Quarterly Report for Quarter Ending September 30, 2025 (Form 10-Q)

Management's Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of our financial condition and operating results together with our financial statements and the related notes appearing at the end of this Quarterly Report on Form 10-Q. This discussion contains forward-looking statements that involve risks and uncertainties. As a result of many factors, such as those set forth in the section of the Quarterly Report on Form 10-Q captioned "Risk Factors" and elsewhere in this Quarterly Report on Form 10-Q, our actual results may differ materially from those anticipated in these forward-looking statements.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 under Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements include statements with respect to our beliefs, plans, objectives, goals, expectations, anticipations, assumptions, estimates, intentions, and future performance, and involve known and unknown risks, uncertainties, and other factors, which may be beyond our control, and which may cause our actual results, performance, or achievements to be materially different from future results, performance or achievements expressed or implied by such forward-looking statements. All statements other than statements of historical fact are statements that could be forward-looking statements. You can identify these forward-looking statements through our use of words such as "may," "can," "anticipate," "assume," "should," "indicate," "would," "believe," "contemplate," "expect," "seek," "estimate," "continue," "plan," "point to," "project," "predict," "could," "intend," "target," "potential" and other similar words and expressions of the future.

There are a number of important factors that could cause the actual results to differ materially from those expressed in any forward-looking statement made by us. These factors include, but are not limited to:

The foregoing does not represent an exhaustive list of matters that may be covered by the forward-looking statements contained herein or risk factors that we are faced with that may cause our actual results to differ from those anticipate in our forward-looking statements.

All forward-looking statements are expressly qualified in their entirety by this cautionary notice. You are cautioned not to place undue reliance on any forward-looking statements, which speak only as of the date of this report or the date of the document incorporated by reference into this report. We have no obligation, and expressly disclaim any obligation, to update, revise or correct any of the forward-looking statements, whether as a result of new information, future events or otherwise. We have expressed our expectations, beliefs and projections in good faith and we believe they have a reasonable basis. However, we cannot assure you that our expectations, beliefs, or projections will result or be achieved or accomplished.

Overview

We are a clinical-stage biotechnology company focused on developing proprietary new therapies to enhance the function of regulatory T cells ("Tregs"). Tregs are a subpopulation of T-lymphocytes consisting of CD4+CD25high hFOXP3+ cells that suppress inflammatory responses. Tregs were first discovered in 1995 by Dr. Shimon Sakaguchi. On October 6, 2025, Dr. Sakaguchi, along with two others, was awarded the Nobel Prize in Physiology or Medicine. Since Tregs were discovered, multiple lines of research have contributed to elucidate Treg biology and its role in health and disease. Tregs and their transcription factors have been shown to be essential to maintaining cellular homeostasis by regulating autoimmune and inflammatory responses and maintaining self-tolerance in mammals. Dysfunctional Tregs underlie numerous disease states, and this cellular dysfunction is driven by the chronic inflammatory environment and high levels of oxidative stress commonly observed in certain diseases. Further, the degree of Treg dysfunction is correlated with the severity and progression of serious and life-threatening conditions. These and other recent advances in the understanding of Treg biology, have made this subset of T-lymphocytes an important potential therapeutic target, which we believe may provide new treatments for serious diseases.

Our core focus is developing therapies to target Treg dysfunction. Treg disfunction has been identified as an important pathophysiological component of neurodegenerative, autoimmune, and metabolic diseases, all areas where we believe new and effective therapies are urgently needed. We believe we have expertise in three distinct potential therapeutic modalities: Treg-enhancing biologics, Treg-derived exosomes, and autologous Treg cell therapy. Our expertise includes both ex vivoand in vivoapproaches intended to restore the suppressive and immunomodulatory functions of Tregs.

Our lead asset, COYA 302, is a Treg-enhancing biologic, which was developed from key learnings established in our early work and discoveries of our autologous Treg cell therapy asset. Our autologous Treg cell therapy program has completed a Phase 1 and Phase 2a studies in amyotrophic lateral sclerosis, or ALS. The clinical data from these initial studies has served as an important confirmation of the underlying immunomodulatory properties of Tregs and their potential therapeutic benefits. These studies have also significantly expanded our own foundational knowledge of the biological activity of Tregs and key biomarkers of disease progression and drug effect, which we believe will be critical for the design of our future clinical and preclinical studies, the selection of future targeted diseases and the overall advancement of our development pipeline. We believe our findings have also established mechanistic benefits of combination biologics to address Treg dysfunction as well as highlighted important advantages of scalability and cost.

COYA 302 is the combination of our proprietary low dose interleukin-2 (COYA 301, or LD IL-2) and the immunomodulatory drug CTLA4-Ig, and we believe this combination has the potential to provide a sustained and durable effect on our first series of indications (neurodegenerative disorders) through targeting of multiple pathways. Our research and clinical efforts have led us to believe that combination biologics using our LD IL-2 as a backbone modality could be an effective way to treat neurodegenerative conditions that are inherently driven by a complexity of pathways. We believe COYA 302 is the most clinically advanced of what we hope will be a family of combination therapies that all feature our LD IL-2. Given the growing list of indications for which we are developing it, we can now refer to COYA 302 as a "Pipeline in a Product."

We are currently conducting the ALSTARS Trial, a Phase 2, randomized, multi-center, double-blind, placebo-controlled study to evaluate the efficacy and safety of COYA 302 for the treatment of ALS (ClinicalTrials.gov Identifier: NCT 07161999). COYA 302 is an investigational product not yet approved by the U.S. Food and Drug Administration, or the FDA, or any other regulatory agency.

Our operations have consisted of developing our clinical and preclinical product candidates and we have devoted substantially all of our resources to developing product and technology rights, conducting research and development (which includes preclinical and non-clinical studies of our product candidates), organizing and staffing our company, ongoing business operations and raising capital.

We have funded our operations primarily through the private and public sale of our securities. Our net losses were $2.1 million and $4.0 million for the three months ended September 30, 2025 and 2024, respectively. Our net losses were $15.5 million and $12.0 million for the nine months ended September 30, 2025 and 2024, respectively. As of September 30, 2025, we had an accumulated deficit of $56.3 million. Our primary use of cash is to fund operating expenses, which consist primarily of research and development expenditures and general and administrative expenditures. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our current or future product candidates.

We expect to continue to incur significant expenses and operating losses for the foreseeable future as we advance our product candidates through all stages of development and clinical trials and, ultimately, seek regulatory approval. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to product manufacturing, marketing, sales and distribution. We expect our expenses and capital requirements will increase significantly in connection with our ongoing activities as we:

Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our clinical trials and our expenditures on other research and development activities.

We will need to raise substantial additional capital to support our continuing operations and pursue our growth strategy. Until such time as we can generate significant revenue from product sales, if ever, we plan to finance our operations through the sale of equity, debt financings or other capital sources, which may include collaborations with other companies or other strategic transactions. There are no assurances that we will be successful in obtaining an adequate level of financing as and when needed to finance our operations on terms acceptable to us or at all. Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies. If we are unable to secure adequate additional funding, we may have to significantly delay, scale back or discontinue the development and commercialization of one or more product candidates or delay our pursuit of potential in-licenses or acquisitions. The financial statements included elsewhere in this Quarterly Report on Form 10-Q have been prepared on a going-concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business and do not include any adjustments related to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Recent Developments

On April 21, 2025, we published the results of the study with our new product candidate. The study was designed to evaluate the effects of COYA 303 (LD IL-2 and GLP-1RA), our investigational biologic combination to suppress pro inflammatory myeloid cells, enhance Treg suppressive function, and modulate T cell proliferation, in an in vitrosystem of human immune cells obtained from healthy donors. The research was conducted at the Houston Methodist Research Institute and was led by Dr. Aaron Thome and Dr. Stan Appel. The research article has been published in the Journal NeuroImmune Pharmacology and Therapeutics. The study found, among other things, that following pro-inflammatory activation of myeloid cells co cultured with Tregs, the addition of COYA 301 (LD IL-2) alone enhanced Treg suppressive function by 15%. Similarly, when GLP-1RA alone was added to the system, Treg suppressive function increased by 20%. In contrast, when COYA 303 was added to the cell system a statistically significant increase in Treg suppressive function of 42% (p < 0.001) was observed, when compared to the increase observed with each of the single agents. Consistent with these results, treatment with COYA 303 promoted Treg survival by modulating the apoptotic pathway. COYA 303 significantly reduced BAX transcript levels during prolonged incubation (p < 0.01). These findings suggest a direct effect of COYA 303 supporting Treg

survival through the inhibition of Treg apoptosis. We believe that these data show that the combination approach of COYA 303 enhances Treg suppressive function in highly inflammatory microenvironments, while also promoting Treg survival by preventing apoptosis.

On June 2, 2025, we announced the issuance of a U.S. patent relevant to our investigational ready-to-use liquid formulation of IL-2, which covers methods of producing highly stable liquid formulations of IL-2 (aldesleukin). Through an existing agreement, we have the exclusive in-vivo rights to this patent and other related intellectual property spanning multiple indications both as monotherapy and combination therapies.

On August 29, 2025, the FDA accepted our Investigational New Drug Application, or IND, for the initiation of a planned clinical study entitled "Phase 2, Randomized, Double-Blind, Placebo-Controlled, Multi-Center, 24-Week Study with Additional 24-Week Open Label Extension (OLE) to Evaluate the Safety and Efficacy of COYA 302 for the Treatment of Amyotrophic Lateral Sclerosis (ALS)", or the Phase 2 Study. As a result of the FDA's acceptance of the IND for COYA 302, we received a $4.2 million milestone payment from Dr. Reddy's (defined below) as required under the terms of the Development and License Agreement, or the DRL Development Agreement.

On October 23, 2025, we entered into an Underwriting Agreement with Lucid Capital Markets, LLC, or the Underwriter, relating to an underwritten public offering, or the Offering, of 4,181,818 shares, or the Shares, of our common stock, par value $0.0001 per share, including 545,454 Shares pursuant to the full exercise of an option to purchase additional shares granted to the Underwriter. The Offering closed on October 27, 2025 and each Share was offered and sold to the public at an offering price of $5.50 per Share. Gross proceeds from the Offering, including the proceeds from the exercise by the Underwriter of its option to purchase additional Shares, was approximately $23.0 million, before deducting underwriting discounts and commissions and estimated Offering expenses payable by us.

Components of Results of Operations

Collaboration Revenue

To date, we have not recognized any revenue from product sales, and we do not expect to generate any revenue from the sale of products in the foreseeable future. If our development efforts for our product candidates are successful and result in regulatory approval, or license agreements with third parties, we may generate revenue in the future from product sales. However, there can be no assurance as to when we will generate such revenue, if at all. Collaboration revenue represents revenue from the DRL Development Agreement, as amended in June 2024, pursuant to which we granted Dr. Reddy's Laboratories Ltd. and its affiliate, Dr. Reddy's Laboratories SA, or collectively Dr. Reddy's, an exclusive, royalty-bearing right and license to commercialize COYA 302, solely for use in patients with ALS in the United States, Canada, the European Union and the United Kingdom, or collectively, the New Territories.

Operating Expenses

Research and Development Expenses

Research and development expenses consist primarily of costs incurred in connection with the discovery and development of our potential therapeutic candidates. We expense research and development costs as incurred, including:

We classify and evaluate our research and development expenses in two dimensions: clinical and preclinical, and external and internal. We do not further classify or evaluate our internal research and development expenses by product candidate or by Series as

these expenses primarily relate to compensation, materials and supplies, and other costs which are deployed across multiple potential therapeutic modalities, multiple product candidates, and multiple potential therapeutic areas under development.

Once a product candidate has received approval from the FDA of its IND application, we consider it a clinical product candidate. For each of our clinical product candidates, we report or will report external development costs and other external research and development costs attributable to such clinical product candidates. These external development costs include: fees paid to CROs, CMOs and research laboratories, process development, manufacturing and clinical development activities. Any internal research and development expenses associated with clinical product candidates are captioned as internal research and development costs as described in the paragraph above.

Until such time as a product candidate has received approval of its IND application, we consider it a preclinical product candidate. Each of our preclinical product candidates is being developed on one of our three potential therapeutic modalities: (1) Treg-enhancing biologics; (2) Treg-derived exosomes; and (3) autologous Treg cell therapy. The product candidates utilizing our Treg-enhancing biologics are collectively referred to as the "300 Series." The product candidates utilizing our Treg-derived exosomes are collectively referred to as the "200 Series." The product candidates utilizing our autologous Treg cell therapy are collectively referred to as the "100 Series." Currently, our 300 Series product candidates include COYA 301, COYA 302 and COYA 303, our 200 Series product candidates include COYA 201 and COYA 206, and our 100 Series product candidate is COYA 101. For our preclinical candidates we report external development costs and other external research and development costs collectively by Series. These external development costs include: fees paid to CROs, CMOs and research laboratories, process development, manufacturing and clinical development activities. Preclinical research and development activities often benefit more than one preclinical product candidate within a given Series and so disaggregating the data would neither be practicable or meaningful.

Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. We expect our research and development expenses to increase significantly over the next several years as we increase personnel costs, including stock-based compensation, conduct our clinical trials, including later-stage clinical trials, for current and future product candidates and prepare regulatory filings for our product candidates. In addition, we expect spending in 2025 to increase over 2024 spending levels driven primarily by the advancement of COYA 302 in a Phase 2 study in patients with ALS and in the preparation for an IND for the study of COYA 302 in patients with FTD. As described in the notes to financial statements contained elsewhere in this Quarterly Report on Form 10-Q, under the terms of our license we may be required to make payments to Methodist if certain milestones are achieved. This could result in significant charges to research and development in the period such milestones become probable of being achieved.

In-Process Research and Development

Research and development costs incurred in obtaining technology licenses are charged to research and development expense if the technology licensed has not reached technological feasibility which includes manufacturing, clinical, intellectual property and/or regulatory success which has no alternative future use. The licenses purchased by us require substantial completion of research and development and regulatory and marketing approval efforts in order to reach technological feasibility. As such, and since our inception, the purchase price of licenses acquired is classified as acquired in-process research and development expenses in the statements of operations.

General and Administrative Expenses

General and administrative expenses consist primarily of personnel expenses, including salaries, benefits and stock-based compensation expense, for employees and consultants in executive, finance and accounting, legal, operations support, information technology and human resource functions. General and administrative expense also includes corporate facility costs not otherwise included in research and development expense, including rent, utilities, depreciation and maintenance, as well as legal fees related to intellectual property and corporate matters and fees for accounting and consulting services.

We expect that our general and administrative expense will increase in the future to support our continued research and development activities, potential commercialization efforts and increased costs of operating as a public company. These increases will likely include increased costs related to the hiring of additional personnel and fees to outside consultants, legal support and accountants, among other expenses. Additionally, we anticipate increased costs associated with being a public company, including expenses related to services associated with maintaining compliance with the requirements of the Nasdaq Capital Market and the Securities and Exchange Commission, or SEC, director and officer insurance, investor and public relations costs. If any of our current or future product candidates obtains U.S. regulatory approval, we expect that we would incur significantly increased expenses associated with building a sales and marketing team.

Depreciation

Depreciation expense relates to the fixed assets which consist mainly of lab equipment. The lab equipment is depreciated over its estimated useful life of five years.

Other Income

Other income consists of interest earned on our excess cash.

Income Taxes

Since our inception, we have not recorded any income tax benefits for the net operating losses, or NOLs, we have incurred or for our research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our NOLs and tax credits will not be realized. As such, we have a full valuation allowance against all NOLs and tax credits for all periods presented.

Results of Operations

Comparison of the three months ended September 30, 2025 and 2024

Collaboration Revenue

R&D Services revenue is calculated quarterly using the inputs approach, by applying actual COYA 302 expenses against budgeted COYA 302 expenses as the two inputs. Collaboration revenue was $3.6 million for the three months ended September 30, 2025 primarily due to the immediate recognition of $3.3 million of License revenue upon receiving FDA acceptance of our IND for the Phase 2 Study during the three months ended September 30, 2025.

Research and Development Expenses

Research and development expenses increased by $0.7 million from $2.2 million for the three months ended September 30, 2024 to $2.9 million for the three months ended September 30, 2025. The increase was due to a $0.4 million increase in our preclinical and clinical expenses due to our clinical advancement of COYA 302 in ALS and a $0.3 million increase in internal research and development expenses. For our clinical product candidates, we track our external research and development expenses on a candidate-by-candidate basis. Coincident with FDA's approval of our IND of COYA 302 in patients with ALS, in the third quarter of 2025, we characterized expenses related to COYA 302 for ALS as clinical product candidate expenses. Prior to the third quarter of 2025, all expenses associated with COYA 302 for ALS were included among the preclinical product candidate expenses captioned as COYA 300 Series. For our preclinical product candidates, we track our external research and development expenses by Series. External research and development expenses include fees paid to CROs and CMOs and fees paid to regulatory, clinical trial and manufacturing professional service firms largely in connection with preclinical activities necessary to prepare COYA 302 for its initial IND filing and launch of a Phase 2 clinical trial.

We do not further classify or evaluate our internal research and development expenses by product candidate or by Series as these expenses primarily relate to compensation, materials and supplies, and other costs which are deployed across multiple therapeutic modalities, multiple product candidates, and multiple therapeutic areas under development.

Research and development expenses disaggregated and classified by preclinical, and external and internal expenses are summarized in the table below:

General and Administrative Expenses

General and administrative expenses increased by $0.3 million from $2.2 million for the three months ended September 30, 2024 compared to $2.6 million for the three months ended September 30, 2025. The increase was primarily due to a $0.2 million increase in employee compensation and a $0.1 million increase in public filing and listing costs.

Other Income

Other income was $0.3 million and $0.4 million for the three months ended September 30, 2025 and 2024, respectively. The decrease was primarily due to a decline in interest and dividend income earned on cash balances.

Comparison of the nine months ended September 30, 2025 and 2024

Collaboration Revenue

R&D Services revenue is calculated quarterly using the inputs approach, by applying actual COYA 302 expenses against budgeted COYA 302 expenses as the two inputs. Collaboration revenue was $4.0 million and $3.6 million for the nine months ended September 30, 2025 and 2024, respectively, related to R&D Services and License revenue. The increase of $0.4 million is primarily due to the immediate recognition of $3.3 million of License revenue upon receiving FDA acceptance of our IND for the Phase 2 Study and an increase in R&D Services revenue due to increased incurred expenses related to COYA 302.

Research and Development Expenses

Research and development expenses increased by $1.9 million from $9.9 million for the nine months ended September 30, 2024 to $11.8 million for the nine months ended September 30, 2025. The increase was due to a $0.7 million increase in our preclinical and clinical expenses primarily due to our clinical advancement of COYA 302 in ALS, a $0.9 million increase in internal research and

development expenses, and a $0.3 million increase in sponsored research. For our clinical product candidate (COYA 302), we track our external research and development expenses on a candidate-by-candidate basis. Coincident with FDA's approval of our IND of COYA 302 in patients with ALS, in the third quarter of 2025, we characterized expenses related to COYA 302 for ALS as clinical product candidate expenses. Prior to the third quarter of 2025, all expenses associated with COYA 302 for ALS were included among the preclinical product candidate expenses captioned as COYA 300 Series. For our preclinical product candidates, we track our external research and development expenses by Series. External research and development expenses include fees paid to CROs and CMOs and fees paid to regulatory, clinical trial and manufacturing professional service firms largely in connection with preclinical activities necessary to prepare COYA 302 for its initial IND filing and launch of a Phase 2 clinical trial.

We do not further classify or evaluate our internal research and development expenses by product candidate or by Series as these expenses primarily relate to compensation, materials and supplies, and other costs which are deployed across multiple therapeutic modalities, multiple product candidates, and multiple therapeutic areas under development.

Research and development expenses disaggregated and classified by preclinical, and external and internal expenses are summarized in the table below:

General and Administrative Expenses

General and administrative expenses increased by $1.4 million from $6.7 million for the nine months ended September 30, 2024 compared to $8.2 million for the nine months ended September 30, 2025. The increase was primarily due to an $1.0 million increase in employee compensation, a $0.3 million increase in professional services, and a $0.2 million increase in investor relation related expenses, partially offset by a $0.1 million decrease in board fees and taxes.

Other Income

Other income decreased by $0.2 million from the nine months ended September 30, 2024 compared to the nine months ended September 30, 2025. The decrease was primarily due to a decline in interest and dividend income earned on cash balances.

Liquidity and Capital Resources

Overview

Since our inception, we have incurred operating losses from our operations through 2025. We have not yet commercialized any product and we do not expect to generate revenue from sales of any products for several years, if at all. Since our inception through September 30, 2025, we have funded our operations through the public and private sale of our equity securities, and payments from Dr. Reddy's in accordance with the DRL Development Agreement. As of September 30, 2025, we had $28.1 million in cash and cash equivalents and had an accumulated deficit of $56.3 million. We expect our existing cash and cash equivalents, together with the $23.0 million in gross proceeds from the Offering, to enable us to fund our operating expenses and capital expenditure requirements for at least one year after the financial statements are issued. We have based these estimates on assumptions that may prove to be imprecise, and we could utilize our available capital resources sooner than we expect.

Funding Requirements

Our primary use of cash is to fund operating expenses, primarily research and development expenditures. Cash used to fund operating expenses is impacted by the timing of when we pay these expenses, as reflected in the change in our outstanding accounts payable, accrued expenses and prepaid expenses.

Because of the numerous risks and uncertainties associated with research, development and commercialization of pharmaceutical products, we are unable to estimate the exact amount of our operating capital requirements. Our future funding requirements will depend on many factors, including, but not limited to:

We will need significant additional funds to meet operational needs and capital requirements for clinical trials, other research and development expenditures, and business development activities. We currently have no credit facility or committed sources of capital. Because of the numerous risks and uncertainties associated with the development and commercialization of our product candidates, we are unable to estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated clinical studies.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and marketing, distribution or licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, ownership interests in our common stock will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making acquisitions or capital expenditures or declaring dividends. If we raise additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates, or grant licenses on terms that may not be favorable to us. Our ability to raise additional capital may be adversely impacted by potential worsening of global economic conditions, potential future global pandemics or health crises, and the recent disruptions to, and volatility in, the credit, banking and financial markets in the United States. If we are unable to raise additional funds through equity or debt financings or other arrangements when needed, we may be required to delay, limit, reduce or terminate our research, product development or future commercialization efforts, or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Cash Flows

The following table shows a summary of our cash flows for the periods indicated:

Operating Activities

During the nine months ended September 30, 2025, we used $9.7 million of cash in operating activities. Cash used in operating activities reflected our net loss of $15.5 million, partially offset by a $2.1 million change in operating assets and liabilities and noncash charges of $3.7 million primarily related to stock-based compensation.

During the nine months ended September 30, 2024, we used $7.9 million of cash in operating activities. Cash used in operating activities reflected our net loss of $12.0 million, partially offset by a $2.2 million net increase from our operating assets and liabilities and noncash charges of $1.9 million primarily related to stock-based compensation. The net increase in our operating assets was mainly related to the receipt of a $7.5 million payment from Dr. Reddy's pursuant to the DRL Development Agreement during the nine months ended September 30, 2024.

Investing Activities

During the nine months ended September 30, 2025 and 2024, we purchased $515,996 and $25,000 of in-process research and development assets.

Financing Activities

During the nine months ended September 30, 2025, financing activities were immaterial.

During the nine months ended September 30, 2024, financing activities provided $6.3 million of cash from the proceeds received from the sale of common stock of $5.0 million and the exercise of warrants of $1.5 million, partially offset by $0.1 million in payments of offering costs related to the 2023 private placement.

DRL Development Agreement

In December 2023, we entered into the DRL Development Agreement with Dr. Reddy's, pursuant to which, among other things, we granted to Dr. Reddy's an exclusive, royalty-bearing right and license to commercialize COYA 302 solely for use in patients with ALS in the United States, Canada, the European Union and the United Kingdom, or collectively, the New Territories. We previously granted DRL an exclusive license to obtain regulatory approval and commercialize COYA 302 for ALS and certain other indications in all other countries (other than the New Territories, Japan, Mexico, and in each country in South America), pursuant to the License and Supply Agreement entered between with DRL, or the DRL Agreement, effective as of April 1, 2023. COYA 302 is comprised of two components, COYA 301 and DRL_AB. In accordance with the DRL Agreement, we in-licensed DRL_AB for the development and commercialization of COYA 302. Further, under the DRL Development Agreement, Dr. Reddy's is responsible for the development of DRL_AB. We will have the responsibility for the clinical development of COYA 302 and for seeking regulatory approval in the United States for COYA 302 in ALS.

The collaboration is managed by a joint steering committee, or JSC, which is comprised of representatives from both parties. Decisions of the JSC are made by consensus. If the JSC is unable to reach a consensus, and the parties' executives are not able to resolve the dispute, then Dr. Reddy's has final decision-making authority, subject to specified limitations (as set forth in the DRL Development Agreement).

Pursuant to the DRL Development Agreement, we received an up-front, nonrefundable payment of $7.5 million in January 2024. Additionally, we are entitled to receive (i) an additional $4.2 million upon FDA acceptance of an IND application for COYA 302

for the treatment of ALS and (ii) an additional $4.2 million payment upon the dosing of the first patient in the first phase 2 clinical trial for COYA 302 for the treatment of ALS in the United States. The DRL Development Agreement also calls for up to an aggregate of $40.0 million in development milestones and up to an aggregate of $677.3 million in sales milestones, related to the New Territories, should all such development and sales milestones be achieved. We will also be owed royalties by Dr. Reddy's on Net Sales (as defined in the DRL Development Agreement) of COYA 302 in the low to mid-teens (prior to paying royalties due pursuant to previously disclosed license agreements related to COYA 302). In June 2024, we entered into the First Amendment to the DRL Development Agreement, or the First Amendment, with Dr. Reddy's, pursuant to which, among other things, Dr. Reddy's paid us a one-time payment of $3.9 million and, in return, Dr. Reddy's will have no obligation to pay the first $6.0 million in royalty payments that would have otherwise been payable to us under the DRL Development Agreement. Pursuant to the First Amendment, as discussed above, the first $6.0 million of royalty payments will not be owed to us.

Commitments and Contingencies, including License and Sponsored Research Agreements

Patent Know How and License Agreement with The Methodist Hospital

In September 2022, we entered into the Methodist License Agreement with Methodist to make, sell and sublicense products and services using the intellectual property and know-how of Methodist. As part of the Methodist License Agreement, we will pay Methodist a four-figure license maintenance fee annually until the first sale of licensed product occurs. The term of the Methodist License Agreement is effective until no intellectual property patent rights remain, unless terminated sooner by (1) bankruptcy or insolvency, (2) the failure by us to monetize the intellectual property within five years of the date of the agreement (further discussed below), (3) due to breach of contract, or (4) at our election for any or no reason.

In addition to the equity issuance and reimbursement of patent related expenses, we agreed to make contingent milestone payments to Methodist on a Licensed Product-by-Licensed Product or Licensed Service-by-Licensed Service basis upon the achievement of certain development, approval and sales milestones (i) related to the treatment of ALS totaling up to $0.3 million in the aggregate, and (ii) related to the treatment of each other indication (that is not ALS) totaling between $0.2 million and up to $0.4 million in the aggregate per indication. We are also required to pay Methodist, on a licensed product-by-licensed product and country-by-country basis, royalties (subject to customary reductions) equal to 1% to 10% of annual worldwide net sales of such licensed product during a defined royalty term. The applicable royalty percentage increases as Licensed Products are used to treat from one to more than three indications and if a given Licensed Product utilizes only T-reg cell therapy or is a combination of both T-reg cell therapy and exosomes. Therefore, the lowest tier is paid when there is only a single indication being addressed with a single product. The highest tier is paid only on combination products where there are three or more indications being served. We are also required to pay a low single digit percentage for certain licensed services. We are required to pay royalties at between 10%-20% of sublicense revenue. Effective January 1, 2025, the minimum amount which will be owed by us once commercialization occurs is $0.1 million annually.

The Methodist License Agreement provides that in the event we sublicense products and services covered by the Methodist License Agreement, then royalties owed to Houston Methodist would be computed as a percentage of payments received by us from the sublicensee. In addition, the termination provisions provide that Houston Methodist may only terminate the Methodist License Agreement, among other things, in the event that after five years we are not "Actively Attempting to Develop or Commercialize," as such term is defined in the Methodist License Agreement.

Sponsored Research Agreement with Houston Methodist Research Institute

In May 2023, we executed a Sponsored Research Agreement, or SRA, with Houston Methodist Research Institute, or HMRI, in which we agreed to fund approximately $0.5 million through May 2024. We have subsequently amended the SRA to increase agreed funding and, at times, extend the term. The latest amendment was entered in July 2025 to increase the total funding from $1.2 million to $1.4 million and to extend the term through December 31, 2025.

ARScience License Agreement

In August 2022, we entered into the ARS License Agreement with ARS pursuant to which ARS granted us an option to, if we choose to exercise such option, to acquire an exclusive, royalty-bearing license for two patents regarding certain formulations of IL-2 (the product that serves as the basis for COYA 301), with the right to grant sublicenses through multiple tiers under these patents. In consideration for the ARS Option, we paid ARS a one-time, non-refundable, non-creditable option fee of $0.1 million.

On December 1, 2022, we exercised the ARS Option by written notice to ARS, or the Option Exercise Notice. Upon the delivery of the Option Exercise Notice (such date of delivery, the "Effective Date"), ARS automatically was deemed to have granted to

us the licenses and all provisions of the ARS License Agreement and the ARS License Agreement became effective as of the Effective Date. Pursuant to the terms of the ARS License Agreement, we paid to ARS a mid-six-figure up-front fee.

In addition, we may also owe tiered payments to ARS based on our achievement of certain developmental milestones. Under the ARS License Agreement, we will pay an aggregate of $13.3 million in developmental milestone payments for the first Combination Product (as defined in the ARS License Agreement) in a new indication. We will then pay an aggregate of $11.6 million in developmental milestone payments for each Combination Product in each subsequent new indication. Further, for the first Mono Product (as defined in the ARS License Agreement), we will pay an aggregate of $11.8 million in developmental milestone payments. We will then pay an aggregate of $5.9 million in developmental milestone payments for each Mono Product in each subsequent new indication, and we will owe an aggregate of $5.9 million if all developmental milestones are achieved for each new indication. We will also owe royalties on net sales of licensed products ranging from low to mid-single digit percentages. In the event we sublicense our rights under the ARS License Agreement, we will owe royalties on sublicense income within the range of 10% to 20%. To date, the $0.1 million option fee and the mid-six-figure up-front fee (upon exercise of the ARS Option) are the only payments made to ARS under the ARS License Agreement. During the three and nine months ended September 30, 2025, we paid a $0.3 million milestone to ARS in connection with the IND Milestone.

Dr. Reddy's License and Supply Agreement

In March 2023, we entered into the DRL Agreement with DRL. The DRL Agreement became effective on April 1, 2023. Pursuant to the terms of the DRL Agreement, we will in-license DRL_AB to be used in the development and commercialization of COYA 302 in the U.S., Canada, Mexico, South America, the European Union, the United Kingdom, and Japan. In consideration for the license, we paid a one-time, non-refundable upfront fee of $0.4 million. We will pay to DRL up to an aggregate of approximately $2.9 million of pre-approval regulatory milestone payments for the first indication in the Field (as defined in the DRL Agreement) and an additional approximately $20.0 million if all other development, regulatory approval and sales milestones are incurred under the DRL Agreement. We will also pay to DRL a low-six figure milestone payment per additional indication. Further, pursuant to the DRL Agreement, we will pay to DRL single-digit royalties on Net Sales (as defined in the DRL Agreement). During the three and nine months ended September 30, 2025, we paid a $0.3 million milestone to DRL in connection with the IND Milestone.

Recent Accounting Pronouncements

See Note 2 to our financial statements found elsewhere in this Quarterly Report on Form 10-Q for a description of recent accounting pronouncements applicable to our financial statements.