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Xilio Therapeutics, Inc.

For the period ended Dec 31, 2025. Filed Mar 23, 2026.

View on SEC.gov

About this filing

A company's yearly report to the SEC, with audited financial statements. It is the fullest account a company gives of its business, its finances and the risks it sees.

FY2025 · Filed Mar 23, 2026

XLO$8.62+1.4%Stored close · as of Nov 6, 2026

What changed in Risk Factors?

Read the current filing

Previous report: 10-K

Period ended 2024-12-31; filed 2025-03-11.

0001558370-25-002640

Item 1A. Risk Factors

Current report: 10-K

Period ended 2025-12-31; filed 2026-03-23.

0001193125-26-118550

Item 1A. Risk Factors

The baseline is this issuer’s latest earlier reporting period of the same form that was filed before the current report. A previous 10-Q is a different quarter, not a year-over-year comparison. Amendments are excluded.

Compared 372 previous paragraphs and 545 current paragraphs.

193 unchanged; 120 reworded; 227 added; 31 removed; 28 previous and 5 current paragraphs rearranged.

Tables are not compared: 191 previous and 0 current tables excluded. Dates, whitespace, punctuation and numbering changes are ignored; changes to financial figures remain significant.

A changed paragraph is not evidence that risk increased or decreased. An unchanged paragraph does not establish that risk stayed the same.

Added paragraphs (227)

Current report

We will need to obtain substantial additional capital in the future to finance our operations and complete the development of any current or future product candidates.

Current report

As of December 31, 2025, we had cash and cash equivalents of $137.5 million. In the first quarter of 2026, we received net proceeds of approximately $37.3 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us, upon the closing of a follow-on offering of prefunded warrants and a $5.0 million development milestone related to the collaboration agreement with AbbVie Group Holdings Limited, or AbbVie. Based on our current operating plans, we anticipate that our existing cash and cash equivalents will be sufficient to enable us to fund our operating expenses and capital expenditure requirements through the end of 2027. This estimate excludes any potential future milestone payments, option-related fees or other contingent payments under our existing collaboration and partnership agreements with AbbVie and Gilead Sciences, Inc., or Gilead, and excludes the potential receipt of up to $36.2 million in additional gross proceeds in the second half of 2026 if all outstanding Series C warrants are exercised at their current exercise price. In addition, we have based our estimates on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we anticipate and may need to seek additional capital sooner than anticipated.

Current report

the scope, progress, results and costs of research and development for our current and future product candidates, including our current and planned clinical trials for our clinical-stage product candidates, vilastobart and efarindodekin alfa, and ongoing preclinical development for our current and future product candidates;

Current report

our ability to maintain our collaboration and license agreements with AbbVie and Gilead;

Current report

the timing and amount of milestones, option-related fees and other contingent payments under our collaboration, license and option agreement with AbbVie for masked immunotherapies and our license agreement with Gilead for efarindodekin alfa, as well as the scope, costs and timing of our development obligations under these agreements;

Current report

the potential receipt of up to $36.2 million in additional gross proceeds in the second half of 2026 if all of the outstanding Series C common stock warrants issued in connection with our June 2025 follow-on offering are exercised at their current exercise price of $10.50 per warrant;

Current report

the costs of securing manufacturing materials for use in preclinical studies, clinical trials and, for any product candidates for which we receive regulatory approval, if any, commercial supply;

Current report

the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property and proprietary rights and defending any intellectual property-related claims;

Current report

the extent to which we may acquire or in-license other products, product candidates, technologies or intellectual property, as well as the terms of any such arrangements;

Current report

the scope, costs, timing and outcome of regulatory review of our product candidates;

Current report

the costs and timing of future commercialization activities for any of our product candidates for which we receive regulatory approval;

Current report

the amount and timing of revenue, if any, received from commercial sales of any product candidates for which we receive regulatory approval;

Current report

general economic conditions, including inflation and the imposition of new or revised global trade tariffs; and

Current report

the costs of maintaining our operations and continuing to operate as a public company.

Current report

On August 22, 2025, we received a second deficiency notice from the Nasdaq Staff notifying us that we were not in compliance with the minimum $10.0 million stockholders' equity requirement for continued listing on the Nasdaq Global Select Market. This second deficiency notice was only a notification of deficiency, not of imminent delisting, and had no immediate effect on the listing or trading of our securities on the Nasdaq Global Select Market.

Current report

On October 2, 2025, we received a letter from the Nasdaq Staff approving our application to list our securities on the Nasdaq Capital Market. Our securities were transferred to the Nasdaq Capital Market at the opening of business on October 6, 2025. In connection with the transfer to the Nasdaq Capital Market, Nasdaq granted us an additional 180 calendar day period, or until March 30, 2026, to regain compliance with the minimum bid price requirement. If, at any time before March 30, 2026, the closing bid price for our common stock is at least $1.00 per share for a minimum of 10 consecutive business days, the Nasdaq Staff will provide written notification to us that we are in compliance with the minimum bid price requirement, unless the Nasdaq Staff exercises its discretion to extend this 10-day period pursuant to the Nasdaq Listing Rules.

Current report

On February 23, 2026, our stockholders voted to adopt and approve an amendment to our restated certificate of incorporation, as amended, to effect a reverse stock split of our issued shares of common stock and our board of directors elected to implement a reverse stock split at a ratio of 1-for-14, which reverse stock split became effective on March 13, 2026 at 5:00 p.m. Eastern Time. However, if we do not regain compliance with the minimum bid price requirement by March 30, 2026, or if we do not meet the other listing standards, the Nasdaq Staff will provide us with notice that our common stock may be delisted. At that time, we may appeal the Nasdaq Staff’s delisting determination to a Nasdaq Listing Qualifications Panel. However, there can be no assurance that, even if we appeal the Nasdaq Staff’s delisting determination to the panel, such appeal would be successful.

Current report

The recently implemented reverse stock split of our common stock may not achieve the intended benefits and could have a materially adverse effect on the market price of our common stock.

Current report

As discussed above, we recently implemented a reverse stock split of our common stock. The reverse stock split may not achieve the intended benefit of increasing the per share market price of our common stock, and there are a number of risks associated with the reverse stock split, including, without limitation:

Current report

the reverse stock split may not result in a price per share that will successfully attract certain types of investors, and such resulting share price may not satisfy the investing guidelines of institutional investors or investment funds;

Current report

the trading liquidity of the shares of our common stock may not improve, or may decline, as a result of the reverse stock split and there can be no assurance that the reverse stock split will result in the intended benefits; and

Current report

the reverse stock split could be viewed negatively by the market and other factors, which may adversely affect the market price of our common stock.

Current report

There can also be no assurances the reverse stock split will prevent the delisting of our common stock from the Nasdaq Capital Market, which could have a material adverse effect on our business.

Current report

To date, we have financed our operations primarily from proceeds raised through private placements of equity securities; sales of common stock in our initial public offering, or IPO, and through “at-the-market” offerings; the sale of prefunded warrants in our June 2025 and February 2026 follow-on offerings; the exercise of certain common stock warrants issued in connection with our June 2025 follow-on offering; development event payments under our co-funded clinical trial collaboration with F. Hoffmann-La Roche Ltd, or Roche; and upfront and milestone payments under our collaboration and license agreements with AbbVie and Gilead. All of our programs are in clinical or preclinical development. As a result, we have not generated any revenue from product sales and do not expect to generate any revenue from product sales for at least the next several years, if at all.

Current report

We expect our operating losses and negative operating cash flows to continue for the foreseeable future as we continue to advance our pipeline of novel, masked I-O molecules through development. Our operating expenses and net losses may fluctuate significantly from quarter to quarter and year to year, and we expect to continue to incur significant expenses and operating losses for the foreseeable future, particularly to the extent we:

Current report

continue to advance our current research programs and conduct additional research programs;

Current report

advance our current product candidates and any future product candidates we may develop into preclinical and clinical development;

Current report

seek marketing approvals for product candidates that successfully complete clinical trials, if any;

Current report

obtain, expand, maintain, defend and enforce our intellectual property;

Current report

continue to discover, validate and develop additional product candidates;

Current report

continue to manufacture increasing quantities of our current or future product candidates for use in preclinical studies, clinical trials and for any potential commercialization;

Current report

acquire or in-license other product candidates, technologies or intellectual property;

Current report

hire additional personnel to support current or future programs;

Current report

establish a commercial and distribution infrastructure to commercialize products for which we may obtain marketing approval, if any; and

Current report

incur additional costs associated with current and future research, development and commercialization efforts and operations as a public company.

Current report

Even if we successfully complete clinical trials and obtain regulatory approval for one or more of our product candidates, our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful commercialization of those product candidates. Because of the numerous risks and uncertainties associated with product development, we are unable to predict the timing or amount of increased expenses or when or if we will be able to achieve profitability. In addition, even if we are able to generate revenue from product sales, we may not become profitable.

Current report

successfully complete our ongoing and planned preclinical studies and clinical trials for any current or future product candidates;

Current report

successfully receive U.S. Food and Drug Administration, or FDA, clearance for any investigational new drug application, or IND, for any current or future product candidates;

Current report

successfully initiate and complete clinical trials for our clinical-stage product candidates and any other current or future product candidates, including all safety and efficacy studies necessary to obtain U.S. and foreign regulatory approval for our product candidates;

Current report

establish and maintain clinical and commercial manufacturing capabilities or make arrangements with third-party manufacturers for clinical supply and commercial manufacturing;

Showing the first 40 of 227 passages. Open the source sections for the rest.

Removed paragraphs (31)

Previous report

Item 1A. Risk Factors

Previous report

Our recurring losses from operations raise substantial doubt regarding our ability to continue as a going concern. If we are unable to raise sufficient additional capital in the near term, we will need to implement additional cost reduction strategies, which could include delaying, limiting, reducing or eliminating both internal and external costs related to our operations and research and development programs.

Previous report

As of December 31, 2024, we had cash and cash equivalents of $55.3 million. Based on our current operating plans, we anticipate that our cash and cash equivalents as of December 31, 2024, together with the $52.0 million in upfront payments received in the first quarter of 2025 in connection with our collaboration agreement with AbbVie Group Holdings Limited, or AbbVie, will be sufficient to enable us to fund our operating expenses and capital expenditure requirements into the first quarter of 2026. However, since these amounts are not expected to be sufficient to fund our operations for at least twelve months from the date of issuance of the consolidated financial statements included elsewhere in this Annual Report on Form 10-K, there is substantial doubt about our ability to continue as a going concern. Our future capital requirements and the period for which we expect our existing resources to support our operations may vary from what we expect. Our management has developed plans to continue to fund our operations, which primarily consist of raising additional capital through one or more of the following: additional equity or debt financings; additional collaborations, partnerships or licensing transactions; or other sources. However, there can be no assurance that we will be able to complete any such transaction on acceptable terms or otherwise, and we may be unable to obtain sufficient additional capital in the near term.

Previous report

If we are not able to secure sufficient additional capital, we will need to implement additional cost reduction strategies, which could include delaying, limiting, further reducing or eliminating both internal and external costs related to our operations and research and development programs. If we are unsuccessful in our efforts in the near term to raise additional capital or in the future to engage in one or more other strategic alternatives, we could be required to liquidate, dissolve or otherwise wind down our operations. Furthermore, our cash forecasts are based on assumptions that may prove to be wrong, and we could use our available capital resources earlier than we currently expect. Please see Note 1 to our consolidated financial statements appearing elsewhere in our Annual Report on Form 10-K for additional information on our assessment.

Previous report

We have incurred significant operating losses since our inception and have not yet generated any revenue from the sale of products. If our product candidates are not successfully developed and approved, we may never generate any revenue from product sales. Our net losses were $58.2 million and $76.4 million for the years ended December 31, 2024 and 2023, respectively. As of December 31, 2024, we had an accumulated deficit of $383.8 million. To date, we have financed our operations primarily from proceeds raised through private placements of preferred units and convertible preferred stock, a debt financing, our initial public offering, or IPO, of common stock in October 2021, private placements of our common stock and prefunded warrants, upfront payments under our license agreement with Gilead and collaboration agreement with AbbVie and our ATM offering program. We have devoted substantially all of our financial resources and efforts to research and development. We are still in the early stages of development of our tumor-activated, or masked, product candidates, and we have not completed clinical development for our clinical-stage product candidates, vilastobart (anti-CTLA-4) and XTX301 (IL-12). We expect to continue to incur significant expenses and operating losses for the foreseeable future, particularly to the extent we:

Previous report

Even if we successfully complete clinical trials and obtain regulatory approval for one or more of our product candidates, our product candidates may not be commercially successful. In addition, we will continue to incur substantial research and development and other expenditures to develop and market additional product candidates. We may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. We may not achieve profitability soon after generating product sales, if ever. If we are unable to generate revenue, we will not become profitable and may be unable to continue operations without continued funding.

Previous report

Risks Relating to Manufacturing and Supply

Previous report

Risks Related to Commercialization

Previous report

Risks Related to Our Intellectual Property

Previous report

Disruptions in the FDA and other government agencies for any reason could hinder their ability to hire and retain key leadership and other personnel, or otherwise prevent new products and services from being developed or commercialized in a timely manner, which could negatively impact our business.

Previous report

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

Previous report

Disruptions at the FDA, EMA and other agencies may also slow the time necessary for new drugs to be reviewed or approved by necessary government agencies, which would adversely affect our business. For example, in recent years, including in 2018 and 2019, the U.S. government shut down several times and certain regulatory agencies, such as the FDA and the Securities and Exchange Commission, or the SEC, had to furlough critical employees and stop critical activities.

Previous report

Further, with the change in U.S. presidential administrations in 2025, there is substantial uncertainty as to how, if at all, the new presidential administration will seek to modify or revise the requirements and policies of the FDA and other regulatory agencies with jurisdiction over our product candidates. There is also uncertainty as to how other measures being implemented by the Trump Administration across the government will impact our activities and those of the FDA and its operations. For example, the potential loss of FDA personnel could lead to further disruptions and delays in FDA review of our product candidates. Similarly, efforts by the new presidential administration to substantially reduce research funding by the U.S. National Institutes of Health of medical research could have substantial direct or indirect impacts on our research activities.

Previous report

unlawful promotion of a new intended use for the approved product. We will need to carefully navigate the FDA’s various regulations, guidance and policies, along with recently enacted legislation, to ensure compliance with restrictions governing promotion of our products.

Previous report

Under current legislation, the actual reductions in Medicare payments may vary up to 4%. The Consolidated Appropriations Act, which was signed into law by President Biden in December 2022, made several changes to sequestration of the Medicare program. Section 1001 of the Consolidated Appropriations Act delays the 4% Statutory Pay-As-You-Go Act of 2010, or PAYGO, sequester for two years, through the end of calendar year 2024. Triggered by enactment of the American Rescue Plan Act of 2021, the 4% cut to the Medicare program would have taken effect in January 2023. The Consolidated Appropriation Act’s health care offset title includes Section 4163, which extends the 2% Budget Control Act of 2011 Medicare sequester for six months into fiscal year 2032 and lowers the payment reduction percentages in fiscal years 2030 and 2031.

Previous report

During the first Trump presidential administration, Congress and administration sought to overturn the ACA and related measures. Shortly after taking office in January 2025, President Trump revoked numerous executive orders issued by President Biden, including at least two executive orders, EO 14009, Strengthening Medicaid and the Affordable Care Act, and EO 14070, Continuing to Strengthen Americans’ Access to Affordable, Quality Health Coverage, which were designed to further implement the ACA. We anticipate similar efforts to undermine the ACA, and the accompanying uncertainty, for the foreseeable future.

Previous report

We expect that these healthcare reforms, 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 and/or the level of reimbursement physicians receive for administering any approved product we might bring to market. Reductions in reimbursement levels may negatively impact the prices we receive or the frequency with which our products

Previous report

are prescribed or administered. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction in payments from private payors. Accordingly, such reforms, if enacted, could have an adverse effect on anticipated revenue from product candidates that we may successfully develop and for which we may obtain marketing approval and may affect our overall financial condition and ability to develop or commercialize product candidates.

Previous report

Further, on November 20, 2020, HHS finalized a regulation removing safe harbor protection for price reductions from pharmaceutical manufacturers to plan sponsors under Part D, either directly or through pharmacy benefit managers, unless the price reduction is required by law. The implementation of the rule has been delayed by the Biden administration until January 1, 2026 by the Infrastructure Investment and Jobs Act. The final rule would eliminate the current safe harbor for Medicare drug rebates and create new safe harbors for beneficiary point-of-sale discounts and pharmacy benefit manager service fees. It originally was set to go into effect on January 1, 2022, but with the passage of the Inflation Reduction Act of 2022, or the IRA, has been delayed by Congress to January 1, 2032.

Previous report

physician assistants, nurse practitioners, clinical nurse specialists, anesthesiologist assistants, certified registered nurse anesthetists and certified nurse midwives during the previous year.

Previous report

There are numerous U.S. federal and state laws and regulations related to the privacy and security of personal information. In particular, regulations promulgated pursuant to HIPAA establish privacy and security standards that limit the use and disclosure of individually identifiable health information, or protected health information, and require the implementation of administrative, physical and technological safeguards to protect the privacy of protected health information and ensure the confidentiality, integrity and availability of electronic protected health information. Determining whether protected health information has been handled in compliance with applicable privacy standards and our contractual obligations can

Previous report

be complex and may be subject to changing interpretation. These obligations may be applicable to some or all of our business activities now or in the future.

Previous report

Additionally, in October 2022, President Biden signed an executive order to implement the EU-U.S. Data Privacy Framework, which would serve as a replacement to the EU-U.S. Privacy Shield. The EU initiated the process to adopt an adequacy decision for the EU-U.S. Data Privacy Framework in December 2022 and the European Commission adopted the adequacy decision on July 10, 2023. The adequacy decision will permit U.S. companies who self-certify to the EU-U.S. Data Privacy Framework to rely on it as a valid data transfer mechanism for data transfers from the EU to the United States. However, some privacy advocacy groups have already suggested that they will be challenging the EU-U.S. Data Privacy Framework. If these challenges are successful, they may not only impact the EU-U.S. Data Privacy Framework, but also further limit the viability of the standard contractual clauses and other data transfer mechanisms. The uncertainty around this issue has the potential to impact our business at the international level.

Previous report

Furthermore, while the Data Protection Act of 2018 in the United Kingdom that “implements” and complements the GDPR has achieved Royal Assent on May 23, 2018 and is now effective in the United Kingdom, it is still unclear whether transfer of data from the EEA to the United Kingdom will remain lawful under GDPR. The Trade and Cooperation Agreement provides for a transitional period during which the United Kingdom will be treated like a EU member state in relation to processing and transfers of personal data for four months from January 1, 2021. This may be extended by two further months. After such period, the United Kingdom will be a “third country” under the GDPR unless the European Commission adopts an adequacy decision in respect of transfers of personal data to the United Kingdom. The United Kingdom has already determined that it considers all of the EU 27 and EEA member states to be adequate for the purposes of data protection, ensuring that data flows from the United Kingdom to the EU/EEA remain unaffected.

Previous report

The U.S. government has recently made statements and taken certain actions that may lead to potential changes to U.S. and international trade policies, including imposing several rounds of tariffs and export control restrictions affecting certain products manufactured in China, and most recently, proposing legislation that, if enacted would restrict trade with certain Chinese companies that provide biopharmaceutical research, development, and manufacturing services. Recently both China and the United States have each imposed tariffs indicating the potential for further trade barriers. In addition, in the past the U.S. Commerce Department has implemented export controls adding numerous Chinese entities to its “unverified list,” which requires U.S. exporters to go through more procedures before exporting goods to such entities. It is unknown

Previous report

whether and to what extent new tariffs, export controls, trade restrictions, or other new laws or regulations will be adopted, or the effect that any such actions would have on us or our industry. Sustained uncertainty about, or the further escalation of, trade and political tensions between the United States and China could result in a disadvantageous research and manufacturing environment in China, particularly for U.S. based companies, including retaliatory restrictions that hinder or potentially inhibit our ability to rely on CDMOs and other service providers that operate in China. For example, proposed legislation has been introduced in Congress that could prohibit, among other things, the use of U.S. government executive agency contract, grant, or loan funding to procure or obtain, or enter into, extend or renew contracts involving the use of certain equipment or services produced or provided by certain Chinese companies, including our current CDMO, WuXi Biologics, which could cause us to reevaluate our relationship with our current CDMO.

Previous report

In addition to our CDMO, WuXi Biologics, some of our other suppliers, vendors and service providers are located in China. Trade tensions and conflicts between the United States and China have been escalating in recent years and, as such, we are exposed to the possibility of supply disruptions and increased costs and expenses in the event of changes to the laws, rules, regulations and policies of the governments of the United States or China, or due to geopolitical unrest and unstable economic conditions. Certain Chinese biotechnology companies may become subject to trade restrictions, sanctions, other regulatory requirements or proposed legislation by the U.S. government, which could restrict or even prohibit our ability to work with such entities, thereby potentially disrupting their supply of material to us. For example, in February 2024, U.S. lawmakers called for investigations into and the imposition of possible trade sanctions against certain Chinese biotechnology companies including WuXi AppTec and WuXi Biologics, or collectively WuXi, over alleged ties to the Chinese military. Escalating tensions between the United States and China may prevent or hinder the export of materials or technical information between us and our CDMO and third parties, such as pharmaceutical partners. Additionally, third parties may voluntarily require compliance or supply chain requirements that go above and beyond potential legislation to address perceived risk of “pass through,” which would make it difficult for us to operate our business.

Previous report

In addition, in September 2024 during the 118th Congress, the U.S. House of Representatives passed the BIOSECURE Act (H.R. 8333). This bill names the following as biotechnology companies of concern: BGI, MGI, Complete Genomics, WuXi AppTec, and WuXi Biologics. The Senate advanced a substantially similar bill (S. 3558) but it did not pass. The Senate bill named the following as biotechnology companies of concern: “BGI, MGI, Complete Genomics, WuXi, AppTec and any subsidiary, parent affiliate, or successor of such entities.” If this legislation had been enacted into law while both bills had certain grandfather provisions, the legislation would have potentially restricted the ability of U.S. biotechnology companies like ours to purchase services or products from, or otherwise collaborate with, specifically named Chinese biotechnology companies, including WuXi, and it would have authorized the U.S. government to impose such restrictions on entities' transactions with additional Chinese biotechnology companies as a condition of U.S. government contract, grant and loan funding. We anticipate these bills will be reintroduced during the 119th Congress, but as of February 20, 2025, they have not been introduced in either chamber. If these bills become law, or similar laws are passed, they would have the potential to severely restrict the ability of companies like ours to contract with certain Chinese biotechnology companies of concern without losing the ability to contract with, or otherwise received funding from, the U.S. government. Such disruptions could have adverse effects on the development of our product candidates and our business operations.

Previous report

Any unfavorable government policies on international trade, such as export controls, capital controls or tariffs, may increase the cost of manufacturing our product candidates and platform materials, affect the demand for our drug products (if and once approved), the competitive position of our product candidates, and import or export of raw materials and finished product candidate used in our and our collaborators’ preclinical studies and clinical trials, particularly with respect to any product candidates and materials that we import from China, including pursuant to our manufacturing service arrangements with WuXi. If any new tariffs, export controls, legislation and/or regulations are implemented, or if existing trade agreements are renegotiated or, in particular, if either the U.S. or Chinese government takes retaliatory trade actions due to the recent trade tension, such changes could have an adverse effect on our business, financial condition and results of operations.

Previous report

Changes in tax law may adversely affect our business or financial condition. The Tax Act, enacted on December 22, 2017, as amended by the CARES Act, enacted on March 27, 2020, significantly revises the Code. The Tax Act contains, among other things, significant changes to corporate taxation, including a reduction of the corporate tax rate from a top marginal rate of 35% to a flat rate of 21% and the limitation of the deduction for net operating losses to 80% of current-year taxable income for losses arising in taxable years beginning after December 31, 2017 (though any such net operating losses may be carried forward indefinitely). In addition, beginning in 2022, the Tax Act eliminates the option to deduct research and

Previous report

development expenditures currently and requires corporations to capitalize and amortize them over five years or fifteen years (for expenditures attributable to foreign research).
Reworded paragraphs (120)

Previous wording

Our future capital requirements, both short-term and long-term, will depend on many factors, including:

Current wording

Our future capital requirements, both short-term and long-term, will depend on many factors, including, but not limited to:

Previous wording

We will require additional capital to sustain our operations. We currently do not have any committed external sources of funds and adequate additional capital may not be available to us on acceptable terms, or at all. In addition, our ability to raise additional capital may be adversely impacted by potential worsening economic conditions, both inside and outside the United States, including without limitation heightened inflation, capital market volatility, interest rate and currency rate fluctuations, any potential economic slowdown or recession, future pandemics, geopolitical tensions, including trade wars or civil or political unrest, or wars or other armed conflicts. We can give no assurance that we will be able to secure additional capital to support our operations, or if such funds are available to us, that such additional funding will be sufficient to meet our needs. These factors raise substantial doubt about our ability to continue as a going concern, and our failure to raise capital, on attractive terms or at all, would have a material adverse effect on our business, results of operations and financial condition.

Current wording

Our existing cash and cash equivalents will not be sufficient to complete development of any current or future product candidates, and we will require additional capital in the future to sustain our operations. We currently do not have any committed external sources of funds and will be required to obtain further funding in the future through public or private equity offerings, debt, collaborations, licensing arrangements, the conversion of common stock warrants for cash, or other sources. However, adequate additional capital may not be available to us in the future on acceptable terms, or at all. In addition, our ability to raise additional capital may be adversely impacted by potential worsening economic conditions, both inside and outside the United States, including without limitation heightened inflation, capital market volatility, interest rate and currency rate fluctuations, any potential economic slowdown or recession, future pandemics, geopolitical tensions, including trade wars or civil or political unrest, or wars or other armed conflicts. Our failure to raise additional capital in the future as and when needed to support our operations would have a material adverse effect on our financial condition, our ability to develop and commercialize our current and any future product candidates or otherwise pursue our business strategy.

Previous wording

If in the future we fail to comply with the continued listing requirements of Nasdaq, our common stock may be delisted and the price of our common stock and our ability to access the capital markets could be negatively impacted.

Current wording

If we fail to regain and maintain compliance with the continued listing requirements of Nasdaq, our common stock may be delisted and the price of our common stock and our ability to access the capital markets could be negatively impacted.

Previous wording

We are required to comply with the continued listing requirements of the Nasdaq Stock Market LLC, or Nasdaq, including, among other things, maintaining a minimum closing bid price of $1.00 per share, referred to as the minimum bid price requirement, or shares of our common stock may be subject to delisting, which would have a material adverse effect on our business. In September 2024, we received a deficiency letter from the Listing Qualifications Department, or the Nasdaq Staff, informing us that we were not in compliance with the continued listing requirements of the Nasdaq Global Select Market because the bid price for our common stock had closed below $1.00 per share for 30 consecutive business days. In January 2025, we received written notification from the Nasdaq Staff informing us that we had regained compliance with the minimum bid price requirement as a result of our common stock maintaining a closing bid price of $1.00 per share or greater for at for at least 10 consecutive business days. However, there can be no assurance that we will be able to continue to maintain compliance with the minimum bid price requirement or any of the other Nasdaq continued listing requirements.

Current wording

On April 4, 2025, we received a deficiency letter from the Listing Qualifications Department, or the Nasdaq Staff, of the Nasdaq Stock Market LLC, or Nasdaq, notifying us that, for the last 30 consecutive business days, the bid price for our common stock had closed below $1.00 per share, which is the minimum bid price required to maintain continued listing on the Nasdaq Global Select Market, referred to as the minimum bid price requirement. In accordance with Nasdaq Listing Rules, we had an initial period of 180 calendar days, or until October 1, 2025, to regain compliance with the minimum bid price requirement.

Previous wording

Any potential delisting of our common stock could have a material adverse effect on the market for, and liquidity and price of, our common stock and would adversely affect our ability to raise capital on terms acceptable to us, or at all. Delisting from Nasdaq could also have other negative results, including, without limitation, the potential loss of confidence by investors, customers and employees and fewer business development opportunities. Any delisting of our common stock from Nasdaq would also make it more difficult for our stockholders to sell their shares of our common stock in the public market.

Current wording

If we are unable to comply with applicable Nasdaq listing standards, shares of our common stock would be subject to delisting, which could have a material adverse effect on the market for, and liquidity and price of, our common stock and would adversely affect our ability to raise capital on terms acceptable to us, or at all. Delisting from Nasdaq could also have other negative results, including, without limitation, the potential loss of confidence by investors, customers and employees and fewer business development opportunities. Any delisting of our common stock from Nasdaq would also make it more difficult for our stockholders to sell their shares of our common stock in the public market.

Previous wording

We expect to continue to incur operating losses in connection with our ongoing research and development activities, particularly as we advance our product candidates through clinical trials, maintain the infrastructure necessary to support these activities and incur costs associated with operating as a public company. We do not expect to generate any revenue from the sale of products for a number of years, if at all, and any such revenue will not be realized unless and until we obtain marketing approval for and successfully launch and commercialize a product candidate. If we obtain marketing approval for any current or future product candidates that we develop, we expect to incur significant commercialization expenses related to product sales, marketing, distribution and manufacturing. Some of these expenses may be incurred in advance of marketing approval and could be substantial.

Current wording

Since inception, we have incurred significant operating losses, including net losses of $35.0 and $58.2 million for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, we had an accumulated deficit of $418.8 million. We expect our operating losses and negative operating cash flows to continue for the foreseeable future as we continue to advance our pipeline of novel, masked immuno-oncology, or I-O, molecules through preclinical and clinical development, maintain the infrastructure necessary to support these activities and continue to incur costs associated with operating as a public company. We do not expect to generate any revenue from the sale of products for a number of years, if at all, and any such revenue will not be realized unless and until we obtain marketing approval for and successfully launch and commercialize a product candidate. If we obtain marketing approval for any current or future product candidates that we develop, we expect to incur significant commercialization expenses related to product sales, marketing, distribution and manufacturing. Some of these expenses may be incurred in advance of marketing approval and could be substantial.

Previous wording

Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to product candidates or our technology.

Current wording

Raising additional capital in the future may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to product candidates or our technology. In addition, the issuance of shares of common stock upon the exercise of our outstanding prefunded warrants or common stock warrants will result in immediate and substantial dilution to our existing stockholders.

Previous wording

Unless and until we can generate a substantial amount of product revenue, we expect to seek additional capital through a combination of public or private equity offerings, debt, collaborations, licensing arrangements or other sources. Our issuance of additional securities, whether equity or debt, or the possibility of such issuance, may cause the market price of our common stock to decline, and our stockholders may not agree with our plans for additional capital or the terms of such capital. To the extent that we raise additional capital through the sale of equity or convertible debt securities, our stockholders’ ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our existing stockholders. For example, when we issue shares of common stock upon the exercise of our outstanding prefunded warrants, or if we issue additional shares of our common stock in one or more “at-the-market,” or ATM, offerings, our existing stockholders will suffer dilution. In addition, as a condition to providing additional funds to us, Gilead and AbbVie received, and future investors may receive, rights superior to those of existing stockholders. To the extent that we incur additional indebtedness, we would become obligated to make payments to repay the loan balance with interest. The incurrence of any additional indebtedness would result in additional payment obligations and is likely to involve restrictive covenants limiting our flexibility in conducting future business activities, and, in the event of insolvency, would be repaid before holders of our equity securities received any distribution of our corporate assets. Additionally, in raising funds through our collaborations and licensing arrangements with third parties, we have had to, and may in the future need to, relinquish valuable rights, partially or fully, to our technologies, future revenue streams, research programs or product candidates and grant licenses on terms unfavorable to us. In addition, securing additional capital would require a substantial amount of time and attention from our management and may divert a disproportionate amount of their attention away from day-to-day activities, which may adversely affect our management’s ability to oversee the development of our product candidates.

Current wording

Unless and until we can generate a substantial amount of product revenue, we expect to seek additional capital through a combination of public or private equity offerings, debt, collaborations, licensing arrangements or other sources. Our issuance of additional securities, whether equity or debt, or the possibility of such issuance, may cause the market price of our common stock to decline, and our stockholders may not agree with our plans for additional capital or the terms of such capital. To the extent that we raise additional capital through the sale of equity or convertible debt securities, our stockholders’ ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our existing stockholders. In addition, the issuance of shares of common stock upon the exercise of our outstanding prefunded warrants or common stock warrants will result in immediate and substantial dilution to our existing stockholders. Similarly, if we issue additional shares of our common stock in one or more public or private offerings in the future, our existing stockholders will suffer further dilution. In addition, as a condition to providing additional funds to us, Gilead and AbbVie received rights superior to those of existing stockholders, and in connection with the issuance of prefunded warrants and common stock warrants in June 2025, we agreed to specified restrictions on our future equity issuances, unless we obtain the requisite prior approval of the warrant holders. Future investors may similarly receive rights that are superior to those of existing investors or which place restrictions on our future equity issuances. In addition, the incurrence of any indebtedness would result in additional payment obligations and is likely to involve restrictive covenants limiting our flexibility in conducting future business activities, and, in the event of insolvency, would be repaid before holders of our equity securities received any distribution of our corporate assets. Further, in raising funds through our collaborations and licensing arrangements with third parties, we have had to, and may in the future need to, relinquish valuable rights, partially or fully, to our technologies, future revenue streams, research programs or product candidates and grant licenses on terms unfavorable to us. In addition, securing additional capital would require a substantial amount of time and attention from our management and may divert a disproportionate amount of their attention away from day-to-day activities, which may adversely affect our management’s ability to oversee the development of our product candidates.

Previous wording

generate revenues that are significant enough to achieve profitability. Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would depress the value of our company and could impair our ability to raise capital, expand our business, maintain our research and development efforts, diversify our product candidates or even continue our operations. A decline in the value of our company could also cause our stockholders to lose all or part of their investment.

Current wording

Because of the numerous risks and uncertainties associated with biopharmaceutical product development, we are unable to accurately predict the timing or amount of expenses we may incur in connection with these activities prior to generating revenue from product sales. In addition, we may never succeed in these activities, and, even if we do, we may never generate revenues that are significant enough to achieve profitability. Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would depress the value of our company and could impair our ability to raise capital, expand our business, maintain our research and development efforts, diversify our product candidates or even continue our operations. A decline in the value of our company could also cause our stockholders to lose all or part of their investment.

Previous wording

We are a clinical-stage biotechnology company with a limited operating history upon which investors can evaluate our business and prospects. Since inception, we have devoted substantially all of our financial resources and efforts to performing research and development activities. Our approach to the discovery and development of tumor-activated product candidates using our proprietary platform technology is unproven, and we do not know whether we will be able to develop any approved products of commercial value. In addition, each of our product candidates is either in early clinical or preclinical development, and all of our other development programs are still in discovery stages. We have not yet demonstrated an ability to successfully complete any late-stage clinical trials, obtain regulatory approvals, manufacture a commercial-scale product, or arrange for a third party to do so on our behalf, or conduct the sales and marketing activities necessary for successful product commercialization. Consequently, any predictions made about our future success or viability may not be as accurate as they could be if we had a history of successfully developing and commercializing biopharmaceutical products.

Current wording

We are a clinical-stage biotechnology company with a limited operating history upon which investors can evaluate our business and prospects. Since inception, we have devoted substantially all of our financial resources and efforts to performing research and development activities. Our approach to the discovery and development of masked I-O product candidates using our proprietary platform technology is unproven, and we do not know whether we will be able to develop any approved products of commercial value. In addition, each of our product candidates is either in early clinical or preclinical development, and all of our other development programs are still in discovery stages. We have not yet demonstrated an ability to successfully complete any late-stage clinical trials, obtain regulatory approvals, manufacture a commercial-scale product, or arrange for a third party to do so on our behalf, or conduct the sales and marketing activities necessary for successful product commercialization. Consequently, any predictions made about our future success or viability may not be as accurate as they could be if we had a history of successfully developing and commercializing biopharmaceutical products.

Previous wording

We have incurred substantial losses during our history. As of December 31, 2024, we had federal and state net operating loss, or NOL, carryforwards of $245.5 million and $217.5 million, respectively. We do not anticipate generating revenue from sales of products for the foreseeable future, if ever, and we do not know whether or when we will generate taxable income necessary to utilize our NOLs.

Current wording

We have incurred substantial losses during our history. As of December 31, 2025, we had federal and state net operating loss, or NOL, carryforwards of $263.5 million and $234.6 million, respectively. We do not anticipate generating revenue from sales of products for the foreseeable future, if ever, and we do not know whether or when we will generate taxable income necessary to utilize our NOLs.

Previous wording

Our business and future success is highly dependent on our ability to obtain regulatory approval for, and if approved, successfully launch and commercialize, our current product candidates, including our clinical-stage, tumor-activated product candidates: vilastobart and XTX301. We are currently evaluating vilastobart in combination with atezolizumab (Tecentriq®) in Phase 1 combination dose escalation in patients with advanced solid tumors and in a Phase 2 clinical trial evaluating the combination in patients with microsatellite stable colorectal cancer, or MSS CRC. We are currently evaluating XTX301 in a Phase 1 clinical trial. We also have a portfolio of programs that are in even earlier stages of preclinical development and may never advance to clinical-stage development, including XTX501, our masked PD-1/IL-2 bispecific, which is designed to selectively stimulate PD-1 positive antigen-experienced T cells and enhance their function and is currently advancing in initial IND-enabling activities, and our preclinical programs for masked T cell engagers targeting prostate-specific membrane antigen, or PSMA, claudin 18.2, or CLDN18.2, and six-transmembrane epithelial antigen of prostate 1, or STEAP1.

Current wording

Our business and future success is highly dependent on our ability to obtain regulatory approval for, and if approved, successfully launch and commercialize, our current product candidates, including our clinical-stage, masked I-O product candidates: vilastobart and efarindodekin alfa. We are currently evaluating vilastobart in combination with atezolizumab (Tecentriq®) in an ongoing Phase 2 clinical trial in patients with microsatellite stable, or MSS, metastatic colorectal cancer, or mCRC, and we are currently evaluating efarindodekin alfa as a monotherapy in an ongoing Phase 2 clinical trial in patients with certain advanced solid tumors. We also have a portfolio of programs that are in earlier stages of development and may never advance to clinical-stage development, including XTX501, our bispecific PD-1/masked IL-2, which is designed to selectively stimulate PD-1 positive antigen-experienced T cells and enhance their function and is currently advancing in initial IND-enabling activities, and our wholly-owned preclinical programs for a multi-specific masked T cell engager targeting prostate-specific membrane antigen, or PSMA, and six-transmembrane epithelial antigen of prostate 1, or STEAP1, and a masked T cell engager targeting claudin 18.2, or CLDN18.2, as well as an additional masked T cell engager program in collaboration with AbbVie.

Previous wording

Commencing clinical trials in the United States is subject to acceptance by the FDA of an IND and finalizing the trial design based on discussions with the FDA and other regulatory authorities. In the event that the FDA requires us to complete additional preclinical studies, or we are required to satisfy other FDA requests prior to commencing clinical trials, the start of our clinical trials may be delayed. Even after we receive and incorporate guidance from these regulatory authorities, the FDA or other regulatory authorities could disagree that we have satisfied their requirements to commence any clinical trial or change their position on the acceptability of our trial design or the clinical endpoints selected, which may require us to complete additional preclinical studies or clinical trials or impose stricter approval conditions than we currently expect. There are equivalent processes and risks applicable to clinical trial applications in other countries, including countries in the European Union, or EU.

Current wording

Commencing clinical trials in the U.S. is subject to acceptance by the FDA of an IND and finalizing the trial design based on discussions with the FDA and other regulatory authorities. In the event that the FDA requires us to complete additional preclinical studies, or we are required to satisfy other FDA requests prior to commencing clinical trials, the start of our clinical trials may be delayed. Even after we receive and incorporate guidance from these regulatory authorities, the FDA or other regulatory authorities could disagree that we have satisfied their requirements to commence any clinical trial or change their position on the acceptability of our trial design or the clinical endpoints selected, which may require us to complete additional preclinical studies or clinical trials or impose stricter approval conditions than we currently expect. There are equivalent processes and risks applicable to clinical trial applications in other countries, including countries in the European Union, or EU.

Previous wording

We are not permitted to market any biological product in the United States until we receive approval of a Biologics License Application, or BLA, from the FDA. We have not previously submitted a BLA to the FDA, or similar marketing application to comparable foreign regulatory authorities. A BLA must include extensive preclinical and clinical data and supporting information to establish that the product candidate is safe, pure and potent for each desired indication. A BLA must also include significant information regarding the chemistry, manufacturing and controls for the product, and the manufacturing facilities must complete a successful pre-license inspection.

Current wording

We are not permitted to market any biological product in the U.S. until we receive approval of a Biologics License Application, or BLA, from the FDA. We have not previously submitted a BLA to the FDA, or similar marketing application to comparable foreign regulatory authorities. A BLA must include extensive preclinical and clinical data and supporting information to establish that the product candidate is safe, pure and potent for each desired indication. A BLA must also include significant information regarding the chemistry, manufacturing and controls for the product, and the manufacturing facilities must complete a successful pre-license inspection.

Previous wording

activities that may entail additional costs. We have not obtained FDA approval for any product. This lack of experience may impede our ability to obtain FDA approval in a timely manner, if at all, for any current or future product candidates.

Current wording

Generally, public concern regarding the safety of biopharmaceutical products could delay or limit our ability to obtain regulatory approval, result in the inclusion of unfavorable information in our labeling or require us to undertake other activities that may entail additional costs. We have not obtained FDA approval for any product. This lack of experience may impede our ability to obtain FDA approval in a timely manner, if at all, for any current or future product candidates.

Previous wording

All our product candidates are still in the early clinical stage or preclinical stage of development, and their risk of failure is high. Before we can commence clinical trials for a product candidate, we must complete extensive preclinical testing and studies that support our planned INDs in the United States, or similar applications in other jurisdictions. We cannot be certain of the timely completion or outcome of our preclinical testing and studies, and we cannot predict if the FDA or other regulatory authorities will accept our proposed clinical programs or if the outcome of our preclinical testing and studies will ultimately support the further development of our programs. As a result, we cannot be sure that we will be able to submit INDs or similar applications for our current or future preclinical programs on the timelines we expect, if at all, and we cannot be sure that submission of INDs or similar applications will result in the FDA or other regulatory authorities allowing clinical trials to begin.

Current wording

All our product candidates are still in the early clinical stage or preclinical stage of development, and their risk of failure is high. Before we can commence clinical trials for a product candidate, we must complete extensive preclinical testing and studies that support our planned INDs in the U.S., or similar applications in other jurisdictions. We cannot be certain of the timely completion or outcome of our preclinical testing and studies, and we cannot predict if the FDA or other regulatory authorities will accept our proposed clinical programs or if the outcome of our preclinical testing and studies will ultimately support the further development of our programs. As a result, we cannot be sure that we will be able to submit INDs or similar applications for our current or future preclinical programs, including without limitation, the planned IND for XTX501, on the timelines we expect, if at all, and we cannot be sure that submission of INDs or similar applications will result in the FDA or other regulatory authorities allowing clinical trials to begin.

Previous wording

The risk of failure for our current and any future product candidates is high. It is impossible to predict when or if any of our product candidates will successfully complete preclinical studies or clinical trials evaluating their safety and effectiveness in humans or will ultimately receive regulatory approval. To obtain the requisite regulatory approvals to market and sell any of our product candidates, we must demonstrate through extensive preclinical studies and clinical trials that our product candidates are safe and effective in humans for use in each target indication. Preclinical and clinical testing is expensive and can take many years to complete, and the outcome is inherently uncertain. Failure can occur at any time during the preclinical or clinical trial process. The outcome of preclinical testing and early clinical trials may not be predictive of the results of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. In particular, while we have conducted certain preclinical studies for each of our clinical stage product candidates, we do not know whether these product candidates will perform in our clinical trials as they have performed in these prior preclinical studies. Similarly, there can be no assurance that early, interim or preliminary clinical data or results will be predictive of or replicated in future clinical data or results, including without limitation, the Phase 2 data for vilastobart in combination with atezolizumab and the Phase 1 data for XTX301 reported to date. Many companies in the biopharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials after achieving positive results in early-stage development and we cannot be certain that we will not face similar setbacks. These setbacks have been caused by, among other things, preclinical findings made while clinical trials were underway, or safety or efficacy observations made in preclinical studies and clinical trials, including previously unreported adverse events, or AEs. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their products.

Current wording

The risk of failure for our current and any future product candidates is high. It is impossible to predict when or if any of our product candidates will successfully complete preclinical studies or clinical trials evaluating their safety and effectiveness in humans or will ultimately receive regulatory approval. To obtain the requisite regulatory approvals to market and sell any of our product candidates, we must demonstrate through extensive preclinical studies and clinical trials that our product candidates are safe and effective in humans for use in each target indication. Preclinical and clinical testing is expensive and can take many years to complete, and the outcome is inherently uncertain. Failure can occur at any time during the preclinical or clinical trial process. The outcome of preclinical testing and early clinical trials may not be predictive of the results of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. In particular, while we have conducted certain preclinical studies for each of our clinical stage product candidates, we do not know whether these product candidates will perform in our clinical trials as they have performed in these prior preclinical studies. Similarly, there can be no assurance that early, interim or preliminary clinical data or results will be predictive of or replicated in future clinical data or results, including without limitation, data reported to date for our Phase 1/2 trial for vilastobart in combination with atezolizumab and our Phase 1 trial for efarindodekin alfa. Many companies in the biopharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials after achieving positive results in early-stage development and we cannot be certain that we will not face similar setbacks. These setbacks have been caused by, among other things, preclinical findings made while clinical trials were underway, or safety or efficacy observations made in preclinical studies and clinical trials, including previously unreported adverse events, or AEs. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their products.

Previous wording

In some instances, there can be significant variability in safety or efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in clinical trial procedures set forth in protocols, differences in the size and type of the patient populations, adherence to the dosing regimen and other clinical trial protocols, and the rate of dropout among clinical trial participants. If we fail to produce positive results in our planned and ongoing

Current wording

In some instances, there can be significant variability in safety or efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in clinical trial procedures set forth in protocols, differences in the size and type of the patient populations, adherence to the dosing regimen and other clinical trial protocols, and the rate of dropout among clinical trial participants. If we fail to produce positive results in our planned and ongoing preclinical studies or clinical trials, or if we experience material changes in clinical data or results from those we have previously reported, the development timeline and regulatory approval and commercialization prospects for our product candidates, and, correspondingly, our business, financial condition and results of operations would be materially and adversely affected.

Previous wording

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. We cannot guarantee that any clinical trials, including our Phase 2 clinical trial evaluating vilastobart in combination with atezolizumab or our Phase 1 clinical trial evaluating XTX301 as a monotherapy, will be conducted as planned or completed on schedule, if at all. For example, in the first quarter of 2024, we announced plans to discontinue further investment in XTX202, our tumor-activated IL-2, as a monotherapy. We may experience numerous unforeseen events leading up to, during or as a result of clinical trials that could delay or prevent the initiation or completion of a clinical trial or our ability to receive marketing approval or commercialize our product candidates, including:

Current wording

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. We cannot guarantee that any clinical trials, including our ongoing Phase 2 clinical trial evaluating vilastobart in combination with atezolizumab or our Phase 2 clinical trial evaluating efarindodekin alfa as a monotherapy, will be conducted as planned or completed on schedule, if at all. We may experience numerous unforeseen events leading up to, during or as a result of clinical trials that could delay or prevent the initiation or completion of a clinical trial or our ability to receive marketing approval or commercialize our product candidates, including:

Previous wording

Undesirable or unexpectedly severe side effects caused by our product candidates could cause us to interrupt, delay or halt preclinical studies or could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities. Traditional cytokine therapies and checkpoint inhibitors have long been associated with severe toxicities, which can be life-threatening or fatal, that have resulted in the need to dose-reduce, dose-interrupt and discontinue many patients from treatment. As has been the case with traditional immuno-oncology, or I-O, treatments for cancer, it is possible that there may be severe side effects associated with the use of our current or future product candidates. Results of our clinical trials could reveal a high and unacceptable severity and prevalence of these or other side effects. In such an event, our clinical 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. Treatment-related side effects could also affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.

Current wording

Undesirable or unexpectedly severe side effects caused by our product candidates could cause us to interrupt, delay or halt preclinical studies or could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities. Traditional cytokine therapies and checkpoint inhibitors have long been associated with severe toxicities, which can be life-threatening or fatal, that have resulted in the need to dose-reduce, dose-interrupt and discontinue many patients from treatment. As has been the case with traditional I-O treatments for cancer, it is possible that there may be severe side effects associated with the use of our current or future product candidates. Results of our clinical trials could reveal a high and unacceptable severity and prevalence of these or other side effects. In such an event, our clinical 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. Treatment-related side effects could also affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.

Previous wording

From time to time, we may publish interim top-line or preliminary data from our clinical trials. For example, we most recently reported initial data from our Phase 2 clinical trial for vilastobart in combination with atezolizumab in January 2025, and we plan to report additional Phase 2 data in the middle of 2025, and we most recently reported safety data from our Phase 1 clinical trial for XTX301 in December 2024. Preliminary and interim data from clinical trials that we may complete 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. 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 previously published. As a result, interim and preliminary data should be viewed with caution until the final data are available. Adverse differences between preliminary or interim data and final data could significantly harm our business prospects.

Current wording

From time to time, we may publish interim top-line or preliminary data from our clinical trials. For example, we most recently reported updated data from our Phase 2 clinical trial for vilastobart in combination with atezolizumab and from our Phase 1 clinical trial for efarindodekin alfa in November 2025 at the Society for Immunotherapy of Cancer (SITC) 40 th Annual Meeting. Preliminary and interim data from clinical trials that we may complete 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. 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 previously published. As a result, interim and preliminary data should be viewed with caution until the final data are available. Adverse differences between preliminary or interim data and final data could significantly harm our business prospects.

Previous wording

We intend to develop our clinical-stage product candidates, and likely other future product candidates, in combination with third-party cancer drugs, which may be either approved or unapproved. For example, we are currently evaluating vilastobart in combination with atezolizumab (Tecentriq®) in Phase 1 combination dose escalation in patients with advanced solid tumors and in a Phase 2 clinical trial evaluating the combination in patients with MSS CRC. Our ability to develop and ultimately commercialize our current product candidates, and any future product candidates, used in combination with third-party drugs will depend on our ability to access such drugs on commercially reasonable terms for clinical trials and their availability for use with our commercialized product, if approved. We cannot be certain that current or potential future commercial relationships will provide us with a steady supply of such drugs on commercially reasonable terms or at all. Any failure to maintain or enter into new successful commercial relationships, or the expense of purchasing such third-party drugs in the market, may delay our development timelines, increase our costs and jeopardize our ability to develop our current product candidates and any future product candidates as commercially viable therapies. If any of these occur, our business, financial condition, operating results or prospects may be materially harmed.

Current wording

We intend to develop our clinical-stage product candidates, and likely other future product candidates, in combination with third-party cancer drugs, which may be either approved or unapproved. For example, we are currently evaluating vilastobart in combination with atezolizumab (Tecentriq®) in a Phase 2 clinical trial in patients with MSS mCRC. Our ability to develop and ultimately commercialize our current product candidates, and any future product candidates, used in combination with third-party drugs will depend on our ability to access such drugs on commercially reasonable terms for clinical trials and their availability for use with our commercialized product, if approved. We cannot be certain that current or potential future commercial relationships will provide us with a steady supply of such drugs on commercially reasonable terms or at all. Any failure to maintain or enter into new successful commercial relationships, or the expense of purchasing such third-party drugs in the market, may delay our development timelines, increase our costs and jeopardize our ability to develop our current product candidates and any future product candidates as commercially viable therapies. If any of these occur, our business, financial condition, operating results or prospects may be materially harmed.

Previous wording

Moreover, the development of product candidates for use in combination with another product or product candidate may present challenges that are not faced for single agent product candidates. For example, our plans to evaluate current or future product candidates in combination with other agents may result in AEs based on the combination therapy that may negatively impact the reported safety profile of the monotherapy in clinical trials. In addition, the FDA or comparable foreign regulatory authorities may require us to use more complex clinical trial designs in order to evaluate the contribution of each product and product candidate to any observed effects. It is possible that the results of such trials could show that any positive previous trial results are attributable to the third-party drug and not our product candidate. Developments

Current wording

Moreover, the development of product candidates for use in combination with another product or product candidate may present challenges that are not faced for single agent product candidates. For example, our plans to evaluate current or future product candidates in combination with other agents may result in AEs based on the combination therapy that may negatively impact the reported safety profile of the monotherapy in clinical trials. In addition, the FDA or comparable foreign regulatory authorities may require us to use more complex clinical trial designs in order to evaluate the contribution of each product and product candidate to any observed effects. It is possible that the results of such trials could show that any positive previous trial results are attributable to the third-party drug and not our product candidate. Developments related to the third-party drug may also impact our clinical trials for the combination therapy as well as our commercial prospects should we receive regulatory approval. Such developments may include changes to the third-party drug’s safety or efficacy profile, changes to the availability of the third-party drug, quality, and manufacturing and supply issues with respect to the third-party drug.

Previous wording

We may not be successful in our efforts to use our platform technology to enable the development of a pipeline of tumor-activated product candidates.

Current wording

We may not be successful in our efforts to use our platform technology to enable the development of a pipeline of masked I-O product candidates.

Previous wording

A key element of our strategy is to use our novel platform technology to engineer and develop tumor-activated molecules with the potential to trigger anti-tumor immunity with minimal systemic toxicity in order to advance a pipeline of product candidates. We may not be able to continue to identify and develop novel I-O therapies. Even if we are successful in continuing to advance our pipeline, the potential product candidates that we identify may not be suitable for clinical development. For example, potential product candidates may be shown to have harmful side effects or other characteristics that indicate that they are unlikely to or will not be drugs that will receive marketing approval and achieve market acceptance. If we do not successfully develop and commercialize product candidates based upon our platform approach or take longer to do so than anticipated, we will not or may not be able to obtain drug revenues in future periods, which likely would result in significant harm to our financial position and adversely affect our stock price.

Current wording

A key element of our strategy is to use our novel platform technology to engineer and develop masked I-O molecules with the potential to trigger anti-tumor immunity with minimal systemic toxicity in order to advance a pipeline of product candidates. We may not be able to continue to identify and develop novel I-O therapies. Even if we are successful in continuing to advance our pipeline, the potential product candidates that we identify may not be suitable for clinical development. For example, potential product candidates may be shown to have harmful side effects or other characteristics that indicate that they are unlikely to or will not be drugs that will receive marketing approval and achieve market acceptance. If we do not successfully develop and commercialize product candidates based upon our platform approach or take longer to do so than anticipated, we will not or may not be able to obtain drug revenues in future periods, which likely would result in significant harm to our financial position and adversely affect our stock price.

Previous wording

The success of our business depends primarily upon our ability to discover, develop and commercialize products based on our technological approaches. While we have had favorable preclinical and early clinical results related to our clinical-stage product candidates, vilastobart and XTX301, we have not yet succeeded and may not succeed in demonstrating efficacy and safety for any product candidates in current or future clinical trials or in obtaining marketing approval thereafter. We rely on matrix metalloproteases, or MMPs, to activate our molecules within the tumor microenvironment. If MMP activity in human tumors is not sufficient to cleave the masking protein domain, the potential efficacy of our product candidates would be limited. We have no assurance that our product candidates will successfully progress through clinical development and ultimately marketing approval. We have invested substantially all of our efforts and financial resources in developing our initial product candidates and our future success is highly dependent on the outcome of our ongoing clinical trials and the successful development of our technology and product candidates.

Current wording

The success of our business depends primarily upon our ability to discover, develop and commercialize products based on our technological approaches. While we have had favorable preclinical and early clinical results related to our clinical-stage product candidates, vilastobart and efarindodekin alfa, we have not yet succeeded and may not succeed in demonstrating efficacy and safety for any product candidates in current or future clinical trials or in obtaining marketing approval thereafter. We rely on matrix metalloproteases, or MMPs, to activate our molecules within the tumor microenvironment. If MMP activity in human tumors is not sufficient to cleave the masking protein domain, the potential efficacy of our product candidates would be limited. We have no assurance that our product candidates will successfully progress through clinical development and ultimately marketing approval. We have invested substantially all of our efforts and financial resources in developing our initial product candidates and our future success is highly dependent on the outcome of our ongoing clinical trials and the successful development of our technology and product candidates.

Previous wording

side effects during clinical trials or after approval thereof, we may be exposed to substantial liabilities. Physicians and patients may not comply with any warnings that identify known potential adverse effects and patients who should not use our product candidates. If we cannot successfully defend ourselves against product liability claims, we may incur substantial liabilities or be required to limit or cease the development or commercialization of our product candidates or any products for which we may have received marketing approval. Even a successful defense would require significant financial and management resources. Regardless of the merits or eventual outcome, liability claims may result in:

Current wording

Although the clinical trial process is designed to identify and assess potential side effects, it is always possible that a drug, even after regulatory approval, may exhibit unforeseen side effects. If any of our product candidates were to cause adverse side effects during clinical trials or after approval thereof, we may be exposed to substantial liabilities. Physicians and patients may not comply with any warnings that identify known potential adverse effects and patients who should not use our product candidates. If we cannot successfully defend ourselves against product liability claims, we may incur substantial liabilities or be required to limit or cease the development or commercialization of our product candidates or any products for which we may have received marketing approval. Even a successful defense would require significant financial and management resources. Regardless of the merits or eventual outcome, liability claims may result in:

Previous wording

The manufacturing of biologics is complex and difficult and we may experience production issues or interruptions in supply for our product candidates, including variability of raw material, consumable or starting material quality, cell line viability, productivity or stability issues, shortages of any kind, shipping, distribution, storage and supply chain failures, media contamination, equipment malfunctions or failures, operator errors, facility contamination, labor problems, quality system and regulatory inspection failures, natural disasters, disruption in utility services, terrorist activities, or acts of god that are beyond our control or the control of our third-party contract development and manufacturing organizations, or CDMOs.

Current wording

The manufacturing of biologics is complex and difficult and we may experience production issues or interruptions in supply for our product candidates, including variability of raw material, consumable or starting material quality, cell line viability, productivity or stability issues, shortages of any kind, shipping, distribution, storage and supply chain failures, media contamination, equipment malfunctions or failures, operator errors, facility contamination, labor problems, quality system and regulatory inspection failures, adverse impacts from current or future trade sanctions, tariffs or similar actions, natural disasters, disruption in utility services, terrorist activities, or acts of god that are beyond our control or the control of our third-party contract development and manufacturing organizations, or CDMOs.

Previous wording

Given the nature of biologics manufacturing, there is a risk of contamination during manufacturing. Any contamination could materially harm our ability to produce product candidates on schedule and could harm our results of operations and

Current wording

Given the nature of biologics manufacturing, there is a risk of contamination during manufacturing. Any contamination could materially harm our ability to produce product candidates on schedule and could harm our results of operations and cause reputational damage. In the event that raw materials required in our manufacturing process need to be derived from biologic sources, they may be difficult to procure and may be subject to contamination or recall.

Previous wording

These factors could cause the delay of clinical trials, regulatory submissions, required approvals or commercialization of our product candidates, cause us to incur higher costs and prevent us from commercializing our products successfully. Furthermore, if our suppliers fail to meet contractual requirements, and we are unable to secure one or more replacement

Current wording

These factors could cause the delay of clinical trials, regulatory submissions, required approvals or commercialization of our product candidates, cause us to incur higher costs and prevent us from commercializing our products successfully. Furthermore, if our suppliers fail to meet contractual requirements, and we are unable to secure one or more replacement suppliers capable of production at a substantially equivalent cost, our clinical trials may be delayed, or we could lose potential revenue or market share with respect to any product that has received marketing approval.

Previous wording

We have relied on WuXi Biologics in China to manufacture and supply certain raw materials used in our product candidates, and we expect to continue to use WuXi Biologics as our CDMO for such purposes. A natural disaster, epidemic or pandemic, such as the COVID-19 pandemic, trade war, political unrest, economic conditions, changes in legislation, including the passage of the People’s Republic of China Biosecurity law, which became effective on April 15, 2021, and subsequent legislation that China or the United States may adopt in the future, or other events in China could disrupt our ability to continue to rely upon CROs, CDMOs, collaborators, manufacturers or other third parties with whom we conduct business now or in the future. Any disruption in China or the United States that significantly impacts such third parties, including services provided by CROs for our research and development programs, or our manufacturers’ ability to produce and export raw or manufactured materials in adequate quantities to meet our needs, could impair our ability to operate our business on a day-to-day basis and impede, delay, limit or prevent the research, development or commercialization of our current and future products or product candidates. In addition, for any activities conducted in China, we are exposed to the possibility of product supply disruption and increased costs in the event of changes in the policies of the U.S. or Chinese governments, political unrest or unstable economic or geopolitical conditions, including sanctions in China or against certain Chinese companies; changes in U.S. export laws or the imposition by the United States of trade barriers; sanctions; limitations on uses of U.S. government executive agency contract, grant or loan funds; or other restrictions on doing business with certain Chinese companies, including WuXi Biologics, which could have a material adverse effect on our business. Additionally, we may be exposed to fluctuations in the value of the local currency in China for goods and services. Our costs for any of these services or activities could also increase as a result of future appreciation of the local currency in China or increased labor costs if the demand for skilled laborers increases and/or the availability of skilled labor declines in China.

Current wording

Any disruption in China or the U.S. that significantly impacts WuXi Biologics or other third parties with whom we conduct business now or in the future, including CROs that provide services for our research and development programs, or manufacturers that produce and export raw or manufactured materials in adequate quantities to meet our needs, could impair our ability to operate our business on a day-to-day basis and impede, delay, limit or prevent the research, development or commercialization of our current and future products or product candidates. In addition, for any activities conducted in China, we are exposed to the possibility of product supply disruption and increased costs in the event of changes in the policies of the U.S. or Chinese governments, political unrest or unstable economic or geopolitical conditions, including sanctions in China or against certain Chinese companies; changes in U.S. export laws or the imposition by the U.S. of trade barriers; sanctions; limitations on uses of U.S. government executive agency contract, grant or loan funds; or other restrictions on doing business with certain Chinese companies, including WuXi Biologics, which could have a material adverse effect on our business. Additionally, we may be exposed to fluctuations in the value of the local currency in China for goods and services. Our costs for any of these services or activities could also increase as a result of future appreciation of the local currency in China or increased labor costs if the demand for skilled laborers increases and/or the availability of skilled labor declines in China.

Previous wording

We expect to rely on third parties to conduct, supervise and monitor IND-enabling studies and clinical trials, and if these third parties perform in an unsatisfactory manner, it may harm our business, reputation and results of operations.

Current wording

We expect to rely on third parties to conduct, supervise and monitor IND-enabling studies and clinical trials, and to perform other functions for us, and if these third parties perform in an unsatisfactory manner, it may harm our business, reputation and results of operations.

Previous wording

We expect to rely on CROs and research and clinical trial sites to ensure our IND-enabling studies and clinical trials are conducted properly and on time, and we expect to rely in the future on CROs for additional research programs. While we will have agreements governing their activities, we will have limited influence over their actual performance. We will control only certain aspects of our CROs’ activities. Nevertheless, we will be responsible for ensuring that each of these studies is conducted in accordance with the applicable protocol, legal, regulatory and scientific standards, and our reliance on the CROs does not relieve us of our regulatory responsibilities.

Current wording

We expect to rely on third parties, including but not limited to, CROs and research and clinical trial sites to ensure our IND-enabling studies and clinical trials are conducted properly and on time, and we expect to rely in the future on third-party vendors for additional research programs as well as other functions. While we will have agreements governing their activities, we will have limited influence over their actual performance. We will control only certain aspects of our third-party vendors’ activities. Nevertheless, we will be responsible for ensuring that each of these studies is conducted in accordance with the applicable protocol, legal, regulatory and scientific standards, and our reliance on the third-party vendors does not relieve us of our regulatory responsibilities.

Previous wording

Our CROs are not our employees, and we are therefore unable to directly monitor whether or not they devote sufficient time and resources to our clinical and nonclinical programs. These CROs may also have relationships with other commercial entities, including our competitors, for whom they may also be conducting clinical trials or other drug development activities that could harm our competitive position. If our CROs do not successfully carry out their contractual duties or obligations, fail to meet expected deadlines, or if the quality or accuracy of the data they obtain is compromised due to the failure to adhere to our protocols or regulatory requirements, or for any other reasons, our studies may be extended, delayed or terminated, and we may not be able to obtain regulatory approval for, or successfully commercialize any product candidates we may develop. As a result, our financial results and commercial prospects would be harmed, our costs could increase, and our ability to generate revenues could be delayed.

Current wording

Our CROs and other third-party vendors are not our employees, and we are therefore unable to directly monitor whether or not they devote sufficient time and resources to our clinical and nonclinical programs or other functions. These third-party vendors may also have relationships with other commercial entities, including our competitors, for whom they may also be conducting clinical trials or other drug development activities that could harm our competitive position. If our third-party vendors do not successfully carry out their contractual duties or obligations, fail to meet expected deadlines, or if the quality or accuracy of the data they obtain is compromised due to the failure to adhere to our protocols or regulatory requirements, or for any other reasons, our studies may be extended, delayed or terminated, and we may not be able to obtain regulatory approval for, or successfully commercialize any product candidates we may develop. As a result, our financial results and commercial prospects would be harmed, our costs could increase, and our ability to generate revenues could be delayed.

Previous wording

masked antibody-based immunotherapy. We may in the future seek third-party collaborators or licensors for the research, development and commercialization of other current or future product candidates. With respect to our agreements with Gilead and AbbVie, and what we expect will be the case with any future collaboration agreements we enter into, we have and would likely have limited control over whether such collaborators pursue the development of our product candidates or the amount and timing of resources that our collaborators dedicate to the development or commercialization of our product candidates that we seek to develop with them. For example, under the license agreement with Gilead, if Gilead exercises its right to transition responsibilities for the development and commercialization of XTX301 and the rest of our IL-12 program, it will have sole decision-making authority with respect to the continued development and future commercialization of our IL-12 program and may elect to prioritize other assets that it believes are more competitive, or it may exercise its right to terminate the license and return the licensed IL-12 program assets to us. Similarly, subject to limited exceptions, AbbVie has sole decision-making authority with respect to the development and commercialization of the masked antibody-based immunotherapy program. With respect to any T cell engager program for which AbbVie exercises its option, AbbVie will have sole decision-making authority with respect to the continued development and future commercialization of such option program and may elect to prioritize other assets that it believes are more competitive, or it may exercise its right to terminate the license and return the licensed T cell engager program assets to us. As a result, there can be no assurances that any of the programs covered by our existing or future collaborations or licenses will be developed further or reach commercialization. Further, our ability to generate revenues from these existing and future arrangements will depend on our collaborators’ abilities to successfully perform the functions assigned to them in these arrangements. We cannot predict the success of any collaboration that we enter into.

Current wording

In March 2024, our wholly-owned subsidiary, Xilio Development, Inc., or Xilio Development, entered into a license agreement with Gilead, pursuant to which Gilead was granted an exclusive global license to develop and commercialize efarindodekin alfa, our masked IL-12, and other specified molecules directed toward IL-12. In February 2025, Xilio Development entered into a collaboration, license and option agreement with AbbVie, pursuant to which AbbVie was granted (i) an exclusive option for (a) an initial program to discover, develop and commercialize masked T cell engager molecules for an agreed upon initial target and backup target and (b) subject to the terms of the agreement, up to two additional programs to discover, develop, and commercialize masked T cell engager molecules for an initial target and backup target determined at the time of program initiation and (ii) an exclusive license to develop and commercialize a masked antibody-based immunotherapy. We may in the future seek third-party collaborators or licensors for the research, development and commercialization of other current or future product candidates. With respect to our agreements with Gilead and AbbVie, and what we expect will be the case with any future collaboration agreements we enter into, we have and would likely have limited control over whether such collaborators pursue the development of our product candidates or the amount and timing of resources that our collaborators dedicate to the development or commercialization of our product candidates that we seek to develop with them. For example, under the license agreement with Gilead, if Gilead exercises its right to transition responsibilities for the development and commercialization of efarindodekin alfa and the rest of our IL-12 program, it will have sole decision-making authority with respect to the continued development and future commercialization of our IL-12 program and may elect to prioritize other assets that it believes are more competitive, or it may exercise its right to terminate the license and return the licensed IL-12 program assets to us. Similarly, subject to limited exceptions, AbbVie has sole decision-making authority with respect to the development and commercialization of the masked antibody-based immunotherapy program. With respect to any T cell engager program for which AbbVie exercises its option, AbbVie will have sole decision-making authority with respect to the continued development and future commercialization of such option program and may elect to prioritize other assets that it believes are more competitive, or it may exercise its right to terminate the license and return the licensed T cell engager program assets to us. As a result, there can be no assurances that any of the programs covered by our existing or future collaborations or licenses will be developed further or reach commercialization. Further, our ability to generate revenues from these existing and future arrangements will de…

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Previous wording

result in costly litigation or arbitration that diverts management attention and resources or that jeopardize or invalidate our intellectual property or proprietary information;

Current wording

disputes may arise between the collaborators or licensors and us that result in the delay or termination of the research, development, or commercialization of our product candidates or any of our product candidates or that result in costly litigation or arbitration that diverts management attention and resources or that jeopardize or invalidate our intellectual property or proprietary information;

Previous wording

We have never commercialized a product candidate. We currently have no sales force or marketing or distribution capabilities. To achieve commercial success of our product candidates, if any are approved, we will have to develop our own sales, marketing and supply capabilities or outsource these activities to one or more third parties. Factors that may affect our ability to commercialize our product candidates on our own include our ability to recruit and retain adequate numbers of effective sales and marketing personnel and obtain access to or persuade adequate numbers of physicians to prescribe our product candidates, as well as any unforeseen costs we may incur in connection with creating an independent sales and marketing organization. Developing a sales and marketing organization requires significant investment and substantial amount of time and attention from our management and may divert a disproportionate amount of their attention away from day-to-day activities, which could delay the launch of our product candidates. We may not be able to build an effective sales and marketing organization in the United States, the EU or other key global markets. To the extent we need to rely upon one or more third parties, we may have little or no control over the marketing and sales efforts of those third parties and our revenue from product sales may be lower than if we had commercialized our product candidates ourselves. We will also face competition in any search for third parties to assist us with sales and marketing efforts for our product candidates. If we are unable to build our own distribution and marketing capabilities or to find suitable partners for the commercialization of our product candidates, we may have difficulties generating revenue from them.

Current wording

We have never commercialized a product candidate. We currently have no sales force or marketing or distribution capabilities. To achieve commercial success of our product candidates, if any are approved, we will have to develop our own sales, marketing and supply capabilities or outsource these activities to one or more third parties. Factors that may affect our ability to commercialize our product candidates on our own include our ability to recruit and retain adequate numbers of effective sales and marketing personnel and obtain access to or persuade adequate numbers of physicians to prescribe our product candidates, as well as any unforeseen costs we may incur in connection with creating an independent sales and marketing organization. Developing a sales and marketing organization requires significant investment and substantial amount of time and attention from our management and may divert a disproportionate amount of their attention away from day-to-day activities, which could delay the launch of our product candidates. We may not be able to build an effective sales and marketing organization in the U.S., the EU or other key global markets. To the extent we need to rely upon one or more third parties, we may have little or no control over the marketing and sales efforts of those third parties and our revenue from product sales may be lower than if we had commercialized our product candidates ourselves. We will also face competition in any search for third parties to assist us with sales and marketing efforts for our product candidates. If we are unable to build our own distribution and marketing capabilities or to find suitable partners for the commercialization of our product candidates, we may have difficulties generating revenue from them.

Previous wording

We are developing our most advanced clinical-stage, tumor-activated product candidates for the treatment of cancer and have not completed clinical development or received marketing approval for either vilastobart or XTX301. There are already a variety of available therapies marketed for cancer and some of the currently approved therapies are branded and subject to patent protection, and others are available on a generic basis. Many of these approved therapies are well-established and widely accepted by physicians, patients and third-party payors. Insurers and other third-party payors may also encourage the use of generic products. We expect that if our product candidates are approved, they will be priced at a significant premium over competitive generic products. This may make it difficult for us to achieve our business strategy of using our product candidates in combination with existing therapies or replacing existing therapies with our product

Current wording

We are developing our most advanced clinical-stage, masked I-O product candidates for the treatment of cancer and have not completed clinical development or received marketing approval for either vilastobart or efarindodekin alfa. There are already a variety of available therapies marketed for cancer and some of the currently approved therapies are branded and subject to patent protection, and others are available on a generic basis. Many of these approved therapies are well-established and widely accepted by physicians, patients and third-party payors. Insurers and other third-party payors may also encourage the use of generic products. We expect that if our product candidates are approved, they will be priced at a significant premium over competitive generic products. This may make it difficult for us to achieve our business strategy of using our product candidates in combination with existing therapies or replacing existing therapies with our product candidates. Competition may further increase with advances in the commercial applicability of technologies and greater availability of capital for investment in these industries.

Previous wording

With respect to our most advanced research-stage product candidate, XTX501, currently, there are no bispecific PD-1 targeted IL-2 therapies approved for the treatment of cancer. However, if we continue to advance development of XTX501, we are aware of several other companies that have modified PD-1 targeted IL-2 bispecific antibodies in development, including Anaveon AG, Innovent Biologics, Inc., Regeneron Pharmaceuticals, Inc. and Roche.

Current wording

With respect to XTX501, currently there are no bispecific PD-1 targeted IL-2 therapies approved for the treatment of cancer. However, we are aware of several companies that have bispecific PD-1 targeted IL-2 programs in development, including but not limited to Anaveon AG, Bright Peak Therapeutics, Inc., Innovent Biologics, Inc., Medicenna Therapeutics Corp., Regeneron Pharmaceuticals, Inc., Roche, and Teva Pharmaceutical Industries, Ltd.

Previous wording

With respect to our masked T cell engager programs, currently there are no T cell engager therapies targeting PSMA, CLDN18.2 or STEAP1 approved for the treatment of cancer. We are aware of several other companies that have masked T cell engager programs in development for PSMA, including Janux Therapeutics, Inc. and Vir Biotechnology, Inc. To our knowledge, there are no companies currently developing masked T cell engager programs for CLDN18.2 or STEAP1. However, we are aware of several companies developing non-masked T cell engager programs for CLDN18.2, including Amgen Inc., Innovent Biologics, Inc., Transcenta Holding Ltd. and Zai Lab Limited, and for STEAP1, including Amgen Inc., Nutcracker Therapeutics and Xencor Inc.

Current wording

With respect to our masked T cell engager programs, currently there are no T cell engager therapies targeting PSMA, CLDN18.2 or STEAP1 approved for the treatment of cancer. However, we are aware of other companies that have masked T cell engager programs in development for PSMA, including but not limited to Janux Therapeutics, Inc. and Vir Biotechnology, Inc., and at least one other company, Werewolf Therapeutics, Inc., that has a masked T cell engager program in development for STEAP1. To our knowledge, there are no companies currently developing a masked T cell engager program targeting both PSMA and STEAP1 or a masked T cell engager program for CLDN18.2. However, we are aware of several companies developing non-masked T cell engager programs for CLDN18.2, including but not limited to Amgen Inc., Astellas Pharma Inc., AstraZeneca PLC, Innovent Biologics, Inc., Transcenta Holding Ltd. and Zai Lab Limited, for PSMA, including but not limited to AbCellera Biologics Inc., Regeneron Pharmaceuticals Inc. and Xencor, Inc., and for STEAP1, including but not limited to Amgen Inc. and Xencor Inc.

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The American Taxpayer Relief Act of 2012, among other things, reduced Medicare payments to several providers and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. These laws may result in additional reductions in Medicare and other healthcare funding and otherwise affect the prices we may obtain for any of our drug product candidates for which we may obtain regulatory approval or the frequency with which any such product candidate is prescribed or used. For example, under current legislation, the actual reductions in Medicare payments may vary by up to 4%.

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4% of the total worldwide annual turnover of the preceding financial year, whichever is higher, as well as compensation claims by affected individuals, negative publicity, reputational harm and a potential loss of business and goodwill.

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We 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. From time to time and in the future, our operations may involve the use of hazardous and flammable materials, including chemicals and biological materials, and may also produce hazardous waste products. Even if we contract with third parties for the disposal of these materials and waste products, we cannot completely eliminate the risk of contamination or injury resulting from these materials. In the event of contamination or injury resulting from the use or disposal of our 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.

Current report — wording carried from elsewhere

Recruiting and retaining qualified scientific and clinical personnel and, if we are successful in obtaining marketing approval for our product candidates, sales and marketing personnel, is and will be critical to our success. The loss of the services of our executive officers or other key employees could impede, delay or prevent 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 other 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 for and commercialize products in the life sciences industry, and specifically our product candidates. We are based in Massachusetts, a state that is home to many other biopharmaceutical companies as well as many academic and research institutions, resulting in fierce competition for qualified personnel.

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reduced disclosure obligations regarding executive compensation; and
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Previous report — wording carried elsewhere

Because of the numerous risks and uncertainties associated with biopharmaceutical product development, we are unable to accurately predict the timing or amount of expenses we may incur in connection with these activities prior to generating revenue from product sales. In addition, we may never succeed in these activities, and, even if we do, we may never

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Generally, public concern regarding the safety of biopharmaceutical products could delay or limit our ability to obtain regulatory approval, result in the inclusion of unfavorable information in our labeling or require us to undertake other

Previous report — wording carried elsewhere

preclinical studies or clinical trials, or if we experience material changes in clinical data or results from those we have previously reported, the development timeline and regulatory approval and commercialization prospects for our product candidates, and, correspondingly, our business, financial condition and results of operations would be materially and adversely affected.

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related to the third-party drug may also impact our clinical trials for the combination therapy as well as our commercial prospects should we receive regulatory approval. Such developments may include changes to the third-party drug’s safety or efficacy profile, changes to the availability of the third-party drug, quality, and manufacturing and supply issues with respect to the third-party drug.

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Although the clinical trial process is designed to identify and assess potential side effects, it is always possible that a drug, even after regulatory approval, may exhibit unforeseen side effects. If any of our product candidates were to cause adverse

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cause reputational damage. In the event that raw materials required in our manufacturing process need to be derived from biologic sources, they may be difficult to procure and may be subject to contamination or recall.

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suppliers capable of production at a substantially equivalent cost, our clinical trials may be delayed, or we could lose potential revenue or market share with respect to any product that has received marketing approval.

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In March 2024, our wholly-owned subsidiary, Xilio Development, Inc., or Xilio Development, entered into a license agreement with Gilead, pursuant to which Gilead was granted an exclusive global license to develop and commercialize XTX301, our tumor activated IL-12, and other specified molecules directed toward IL-12. In February 2025, Xilio Development entered into a collaboration, license and option agreement with AbbVie, pursuant to which AbbVie was granted (i) an exclusive option for (a) an initial program to discover, develop and commercialize masked T cell engager molecules for an agreed upon initial target and backup target and (b) subject to the terms of the agreement, up to two additional programs to discover, develop, and commercialize masked T cell engager molecules for an initial target and backup target determined at the time of program initiation and (ii) an exclusive license to develop and commercialize a

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candidates. Competition may further increase with advances in the commercial applicability of technologies and greater availability of capital for investment in these industries.

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control. All of these milestones are based on a variety of assumptions which may cause the timing of achievement of the milestones to vary considerably from our estimates, including:

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There is significant uncertainty related to the insurance coverage and reimbursement of newly approved products. The regulations that govern marketing approvals, pricing and reimbursement for new medicines vary widely from country to

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Patent positions of life sciences companies can be uncertain and involve complex factual and legal questions and have in recent years been the subject of much litigation. No consistent policy governing the scope of claims allowable in the field of engineered therapeutic proteins has emerged in the United States. The scope of patent protection in jurisdictions outside of the United States is also uncertain. Changes in either the patent laws or their interpretation in any jurisdiction that we seek patent protection may diminish our ability to protect our inventions, maintain and enforce our intellectual property rights; and, more generally, may affect the value of our intellectual property, including the narrowing of the scope of our patents and any that we may license. Under the Leahy-Smith America Invents Act enacted in 2011, or the AIA, the United

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competitors, and our competitors could market competing products and technology. In addition, we or our licensors may need the cooperation of any such co-owners of our owned and in-licensed patents in order to enforce such patents against third parties, and such cooperation may not be provided to us or our licensors. Any of the foregoing could have a material adverse effect on our competitive position, business, financial conditions, results of operations and prospects.

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In addition, many countries have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties. Many countries also limit the enforceability of patents against government agencies or government

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Composition of matter patents for biological and pharmaceutical products are generally considered to be the strongest form of intellectual property protection for those types of products, as such patents provide protection without regard to any method of making or method of use. We cannot be certain, however, that the claims in our pending patent applications, including those claims covering the composition of matter of our product candidates, will be considered patentable by the USPTO or by patent offices in foreign countries, or that the claims in any of our patents that have issued or may issue will be considered valid and enforceable by courts in the United States or foreign countries. Furthermore, in some cases, we may not be able to obtain issued claims covering compositions of matter relating to our product candidates, and instead

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Our commercial success depends in part on our avoiding infringement of the patents and violation of other proprietary rights of third parties. There is a substantial amount of litigation involving patents and other intellectual property rights in the biotechnology and pharmaceutical industries, as well as administrative proceedings for challenging patents, including interference, reexamination, and post-grant review proceedings before the USPTO or oppositions and other comparable proceedings in foreign jurisdictions. We may be exposed to, or threatened with, future litigation or other adversarial proceedings by third parties having patent or other intellectual property rights alleging that our product candidates and/or

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We cannot guarantee that any of our patent searches or analyses, including the identification of relevant patents or patent applications, the scope of pending or issued patent claims, or the expiration of relevant patents are complete, nor can we be certain that we have identified each and every third-party patent and pending application in the United States and abroad that is relevant to or necessary to commercialization of our product candidates in any jurisdiction. There may be currently pending patent applications which may later result in issued patents that our product candidates may infringe. In addition, third parties may obtain patents in the future and claim that use of our technologies infringes upon these patents. Moreover, we may fail to identify relevant third-party patents or incorrectly interpret the relevance, scope, or expiration of a third-party patent or incorrectly conclude that a patent is invalid, not enforceable, exhausted, or not infringed by our activities. If any third-party patents were held by a court of competent jurisdiction to cover the manufacturing process of our product candidates, constructs or molecules used in or formed during the manufacturing process, or any final product itself, the

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intellectual property or to maintain the existing intellectual property rights we have, we may have to abandon development of such program and our business and financial condition could suffer.

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Depending upon the timing, duration and specifics of any FDA marketing approval of any of our current or future product candidates, one or more of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, or the Hatch-Waxman Act. The Hatch-Waxman Act permits a patent extension term of up to five years as compensation for patent term lost during the FDA regulatory review process.

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Further, under the Pediatric Research Equity Act, or PREA, a BLA or supplement to a BLA for certain biological products must contain data to assess the safety and effectiveness of the biological product in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective, unless the sponsor receives a deferral or waiver from the FDA. A deferral may be granted for several reasons, including a

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the manufacturer is unable to assure sufficient quantity of the product to meet the needs of patients with the rare disease or condition.

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implementing significant coverage barriers, or refusing to cover these products outright, arguing that accelerated approval drugs have insufficient or limited evidence despite meeting the FDA’s standards for accelerated approval.

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For example, the FTC has been particularly focused on the unpermitted processing of health and genetic data through its recent enforcement actions and is expanding the types of privacy violations that it interprets to be “unfair” under Section 5 of the FTC Act, as well as the types of activities it views to trigger the Health Breach Notification Rule, which the FTC also has the authority to enforce, and is in the process of developing rules related to commercial surveillance and data security.

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We are highly dependent on the management, research and development, clinical, financial and business development expertise of our executive officers, as well as the other members of our scientific and clinical teams. Although we have employment agreements that outline the terms of employment with each of our executive officers, each of them may terminate their employment with us at any time. As such, these employment agreements do not guarantee our retention of

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internet technology and the number of our employees who are working remotely, which may create additional opportunities for cybercriminals to exploit vulnerabilities. The costs to us to mitigate network security problems, bugs, viruses, worms, malicious software programs and security vulnerabilities could be significant, and while we have implemented security measures to protect our data security and information technology systems, our efforts to address these problems may not be successful, and these problems could result in unexpected interruptions, delays, cessation of service, negative publicity and other harm to our business and our competitive position. If such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our product development programs.

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other major corporate transaction. This may prevent or discourage unsolicited acquisition proposals or offers for our common stock that our stockholders may feel are in their best interest.

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appropriate, validate through testing that controls are functioning as documented and implement a continuous reporting and improvement process for internal control over financial reporting. Despite our efforts, there is a risk that we will not be able to conclude, within the prescribed timeframe or at all, that our internal control over financial reporting is effective as required by Section 404. If we identify one or more material weaknesses in our internal control over financial reporting, it could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

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person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.