarepta would not be exercising its exclusive option under the Sarepta Agreement. The Sarepta Agreement terminated upon the expiration of the

option in March 2023. For further description of the Sarepta Agreement, see Note 13 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

On October 25, 2021, we entered into a Sales Agreement (the “2021 Sales Agreement”), with Leerink Partners LLC (“Leerink Partners,” then known as SVB Leerink LLC), to sell shares of our Common Stock, from time to time, through an “at the market” equity offering program under which Leerink Partners will act as sales agent. The shares of Common Stock sold pursuant to the 2021 Sales Agreement, if any, would be issued and sold pursuant to a registration statement filed with the Securities and Exchange Commission (the “SEC”) for remaining aggregate gross sales proceeds of up to $51.0 million.

During the three months ended March 31, 2024 and the year ended December 31, 2023, we sold no shares of our Common Stock pursuant to the 2021 Sales Agreement. During the year ended December 31, 2022, we sold 25,818 shares of our Common Stock pursuant to the 2021 Sales Agreement for aggregate net proceeds of $2.1 million, after deducting commissions and other transaction costs.

On November 13, 2023, we entered into the November 2023 Securities Purchase Agreement with (i) Dr. Timothy A. Springer, a member of our Board of Directors; (ii) TAS Partners LLC, an affiliate of Dr. Springer, and (iii) Seven One Eight Three Four Irrevocable Trust, a trust associated with Dr. Murat Kalayoglu, a co-founder and the former chief executive officer of Old Cartesian, who joined our Board of Directors effective immediately after the effective time of the Merger, providing for the November 2023 Private Placement. In the November 2023 Private Placement, we issued and sold an aggregate of 149,330.115 shares of Series A Preferred Stock for an aggregate purchase price of $60.25 million, of which 50,189.789 shares of Series A Preferred Stock were issued and sold in the year ended December 31, 2023 for gross proceeds of $20.25 million, and 99,140.326 shares of Series A Preferred Stock were issued and sold during the three months ended March 31, 2024 for gross proceeds of $40.0 million.

On July 2, 2023, we entered into a securities purchase agreement with the purchasers party thereto (the “Securities Purchase Agreement”) pursuant to which we agreed to issue and sell an aggregate of 3,563,247 shares of Common Stock and 2,937,903 shares of Series B Preferred Stock for gross proceeds of approximately $130.0 million.

We previously maintained a term loan of up to $35.0 million, of which $25.0 million was funded in August 2020. In September 2023, we entered into a payoff letter with Oxford Finance LLC and Silicon Valley Bank, a division of First-Citizens Bank & Trust Company (successor by purchase to the Federal Deposit Insurance Corporation as Receiver for SVBB (as successor to Silicon Valley Bank)), the lenders under the term loan, pursuant to which we paid all outstanding amounts under such term loan, together with accrued interest and a prepayment penalty, resulting in the full extinguishment of such term loan. The total payoff amount was $22.3 million, consisting of the remaining principal amount due of $19.8 million, the final payment fee of $2.3 million, the prepayment penalty of $0.2 million, and less than $0.1 million of accrued interest.

If in the future we seek debt financing, the terms of such debt could restrict our operating and financial flexibility by imposing liens on our assets and covenants on the operation of our business.

As of the date of this prospectus, we have not generated any revenue from product sales. We do not know when, or if, we will generate revenue from product sales. We will not generate significant revenue from product sales unless and until we obtain regulatory approval and commercialize one of our current or future product candidates. Our primary uses of capital are, and we expect will continue to be, compensation and related expenses, third-party clinical research and development services, laboratory and related supplies, clinical costs, legal and other regulatory expenses, milestone and royalty payments for in-licenses, and general overhead costs. We expect that we will continue to generate losses for the foreseeable future, and we expect the losses to increase as we continue the development of, and seek regulatory approvals for, our product candidates, and begin to commercialize any approved products. We are subject to risks in the development of our products, and we

may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. We expect that we will need substantial additional funding to support our continuing operations.

As of March 31, 2024, we had an accumulated deficit of $671.5 million. We anticipate operating losses to continue for the foreseeable future due to, among other things, costs related to research, development of our product candidates, conducting preclinical studies and clinical trials, and our administrative organization. We will require substantial additional financing to fund our operations and to continue to execute our strategy, and we will pursue a range of options to secure additional capital.

We regularly evaluate various potential sources of additional funding such as strategic collaborations, license agreements, debt issuance, potential royalty and/or milestone monetization transactions and the issuance of equity instruments to fund our operations. If we raise additional funds through strategic collaborations and alliances, which may include existing collaboration partners, we may have to relinquish valuable rights to our technologies or product candidates, or grant licenses on terms that are not favorable to us. To the extent that we raise additional capital through the sale of equity instruments, the ownership interest of our existing stockholders will be diluted, and other preferences may be necessary that adversely affect the rights of existing stockholders.

We believe that our existing cash, cash equivalents, and restricted cash as of March 31, 2024 will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months. We may pursue additional cash resources through public or private equity or debt financings, by establishing collaborations with other companies or through the monetization of potential royalty and/or milestone payments pursuant to our existing collaboration and license arrangements. Management’s expectations with respect to our ability to fund current and long-term planned operations are based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, we may need to seek additional strategic or financing opportunities sooner than would otherwise be expected. However, there is no guarantee that any of these strategic or financing opportunities will be executed on favorable terms, and some could be dilutive to existing stockholders. If we are unable to obtain additional funding on a timely basis, we may be forced to significantly curtail, delay, or discontinue one or more of our planned research or development programs or be unable to expand our operations, meet long-term obligations or otherwise capitalize on our commercialization of our product candidates.

Our future capital requirements will depend on many factors, including:

The following table summarizes our cash flows for the three months ended March 31, 2024 and 2023:

Net cash used in operating activities for the three months ended March 31, 2024 was $15.9 million compared to $8.8 million for the three months ended March 31, 2023. The increase in net cash used in operating activities of $7.1 million was primarily due to $9.5 million of net loss, adjusted for non-cash items, and approximately $6.4 million cash used in changes in operating assets and liabilities.

Net cash used in investing activities for the three months ended March 31, 2024 was $0.6 million compared to net cash provided by investing activities of $28.1 million for the three months ended March 31, 2023, a decrease of $28.7 million. The net cash used in investing activities for the three months ended March 31, 2024 consisted primarily of purchases of property and equipment. The net cash provided by investing activities for the three months ended March 31, 2023 was primarily proceeds from the maturities of marketable securities offset by purchases of property and equipment.

Net cash provided by financing activities for the three months ended March 31, 2024 was $43.0 million compared to net cash provided by financing activities of $0.1 million for the three months ended March 31, 2023, an increase of $42.9 million. The net cash provided by financing activities in the three months ended March 31, 2024 was primarily the result of proceeds of the November 2023 Private Placement. The net cash provided by financing activities in the three months ended March 31, 2023 was primarily the result of proceeds from issuance of Common Stock under the 2016 ESPP.

The following table summarizes our cash flows for the years ended December 31, 2023 and 2022:

Net cash used in operating activities for the year ended December 31, 2023 was $51.2 million compared to $31.6 million in the same period in 2022. The increase in net cash used in operating activities of $19.6 million was primarily due to $56.2 million of net loss, adjusted for non-cash items, and $5.0 million of cash provided by changes in operating assets and liabilities, in each case during the year ended December 31, 2023.

Net cash provided by investing activities for the year ended December 31, 2023 was $34.6 million compared to net cash used in investing activities of $15.0 million in the same period in 2022, an increase of $49.6 million. The net cash provided by investing activities for the year ended December 31, 2023 was primarily proceeds from the maturities of marketable securities and cash assumed in the Merger offset by purchases of property and equipment. The net cash used in investing activities for the year ended December 31, 2022 was to purchase marketable securities and property and equipment, offset by proceeds from the maturities of marketable securities.

Net cash used in financing activities for the year ended December 31, 2023 was $13.1 million compared to net cash provided by financing activities of $39.2 million in the same period in 2022, a decrease of $52.3 million. The net cash used in financing activities for the year ended December 31, 2023 was primarily the result of repayments of principal on outstanding debt and settlement of equity awards in the Merger partially offset by proceeds from the November 2023 Private Placement. The net cash provided by financing activities for the year ended December 31, 2022 was primarily the result of net proceeds from issuance of Common Stock and warrants to purchase Common Stock and the issuance of Common Stock in the “at-the-market” offering contemplated by the 2021 Sales Agreement.

For a discussion of recently adopted or issued accounting pronouncements please see Note 2 to our unaudited consolidated financial statements included elsewhere in the registration statement of which this prospectus forms a part.

As of March 31, 2024, we did not have any off-balance sheet arrangements as defined in the rules and regulations of the SEC.

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of these consolidated financial statements requires us to make estimates and judgements that affect the reported amounts of assets, liabilities, revenues and expenses, and disclosure of contingent assets and liabilities in our consolidated financial statements. Actual results may differ from these estimates under different assumptions or conditions and could have a material impact on our reported results. While our significant accounting policies are more fully described in the notes to our consolidated financial statements and unaudited consolidated financial statements, both appearing elsewhere in the registration statement of which this prospectus forms a part, we believe the following accounting policies to be the most critical in understanding the judgments and estimates we use in preparing our consolidated financial statements:

Revenue is recognized when a customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. Pursuant to ASC Topic 606, Revenue from Contracts with Customers (ASC 606), a customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract, including whether they are distinct in the context of the contract; (iii) determine the transaction price, including the constraint on variable consideration; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy each performance obligation. We only apply the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the

customer. At contract inception, once the contract is determined to be within the scope of ASC 606, we assess the goods or services promised within each contract and determine those that are performance obligations, and assess whether each promised good or service is distinct. If a promised good or service is not distinct, it is combined with other promised goods or services into a performance obligation. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. For example, certain performance obligations associated with the Astellas Agreement, (see Note 14 to our consolidated financial statements and Note 13 unaudited consolidated financial statements elsewhere in the registration statement of which this prospectus forms a part) will be satisfied over time, and revenue will be recognized utilizing the input method.

Collaboration and License Revenue: We currently generate revenue through collaboration and license agreements with strategic collaborators for the development and commercialization of product candidates. Collaboration and license agreements with customers are generally accounted for in accordance with ASC 606. We analyze collaboration arrangements by first assessing whether they are within the scope of ASC Topic 808, Collaborative Arrangements (ASC 808), and evaluate whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. Collaboration agreements with customers that are not within the scope of ASC 808 are accounted for in accordance with ASC 606. To the extent the collaboration agreement is within the scope of ASC 808, we also assess whether any aspects of the agreement are within the scope of other accounting literature (specifically ASC 606). If we conclude that some or all aspects of the agreement are distinct and represent a transaction with a customer, we account for those aspects of the arrangement within the scope of ASC 606. We recognize the shared costs incurred that are not within the scope of other accounting literature as a component of the related expense in the period incurred by analogy to ASC Topic 730, Research and Development (ASC 730), and record reimbursements from counterparties as an offset to the related research and development costs. In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under the agreements in accordance with ASC 606, we perform the five steps above. As part of the accounting for the arrangement, we must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. We use key assumptions to determine the stand-alone selling price, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success. The assumptions used to determine the stand-alone selling price and our satisfaction of performance obligations have a material effect on our collaboration and license revenue and may prove to be wrong.

The terms of our arrangements typically include one or more of the following: (i) upfront fees; (ii) milestone payments related to the achievement of development, regulatory, or commercial goals; (iii) royalties on net sales of licensed products; (iv) reimbursements or cost-sharing of research and development expenses; and (v) profit/loss sharing arising from co-promotion arrangements.

Licenses of Intellectual Property: If the license to our intellectual property is determined to be distinct from the other promised goods and services identified in the arrangement, we recognize revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. If not distinct, the license is combined with other promised goods and services in the contract. For licenses that are combined with other promised goods and services, we assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Optional licenses are evaluated to determine if they are issued at a discount, and therefore, represent material rights and should be accounted for as separate performance obligations.

Milestone Payments: At the inception of each arrangement that includes developmental and regulatory milestone payments, we evaluate whether the achievement of each milestone specifically relates to our efforts to satisfy a performance obligation or transfer a distinct good or service within a performance obligation. If the achievement of a milestone is considered a direct result of our efforts to satisfy a performance obligation or transfer a distinct good or service and the receipt of the payment is based upon the achievement of the milestone, the associated milestone value is allocated to that distinct good or service. If the milestone payment is not specifically related to our efforts to satisfy a performance obligation or transfer a distinct good or service, the amount is allocated to all

performance obligations using the relative standalone selling price method. We also evaluate the milestone to determine whether they are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price to be allocated, otherwise, such amounts are constrained and excluded from the transaction price. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of such development milestones and any related constraint, and if necessary, adjust our estimate of the transaction price. Any such adjustments to the transaction price are allocated to the performance obligations on the same basis as at contract inception. Amounts allocated to a satisfied performance obligation shall be recognized as revenue, or as a reduction of revenue, in the period in which the transaction price changes.

Manufacturing Supply Services: Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are evaluated to determine if they are distinct and optional. For optional services that are distinct, we assess if they are priced at a discount, and therefore, provide a material right to the licensee to be accounted for as separate performance obligations.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied) in accordance with the royalty recognition constraint.

Clinical trial expenses are a significant component of research and development expenses, and we outsource a significant portion of these costs to third parties. Third party clinical trial expenses include patient costs, clinical research organization costs and costs for data management. The accrual for site and patient costs includes inputs such as estimates of patient enrollment, patient cycles incurred, clinical site activations, and other pass-through costs. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the consolidated balance sheets as a prepaid asset or accrued clinical trial cost. These third party agreements are generally cancellable, and related costs are recorded as research and development expenses as incurred. Non-refundable advance clinical payments for goods or services that will be used or rendered for future research and development activities are recorded as a prepaid asset and recognized as expense as the related goods are delivered or the related services are performed. We also record accruals for estimated ongoing clinical research and development costs. When evaluating the adequacy of the accrued liabilities, we analyze progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by us materially affecting our results of operations. The historical clinical accrual estimates made by us have not been materially different from the actual costs.

In December 2019, we issued common warrants in connection with a securities purchase agreement between us and a group of institutional investors and certain members of our Board of Directors (the “2019 Warrants”). Pursuant to the terms of the 2019 Warrants, we could be required to settle the 2019 Warrants in cash in the event of certain acquisitions of us and, as a result, the 2019 Warrants are required to be measured at fair value and reported as a liability on the balance sheet.

In April 2022, we issued warrants in connection with an underwritten offering of shares of common stock and warrants to purchase shares of common stock (the “2022 Warrants”). Pursuant to the terms of the 2022 Warrants, we could be required to settle the 2022 Warrants in cash in the event we are acquired under certain circumstances and, as a result, the 2022 Warrants are required to be measured at fair value and reported as a liability on the balance sheet.

We recorded the fair value of the 2019 Warrants and 2022 Warrants upon issuance using the Black-Scholes valuation model, and are required to revalue the common warrants at each reporting date with any changes in fair value recorded on our statement of operations. In December 2022, we amended the terms of the outstanding

2019 Warrants held by certain members of our Board of Directors to remove the cash settlement provision (as so amended, the “Amended 2019 Warrants”). As a result, the Amended 2019 Warrants were remeasured at fair value on December 20, 2022 and reclassified from a liability to equity on the balance sheet.

Inputs used to determine estimated fair value of the common warrant liabilities include the estimated fair value of the underlying stock at the valuation date, the estimated term of the warrants, risk-free interest rates, expected dividends and the expected volatility of the underlying stock. The estimates used to determine the fair value of these common warrants represent our best estimates, but may prove to be wrong. Therefore, the change in fair value of warrant liabilities could be materially different in the future.

The CVRs distributed pursuant to the terms of the CVR Agreement represent financial instruments that are accounted for under the fair value option election in ASC 825, Financial Instruments, or ASC 825. Under the fair value option election, the CVRs are initially measured at the aggregate estimated fair value of the CVRs and will be subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. The estimated fair value of the CVR liability was determined using a discounted cash flow methodology as of December 31, 2023 and a Monte Carlo simulation model as of March 31, 2024 to estimate future cash flows associated with the legacy assets, including the expected milestone and royalty payments under the Sobi License, net of deductions. Changes in fair value of the CVR liability are presented in the consolidated statements of operations and comprehensive income (loss). The liability value is based on significant inputs not observable in the market such as estimated cash flows, estimated probabilities of success, expected volatility of future revenues (Monte Carlo simulation model) and risk-adjustment discount rates (discounted cash flow methodology), which represent a Level 3 measurement within the fair value hierarchy.

We account for all stock-based compensation granted to employees and non-employees using a fair value method. Stock-based compensation is measured at the grant date fair value and is recognized over the requisite service period of the awards, usually the vesting period, on a straight-line basis, net of estimated forfeitures. To the extent that actual forfeitures differ from our estimates, the differences are recorded as a cumulative adjustment in the period the estimates were adjusted. Stock-based compensation expense recognized in the consolidated financial statements is based on awards that ultimately vest.

The assumptions used in determining the fair value of stock-based awards represent our best estimates, but the estimates involve inherent uncertainties and the application of our judgment. As a result, if factors change and we use significantly different assumptions or estimates, our stock-based compensation expense could be materially different in the future.

We qualify as a “smaller reporting company” under the rules of the Securities Act and the Exchange Act. As a result, we may choose to take advantage of certain scaled disclosure requirements available specifically to smaller reporting companies. We will remain a smaller reporting company until the last day of the fiscal year in which the aggregate market value of our Common Stock held by non-affiliated persons and entities, or our public float, is more than $700 million as of the last business day of our most recently completed second fiscal quarter, or until the fiscal year following the year in which we have at least $100 million in revenue and at least $250 million in public float as of the last business day of our most recently completed second fiscal quarter.

None.

The Company (formerly known as Selecta Biosciences, Inc. (“Selecta”)) was incorporated in Delaware on December 10, 2007, and is headquartered in Gaithersburg, Maryland. On November 13, 2023, the Company and the Delaware corporation which then known as Cartesian Therapeutics, Inc., entered into the Merger Agreement. Pursuant to the Merger Agreement, and simultaneously with execution thereof, (i) First Merger Sub merged with and into Old Cartesian, pursuant to which Old Cartesian was the surviving corporation, and became a wholly owned subsidiary of the Company, and (ii) immediately following the First Merger, Old Cartesian (as the First Step Surviving Corporation) merged with and into Second Merger Sub, pursuant to which Second Merger Sub was the surviving company, and continued under the name “Cartesian Bio, LLC.” In connection with the Merger and pursuant to the Merger Agreement, the Company (which was known as Selecta Biosciences, Inc. until immediately prior to the Merger) changed its corporate name to Cartesian Therapeutics, Inc.

We are a clinical-stage biotechnology company developing mRNA cell therapies for the treatment of autoimmune diseases. We leverage our proprietary technology and manufacturing platform to introduce one or more mRNA molecules into cells to enhance their function. Unlike DNA, mRNA degrades naturally over time without integrating into the cell’s genetic material. Therefore, our mRNA cell therapies are distinguished by their capacity to be dosed repeatedly like conventional drugs, administered in an outpatient setting, and given without pre-treatment chemotherapy required with many conventional cell therapies. In an open-label Phase 2 clinical trial in patients with MG, a chronic autoimmune disease that causes disabling muscle weakness and fatigue, we observed that our lead product candidate, Descartes-08, generated a deep and durable clinical benefit.

Autoimmune diseases, where the immune system mistakenly attacks the body, are a family of more than 80 disorders. Autoimmune diseases are typically treated with immunosuppressant medications, such as steroids. These treatments must be administered continually and carry risks, including infection, osteoporosis, and metabolic disease. Newer agents that block the complement pathway or inhibit the neonatal Fc receptor (“FcRn”), must also typically be administered continually. We believe there is a significant unmet need for outpatient treatments, completed over a short period of time, that provide deep, durable clinical benefit.

Cell therapies have the potential to provide this benefit, but conventional cell therapies that use DNA are associated with toxicities, including cytokine release syndrome, neurotoxicity, transformation to cancer, and death. Further, conventional cell therapies typically require pre-treatment with chemotherapy, which suppresses the immune system and increases the risk of infection, anemia, and neurotoxicity. As a result, conventional DNA cell therapies typically require close monitoring in an inpatient setting, increasing the total cost of care and generally limiting their reach to only the sickest patients.

We believe our mRNA cell therapies have the potential to deliver deep, durable clinical benefit to a broad group of patients with autoimmune diseases because they can be administered over a short period of time, in an outpatient setting, and without pre-treatment chemotherapy.

We are leveraging our proprietary technology and manufacturing platform, RNA Armory^®, to develop mRNA cell therapies for autoimmune diseases across three modalities. Our mRNA CAR-T modality is a personalized approach that collects a patient’s T-cells and uses mRNA to introduce a chimeric antigen receptor (“CAR”), into the cell. The CAR redirects the T-cells to target and destroy pathogenic self-reactive cells. Our mRNA MSC modality is an allogeneic approach that introduces one or more mRNAs into donor-sourced mesenchymal stem cells (“MSCs”), enabling them to produce proteins that target key pathways involved in autoimmunity. These cells are banked and are designed to be administered off-the-shelf to any patient. Our mRNA in situ modality is designed to deliver mRNA into a patient’s lymph node to generate CAR-T cells and other proteins that target autoimmunity. The figure below illustrates each modality.

 

The table below summarizes key information about our development pipeline.

 

Our lead product candidate, Descartes-08, is an autologous mRNA CAR-T directed against the B cell maturation antigen (“BCMA”), that we are developing for the treatment of autoimmune diseases. Descartes-08 has been granted Orphan Drug Designation and RMAT Designation by the FDA for the treatment of MG.

In July 2024, we reported topline results from a Phase 2b randomized, double-blind, placebo-controlled trial in patients with MG. The trial achieved its primary endpoint with statistical significance in the pre-specified modified intent-to-treat (“mITT”) efficacy population, with 71% (10/14) of patients treated with Descartes-08 observed to have 5-point or greater improvements in MG Composite (“MGC”) score at Month 3 compared to 25% (3/12) of patients treated with placebo (p=0.018). In addition, the trial also achieved its primary endpoint with statistical significance in the per-protocol population, with 69% (11/16) of patients treated with Descartes-08 observed to have 5-point or greater improvements in MGC score at Month 3 compared to 33% (5/15) of patients treated with placebo (p=0.048).

Consistent with previously reported results from the Phase 2a open-label portion of the trial, Descartes-08 responders experienced deep improvements across the MG severity scales at Month 3 (average MG-ADL (Activities of Daily Living) = -5.6; MGC= -8.3; QMG (Quantitative MG) = -5.0; QoL-15r (Quality of Life Revised Scale) = -7.9). The improvements seen at Month 3 persisted or further improved in patients evaluated at their Month 4 (n=5) and Month 6 (n=3) follow-up visits, as of the June 19, 2024 data cutoff date. In the Phase 2b trial, Descartes-08 continued to demonstrate a favorable safety profile supporting outpatient

administration without the need for lymphodepleting chemotherapy. Consistent with findings from the Phase 2a open-label portion of the trial, Descartes-08 was observed to be well tolerated, and adverse events were transient and mostly mild. Notably, there were no cases of cytokine release syndrome, and no cases of immune effector cell-associated neurotoxicity syndrome.

Previously, Descartes-08 was observed to be safe and well-tolerated in a Phase 1b/2a trial of 14 patients with MG who received outpatient treatment without pre-treatment chemotherapy. All seven participants who received six once-weekly infusions at the highest dose continued to experience marked and long-lasting clinical improvement across validated MG disease scoring systems at month nine follow-up. At month 12, five of these seven participants maintained clinically meaningful improvement. One participant, who lost response after one year, experienced rapid improvement in clinical scores after re-treatment, which was ongoing at month six of follow-up. Clinical responses correlated with large reductions in autoantibody titers.

We are also developing Descartes-08 for the treatment of other autoimmune diseases. We have received FDA allowance for our investigational new drug application (“IND”) for a Phase 2 trial of Descartes-08 for the treatment of patients with systemic lupus erythematosus (“SLE”), a chronic autoimmune disease that causes systemic inflammation affecting multiple organ systems, and announced dosing of the first patient in the trial in July 2024.

Descartes-15 is our next-generation autologous anti-BCMA mRNA CAR-T. In preclinical studies, we have observed Descartes-15 to be 10-fold more potent than Descartes-08. We intend to test the safety of Descartes-15 in an open label, single-arm Phase 1 trial in patients with relapsed/refractory multiple myeloma. This program has already received IND allowance from the FDA and we expect to dose the first patient of the planned Phase 1 trial with Descartes-15 in the second half of 2024. We expect that these Phase 1 trial data will inform our clinical development plan for Descartes-15 in autoimmune diseases.

Descartes-33 is an allogeneic mRNA MSC in preclinical development for treatment of autoimmune diseases. We are developing Descartes-33 to deliver a combination of therapeutic proteins that target key drivers in the pathogenesis of autoimmunity.

Conventional DNA cell therapies have been associated with cytokine release syndrome, neurological toxicities and Parkinsonism, infection, risk of secondary malignancy, and death. The acute toxicities are from exponential amplification of the modified cell, and the pre-treatment chemotherapy administered to enable cell amplification.

Conventional DNA-engineered CAR-T cells are in clinical development for several autoimmune diseases. DNA CAR-T cells are typically administered to patients in a subtherapeutic dose, which means that the cells must proliferate to reach therapeutic numbers in the body. However, this proliferation is not controlled in magnitude or duration, varies from patient to patient, and can be unpredictable. This proliferation occurs because the CAR gene is irreversibly integrated into the T-cell’s genome, causing a cascade in which every daughter cell carries the same CAR as the parent cells. The resulting unconstrained proliferation frequently exceeds the toxicity threshold, leading to serious adverse events. In November 2023, the FDA announced that it is investigating the risk of T-cell malignancies in approved DNA CAR-T cell immunotherapies.

The proliferation of DNA CAR-T cells has typically required pre-treatment chemotherapy, usually fludarabine and cyclophosphamide administered for several days before CAR-T cell treatment. This chemotherapy is toxic, suppressing the immune system and increasing the risk of infection, anemia, and neurotoxicity.

Given these risks and requirements, conventional DNA cell therapies are administered under close monitoring in an inpatient setting, increasing their cost and limiting their reach to only the sickest patients.

We believe that mRNA cell therapy has the potential to be a potent yet safer alternative to DNA cell therapy for treating autoimmune diseases. We believe the mRNA cell therapies we are developing have the potential to deliver deep, durable clinical benefit to many patients with autoimmune diseases because they can be administered over a short period of time, in an outpatient setting, and without pre-treatment chemotherapy. These attributes may extend the reach and potential of mRNA cell therapy to a broader group of patients with autoimmunity.

mRNA CAR-T cells locate their target, become activated, and proliferate like DNA CAR-T cells. However, because mRNA does not replicate and degrades naturally over time, the maximum number of mRNA molecules can be determined by the dose. The actual number of mRNA molecules declines to zero over time. The number of mRNA molecules determines the degree of CAR protein expression, and the persistence of the mRNA molecules determines the duration of mRNA CAR-T cell activity. Thus, unlike DNA CAR-T cells, our mRNA CAR-T cells provide pharmacokinetic control. In other words, a patient’s exposure to our cells is determined by the dose. The time, course and duration of that exposure are substantially determined by the nature of the mRNA we use. Therefore, while DNA CAR-T therapies are administered at subtherapeutic levels, we can administer a therapeutic number of mRNA CAR-T cells and re-dose these cells over time, much like a conventional drug. Because the mRNA cannot be replicated, we believe, and have thus far observed, that mRNA CAR-T cells do not cause the types of severe toxicity associated with DNA CAR-T cells. Also, because mRNA CAR-T is dosed at a therapeutic dose and does not rely on cell proliferation to reach the therapeutic window, there is no need to administer pre-treatment chemotherapy. The graphs below contrast our mRNA cell therapy approach with that of conventional DNA cell therapy.

 

As of the 2023 safety cutoff date, we have administered Descartes-08 to over 60 patients suffering from one of MG, multiple myeloma, and other diseases in open-label trials on an outpatient basis, many at community clinics. We have not observed product-related cytokine release syndrome, neurotoxicity or infection of any grade. The most common product-related adverse events observed-headache, nausea and fever-were self-limited and resolved within 72 hours of onset. One participant with MG with a history of allergic reaction to biologics developed hives after the third infusion and was hospitalized for monitoring. The patient’s hives resolved completely after a brief course of steroids.

Our lead product candidate is Descartes-08, a potential first-in-class mRNA CAR-T. Descartes-08 targets BCMA, which exists on the surface of long-lived plasma cells (“LLPCs”), and plasmacytoid dendritic cells (“pDCs”). LLPCs, which can survive for decades, are the main producers of disease-causing autoantibodies. pDCs, which secrete type-I interferons, may also play a critical role in autoimmunity. While the lead indication for Descartes-08 is MG, we believe that Descartes-08 has potential to treat other autoimmune diseases, such as lupus.

Descartes-08 has been granted Orphan Drug Designation by the FDA for the treatment of MG. We chose MG as our lead indication because the pathogenesis for MG is common to many autoimmune diseases.

MG is a rare autoimmune disease that causes debilitating muscle weakness and fatigue. It is estimated to affect over 120,000 patients in the U.S. and Europe. MG patients develop antibodies that lead to an immunological attack on critical signaling proteins at the junction between nerve and muscle cells, thereby inhibiting the ability

of nerves to communicate properly with muscles. This results in muscle weakness in tissues throughout the body, potentially manifesting in partial paralysis of eye movements, problems in chewing and swallowing, respiratory problems, speech difficulties and weakness in skeletal muscles. The symptoms of the disease can be transient and in the early stages of the disease can remit spontaneously. However, as the disease progresses, symptom-free periods become less frequent and disease exacerbations can last for months. Disease symptoms reach their maximum levels within two to three years in approximately 80% of patients. Up to 20% of MG patients experience a respiratory crisis at least once in their lives. During the crisis phase, decline in respiratory function can become life-threatening. Patients in crisis often require intubation and mechanical ventilation.

There are no known cures for MG and the current standard of care consists of chronic use of steroids and other immunosuppressants. These treatments must be administered continually and carry risks such as infection, osteoporosis, and metabolic diseases. Newer agents, such as those that block the complement pathway or inhibit FcRn, are typically administered continually.

To date, we have completed the Phase 1b portion of the Phase 1/2 trial of Descartes-08 in MG, as well as the primary readout of the Phase 2a portion of the trial and topline results from the Phase 2b portion of this trial.

The primary objective of the Phase 1b portion of the trial was to determine the maximum tolerated dose of Descartes-08 for patients with MG. To assess the safety and manufacturability of Descartes-08, the product candidate was administered in three ascending doses (3.5 x106 cells/kg; 17.5 x106 cells; 52.5 x106 cells/kg) to three patients with MG. After each infusion, patients were observed for at least one week, and a higher dose level was administered if there were no significant adverse effects observed at the initial dose. We observed Descartes-08 to be well-tolerated by the three patients who participated in this portion of the trial with no cytokine release syndrome or other serious product-related adverse events.

The primary objective of the Phase 2a portion of the trial was to determine the optimal dosing schedule for patients with MG using the highest dose level tested in Phase 1b (52.5 x106 cells/kg). This portion of the trial was designed to assess the safety and preliminary efficacy of Descartes-08 when administered across three different treatment schedules (six doses given twice-weekly, once-weekly, or once-monthly). This portion of the trial evaluated 11 patients with particularly advanced disease as assessed by both patient and clinician-reported outcomes. 79% of the 14 patients included in the Phase 1b and Phase 2a portions of the trial were classified at screening to have Class III or IV disease, as defined by the Myasthenia Gravis Foundation of America, indicating they have moderate-to-severe weakness affecting their muscles.

The results of the Phase 2a portion of the trial, published in the Lancet Neurology in July 2023, indicated that after six weekly infusions of Descartes-08, the average improvement in all disease severity scores was three-to-five-fold greater than what is considered clinically meaningful by expert consensus. As shown in the figure below, clinical improvements persisted in all patients at month nine, and in five of the seven remaining patients at a final, 12-month follow-up. Of the two participants who lost response, one was retreated and experienced rapid improvement in clinical scores which was durable after 24 months of total follow-up. A third participant lost their response after approximately 18 months and experienced another deep response after treatment that was ongoing at the most recent, 23-month follow-up. Descartes-08 was observed to be well-tolerated with no reports of dose-limiting toxicities, cytokine release syndrome or neurotoxicity.Descartes-08 was observed to be well-tolerated with no reports of dose-limiting toxicities, cytokine release syndrome or neurotoxicity.

 

All three participants with detectable anti-acetylcholine receptor antibody levels before treatment had an average 42% reduction in antibody levels by month six. These reductions deepened to 68% by month nine and persisted at month 12. In summary, we observed continued clinical improvement and autoantibody reductions after BCMA-directed mRNA CAR-T treatment for MG that persisted through the one-year follow-up period.

We are also conducting a Phase 2b randomized, double-blind, placebo-controlled portion of the Phase 1/2 trial, for which we reported topline results in July 2024. The trial is designed to assess the primary endpoint of the proportion of patients achieving a five-point or greater reduction in their MGC score at day 85. Patients will receive six weekly infusions at the dose established in Phase 1b (52.5 x106 cells/kg). The trial also involves a crossover component, in which any patient originally assigned to placebo will be given the opportunity to receive Descartes-08 after completing trial treatment.

Secondary endpoints are designed to assess a variety of additional clinical outcomes, including determining safety and tolerability, quantifying the clinical effect of Descartes-08 over one year, assessing changes through day 85 in QMG, MG QoL 15R, MG Composite and MG post-intervention status and comparing the effect of Descartes-08 versus placebo on MG scales through day 85 in patients who cross over from placebo to Descartes-08.

In this portion of the trial, a total of 36 heavily pre-treated, highly symptomatic patients with MG were randomized and the pre-specified primary efficacy dataset (n=26) consisted of a modified intent-to-treat (“mITT”) population of all subjects enrolled at academic medical centers who received at least one dose of Descartes-08 (n=14) or placebo (n=12) and completed at least one post-baseline MG Composite (“MGC”) score follow-up assessment. The safety dataset comprised all subjects who received at least one dose of Descartes-08 (n=19) or placebo (n=17).

The trial achieved its primary endpoint with statistical significance in the pre-specified mITT efficacy population, with 71% (10/14) of patients treated with Descartes-08 observed to have 5-point or greater improvements in

MGC score at Month 3 compared to 25% (3/12) of patients treated with placebo (p=0.018). In addition, the trial also achieved its primary endpoint with statistical significance in the per-protocol population, with 69% (11/16) of patients treated with Descartes-08 observed to have 5-point or greater improvements in MGC score at Month 3 compared to 33% (5/15) of patients treated with placebo (p=0.048).

Consistent with previously reported results from the Phase 2a open-label portion of the trial, Descartes-08 responders experienced deep improvements across the MG severity scales at Month 3 (average MG-ADL (Activities of Daily Living) = -5.6; MGC= -8.3; QMG (Quantitative MG) = -5.0; QoL-15r (Quality of Life Revised Scale) = -7.9). The improvements seen at Month 3 persisted or further improved in patients evaluated at their Month 4 (n=5) and Month 6 (n=3) follow-up visits, as of the June 19, 2024 data cutoff date. In the Phase 2b trial, Descartes-08 continued to demonstrate a favorable safety profile supporting outpatient administration without the need for lymphodepleting chemotherapy. Consistent with findings from the Phase 2a open-label portion of the trial, Descartes-08 was observed to be well tolerated, and adverse events were transient and mostly mild. Notably, there were no cases of cytokine release syndrome, and no cases of immune effector cell-associated neurotoxicity syndrome.

We are also developing Descartes-08 for the treatment of SLE, a chronic autoimmune disease that causes systemic inflammation which affects multiple organ systems.

SLE is a chronic, immune-mediated connective tissue disease that can impact nearly all major organ systems. The most common manifestations of SLE are cutaneous and musculoskeletal symptoms, although neurological, gastrointestinal, hematological, and renal symptoms are regularly observed as well. Patients with SLE are at a substantially increased risk of infection and cardiovascular disease, contributing to estimated 10- and 15-year mortality rates of 9% and 15%, respectively. SLE is the most common form of lupus, representing approximately 70% of lupus patients, and approximately three million adults worldwide are estimated to have SLE.

We recently initiated a multi-center open-label single-arm Phase 2 trial, for which we have received FDA IND allowance. The primary objective of this trial is to evaluate the safety, tolerability, and manufacturing feasibility of Descartes-08 mRNA CAR-T cells administered as six once-weekly outpatient infusions of 52.5x106 cells/kg without pre-treatment chemotherapy in approximately 30 patients with SLE. We also plan to file an IND application with our Descartes-08 product candidate in pediatric autoimmune disease by year-end 2024.

We expect to hold our next meeting with the FDA before year-end 2024 to discuss plans for initiating a phase 3 clinical trial.

Descartes-15 is a next-generation, autologous anti-BCMA mRNA CAR-T. Using our proprietary technology and manufacturing platform, we designed Descartes-15 to be more resistant than Descartes-08 to recycling of the CAR upon multiple antigen exposures. We believe this is a particularly important feature to increase the durability of CAR expression on the surface of these cells. We observed that Descartes-15 was 10-fold more potent than Descartes-08 in preclinical studies, as illustrated in the below charts. In November 2023, we received IND allowance from the FDA to initiate the Phase 1 trial to test the safety of Descartes-15 in patients with multiple myeloma.

 

We intend to leverage our preclinical and clinical observations from the Descartes-08 development program and the Descartes-15 Phase 1 program to inform our clinical strategy for Descartes-15 for the treatment of autoimmune diseases.

Descartes-33 is our allogeneic mRNA MSC in preclinical development for treatment of autoimmune diseases. We are developing Descartes-33 to deliver a combination of therapeutic proteins that target key drivers in the pathogenesis of autoimmunity.

We have established wholly owned internal manufacturing and research and development capabilities, which allow us to optimize processes rapidly and in an iterative manner. Our main manufacturing facility is located in Gaithersburg, Maryland and operates under current good manufacturing practice (“cGMP”). This facility enhances our control of product quality and production schedules and costs, allowing us to move assets from discovery to preclinical to clinical development quickly. We also entered into an agreement to lease additional manufacturing space located in Frederick, Maryland to transition and expand our clinical and commercial manufacturing capabilities for our maturing pipeline of innovative mRNA cell therapies for the treatment of autoimmune disease.

Our cGMP cell manufacturing facilities, with their dedicated quality management system, are also capable of mRNA production used in Descartes-08. We manufacture Descartes-08 in-house and are typically able to process and release lots for infusion within approximately three weeks. Our autologous cell therapy product candidates, including Descartes-08, are manufactured on a patient-by-patient basis. We have optimized our manufacturing processes through over 200 cGMP runs. We also maintain FDA-reviewed human umbilical cord MSC cell collection and banking operations.

Our success depends in part on our ability to obtain, maintain, protect, defend and enforce proprietary protection for our drug candidates and other discoveries, inventions, trade secrets and know-how that are critical to our business

operations. Our success also depends in part on our ability to operate without infringing, misappropriating or otherwise violating the proprietary rights of others, and in part on our ability to prevent others from infringing, misappropriating or violating our proprietary rights. A discussion of risks relating to intellectual property is provided under the section titled “Risk Factors—Risks Related to Our Intellectual Property.”

We intend to continue developing intellectual property, and we intend to aggressively protect our position in key technologies. Our patents are focused on several key technologies, including the use of our mRNA CAR-T technology and other developments in our mRNA cell therapy pipeline. As of December 31, 2023, we had five issued patents worldwide, including two patents issued in the United States and three issued outside the United States. Our patents are set to expire on various dates in 2040 through 2043. Additionally, as of December 31, 2023, we had 14 patent applications pending worldwide, including five U.S. applications and nine applications outside the United States. In addition, we had two registered marks protecting our brand and prospective products both domestically and internationally. With respect to the legacy Selecta assets, as of December 31, 2023, we had (i) 233 issued patents worldwide, including 20 patents issued in the United States and 213 issued outside the United States, set to expire on various dates in 2032 through 2043, (ii) 476 patent applications pending worldwide, including 42 U.S. applications and 434 applications outside the United States and (iii) two registered marks.

In addition to patent protection, we also rely on trade secrets, know-how, trademarks, confidential information, other proprietary information and continuing technological innovation to develop, strengthen and maintain our competitive position. We seek to protect and maintain the confidentiality of proprietary information to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection. Although we take steps to protect our proprietary information and trade secrets, including through contractual means with our employees, consultants, contractors and collaborators, third parties may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or disclose our technology. Thus, we may not be able to meaningfully protect our trade secrets. It is our policy to require our employees, consultants, outside scientific collaborators, sponsored researchers and other advisors to execute confidentiality and invention assignment agreements upon the commencement of employment or consulting relationships with us. However, such confidentiality agreements can be breached, and we may not have adequate remedies for any such breach. For more information regarding the risks related to our intellectual property, see the section titled “Risk Factors—Risks Related to Our Intellectual Property.”

On September 8, 2023, we entered into the Biogen Agreement with Biogen to research, develop, make, use, offer, sell and import products or processes containing or using an engineering T-cell modified with an mRNA comprising, or encoding a protein comprising, certain sequences licensed under the Biogen Agreement for the prevention, treatment, palliation and management of autoimmune diseases and disorders, excluding cancers, neoplastic disorders, and paraneoplastic disorders. We are not obligated to pay Biogen any expenses, fees, or royalties.

We may terminate the Biogen Agreement for any reason or no reason, and Biogen may terminate the agreement after a notice-and-cure period of 30 days if we fail to pay a fee owed to Biogen or for any other material breach of the agreement. The Biogen Agreement will otherwise expire when all claims of all issued patents within the patents and patent applications licensed to us under the Biogen Agreement have expired or been finally rendered revoked, invalid or unenforceable by a decision of a court or government agency.

Effective September 16, 2019, we entered into the NCI Agreement with NCI.

Under the NCI Agreement, we were granted a license under certain NCI patents and patent applications designated in the agreement, to make, use, sell, offer and import products and processes within the scope of the patents and applications licensed under the NCI Agreement when developing and manufacturing anti-BCMA CAR-T cell products for the treatment of MG, pemphigus vulgaris, and immune thrombocytopenic purpura according to methods designated in the NCI Agreement.

In connection with our entry into the NCI Agreement, we paid to NCI a one-time $100,000 license royalty payment. Under the NCI Agreement, we are further required to pay NCI a low five-digit annual royalty. We must also pay earned royalties on net sales in a low single-digit percentage and pay up to $0.8 million in benchmark royalties upon our achievement of designated benchmarks that are based on the commercial development plan agreed between the parties.

Under the NCI Agreement, we must use reasonable commercial efforts to bring licensed products and licensed processes to the point of Practical Application (as defined in the NCI Agreement). Upon our first commercial sale, we must use reasonable commercial efforts to make licensed products and licensed processes reasonably accessible to the United States public. After our first commercial sale, we must make reasonable quantities of licensed products or materials produced via licensed processes available to patient assistance programs and develop educational materials detailing the licensed products. Unless we obtain a waiver from NCI, we must have licensed products and licensed processes manufactured substantially in the United States. Prior to the first commercial sale, upon NCI’s request, we are obligated to provide NCI with commercially reasonable quantities of licensed products made through licensed processes to be used for in vitro research.

Additionally, we must use reasonable commercial efforts to initiate a Phase 3 clinical trial of a licensed product by the fourth quarter of 2024, submit a biologics license application (“BLA”), with respect to a licensed product by the fourth quarter of 2026, and make a first commercial sale of a licensed product by the fourth quarter of 2028.

The NCI Agreement terminates upon the expiration of the last to expire of the patent rights licensed thereunder, if not sooner terminated. NCI has the right to terminate this agreement, after giving written notice and providing a cure period in accordance with its terms, if we are in default of a material obligation. We have the unilateral right to terminate the agreement in any country or territory by giving NCI 60 days’ written notice. We agreed to indemnify NCI against any liability arising out of our, sublicensees’ or third parties’ use of the licensed patent rights and licensed products or licensed processes developed in connection with the licensed patent rights.

On January 8, 2023, we entered into the Astellas Agreement with Astellas. Under the Astellas Agreement, we granted Astellas an exclusive license to the Company’s IdeXork technology arising from Xork, to develop and commercialize Xork for use in Pompe disease in combination with an Astellas gene therapy investigational or authorized product. Xork, a bacterial IgG protease licensed from Genovis is licensed pursuant to the Genovis Agreement. Astellas paid to us a $10.0 million upfront payment upon signing of the Astellas Agreement, and we are entitled to receive up to $340.0 million in future additional payments over the course of the partnership that are contingent on the achievement of various development and regulatory milestones and, if commercialized, sales thresholds for annual net sales where Xork is used as a pre-treatment for an Astellas investigational or authorized product. We are also eligible for tiered royalty payments ranging from low to high single digits. Any proceeds received from milestone payments or royalties relating to Xork would be required to be distributed to holders of CVRs, net of certain deductions.

Pursuant to the Astellas Agreement, we will have the exclusive right and responsibility to complete research and development of Xork products and to conduct all preclinical studies and clinical trials for Xork for use in Pompe disease with an Astellas gene therapy investigational or authorized product (the “Xork Development Services”). Astellas will reimburse us for 25% of all budgeted costs incurred to complete the development of Xork for use in Pompe disease with an Astellas gene therapy investigational or authorized product. We will have control and responsibility over regulatory filings, including any IND, BLA, and marketing authorization applications relating to the licensed product. Astellas will have the exclusive right and responsibility to research, develop, and commercialize Astellas products used in combination with Xork and will have control and responsibility over all regulatory filings, including any IND, BLA, and marketing authorization applications, relating to Astellas products and Astellas products used in combination with Xork.

On June 11, 2020, we entered into the Sobi License with Sobi. Pursuant to the Sobi License, we agreed to grant Sobi an exclusive, worldwide (except as to Greater China) license to develop, manufacture and commercialize the SEL-212 drug candidate, which is currently in development for the treatment of chronic refractory gout. The SEL-212 drug candidate is a pharmaceutical composition containing a combination of SEL-037, which we refer to as the Compound, and ImmTOR. Pursuant to the Sobi License, in consideration of the license, Sobi agreed to pay us a one-time, upfront

payment of $75.0 million. Sobi has also agreed to make milestone payments totaling up to $630.0 million to us upon the achievement of various development and regulatory milestones and, if commercialized, sales thresholds for annual net sales of SEL-212, and tiered royalty payments ranging from the low double digits on the lowest sales tier to the high teens on the highest sales tier. Any proceeds received from milestone payments or royalties relating to the Sobi License would be required to be distributed to holders of CVRs, net of certain deductions.

Pursuant to the Sobi License, we agreed to supply (at cost) quantities of the Compound and ImmTOR as necessary for completion of the two Phase 3 clinical trials of SEL-212 (DISSOLVE I and DISSOLVE II) and a six-month placebo extension. We were required to supply quantities of the Compound until all rights to the Compound and any materials needed to manufacture the Compound were transferred to Sobi, which transfer occurred upon the execution of Amendment No. 1 to the License and Development Agreement on October 31, 2023. Sobi agreed to reimburse us for all budgeted costs incurred to complete development of SEL-212, including but not limited to costs incurred while conducting and completing the Phase 3 DISSOLVE trials, except for any costs of additional development activities required that are related to ImmTOR and that are unrelated to SEL-212. Sobi will have control and responsibility over all regulatory filings, including any IND, BLA, and marketing authorization applications relating to the licensed product.

The transactions contemplated by the Sobi License were consummated on July 28, 2020. Sobi may terminate the Sobi License for any reason upon 180 days’ written notice, whereby all rights granted under the Sobi License would revert back to us. In addition, if Sobi were to terminate the Sobi License, we have the option to obtain a license to all patents and know-how necessary to exploit SEL-212 in existence as of the termination date from Sobi in return for making an equitable royalty payment to Sobi.

The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition, and a strong emphasis on proprietary products. We face potential competition from many different sources, including pharmaceutical and biotechnology companies, academic institutions, governmental agencies, and public and private research institutions. Product candidates that we successfully develop and commercialize may compete with existing therapies and new therapies that may become available in the future.

Our competitors may have significantly greater financial resources, established presence in the market, expertise in research and development, manufacturing, preclinical and clinical testing, obtaining regulatory approvals and reimbursement and marketing approved products than we do. These competitors also compete with us in recruiting and retaining qualified scientific, sales, marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies.

The key competitive factors affecting the success of any other cell therapy product candidates that we develop, if approved, are likely to be their efficacy, safety, convenience, price, the level of generic competition and the availability of reimbursement from government and other third-party payors.

Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of generic or biosimilar products.

Descartes-08 may compete with products of other companies in the MG market, including Argenx SE, UCB S.A., Johnson & Johnson, Alexion Pharmaceuticals, Inc. and Cabaletta Bio, Inc.

Other companies developing CAR-T therapies include large, fully integrated pharmaceutical companies such as Novartis AG, Gilead Sciences, Inc., through its Kite Pharma, Inc. subsidiary, Bristol-Myers Squibb Company, AstraZeneca PLC and Janssen Pharmaceuticals, Inc. and biopharmaceutical companies such as Kyverna Therapeutics, Inc. and Cabaletta Bio, Inc.

Government authorities in the United States, at the federal, state and local level, and in other countries extensively regulate, among other things, the research, development, testing, manufacturing, quality control,

approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, post-approval monitoring and reporting, marketing and export and import of products such as those we are developing.

We believe our cell therapy product candidates are subject to regulation in the United States as “biologics” or “biological products.” We expect to seek approval of Descartes-08 through a single BLA reviewed by FDA’s Center for Biologics Evaluation and Research (“CBER”).

Biological products are subject to regulation under the Federal Food, Drug, and Cosmetic Act (“FD&C Act”) and the Public Health Service Act (“PHS Act”), and other federal, state, local and foreign statutes and regulations. Descartes-08 and any other product candidates that we develop must be approved by the FDA before they may be legally marketed in the United States and by the appropriate foreign regulatory agency before they may be legally marketed in foreign countries.

We regard our mRNA-modified products as cell therapy products and not as genetic engineering or gene therapy products, because mRNA modifications are not embodied in DNA or incorporated into a genome. However, it is possible that in some jurisdictions, regulations on genetic engineering or genetic therapy may intentionally or unintentionally apply to our technology. This could create additional regulatory burden.

The process required by the FDA before a biologic, including a cell therapy, may be marketed in the United States is summarized below.

Biological product candidates are preclinically tested before any testing is done in humans. These tests, or non-clinical studies, include laboratory evaluations of product chemistry, toxicity and formulation, as well as animal studies to assess the potential safety and activity of the product candidate. The conduct of the preclinical tests must comply with federal requirements including good laboratory practices (“GLPs”).

The clinical study sponsor must submit the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and a proposed clinical protocol, to the FDA as part of the IND which must become effective before human clinical trials may begin. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA places the clinical study on a clinical hold within that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical study can begin. The FDA may also impose clinical holds on a biological product candidate at any time before or during clinical trials due to safety concerns, non-compliance with regulatory requirements, or other issues. If the FDA imposes a clinical hold, trials may not recommence without FDA authorization and then only under terms authorized by the FDA. In addition to these requirements, biological product candidates may also require evaluation and assessment by an institutional biosafety committee (“IBC”), that reviews and oversees research utilizing recombinant or synthetic nucleic acid molecules at an institution participating in a clinical trial.

Clinical trials are conducted under protocols detailing the objectives of the clinical study, dosing procedures, patient selection and exclusion criteria, and the parameters to be used to monitor patient safety. Each protocol and any amendments to the protocol must be submitted to the FDA as part of the IND. Clinical trials must be conducted and monitored in accordance with the FDA’s regulations, including with respect to GCP requirements, including the requirement that all research subjects provide informed consent. Further, each clinical study must be reviewed and approved by an IRB at or servicing each institution at which the clinical study will be conducted. Human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

Cell and gene therapy products may differ from the traditional clinical trial phases. For example, clinical trials for cell and gene therapy products are often structured as a hybrid Phase 1/2 study where a small group of participants with the disease are enrolled and both safety and efficacy tests are performed.

Post-approval clinical trials, sometimes referred to as Phase 4 clinical trials, may be conducted after initial marketing approval to gain additional experience from the treatment of patients in the intended therapeutic indication, particularly for long-term safety follow-up.

The FDA or the sponsor or a separate data safety monitoring board may suspend or terminate a clinical study at any time on various grounds. Similarly, an IRB can suspend or terminate approval of a clinical study at its institution if the clinical study is not being conducted in accordance with the IRB’s requirements or if the biological product candidate has been associated with unexpected serious harm to patients or otherwise in the interest of patient welfare.

Sponsors of clinical trials of FDA-regulated products, including biologics, are also required to register and disclose certain clinical trial information, which is publicly available at www.clinicaltrials.gov.

After the completion of clinical trials of a biological product candidate, FDA approval of a BLA must be obtained before commercial marketing of the biological product. The BLA must include results of product development, laboratory and animal trials, human trials, information on the manufacture and composition of the product, proposed labeling and other relevant information. In addition, under the Pediatric Research Equity Act (“PREA”), a BLA or supplement to a BLA must contain a pediatric assessment unless the applicant has obtained a waiver or deferral. Pediatric assessment contains data gathered from pediatric studies using appropriate formulations for each age group for which the assessment is required and other data adequate to assess the safety and effectiveness of the biological product candidate for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. Sponsors with an application for a new active ingredient, new indication, new dosage form, new dosing regimen, or new route of administration must submit an initial Pediatric Study Plan (“PSP”) (or a deferral or waiver, as appropriate) within 60 days of an end-of-Phase 2 meeting or as may be agreed between the sponsor and FDA. Unless otherwise required by regulation, PREA does not apply to any biological product for an indication for which orphan designation has been granted.

Under the Prescription Drug Fee User Act, as amended (“PDUFA”), each BLA must be accompanied by a substantial user fee. Fee waiver or reductions are available under certain circumstances, including for the first application filed by a small business. In addition, no user fees are assessed on BLAs on products designated as orphan drugs unless the product also includes a non-orphan indication.

Within 60 days following submission of the application, the FDA conducts a preliminary review of a BLA to determine whether they are sufficiently complete to permit substantive review. The FDA may request additional information before deciding whether to accept a BLA for filing. The FDA may refuse to file any BLA that it deems incomplete or otherwise not reviewable and may request additional information. If the submission is accepted for filing, the FDA substantively reviews the BLA to determine, among other things, whether the proposed product is safe, pure and potent, and manufactured in accordance with appropriate procedures and controls to ensure product quality. The FDA may refer applications for novel biological products or biological products that present difficult questions of safety or efficacy to an advisory committee, typically a panel that includes clinicians and other experts, for review, evaluation and a non-binding recommendation on approval. The FDA may waive the review by an advisory committee and is not bound by the recommendation of an advisory committee, but it often follows such recommendations. During the biological product approval process, the FDA also will review proposed product labeling and will determine whether a REMS is necessary to assure the safe use of the biological product candidate. If the FDA concludes a REMS is needed, the sponsor of the BLA must submit a proposed REMS; the FDA will not approve the BLA without a REMS, if required.

Before approving a BLA, the FDA will inspect the facilities in which the product is manufactured to determine whether the manufacturing processes and facilities are in compliance with cGMPs. The FDA may also audit the clinical investigation sites to determine that they have complied with good clinical practices.

Notwithstanding the submission of relevant data and information, the FDA may ultimately deny approval or seek additional information from the applicant. Data obtained from clinical trials are not always conclusive and the FDA may interpret data differently than the applicant interprets the same data. The FDA may also raise questions

about product manufacturing and quality control. If the FDA denies approval of a BLA in its then-current form, the FDA will issue a complete response letter detailing deficiencies in the application. If a response letter is issued, the applicant may either resubmit the BLA, addressing all of the deficiencies identified in the letter, or withdraw the application.

One of the performance goals agreed to by the FDA under PDUFA is to review 90% of standard BLAs in 10 months from the filing date and 90% of priority BLAs in six months from the filing date, whereupon a review decision is to be made. Two additional months are added to these timelines for new molecular entities. The FDA does not always meet its PDUFA goal dates for standard and priority BLAs.

Prior to the submission of a BLA, the FDA may grant orphan designation to drugs or biologics intended to treat a rare disease or condition that affects fewer than 200,000 individuals in the United States, or if it affects more than 200,000 individuals in the United States, there is no reasonable expectation that the cost of developing and marketing the product for this type of disease or condition will be recovered from sales in the United States. After the FDA grants orphan designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan designation does not convey any advantage in or shorten the duration of the regulatory review and approval process.

In the United States, orphan designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers. In addition, if a product receives the first FDA approval for the indication for which it has orphan designation, the product is entitled to orphan exclusivity, which means the FDA may not approve any other application to market the “same drug” for the same indication for a period of seven years, except in limited circumstances, such as a showing of clinical superiority over the product with orphan exclusivity or where the manufacturer with orphan exclusivity is unable to assure sufficient quantities of the approved orphan product. Competitors, however, may receive approval of different products for the indication for which the orphan product has exclusivity or obtain approval for the same product but for a different indication for which the orphan product has exclusivity. Orphan product exclusivity also could block the approval of one of our products for seven years if a competitor obtains approval of the same biological product as defined by the FDA or if our product candidate is determined to be contained within the competitor’s product for the same indication or disease.

Descartes-08 has been granted Orphan Drug Designation for the treatment of MG.

The FDA offers various programs, including the Fast Track program, Breakthrough Therapy designation, and the RMAT designation that are intended to expedite or facilitate the process for reviewing new biological products that meet certain criteria. Specifically, new biological products are eligible for Fast Track designation if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast Track designation applies to the combination of the product and the specific indication for which it is being studied. The sponsor of a new biologic may request that the FDA designate the biologic as a Fast Track product at any time during the clinical development of the product.

Any product submitted to the FDA for marketing, including under a Fast Track program, may be eligible for other types of FDA programs intended to expedite development and review, such as priority review and accelerated approval. Any product is eligible for priority review if it treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness of treatment, diagnosis, or prevention compared to available therapies.

Additionally, a product may be eligible for accelerated approval. The FDA may approve a product for a serious or life-threatening disease or condition based on a determination that the product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments. As a condition of approval, the FDA may require that a sponsor of a biological product subject to accelerated approval perform adequate and well-controlled post-marketing clinical studies to confirm such benefit. The Food and Drug Omnibus Reform Act of 2022 (“FDORA”), added the

failure to conduct post-approval studies with due diligence or to submit timely progress reports on such studies to the list of prohibited acts under the FD&C Act, which means that any such failures, whether they result from a sponsor’s actions or the actions of third parties, could provide the basis for enforcement actions. In addition, the FDA currently requires as a condition for accelerated approval that promotional materials be submitted prior to use, which could adversely impact the timing of the commercial launch of the product.

In addition, under the provisions of The Food and Drug Safety and Innovation Act (“FDASIA”), the FDA established a Breakthrough Therapy Designation which is intended to expedite the development and review of products that treat serious or life-threatening diseases or conditions. A breakthrough therapy is defined as a drug that is intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the features of Fast Track designation, as well as more intensive FDA interaction and guidance. Fast Track, priority review, accelerated approval, and breakthrough therapy designations do not change the standards for approval and may not necessarily expedite the development or approval process.

In 2016, the 21st Century Cures Act established what the FDA describes as a regenerative medicine adventure therapy (“RMAT”) designation. The RMAT designation program is intended to facilitate an efficient development program for, and expedite review of, any product that meets the following criteria: (i) the product qualifies as an RMAT, which is defined as a cell therapy, therapeutic tissue engineering product, human cell and tissue product, or any combination product using such therapies or products, with limited exceptions; (ii) the product is intended to treat, modify, reverse, or cure a serious or life-threatening disease or condition; and (iii) preliminary clinical evidence indicates that the product has the potential to address unmet medical needs for such a disease or condition. RMAT designation provides all the benefits of Breakthrough Therapy Designation, including early interactions to discuss any potential surrogate or intermediate endpoints to be used to support accelerated approval, eligibility for rolling review and potential eligibility for priority review. Product candidates granted RMAT designation may also be eligible for accelerated approval on the basis of a surrogate or intermediate endpoint reasonably likely to predict long-term clinical benefit, or reliance upon data obtained from a meaningful number of clinical trial sites, including through expansion of trials to additional sites, as appropriate. Descartes-08 has been granted RMAT designation for the treatment of MG.

Rigorous and extensive FDA regulation of biological products continues after approval, particularly with respect to cGMP requirements. Manufacturers of our products are required to comply with applicable requirements in the cGMP regulations, including quality control and quality assurance and maintenance of records and documentation. Other post-approval requirements applicable to biological products include record-keeping requirements, reporting of adverse effects and reporting updated safety and efficacy information.

We also must comply with the FDA’s advertising and promotion requirements, such as the prohibition on promoting products for uses or in patient populations that are not described in the product’s approved labeling, known as “off-label use,” and the requirement to balance information provided about a product’s benefits with important safety information. Discovery of previously unknown problems or the failure to comply with the applicable regulatory requirements may result in restrictions on the marketing of a product or withdrawal of the product from the market as well as possible civil or criminal sanctions. Failure to comply may subject an applicant or manufacturer to administrative or judicial civil or criminal sanctions, expensive and onerous government investigations, and adverse publicity.

Conventional DNA-modified CAR-T cell products have been subject to extensive post-approval surveillance requirements. Because the mRNA of our products is temporary, we do not believe that our mRNA-modified products will be subject to requirements of this nature, although other post-approval requirements will apply.

The ACA includes a subtitle called the BPCIA, which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product.

Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity and potency, can be shown through analytical studies, animal studies and a clinical study or studies. The FDA has approved a number of products under these provisions.

To the Company’s knowledge, the definition of “biosimilar” with regard to an mRNA-modified cell therapy has not been expressly stated in statute, regulation, or guidance, and has not been reviewed by a court. The regulatory pathway for a biosimilar to one of our products thus remains somewhat uncertain.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product. A biological product may also obtain pediatric exclusivity in the United States. For a biological product, pediatric exclusivity, if granted, adds six months to existing regulatory exclusivity periods. This six-month exclusivity, which runs from the end of other exclusivity protection, may be granted based on the voluntary completion of a pediatric study in accordance with an FDA-issued “Written Request” for such a study or studies.

The BPCIA is complex and continues to be interpreted and implemented by the FDA. As a result, the ultimate impact, implementation and meaning of the BPCIA is subject to significant uncertainty.

Whether or not we obtain FDA approval for a product, we must obtain the requisite approvals from regulatory authorities in countries outside the United States prior to the commencement of clinical studies or marketing of the product in those countries.

The requirements and process governing the conduct of clinical studies, product licensing, pricing and reimbursement vary from country to country. In all cases, the clinical studies are conducted in accordance with GCP and the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki.

In the European Economic Area (“EEA”), which is composed of the 27 member states of the European Union (“EU”), plus Norway, Iceland and Liechtenstein, medicinal products can only be commercialized after obtaining a Marketing Authorization (“MA”). There are two types of MAs.

The EU MA, which is issued by the European Commission through the Centralized Procedure, is based on the opinion of the Committee for Medicinal Products for Human Use (“CHMP”) of the European Medicines Agency (“EMA”), and which is valid throughout the entire territory of the EEA. The Centralized Procedure is mandatory for certain types of products, such as biotechnology medicinal products, orphan medicinal products, advanced therapy medicinal products (comprising gene therapy, somatic cell therapy and tissue engineered products), among others. The Centralized Procedure is optional for other products containing a new active substance not yet authorized in the EEA, or for other products that constitute a significant therapeutic, scientific or technical innovation or which are in the interest of public health in the EU. Under the Centralized Procedure the maximum timeframe for the evaluation of a marketing authorization application is 210 days (excluding clock stops, when additional written or oral information is to be provided by the applicant in response to questions asked by the CHMP). Accelerated evaluation might be granted by the CHMP in exceptional cases. Under the accelerated procedure the standard 210 days review period is reduced to 150 days.

National MAs, which are issued by the competent authorities of the Member States of the EEA and only cover their respective territory, are available for products not falling within the mandatory scope of the Centralized Procedure. Where a product has already been authorized for marketing in a Member State of the EEA, this National MA can be recognized in another Member States through the Mutual Recognition Procedure. If the product has not received a National MA in any Member State at the time of application, it can be approved simultaneously in various Member States through the Decentralized Procedure.

To obtain regulatory approval of medical product under EU regulatory systems, we must submit a marketing authorization application, which is similar to the U.S. BLA. The EU also provides opportunities for market

exclusivity. Upon receiving marketing authorization, “new active substances” generally receive eight years of data exclusivity, which prevents regulatory authorities in the EU from referencing the innovator’s data to assess a generic or biosimilar application, and an additional two years of market exclusivity, during which no generic or biosimilar product can be marketed. However, there is no guarantee that a product will be considered by the EU’s regulatory authorities to be a new active substance, and products may not qualify for data exclusivity. Products receiving orphan designation in the EU can receive ten years of market exclusivity, during which time no marketing authorization application shall be accepted, and no marketing authorization shall be granted for a similar medicinal product for the same indication. An orphan product can also obtain an additional two years of market exclusivity in the EU for pediatric studies. No extension to any supplementary protection certificate can be granted on the basis of pediatric studies for orphan indications.

The criteria for designating an “orphan medicinal product” in the EU are similar in principle to those in the United States. Under Article 3 of Regulation (EC) 141/2000, a medicinal product may be designated as orphan if (i) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (ii) either (a) such condition affects no more than five in 10,000 persons in the EU when the application is made, or (b) the product, without the benefits derived from orphan status, would not generate sufficient return in the EU to justify investment; and (iii) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU, or if such a method exists, the product will be of significant benefit to those affected by the condition, as defined in Regulation (EC) 847/2000. Orphan medicinal products are eligible for certain financial and exclusivity incentives.

For other countries outside of the EU, such as countries in Eastern Europe, Latin America or Asia, the requirements governing the conduct of clinical studies, product licensing, pricing and reimbursement vary from country to country. In all cases, again, the clinical studies are conducted in accordance with GCP and the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki.

When conducting clinical trials in the EU, we must adhere to the provisions of the EU Clinical Trials Directive (Directive 2001/20/EC) and the laws and regulations of the EU Member States implementing them. These provisions require, among other things, that the prior authorization of an Ethics Committee and the competent Member State authority is obtained before commencing the clinical trial. In 2014, the EU passed the Clinical Trials Regulation (Regulation 536/2014), which will replace the current Clinical Trials Directive, to ensure that the rules for clinical trials are identical throughout the EU.

We are also subject to data privacy and security laws in the jurisdictions outside of the U.S. in which we are established, run clinical trials or in which we sell or market our products once approved. For example, in Europe we are subject to Regulation (EU) 2016/679 (GDPR) in relation to our collection, control, processing and other use of personal data (i.e., data relating to an identifiable living individual). We process personal data in relation to participants in our clinical trials in the EEA, including the health and medical information of these participants. The GDPR is directly applicable in each EU Member State, however, it provides that EU Member States may introduce further conditions, including limitations which could limit our ability to collect, use and share personal data (including health and medical information), or could cause our compliance costs to increase, ultimately having an adverse impact on our business. The GDPR imposes accountability and transparency obligations regarding personal data. We are also subject to EU rules with respect to cross-border transfers of personal data out of the EU and EEA. We are subject to the supervision of local data protection authorities in those EU jurisdictions where we are established or otherwise subject to the GDPR. A breach of the GDPR could result in significant fines, regulatory investigations, reputational damage, orders to cease/ change our use of data, enforcement notices, as well potential civil claims including class action type litigation where individuals suffer harm. Moreover, the United Kingdom leaving the EU could also lead to further legislative and regulatory changes. It remains unclear how the United Kingdom data protection laws or regulations will develop in the medium to longer term and how data transfer to the United Kingdom from the EU will be regulated. However, the United Kingdom has transposed the GDPR into domestic law with the Data Protection Act 2018, which remains in force following the United Kingdom’s departure from the EU.

The federal Anti-Kickback Statute prohibits, among other things, any person or entity from knowingly (regardless of knowledge of this specific statute) and willfully offering, paying, soliciting, receiving or providing any remuneration, directly or indirectly, overtly or covertly, to induce or in return for purchasing, leasing, ordering, or

arranging for or recommending the purchase, lease, or order of any item or service reimbursable, in whole or in part, under Medicare, Medicaid or other federal healthcare programs. The term “remuneration” has been broadly interpreted to include anything of value. The Anti-Kickback Statute has been interpreted to apply to arrangements between pharmaceutical manufacturers on the one hand and prescribers, purchasers, formulary managers, and other third parties on the other. The majority of states also similar have anti-kickback laws, which in some cases apply to items and services reimbursed by private insurance.

The federal false claims and civil monetary penalties laws, including the civil False Claims Act, prohibit any person or entity from, among other things, knowingly presenting, or causing to be presented, a false, fictitious or fraudulent claim for payment to, or approval by, the federal government or knowingly making, using, or causing to be made or used a false record or statement material to a false or fraudulent claim to the federal government, or from knowingly making a false statement to avoid, decrease or conceal an obligation. A claim includes “any request or demand” for money or property presented to the U.S. government. Manufacturers can be held liable under false claims laws, even if they do not submit claims to the government, where they are found to have caused submission of false claims by, among other things, providing incorrect coding or billing advice about their products to customers that file claims, or by engaging or off-label promotion to customers that file claims. Violation of the federal Anti-Kickback Statute may also constitute a false or fraudulent claim for purposes of the federal civil False Claims Act. Actions under the civil False Claims Act may be brought by the Department of Justice or as a qui tam action by a private individual in the name of the government. Many states also have similar fraud and abuse statutes or regulations that apply to items and services reimbursed under Medicaid and other state programs, or, in several states, apply regardless of the payor.

HIPAA prohibits, among other actions, knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program, including private third-party payors, knowingly and willfully embezzling or stealing from a healthcare benefit program, willfully obstructing a criminal investigation of a healthcare offense, and knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false, fictitious or fraudulent statement in connection with the delivery of or payment for healthcare benefits, items or services. A person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation.

In addition, the Physician Payments Sunshine Act requires applicable manufacturers to annually report certain payments and “transfers of value” provided to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain other health care providers, as well as ownership and investment interests held by physicians and their immediate family members.

Sanctions under these federal and state fraud and abuse laws may include civil monetary penalties and criminal fines, exclusion from government healthcare programs, and imprisonment.

We may also be subject to data privacy and security regulation by both the federal government and the states in which we conduct our business. HIPAA, as amended by HITECH and their respective implementing regulations, impose specified requirements relating to the privacy, security and transmission of individually identifiable health information held by covered entities and their business associates. Among other things, HITECH made HIPAA’s security standards directly applicable to, as well as imposed certain other privacy obligations on, “business associates,” defined as independent contractors or agents of covered entities that create, receive, maintain or transmit protected health information in connection with providing a service for or on behalf of a covered entity. HITECH also increased the civil and criminal penalties that may be imposed and gave state attorneys general new authority to file civil actions for damages or injunctions in federal courts to enforce the federal HIPAA laws and seek attorney’s fees and costs associated with pursuing federal civil actions. Even when HIPAA does not apply, according to the Federal Trade Commission (“FTC”), failing to take appropriate steps to keep consumers’ personal information secure constitutes unfair acts or practices in or affecting commerce in violation of Section 5(a) of the Federal Trade Commission Act, 15 U.S.C § 45(a).

Significant uncertainty exists as to the coverage and reimbursement status of any pharmaceutical or biological products for which we obtain regulatory approval. In the United States and markets in other countries, patients who are prescribed treatments for their conditions and providers performing the prescribed services generally rely on third-party payors to reimburse all or part of the associated healthcare costs. Sales of any products for which we receive regulatory approval for commercial sale will therefore depend, in part, on the availability of coverage

and adequate reimbursement from third-party payors. Third-party payors include government authorities, managed care plans, private health insurers and other organizations.

The process for determining whether a third-party payor will provide coverage for a pharmaceutical or biological product typically is separate from the process for setting the price of such product or for establishing the reimbursement rate that the payor will pay for the product once coverage is approved. Third-party payors may limit coverage to specific products on an approved list, also known as a formulary, which might not include all of the FDA-approved products for a particular indication.

A decision by a third-party payor not to cover our product candidates could reduce physician utilization of our products once approved and have a material adverse effect on our sales, results of operations and financial condition. Moreover, a third-party payor’s decision to provide coverage for a pharmaceutical or biological product does not imply that an adequate reimbursement rate will be approved. Adequate third-party reimbursement may not be available to enable us to maintain price levels sufficient to realize an appropriate return on our investment in product development.

A primary trend in the U.S. healthcare industry and elsewhere is cost containment. Government authorities and other third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medical products.

Federal, state and local governments in the U.S. have established and continue to consider policies to limit the growth of healthcare costs, including the cost of prescription drugs. Recently there has also been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed and enacted legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for prescription drugs.

At the federal level, for example, the Inflation Reduction Act of 2022 (“IRA”), was signed into law. Key provisions of the IRA include the following, among others:

Manufacturers that fail to comply with the IRA may be subject to various penalties, including civil monetary penalties or a potential excise tax. The IRA permits the Secretary of Health and Human Services (the “HHS Secretary”) to implement many of the IRA’s provisions through guidance, as opposed to regulation, for the initial years. The effect of the IRA is anticipated to have significant effects on the pharmaceutical industry and may reduce the prices pharmaceutical manufacturers can charge and reimbursement pharmaceutical manufacturers can receive for approved products, among other effects.

In addition, other legislative changes have been proposed and adopted in the United States. This included aggregate reductions of Medicare payments to providers of 2% per fiscal year, which went into effect on April 1, 2013, and, due to subsequent legislative amendments, will stay in effect through 2027 unless additional Congressional action is taken. On January 2, 2013, the American Taxpayer Relief Act was signed into law, which, among other things, further reduced Medicare payments to several providers, including hospitals and imaging centers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years.

The Biden administration has indicated that lowering prescription drug prices is a priority. On October 14, 2022, President Biden signed an executive order to lower prescription drug costs for Americans. In response to this directive, the HHS Secretary announced and the Center for Medicare and Medicaid Innovation is developing three new models intended to lower drug costs under Medicare and Medicaid, including establishing a new approach for administering outcomes-based agreements for cell and gene therapies. President Biden also signed an executive order on July 9, 2021 affirming the administration’s policy to, among other things, support legislative reforms that would lower the prices of prescription drugs, including by supporting the development and market entry of lower-cost generic drugs and biosimilars, and support the enactment of a public health insurance option. Among other things, the executive order directs the HHS Secretary to provide a report on actions to combat excessive pricing of prescription drugs, continue to clarify and improve the approval framework for generic drugs and identify and address any efforts to impede generic drug competition, enhance the domestic drug supply chain, reduce the price that the federal government pays for drugs, and address price gouging in the industry. The executive order also directs the FDA to work with states and Indian Tribes that propose to develop section 804 Importation Programs in accordance with the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, and the FDA’s implementing regulations. The FDA released such implementing regulations on September 24, 2020, which went into effect on November 30, 2020, providing guidance for states to build and submit importation plans for drugs from Canada. In response, authorities in Canada have passed rules designed to safeguard the Canadian drug supply from shortages. On January 5, 2024, the FDA authorized Florida’s Agency for Health Care Administration’s drug importation proposal, the first step toward Florida facilitating importation of certain prescription drugs from Canada.

At Cartesian Therapeutics, we consider human capital to be an essential driver of our business and successful strategy creation and execution. Our people, driven by our collaborative, pioneering, and patient-focused culture, propel our business forward, strengthening us for long-term success.

As of December 31, 2023, we had 38 employees, 26 of whom are primarily engaged in research and development activities and 12 in corporate functions. 37 of our employees are employed by us on a full-time basis. 73.6% of our employees have at least one of a Masters, PhD, or MD degree. All employees reside and work in the United States and our employees are not represented by a labor union. We consider our employee relations to be strong and in good standing.

Our goal is to continually engage our talented and diverse workforce to drive value creation both for our business and ultimately our patient populations. We believe in a proactive approach to talent management focusing on retention of key talent, critical role successor identification, and impactful employment development. Additional priority areas intended to drive engagement include successful recruitment of diverse talent, continual promotion of professional development at all levels, introduction, and evolution of business-friendly human resources solutions, coupled with an intentional culture dialog aimed to drive a high engagement, high performance, patient centric culture.

To further drive attraction and retention of our high-quality, experienced, and diverse workforce, we invest in the physical, emotional, and financial well-being of our employees. These investments include a competitive mix of compensation and generous insurance benefits. To assist employees with the rising cost of healthcare, we pay 100% of an employee’s deductible and co-insurance payments. All employees are eligible to participate in our equity compensation programs. All employees are awarded new hire equity and annual equity. Employees are also eligible to receive an annual cash bonus and to participate in a 401(k) retirement plan with an industry competitive company match.

Our corporate headquarters are currently located at 704 Quince Orchard Road, Gaithersburg, Maryland and consists of 7,909 total square feet of leased office, laboratory, and manufacturing space under a lease that expires in January 2027. Additionally, we lease approximately 27,041 square feet consisting of integrated manufacturing and office space in Frederick, Maryland under a lease expires in June 2031, and we lease approximately 32,294 total square feet of office and laboratory space in Watertown, Massachusetts under a lease that expires in May 2028.

We are not party to any material legal proceedings.

Our Common Stock is listed on the Nasdaq Global Market under the ticker symbol “RNAC.” We have not applied to list, and we do not plan to list, the Series A Preferred Stock or Series B Preferred Stock on any national securities exchange. As of July 29, 2024, there were 116 holders of record of our Common Stock.

The following table provides information on our equity compensation plans as of December 31, 2023.