CTMX 10-K & 10-Q changes, risk factors and insider trading

You should consider carefully the risks and uncertainties described below, together with all of the other information in this Annual Report on Form 10-K, including our financial statements and the related notes and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” If any of the following risks are realized, our business, financial condition, results of operations and prospects could be materially and adversely affected. The risks described below are not the only risks facing the Company.us. Risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect our business, financial condition, results of operations and/or prospects.

We are a clinical-stage biopharmaceutical company with a limited operating history, developing a novel class of therapeutic antibody product candidates, based on our proprietary biologic PROBODY® conditionally activated technology platform. Since our inception, we have devoted our resources to the development of PROBODY therapeutics. We have had significant operating losses since our inception. As of December 31, 20242025 and 2023,December 31, 2024, we had an accumulated deficit of $691.6$711.9 million and $723.4$691.6 million, respectively. Substantially all of our losses have resulted from expenses incurred in connection with our research and development programs and from general and administrative costs associated with our operations.

Though we have developed our PROBODY platform, our technologies and product candidates are in early stages of development, and we are subject to the risks of failure inherent in the development of product candidates based on novel technologies. We have not yet demonstrated our ability to successfully complete any midmid- or late-stage clinical trials, including large-scale, pivotal clinical trials, obtain regulatory approvals, arrange for a third party to manufacture a commercial-scale product candidate, or conduct sales and marketing activities necessary for successful commercialization. Typically, it takes many years to develop one product candidate from the time it enters initial preclinical studies to when it is available for treating patients. Consequently, any predictions made about our future success or viability may not be as accurate as they could be if we had a longer operating history. We will need to transition from a company with a research and development focus to a company capable of supporting commercial activities. We may not be successful in such a transition.

The development of biopharmaceutical product candidates is capital-intensive. To date, we have used substantial funds to develop our technology and product candidates and will require significant funds to conduct our ongoing clinical trials as well as to further our research and development, preclinical testing and future clinical trials of additional product candidates, to seek regulatory approvals for our product candidates and to manufacture and market any products that are approved for commercial sale. In addition, we have incurred and will continue to incur additional costs associated with operating as a public company. In January 2025, we restructured the Companycompany and reduced headcount by approximately 40% to preserve capital and focus on high priority programs. In May 2025, we raised approximately $93.4 million of net proceeds through an underwritten public offering of our common stock. As a result, we believe we have sufficient capital to operate into the second quarter of 2026.2027. We will need to raise additional funds to continue our efforts. However, financial market conditions, including the public equity markets, and government regulation, including the uncertainties of potential legislation under the new administration, may continue to make it difficult for biotechnology companies to raise additional funds. We cannot predict when or if market conditions will change.

As of December 31, 2024,2025, we had cash, cash equivalents and short-term investments of $100.6$137.1 million. We believe that our existing capital resources will be sufficient to fund our planned operations into the second quarter of 2026.2027. Our future capital requirements and the period for which we expect our existing resources to support our operations may vary significantly from what we expect and we may not achieve the expected cash flow savings that we anticipate as a result of our recent restructuring. Our monthly spending levels vary based on our ongoing clinical trials, new and ongoing research and development and other corporate activities. Because the length of time and activities associated with conducting our clinical trials and successfully researching and developing our product candidates is highly uncertain, we are unable to estimate the actual funds we will require for development and, once any product candidate is approved, any subsequent marketing and commercialization activities.

If we are unable to obtain funding on a timely basis or on acceptable terms, we may have to delay, reduce or terminate our research and development programs and preclinical studies or clinical trials, limit strategic opportunities or undergo reductions in our workforce or other corporate restructuring activities. For example, in November 2023, we announced that we would not direct significant further investment in the development of CX-2029 and havein stoppedthe workfirst onquarter of 2025 terminated the program. We also could be required to seek funds through arrangements with collaborators or others that may require us to relinquish rights to some of our technologies or product candidates that we would otherwise pursue on our own. We do not expect to realize revenue from sales of products or royalties from licensed products in the foreseeable future, if at all, and unless and until our product candidates are clinically tested, approved for commercialization and successfully marketed.

To date, we have financed our operations primarily through sales of our common stock, sale of our convertible preferred securities prior to our IPO, payments received under our collaboration agreements, including the collaboration and license agreements that we entered into with each of Regeneron and Moderna in November and December 2022, respectively, and funding we received inthrough athe private placementsales of our commonequity stock, warrants and pre-funded warrantssecurities in July 2023.2023 and May 2025. We will be required to seek additional funding in the future and currently intend to do so through additional collaborations, public or private equity offerings or debt financings, credit or loan facilities or a combination of one or more of these funding sources. Our ability to raise additional funds will depend on financial, economic and other factors, many of which are beyond our control. Additionally, our stock price has declined and our ability to raise adequate funding through equity offerings, if at all, may be limited. Additional funds may not be available to us on acceptable terms or at all. If we raise additional funds by issuing equity securities, our stockholders will suffer dilution and the terms of any financing may adversely affect the rights of our stockholders. For example, when we issue shares of common stock upon exercise of the pre-funded warrants, Tranche 1 warrants and Tranche 2 warrants (collectively, the Tranche 1 warrants and Tranche 2 warrants, the “Tranche Warrants”) issued in our July 2023 private placement, our existing stockholders will suffer dilution and such dilutive impact may be difficult to compute. In addition, as a condition to providing additional funds to us, future investors may demand, and may be granted, rights superior to those of existing stockholders. Debt financing, if available, is likely to involve restrictive covenants limiting our flexibility in conducting future business activities, and, in the event of insolvency, debt holders would be repaid before holders of our equity securities received any distribution of our corporate assets.

We are very early in our development efforts, including with CX-2051Varseta-M and CX-801 currently continuing in early-stage clinical development. We have no products on the market and our ability to achieve and sustain profitability depends on obtaining regulatory approvals for and successfully commercializing our product candidates, either alone or with third parties. Before obtaining regulatory approval for the commercial distribution of our product candidates, we or our collaboratorcollaborators must conduct extensive preclinical tests and clinical trials to demonstrate sufficient safety, purity and potency (or efficacy) of our product candidates in patients.

high drop-outdropout rates of research subjects;

If we or our collaborators experience delays in the completion of, or termination of, any clinical trial of our product candidates, the commercial prospects of our product candidates will be harmed, and our ability to generate product revenues or receive royalties from any of these product candidates will be delayed. In addition, any delays in completing our clinical trials will increase our costs, slow down our product development and approval process and jeopardize our ability to commence product sales and generate revenues. Furthermore, if one or more of our product candidates or our PROBODY therapeutic technology generally prove to be ineffective, unsafe or commercially unviable, the development of our entire platform and pipeline could be delayed, potentially permanently. For example, in March 2023, AbbVie announced that it would not advance CX-2029 into additional clinical trials and terminated our 2016 CD71 License and Collaboration Agreement for CX-2029. In November 2023, we announced that we would not direct significant further investment in the development of CX-2029 and wein havethe stoppedfirst workquarter onof 2025 terminated the program. Any similar occurrences may materially and adversely affect our business, financial condition, results of operations and prospects. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates.

Interim, “top-line,” initial and preliminary data from our clinical trials, including the ongoing Phase 1 clinical trials of CX-2051, CX-904Varseta-M or CX-801, that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we may publicly disclose preliminary or top-line data from our preclinical studies and clinical trials, which is based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study or trial. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, the top-line or preliminary results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Top-line data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, top-line data should be viewed with caution until the final data are available. InFor example, in May 2024, we disclosed initial data from our ongoing Phase 1a dose escalation clinical trial of CX-904. In March 2025, based on clinical observations to date and CytomX pipeline priorities, Amgen and we jointly decided to terminate the CX-904 program.

Our product candidatescandidates, including Varseta-M and CX-801, may cause undesirable side effects at any time during or after the clinical trial process that could delay or prevent their regulatory approval, limit the commercial profile of an approved label, or result in significant negative consequences following marketing approval, if any, including withdrawal from the market.

Undesirable side effects caused by our product candidates could cause us, our collaborators 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 other regulatory authorities. As is the case with all oncology drugs, there may be immediate or late side effects associated with the use of our product candidates, including CX-2051Varseta-M and CX-801. Our lead program, Varseta-M, is an antibody drug conjugate which is in a class of therapy known to drive potent anti-cancer activity, but that often have side effects or adverse events that need to be managed in order for patients to derive benefits from treatment. There can be no assurance that unexpected adverse events will not occur in our ongoing trials, including the ongoing Phase 1 clinical trials of CX-2051Varseta-M or CX-801, or in future trials involving our product candidates or the product candidates of our collaborators. Undesirable side effects may appear in later trials that were not observed in our earlier trials or may be more severe in later trials than earlier trials.

The results of our or our collaborators’ future clinical trials could reveal a high and unacceptable severity of adverse side effects, including immune system related adverse events or increased toxicity, and it is possible that patients enrolled in such clinical trials could respond in unexpected ways or otherwise have unexpected adverse events. For example, in 2022May 2025 and in March 2026, we initiatedannounced apositive first-in-humaninterim data from our ongoing Phase 1 clinical trial with CX-904Varseta-M. and, whileWhile we believe ourinterim preclinicaldata studies indicatesupports the potential to reach a favorable therapeutic index, clinicalwe dataalso willreported betreatment necessaryrelated toadverse specifyevents, anincluding acceptablediarrhea, dose.nausea, vomiting, and anemia, and in August 2025, we announced that a single Grade 5 treatment-related acute kidney injury occurred in a patient with a complex medical history including having a solitary kidney. We cannot provide assurance that we will reach an acceptable or tolerable dose for CX-2051Varseta-M or CX-801. Furthermore, any ongoing or future clinical trials of our product candidates, including those for CX-2051Varseta-M and CX-801, could face risks related to undesirable side effects, including unacceptable toxicity.

In addition, adverse side effects caused by any drugs of other companies utilizing the same or similar antibodiestherapeutic agents of our product candidates, or that are similar in nature to our product candidates could delay or prevent regulatory approval of our product candidates, limit the commercial profile of an approved label for our product candidates, or result in significant negative consequences following marketing approval.

In addition, competing clinical trials and clinicians’ and patients’ perceptions as to the potential advantages of the product candidate being studied in relation to other available therapies, including any new drugs or therapeutic biologics that may be approved for the indications we are investigating, could affect our ability to enroll a sufficient number of eligible patients in our clinical trials. There can be no assurance that new or further trials with our current or future drug candidates will not be adversely affected by a limited patient population. Our clinical trials of CX-2051Varseta-M and CX-801 study patients who have one or a select number of specific tumor types rather than patients suffering from any cancer, which limits the rate of enrollment of the trial. In addition, some of our clinical trials may seek to treat indications with small population sizes which could be particularly difficult to enroll. The clinical trials for our molecules also compete with thousands of clinical trials with alternative anti-cancer drugs in similar classes (e.g. antibody-drug conjugates), and certain arms of the clinical trials may be difficult to enroll due to the emerging standard of care for such indications in certain jurisdictions, including the United States. Likewise, our clinical trials of CX-2051Varseta-M and CX-801 are also competing with thousands of other anti-cancer clinical trials. Any clinical trials of our product candidates initiated by our collaborators will face similar and additional risks relating to enrollment. We or our collaborators could also encounter delays in the development of any of our product candidates if prescribing physicians encounter unresolved ethical issues associated with enrolling patients in clinical trials of our product candidates in lieu of prescribing existing treatments that have established safety and efficacy profiles. Any delays relating to patient enrollment could cause significant delays in the timing of our or our collaborators’ clinical trials, which may materially and adversely affect our business, financial condition, results of operations and prospects.

We will continue to conduct clinical trials and contract with third-party manufacturers in foreign countries, including Europe and China, which could expose us to risks that could have a material adverse effect on the success of our business.

We have enrolled or are planning to enroll patients in our clinical trials outside the United States, including in Europe and South Korea.Europe. While we generally conduct our clinical trials primarily or partially in the U.S., the acceptance of study data from clinical trials conducted outside the U.S. or another jurisdiction by the FDA or comparable foreign regulatory authority may be subject to certain conditions or may not be accepted at all. In cases where data from foreign clinical trials are intended to serve as the sole basis for marketing approval in the U.S., the FDA will generally not approve the application on the basis of foreign data alone unless (i) the data are applicable to the U.S. population and U.S. medical practice; (ii) the trials were performed by clinical investigators of recognized competence and pursuant to good clinical practices (“GCPs”) regulations; and (iii) the data may be considered valid without the need for an on-site inspection by the FDA, or if the FDA considers such inspection to be necessary, the FDA is able to validate the data through an on-site inspection or other appropriate means. In addition, even where the foreign study data are not intended to serve as the sole basis for approval, if the trial was not subject to an IND, the FDA will not accept the data as support for an application for marketing approval unless the study was well-designed and well-conducted in accordance with GCP requirements and the FDA is able to validate the data from the study through an onsite inspection, if deemed necessary. Many foreign regulatory authorities have similar approval requirements. In addition, such foreign trials would be subject to the applicable local laws of the foreign jurisdictions where the trials are conducted. There can be no assurance that the FDA or any comparable foreign regulatory authority will accept data from trials conducted outside of the U.S. or the applicable jurisdiction. If the FDA or any comparable foreign regulatory authority does not accept such data, it would result in the need for additional trials, which could be costly and time-consuming, and which may result in current or future product candidates that we may develop not receiving approval for commercialization in the applicable jurisdiction.

In addition, we currently contract manufacturing operations to third parties, and certain of our product candidates are manufactured by and will in the future be manufactured by third parties outside the U.S., including in Europe and China. For example, we have a contract with a third-party manufacturer located in China for product candidates, including CX-2051Varseta-M and CX-801, and accordingly we are exposed to the possibility of drug product supply disruption, delay and increased costs in the event of changes in the policies of the U.S.U.S., European or Chinese governments, including political unrest or unstable economic conditions in China.China or elsewhere.

Conducting clinical trials and contracting with third-party manufacturers outside the United States also exposes us to additional risks, including risks associated with additional foreign regulatory requirements; foreign exchange fluctuations; tariffs; patient monitoring and compliance; compliance with foreign manufacturing, customs, shipment and storage requirements; and cultural differences in medical practice and clinical research. We are also subject to risks associated with doing business globally, including commercial, political, and financial risks. In addition, we are subject to potential disruption caused by military conflicts; potentially unstable governments or legal systems; civil or political upheaval or unrest; local labor policies and conditions; possible expropriation, nationalization, or confiscation of assets; problems with repatriation of foreign earnings; economic or trade sanctions; closure of markets to imports; anti-American sentiment; terrorism or other types of violence in or outside the United States; health pandemics; and a significant reduction in global travel. Our success will depend, in part, on our ability to overcome the challenges we encounter with respect to these risks and other factors affecting U.S. companies with global operations. If our global clinical trials or foreign third-party suppliers were to experience significant disruption due to these risks or for other reasons, it could have a material adverse effect on our business, financial condition, results of operations and prospects.

We rely on third-party contract manufacturers to manufacture our clinical trial and preclinical study product supplies, some of which are located in foreign countries. Most of our clinical trial manufacturing contractors and suppliers are our sole source for their respective manufacturing and supplies. Failure of any of these contractors could put our ability to have clinical trial material available when needed at risk. Any such failure to have clinical trial material available when needed could result in a substantial delay of our clinical trials. For each of CX-2051Varseta-M and CX-801 our manufacturing supply chain includes several contract manufacturers, and failure by any of these manufacturers could result in interruptions of our clinical studies. For example, beginning in October 2023, one of our contract manufacturers of CX-2051 experienced production failures. Although we are taking steps to manage our long-term supply of CX-2051,Varseta-M, there can be no assurance that we will not have future production failures,failures in the future, which could affect our ability to conduct our trials for CX-2051Varseta-M or any other clinical trial drug candidates, including CX-801, on our planned timeline or at all. We do not own manufacturing facilities for producing such supplies and do not have any long-term contracts and we do not currently have an alternative to any of our third-party contract manufacturers. There can be no assurance that our preclinical and clinical development product supplies will not be limited, interrupted, or of satisfactory quality or continue to be available at acceptable prices. In particular, any replacement of any of our third-party contract manufacturers could require significant effort and expertise because there may be a limited number of qualified replacements. In addition, we may encounter issues with transferring technology to a new third-party manufacturer, and we may encounter regulatory delays if we need to move the manufacturing of our products from one third-party manufacturer to another.

The manufacturing process for a product candidate is subject to FDA and foreign regulatory authority review. Suppliers and manufacturers must meet applicable manufacturing requirements and undergo rigorous facility and process validation tests required by regulatory authorities in order to comply with regulatory standards, such as current Good Manufacturing Practices (“cGMPs”). In the event that any of our manufacturers fails to comply with such requirements or to perform its obligations to us in relation to quality, timing or otherwise, such as the CX-2051Varseta-M manufacturing production failures our contract manufacturer experienced in 2023, or if our supply of components or other materials becomes limited or interrupted for other reasons, such as one of our manufacturers going out of business, we may be forced to manufacture the materials ourselves, for which we currently do not have the capabilities or resources, or enter into an agreement with another third party, which we may not be able to do on reasonable terms, if at all. In some cases, the technical skills or technology required to manufacture our product candidates may be unique or proprietary to the original manufacturer and we may have difficulty transferring such skills or technology to another third party and a feasible alternative may not exist. These factors would increase our reliance on such manufacturer or require us to obtain a license from such manufacturer in order to have another third party manufacture our product candidates. If we are required to change manufacturers for any reason, we will be required to verify that the new manufacturer maintains facilities and procedures that comply with quality standards and with all applicable regulations and guidelines. The delays associated with the verification of a new manufacturer could negatively affect our ability to develop product candidates in a timely manner or within budget.

It may prove more challenging than we anticipate to manufacture products that incorporate our PROBODY therapeutic technology. In order to conduct clinical trials of our product candidates, including our clinical trials for CX-2051Varseta-M and CX-801CX-801, we will need to manufacture them in large quantities. There can be no assurance that we will not have future production failures, which could affect our ability to conduct our trials for CX-2051Varseta-M or CX-801 or any other clinical trial drug candidates on our planned timeline or at all. Furthermore, in order to conduct later stage clinical trials of our product candidates and eventually, if approved, commercial products, we will need to manufacture them in larger quantities. We, or any manufacturing partners, may be unable to successfully increase the manufacturing scale and capacity for any of our product candidates in a timely or cost-effective manner, or at all. However, we may have to start late-stage trials with our early clinical trial drug product and switch to late-stage or commercial drug product mid trial. In such event, the FDA will require us to complete bridging studies to compare the earlier stage material with late-stage or commercial material to assure comparability between the earlier trial material and the late- stage or commercial material. Changing formulation and scaling up the process is a complicated and difficult task. While we believe we can complete this process successfully, there can be no assurances that the changes we make to the drug product and manufacturing process will be successful or completed in a timely manner or that the FDA will not require additional development steps or studies from those we believe are necessary. If we are not able to scale up our manufacturing capabilities with respect to any of our product candidates, increase the life of drug stability of product candidates, or successfully complete the FDA’s bridging requirements, the development, testing, and clinical trials of that product candidate may be delayed or infeasible, and regulatory approval or commercial launch of any resulting product may be delayed or not obtained, which could significantly harm our business.

We plan to continue to develop a pipeline of product candidates using our proprietary PROBODY platform. We believe that product candidates (including cancer immunotherapies, conditionally activated ADCs and bispecific antibodies) identified with our product discovery platform may offer an improved therapeutic approach by taking advantage of unique conditions in the tumor microenvironment, thereby reducing the dose-limiting toxic effects associated with traditional antibody products, which can also attack healthy tissue. However, the scientific research that forms the basis of our efforts to develop product candidates based on our PROBODY platform is ongoing, including the research resulting from our ongoing clinical trials for CX-2051Varseta-M and CX-801.

Since 2013, we have entered into collaborations with AbbVie, Amgen, Astellas, Bristol Myers Squibb, ImmunoGen, Moderna, Pfizer, Regeneron and others to develop certain PROBODY therapeutics. We may in the future seek third-party collaborators for development and commercialization of other therapeutic technologies or product candidates. Biopharmaceutical companies are our prior and likely future collaborators for any marketing, distribution, development, licensing or broader collaboration arrangements. With respect to our existing collaboration agreements, and what we expect will be the case with any future collaboration agreements, we have and would expect to have limited control over whether such collaborations pursue the development of our product candidates or the amount and timing of resources that such collaborators dedicate to the development or commercialization of our product candidates. For instance, in March 2023, AbbVie terminated the collaboration agreement for CX-2029 and the ongoing discovery agreement we had entered into with them in 2016. Our partners have chosen multiple targets for research, some of which continue to be advanced and others which do not continue to advance. Our partners will continue to choose early research targets from time to time, some of which will advance into further research and development and some of which will not. For example, in January 2023, Bristol Myers Squibb announced that it would deprioritize the Phase 2 clinical program for BMS-986249 and advance the BMS-986288 into a Phase 2 program, and on March 6, 2024, Bristol Myers Squibb notified us that it would not continue the BMS-986288 program. As a result, there can be no assurances that any of the programs covered by our existing or future collaborations will be developed further. Further, our ability to generate revenues from our existing and future arrangements will depend on our collaborators’ abilities to successfully perform the functions assigned to them in these arrangements. Additionally, some of our collaborations may require us to share in certain development and commercialization expenses. If we cannot afford to share such expenses when required, our rights under such collaborations may be adversely affected, including potentially that our collaborators may terminate the relevant agreement. Overall, collaborations involving our product candidates currently pose, and will continue to pose, the following risks to us:

collaborators have significant discretion in determining the amount and timing of efforts and resources that they will apply to these collaborations, including, with respect to Amgen, CX-904 as well asincluding the preclinical collaboration programs with Bristol Myers Squibb, Amgen, Astellas, Regeneron and Moderna;

For example, in January 2023, we announced topline results of the Phase 2 expansion cohorts of CX-2029 and in March 2023, AbbVie decided not to continue the future development of CX-2029. CytomX re-acquired full rights to CX-2029, however, in the fourth quarter of 2023, we decided to not to make any further significant investments in the solid tumor CX-2029 program and has terminated the program.program in the first quarter of 2025. Additionally, in March 2025, based on clinical observations to date and CytomXour pipeline priorities, Amgen and we jointly decided to terminate the CX-904 program.

Substantially all of our revenue to date has been derived from our existing collaboration agreements, including, most recently, the agreements that we entered into with Regeneron and Moderna in 2022, and a significant portion of our future revenue and cash resources is expected to be derived from these agreements or other similar agreements we may enter into in the future. Revenue from research and development collaborations depend upon continuation of the collaborations, reimbursement of development costs, the achievement of milestones and royalties, if any, derived from future products developed from our research. If our development partners do not select additional targets and we are unable to successfully advance the development of our product candidates or achieve milestones, revenue and cash resources from milestone payments under our collaboration agreements will be substantially less than expected.

In addition, to the extent that any of our collaborators were to terminate a collaboration agreement, we may decide to independently develop these product candidates to the extent we retain development rights. Such development could include funding preclinical or clinical trials, assuming marketing and distribution costs and defending intellectual property rights. Alternatively, in certain instances, we may choose to abandon product candidates altogether. For instance, in March 2023, AbbVie terminated our 2016 CD71 License and Collaboration Agreement, and from time to time some of our research programs have been terminated by our partners. The termination of any of our collaboration agreements or individual programs within a collaboration agreement could result in a change to our business plan and may have a material adverse effect on our business, financial condition, results of operations and prospects. If a collaboration or program is terminated, we would not be eligible to receive the milestone, royalty or other payments that would have been payable under the collaboration agreement. For example, in March 2024,2025, Bristolbased Myerson Squibbclinical notifiedobservations usto thatdate itand wouldCytomX notpipeline continuepriorities, Amgen and we jointly decided to terminate the BMS-986288CX-904 program and we will not receive any milestone or other payments from them on this program.

If we do not achieve our projected development and commercialization goals in the timeframes we announceannounce, and expect the commercialization of any of our product candidates may be delayed, or never attained, and our business will be harmed.

We may not successfully engage in strategic transactions, including any additional collaborations we seek, which could adversely affect our ability to develop and commercialize product candidates, impact our cash position, increase our expenseexpenses and present significant distractions to our management.

Because we have limited financial and managerial resources, we focus on specific product candidates and indications. For example, in July 2022, we announced that we would not continue the development of pralauzatamab ravtansine without a partner. Additionally, in Novemberthe 2023first quarter of 2025, we decided to not to make any further significant investments interminated the CX-2029 solid tumor program in the near-term.program. As a result, we may forgo or delay pursuit of opportunities with those products in other indications or with other product candidates that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable product candidates. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

Since 2022 we have maintained a relatively steady number of employees in our workforce and maintained activities to manage our pipeline, including research activities and efforts to establish and run clinical trials for CX-2051,Varseta-M, CX-904 and CX-801. However, in January 2025, we announced that we would reduce our workforce, primarily research and general and administrative staff, by approximately 40% to preserve capital for ongoing clinical trials and collaboration partner activities. In the future we may need to grow our organization substantially to continue development and pursue the potential commercialization of our product candidates, including CX-801Varseta-M and CX-2051,CX-801, as well as function as a public company. As we increase the number of our product candidates entering and advancing through preclinical studies and clinical trials, we will need to expand our development, regulatory and manufacturing capabilities or contract with additional organizations to provide these capabilities for us. In addition, we expect our collaborations to require greater resources as the development of our product candidates under such agreements progresses. In the future, we expect to also have to manage additional relationships with collaborators or partners, suppliers and other organizations. In particular, if the third parties on which we currently rely are not capable of delivering services or supplies in a manner that is sufficient to meet our requirements as we expand our operations, we could be required to contract with new third parties and there can be no assurances that the services or supplies of such third parties will be available on commercially reasonable terms, or at all. Furthermore, our ability to manage our operations and future growth will require us to continue to increase headcount as well as improve our operational, financial and management controls, reporting systems and procedures. We may not be able to implement improvements to our management information and control systems in an efficient or timely manner and may discover deficiencies in existing systems and controls.

We face substantial competition from pharmaceutical companies developing products in oncology, including companies such as Amgen, AstraZeneca PLC, Bristol Myers Squibb, GlaxoSmithKline plc, Merck & Co., Inc. Novartis AG, Pfizer, Roche Holding Ltd. and Sanofi SA. Many large and mid-sized biotech companies, including BeiGene, Incyte, Nektar, and Alkermes have ongoing efforts in cancer immunotherapy. Several companies, including Adagene, Amgen, Sanofi, BioAtla, Halozyme, Janux Therapeutics, Roche, Takeda, Vir Biotechnology, Werewolf Therapeutics,Therapeutics and Xilio are exploring antibody masking and/or conditional activation strategies, which could compete with our PROBODY platform. We are also aware of several companies that are developing ADCs, such as AbbVie, ADC Therapeutics, Astra Zeneca, BMS, Daiichi Sankyo, Gilead, Merck & Co., Mersana Therapeutics, Pfizer, Roche Holding Ltd.,Ltd. and Takeda. Companies like Gilead and Jazz are pursuing development programs in the cytokine space. Furthermore, several large pharmaceutical companies, including Amgen, Novartis AG and Roche Holding Ltd., are developing T-cell engaging immunotherapies, and we are aware of several mid-sized biotech companies, such as MacroGenics and Xencor, and small companies with ongoing efforts to develop T-cell engaging immunotherapies. Any of these companies may be well capitalized and may have significant clinical experience. In addition, these companies include our collaborators.

Our success largely depends on the continued service of key management, advisors and other specialized personnel, including Sean A. McCarthy, D.Phil., our chief executive officer and chairman. The loss of one or more members of our management team or other key employees or advisors could delay our research and development programs and have a material and adverse effect on our business, financial condition, results of operations and prospects. The relationships that our key managers have cultivated within our industry make us particularly dependent upon their continued employment with us. We are dependent on the continued service of our technical personnel because of the highly technical nature of our product candidates and technologies and the specialized nature of the regulatory approval process. Because our management team and key employees are not obligated to provide us with continued service, they could terminate their employment with us at any time without penalty. In particular, as a result of the COVID-19 pandemic, the ability of employees to engage in a remote working environment increased the competitive landscape across the country for us in seeking qualified employees. Employees are now able to consider opportunities across the country and it may be more difficult to hire employees. Furthermore, it is more difficult to engage employees in Company culture and build working rapport when they are working remotely. As a result, it may be more difficult to retain employees on a long-term basis. Our future success will depend in large part on our continued ability to attract and retain other highly qualified scientific, technical and management personnel, as well as personnel with expertise in clinical testing, manufacturing, governmental regulation and commercialization. We face competition for personnel from other companies, universities, public and private research institutions, government entities and other organizations, especially as job opportunitiesorganizations in the biotechnology industry increaseacross the country and especially in the San Francisco Bay Area and across the country.Area.

We are exposed to significant product liability risks inherent in the development, testing, manufacturing and marketing of therapeutic treatments, including as a result of the clinical testing of our prior clinical candidates, our current clinical candidates, including CX-2051Varseta-M and CX-801, and any other product candidates we may have or those of our collaborators. Product liability claims could delay or prevent completion of our development programs. If we succeed in marketing product candidates, such claims could result in an FDA investigation of the safety and effectiveness of our product candidates, our manufacturing processes and facilities (or the manufacturing processes and facilities of our third-party manufacturers) or our marketing programs and potentially a recall of our products or more serious enforcement action, limitations on the approved indications for which they may be used or suspension or withdrawal of approvals. Regardless of the merits or eventual outcome, liability claims may also result in decreased demand for our products, injury to our reputation, costs to defend the related litigation, a diversion of management’s time and our resources, substantial monetary awards to trial participants or patients and a decline in our stock price. We currently have insurance that we believe is appropriate for our stage of development and may need to obtain higher levels of insurance prior to marketing any of our product candidates. Any insurance we have or may obtain may not provide sufficient coverage against potential liabilities. Furthermore, clinical trial and product liability insurance is becoming increasingly expensive. As a result, we may be unable to obtain sufficient insurance at a reasonable cost to protect us against losses caused by product liability claims that could have a material and adverse effect on our business, financial condition, results of operations and prospects.

Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the “IRC”), if a corporation undergoes an “ownership change” (generally defined as a greater than 50 percentage points change (by value) in the ownership of its equity over a rolling three-year period), the corporation’s ability to use its pre-change net operating loss carryforwards and certain other pre-change tax attributes to offset its post-change income and taxes may be limited. California has similar rules. For example, we performed an IRC Section 382 analysis in 2017 and determined there was an ownership change that resulted in Section 382 limitations. The ownership change limited our ability to utilize net operating losses against taxable income in 2018 for both federal and California tax purposes. The remaining net operating losses and credit will be available in future years before expiration during their respective carryforward periods. We may experience ownership changes in the future as a result of shifts in our stock ownership, some of which are outside our control, and our ability to utilize net operating loss carryforwards could be limited by an “ownership change” as described above, which could result in additional increased tax liability to the Company.us.

Our success depends in part on our ability to obtain and maintain patents and other forms of intellectual property rights, including in-licenses of intellectual property rights of others, for our product candidates, methods used to manufacture our product candidates and methods for treating patients using our product candidates, as well as our ability to preserve our trade secrets, to prevent third parties from infringing upon our proprietary rights and to operate without infringing upon the proprietary rights of others. We have a substantial number of issued patents and pending patent applications, some of which are co-owned with a third party, covering our PROBODY platformsplatform technology and products as well as methods of use and production thereof; we have exclusively licensed UCSB’s interest in the patent family co-owned with UCSB that covers certain PROBODYconditionally andactivatable other pro-protein technologyantibodies in the fields of therapeutics, in vivo diagnostics and prophylactics. In addition, we have exclusively licensed a patent portfolio of three patent families from UCSB that includes patents and patent applications that cover compositions and methods related to the screening for and identification of the masks that we incorporate into some of our PROBODY candidates. We may not be able to apply for patents on certain aspects of our product candidates in a timely fashion or at all. Our existing issued and granted patents and any future patents we obtain may not be sufficiently broad to prevent others from using our technology or from developing competing products and technology. There is no guarantee that any of our pending patent applications will result in issued or granted patents, that any of our issued or granted patents will not later be found to be invalid or unenforceable or that any issued or granted patents will include claims that are sufficiently broad to cover our product candidates or to provide meaningful protection from our competitors. Moreover, the patent position of biotechnology and biopharmaceutical companies can be highly uncertain because it involves complex legal and factual questions. We will be able to protect our proprietary rights from unauthorized use by third parties only to the extent that our current and future proprietary technology and product candidates are covered by valid and enforceable patents or are effectively maintained as trade secrets. If third parties disclose or misappropriate our proprietary rights, it may materially and adversely affect our position in the market.

The U.S. Patent and Trademark Office (“USPTO”) and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other provisions during the patent process. There are situations in which noncompliance can result in abandonment or lapse of a patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. There could also be delays at the USPTO caused by staffing cuts and other U.S. government actions as a result of the U.S. Department of Government Efficiency or other executive actions to reduce the size of the U.S. government. In such an event, competitors might be able to enter the market earlier than would otherwise have been the case. The standards applied by the USPTO and foreign patent offices in granting patents are not always applied uniformly or predictably. For example, there is no uniform worldwide policy regarding patentable subject matter or the scope of claims allowable in biotechnology and biopharmaceutical patents. As such, we do not know the degree of future protection that we will have on our proprietary products and technology. While we will endeavor to try to protect our product candidates with intellectual property rights such as patents, as appropriate, the process of obtaining patents is time-consuming, expensive and sometimes unpredictable.

In addition, there are numerous recent changes to the patent laws and proposed changes to the rules of the USPTO that may have a significant impact on our ability to protect our technology and enforce our intellectual property rights. For example, the America Invents Act (“AIA”) enacted withinin the last several years2011 involves significant changes in patent legislation. However, there remains many subsisting issued patents and some pending patent applications in the U.S. that were filed prior to its enactment and are therefore subject to the pre-AIA U.S. patent laws and that may have relevance to our freedom-to-operate or ability to obtain patent issuances. The Supreme Court has ruled on several patent cases in recent years, some of which cases either narrow the scope of patent protection available in certain circumstances or weaken the rights of patent owners in certain situations. TheWe recentcan decisionmake byno theassurance that our interpretations of Supreme Court in Association for Molecular Pathology v. Myriad Genetics, Inc. precludes a claim to a nucleic acid having a stated nucleotide sequence that is identical to a sequence found in nature and has not been modified. We currently are not aware of an immediate impact of this decision on our patents or patent applications because we are developing product candidates that contain modifications, such as our PROBODY substrates and masks, that we believe are not found in nature. However, this decision has yet to be clearly interpreted by courts and by the USPTO. We cannot assure you that the interpretations of this decisiondecisions or subsequent rulings will not adversely impact our patents or patent applications. In addition to increasing uncertainty with regard to our ability to obtain patents in the future, this combination of events has created uncertainty with respect to the value of patents, once obtained. Depending on decisions by the U.S. Congress, the federal courts and the USPTO, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future.

Once granted, patents may remainbe opensubject to opposition, interference, re-examination, post-grant review, inter partes review, nullification or derivation action in court or before patent offices or similar proceedings for a given period after allowance or grant, during which time third parties can raise objections against such initial grant. In the course of such proceedings, which may continue for a protracted period of time, the patent owner may be compelled to limit the scope of the allowed or granted claims thus attacked, or may lose the allowed or granted claims altogether. In addition, there can be no assurance that:

PROBODYConditionally-activated therapeutics are a relatively new scientific field. We have obtained grants and issuances of PROBODY therapeutic patents and have licensed one patent family comprising several of these patents from a third party on an exclusive basis for therapeutics applications. The issued patents and pending patent applications in the United States and in key markets around the world that we own or license claim many different methods, compositions and processes relating to the discovery, development, manufacture and commercialization of antibody and immunoregulatory therapeutics. Specifically, we own and have licensed a portfolio of patents, patent applications and other intellectual property covering PROBODY therapeutic compositions of matter as well as their methods of manufacturing and use.

We or our licensors, or any future strategic partners may become subject to third partythird-party claims or litigation alleging infringement of patents or other proprietary rights or seeking to invalidate patents or other proprietary rights, and we may need to resort to litigation to protect or enforce our patents or other proprietary rights, all of which could be costly, time consuming, delay or prevent the development and commercialization of our product candidates, or put our patents and other proprietary rights at risk.

We or our licensors, or any future strategic partners may be subject to third-party claims for infringement or misappropriation of patent or other proprietary rights. We are generally obligated under our license or collaboration agreements to indemnify and hold harmless our licensors or collaborators for damages arising from intellectual property infringement by us. For example, in March 2020, Vytacera filed a patent infringement lawsuit against the Companyus in the U.S. District Court for the District of Delaware. The lawsuit alleged that the Company’sour use, offers to sell, and/or sales of the PROBODY technology platform for basic research applications constituted infringement. The complaint sought unspecified monetary damages. On October 17, 2024 the Court dismissed plaintiff’s case, and on October 28, 2024, the Court ordered the case to be closed.

Because the antibodytherapeutic landscape is still evolving, including the masked antibodybiologics landscape, it is difficult to conclusively assess our freedom to operate without infringing on third-party rights. There are numerous companies that have pending patent applications and issued patents broadly covering antibodiesmasked therapeutics generally or covering antibodiesmasked therapeutics directed against the same targets as, or targets similar to, those we are pursuing. An increasing number of third parties are filing masked antibodytherapeutics patent applications, several of which contain claims that are patterned after our own patent claims. Our competitive position may suffer if patents issued to third parties or other third-party intellectual property rights cover our products or product candidates or elements thereof, or our manufacture or uses relevant to our development plans. In such cases, we may not be in a position to develop or commercialize products or product candidates unless we successfully pursue litigation to nullify or invalidate the third-party intellectual property right concerned, or enter into a license agreement with the intellectual property right holder, if available on commercially reasonable terms. There may be issued patents of which we are not aware, held by third parties that, if found to be valid and enforceable, could be alleged to be infringed by our PROBODY therapeutic technologies. There also may be pending patent applications of which we are not aware that may result in issued patents, which could be alleged to be infringed by our PROBODY therapeutic technologies. If such an infringement claim should be brought and be successful, we may be required to pay substantial damages, be forced to abandon our product candidates or seek a license from any patent holders. No assurances can be given that a license will be available on commercially reasonable terms, if at all.

Our licenses from Amgen, AbbVie (formerly ImmunoGen) and UCSB impose, and any future licenses we enter into are likely to impose, various development, commercialization, funding, diligence, sublicensing, insurance, patent prosecution and enforcement and/or other obligations on us, including various payment obligations such as milestone and royalty payments and payments based on sublicensing revenues. Our rights under our agreements with our licensors or collaborators may be limited or modified according to their terms. Additionally, if we breach any of these obligations, or use the intellectual property licensed to us in an unauthorized manner, we may be required to pay damages and the licensor may have the right to terminate the license, which could result in us being unable to develop, manufacture and sell products that are covered by the licensed technology or enable a competitor to gain access to the licensed technology. Moreover, our licensors and collaborators may own or control intellectual property that has not been licensed to us and, as a result, we may be subject to claims, regardless of their merit, that we are infringing, misappropriating or otherwise violating the licensor’s rights. In addition, while we cannot currently determine the amount of the royalty or sublicense revenue payment obligations we would be required to pay on development or sales of future products, if any, the amounts may be significant. The amount of our future royalty or sublicense revenue payment obligations will depend on the technology and intellectual property we use in products that we successfully develop and commercialize, if any. Therefore, even if we successfully develop and commercialize products, we may be unable to achieve or maintain profitability.

Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts in the U.S. and certain foreign jurisdictions are less willing or unwilling to protect trade secrets. We may also need to share our proprietary know-how with current or future partners, collaborators, contractors and others located in countries at heightened risk of theft of trade secrets, including through direct intrusion by private parties or foreign actors, and those affiliated with or controlled by state actors. As a result, we may encounter significant problems in protecting and defending our intellectual property both in the United States and abroad. If any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor, our competitive position would be harmed.

Our product candidates that we are currently developing are regulated as therapeutic biologics that are subject to requirements for review and approval of a BLA by the FDA’s Center for Drug Evaluation and Research (“CDER”). Therefore, our product candidates are subject to extensive governmental regulations relating to, among other things, research, testing, development, manufacturing, safety, efficacy, approval, recordkeeping, reporting, labeling, storage, packaging, advertising and promotion, pricing, marketing and distribution of drugs and therapeutic biologics. Rigorous preclinical testing and clinical trials and an extensive regulatory approval process are required to be successfully completed in the U.S. and in many foreign jurisdictions before a new drug or therapeutic biologic can be marketed. Satisfaction of these and other regulatory requirements is costly, time consuming, uncertain and subject to unanticipated delays. For example, recently the FDA launched Project Optimus, an initiative to reform the dose optimization and dose selection paradigm in oncology drug development. While the effort is intended to help drive better ultimate outcomes in the development of oncology drugs, these efforts could also lead to longer and more expensive early development efforts for companies, including us, before we are able to initiate registrational studies for our product candidates. It is possible that none of the product candidates we may develop will obtain the regulatory approvals necessary for us or our existing or future collaborators to begin selling them.

As a company, we have limited experience in conducting and managing the clinical trials necessary to obtain regulatory approvals, including approval by the FDA. The time required to obtain FDA and other approvals is unpredictable but typically takes many years following the commencement of clinical trials, depending upon the type, complexity and novelty of the product candidate. The standards that the FDA and its foreign counterparts use when regulating us require judgment and can change, which makes it difficult to predict with certainty how they will be applied. Any analysis we perform of data from preclinical and clinical activities is subject to confirmation and interpretation by regulatory authorities, which could delay, limit or prevent regulatory approval. We may also encounter unexpected delays or increased costs due to new government regulations, for example, from future legislation or administrative action, or from changes in FDA policy during the period of product development, clinical trials and FDA regulatory review. Further, government shutdowns,shutdowns suchor as the partial U.S. federalother government shutdown that occurred in late 2018 or the United Kingdom’s departure from the European Unionactions may impact our ability to access government agencies in a timely manner or otherwise impact our ability to move our product candidates through the regulatory process. It is impossible to predict whether legislative changes will be enacted, or whether FDA or foreign regulations, guidance or interpretations will be changed, or what the impact of such changes, if any, may be.

Disruptions at the FDA and other government agencies caused by funding shortagesshortages, staffing limitations, or globalpolicy health concernschanges could hinder their ability to hire, retain or deploy key leadership and other personnel, or otherwise prevent new or modified products from being developed, approved or commercialized in a timely manner or at all, which could negatively impact our business.

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, statutory, regulatory, and policy changes, the FDA’s ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA’s ability to perform routine functions. Average review times at the FDA have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is inherently fluid and unpredictable. Disruptions at the FDA and other agencies may also slow the time necessary for therapeutic biologics or modifications to approved therapeutic biologics to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. For example, in recent years, the U.S. government has shut down several times and certain regulatory agencies, such as the FDA, have had to furlough FDA employees and stop critical activities. In addition, the current U.S. Presidential administration has issued certain policies and Executive Orders directed towards reducing the employee headcount and costs associated with U.S. administrative agencies, including the FDA, which have led to substantial staff turnover, and it remains unclear the degree to which these efforts may limit or otherwise adversely affect the FDA’s ability to conduct routine activities.

Separately, in response to the COVID-19 pandemic, the FDA postponed most inspections of domestic and foreign manufacturing facilities at various points. If a prolonged government shutdown occurs, or if renewedpolicy globalchanges, healthfunding concernsshortages, or staffing limitations prevent the FDA or other regulatory authorities from conducting their regular inspections, reviews or other regulatory activities, itsuch events could significantly impact the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

In the United States, there have been and continue to be a number of legislative initiatives to contain healthcare costs, and government regulation. In March 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act (together, the “ACA”), was passed, which substantially changed the way healthcare is financed by both governmental and private insurers, and significantly impacts the U.S. pharmaceutical industry. The ACA, among other things, subjected therapeutic biologics to potential competition by lower-cost biosimilars, addressed a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs and therapeutic biologics that are inhaled, infused, instilled, implanted or injected, increased the minimum Medicaid rebates owed by manufacturers under the Medicaid Drug Rebate Program and extended the rebate program to individuals enrolled in Medicaid managed care organizations, and established annual fees and taxes on manufacturers of certain branded prescription drugs and therapeutic biologics. Since its enactment, there have been judicial, executive and Congressional challenges to certain aspects of the ACA. On June 17, 2021, the U.S. Supreme Court dismissed the most recent judicial challenge to the ACA brought by several states without specifically ruling on the constitutionality of the ACA. However, the ACA continues to be discussed in Congress and future changes to the ACA could negatively impact our potential business and financial results.

CX-801 is our interferon ("IFN") alpha-2b PROBODY. IFNα2b provides a potentially superior approach to activating anti-tumor immune responses than other cytokines. CX-801 is a dually masked, conditionally activated version of IFNα2b that has the potential to become a cornerstone of combination therapy for a wide range of tumor types. The IND for CX-801 was allowed to proceed by the FDA in January 2024, and in the third quarter of 2024 the first patient was dosed in the CX-801 Phase 1 dose escalation study in solid tumors. The Phase 1 dose escalation study is focused on patients with advanced melanoma. In Phase 1 dose escalation, the study will evaluate safety, translational biomarkers and signs of clinical activity for CX-801 monotherapy and in combination with KEYTRUDA®. In the second quarter of 2024, CytomX announced a clinical collaboration with Merck to supply KEYTRUDA for evaluation of its combination with CX-801 in the Phase 1 study. The Phase 1 study is currently in the fourth monotherapy dose escalation cohortcohort. whereIn theMay 2025, Phase 1 dose escalation enrollment of CX-801 exceedsin thecombination approvedwith dose of the unmasked peginterferon alfa-2bKEYTRUDA® (SYLATRON™pembrolizumab). Initial Phase 1a translational data in advanced melanoma was initiated and is expectedcurrently inenrolling at the second halfdose of 2025.level.

We have entered, and may in the future seek to enter, into collaborations with third parties for the development and commercialization of our product candidates using our PROBODY® platform. If we fail to enter into such collaborations, or such collaborations are not successful, we may not be able to capitalize on the market potential of our PROBODY platform and resulting product candidates.

We are a clinical-stage biopharmaceutical company with a limited operating history, developing a novel class of therapeutic product candidates, based on our proprietary biologic PROBODY conditionally activated technology platform. Since our inception, we have devoted our resources to the development of PROBODY therapeutics. We have had significant operating losses since our inception. As of MarchJune 31,30, 2026 and December 31, 2025, we had an accumulated deficit of $730.2$750.9 million and $711.9 million, respectively. Substantially all of our losses have resulted from expenses incurred in connection with our research and development programs and from general and administrative costs associated with our operations.

As of MarchJune 31,30, 2026, we had cash, cash equivalents and short-term investments of $346.7$330.3 million. We believe that our existing capital resources will be sufficient to fund our planned operations into the second half of 2028. Our future capital requirements and the period for which we expect our existing resources to support our operations may vary significantly from what we expect and we may not achieve the expected cash flow savings that we anticipate as a result of our recent restructuring. Our monthly spending levels vary based on our ongoing clinical trials, new and ongoing research and development and other corporate activities. Because the length of time and activities associated with conducting our clinical trials and successfully researching and developing our product candidates is highly uncertain, we are unable to estimate the actual funds we will require for development and, once any product candidate is approved, any subsequent marketing and commercialization activities.

Undesirable side effects caused by our product candidates could cause us, our collaborators 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 other regulatory authorities. As is the case with all oncology drugs, there may be immediate or late side effects associated with the use of our product candidates, including Varseta-M and CX-801. Our lead program, Varseta-M, is an antibody-drug conjugate which is in a class of therapy known to drive potent anti-cancer activity, but that often havehas side effects or adverse events that need to be managed in order for patients to derive benefits from treatment. There can be no assurance that unexpected adverse events will not occur in our ongoing trials, including the ongoing Phase 1 clinical trials of Varseta-M or CX-801, or in future trials involving our product candidates or the product candidates of our collaborators. Undesirable side effects may appear in later trials that were not observed in our earlier trials or may be more severe in later trials than earlier trials.

It may prove more challenging than we anticipate to manufacture products that incorporate our PROBODY therapeutic technology. In order to conduct clinical trials of our product candidates, including our clinical trials for Varseta-M and CX-801, we will need to manufacture them in large quantities. There can be no assurance that we will not have future production failures, which could affect our ability to conduct our trials for Varseta-M or CX-801 or any other clinical trial drug candidates on our planned timeline or at all. Furthermore, in order to conduct later stage clinical trials of our product candidates and eventually, if approved, commercial products, we will need to manufacture them in larger quantities. We, or any manufacturing partners, may be unable to successfully increase the manufacturing scale and capacity for any of our product candidates in a timely or cost-effective manner, or at all. However, we may have to start late-stage trials with our early clinical trial drug product and switch to late-stage or commercial drug product mid-trial. In such event, the FDA will require us to complete bridging studies to compare the earlier stage material with late-stage or commercial material to assure comparability between the earlier trial material and the late- stagelate-stage or commercial material. Changing formulation and scaling up the process is a complicated and difficult task. While we believe we can complete this process successfully, there can be no assurances that the changes we make to the drug product and manufacturing process will be successful or completed in a timely manner or that the FDA will not require additional development steps or studies from those we believe are necessary. If we are not able to scale up our manufacturing capabilities with respect to any of our product candidates, extend the life of our drug stability of product candidates, or successfully complete the FDA’s bridging requirements, the development, testing, and clinical trials of that product candidate may be delayed or infeasible, and regulatory approval or commercial launch of any resulting product may be delayed or not obtained, which could significantly harm our business.

Because we have limited financial and managerial resources, we focus on specific product candidates and indications. For example, in July 2022, we announced that we would not continue the development of praluzatamab ravtansine without a partner. Additionally, in the first quarter of 2025, we terminated the CX-2029 program. As a result, weWe may forgo or delay pursuit of opportunities with those products in other indications or with other product candidates that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable product candidates. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

We face substantial competition from pharmaceutical companies developing products in oncology, including companies such as Amgen, AstraZeneca PLC, Bristol Myers Squibb, GlaxoSmithKline plc, Merck & Co., Inc., Novartis AG, Pfizer, Roche Holding Ltd. and Sanofi SA. Many large and mid-sized biotech companies, including BeiGene,BeOne, Incyte, Nektar, and Alkermes have ongoing efforts in cancer immunotherapy. Several companies, including Adagene, Amgen, Sanofi, BioAtla, Halozyme, Janux Therapeutics, Roche, Takeda, Vir Biotechnology, Werewolf Therapeutics and Xilio are exploring antibody masking and/or conditional activation strategies, which could compete with our PROBODY platform. We are also aware of several companies that are developing ADCs, such as AbbVie, ADC Therapeutics, AstraZeneca, Bristol Myers Squibb, Daiichi Sankyo, Gilead, Merck & Co., Pfizer, Roche Holding Ltd. and Takeda. Companies like Gilead and Jazz are pursuing development programs in the cytokine space. Furthermore, several large pharmaceutical companies, including Amgen, Novartis AG and Roche Holding Ltd., are developing T-cell engaging immunotherapies, and we are aware of several mid-sized biotech companies, such as MacroGenics and Xencor, and small companies with ongoing efforts to develop T-cell engaging immunotherapies. Any of these companies may be well capitalized and may have significant clinical experience. In addition, these companies include our collaborators.

Our licenses from Amgen, AbbVie (formerly ImmunoGen) and UCSB impose, and any future licenses we enter into are likely to impose, various development, commercialization, funding, diligence, sublicensing, insurance, patent prosecution and enforcement and/or other obligations on us, including various payment obligations such as milestone and royalty payments and payments based on sublicensing revenues. Our rights under our agreements with our licensors or collaborators may be limited or modified according to their terms. Additionally, if we breach any of these obligations, or use the intellectual property licensed to us in an unauthorized manner, we may be required to pay damages and the licensor may have the right to terminate the license, which could result in us being unable to develop, manufacture and sell products that are covered by the licensed technology or enable a competitor to gain access to the licensed technology. Moreover, our licensors and collaborators may own or control intellectual property that has not been licensed to us and, as a result, we may be subject to claims, regardless of their merit, that we are infringing, misappropriating or otherwise violating the licensor’s rights. In addition, while we cannot currently determine the amount of the royalty or sublicense revenue payment obligations we would be required to pay on development or sales of future products, if any, the amounts may be significant. The amount of our future royalty or sublicense revenue payment obligations will depend on the technology and intellectual property we use in products that we successfully develop and commercialize, if any. Therefore, even if we successfully develop and commercialize products, we may be unable to achieve or maintain profitability.

As of MarchJune 31,30, 2026, our executive officers, directors, holders of 5% or more of our capital stock based on publicly available filings made with the SEC and their respective affiliates beneficially owned approximately 24%26% of our outstanding common stock. These stockholders, acting together, would have significant influence over matters requiring stockholder approval. For example, these stockholders may be able to control elections of directors, amendments of our organizational documents, or approval of any merger, sale of assets, or 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.

Our experience and leadership with the PROBODY platform for over 15 years has led to a highly focused strategy for the application of our technology in product development that has resulted in a current pipeline of novel clinical-stage and pre-clinicalpreclinical stage programs. In identifying and designing potential PROBODY therapeutics, we evaluate the following:

Our two current clinical programs, varsetatug masetecan (“Varseta-M”) and CX-801 are in Phase 1 clinical development and are examples of our focused program development strategy. We aim to continue to advance our clinical pipeline towards later stage development and ultimately build a commercial enterprise to maximize our impact on the treatment of cancer.

EpCAM is a high potential oncology target based on its documented high expression in many solid tumors, including CRC where it was first discovered due to its very high and uniform expression. Historically, previous efforts across the drug development landscape to target this antigen systemically have been limited by dose-limiting toxicities. For example, high affinity EpCAM antibodies were limited by pancreatitis and liver toxicities and were discontinued. However, EpCAM has been validated as a cancer target, including by the drug KORJUNY®, which is approved for the treatment of malignant ascites in Europe. KORJUNY®,KORJUNY, however, must be given directly into the peritoneum due to systemic toxicity, but its approval provides evidence that local delivery of an EpCAM therapeutic to the tumor can be effective.

Varseta-M is designed to potentially address a broad range of EpCAM-expressing tumors, but isour current development had been initially focused in CRCCRC, which is one of the largest unmet needs in oncology with over 1.9 million cases diagnosed annually around the world. It is also a disease that is expected to grow and estimated that there will be over 3 million cases globally by 2040. CRC is the second leading cause of cancer death worldwide and has a 5 year5-year survival rate in the metastatic setting of only 13%. CRC is also the leading cause of cancer death in the U.S. for patients under the age of 50 and has been growing in incidence in younger patients over the last 3 decades.

Varseta-M clinical development ishas initiallyprimarily beingbeen focused on late-line metastatic CRC where there is significant unmet need and treatment options are highly inadequate. In third line or later metastatic CRC, patients have typically progressed through multiple chemotherapy-based regimens. Later stage treatment is limited to therapies that provide single digit percentage response rates, median progression free survival of 2 to 5.6 months and overall survival outcomes ranging from approximately 6 to 11 months. It is estimated that there are more than 35,000 patients in the U.S. with 3rd line or later metastatic CRC, with the number expected to grow over the next decade.

While Varseta-M ishas initially beingbeen developed in late-line metastatic CRC, the program was developed with the vision to help a broad population of metastatic CRC patients, including those in the first- and second-line settings. Given Varseta-M’s mechanism of action, our longer-term development vision is to make Varseta-M a core component of the CRC treatment landscape in earlier lines of therapy, consistent with the development strategy that has been employed for other solid tumor ADCs. We plan to pursue combination strategies to progress this vision toof movemoving Varseta-M to earlier lines of therapytherapy, and we therefore initiated a Phase 1 combination study with bevacizumab in the first quarter of 2026. Varseta-M doses to be assessed in combination with bevacizumab include Q2W and Q4W schedules to align with the approved bevacizumab CRC dose and schedule of 5 mg/kg Q2W. The Phase 1 combination study with bevacizumab continues with initial clinical data anticipated by first half of 2027.

Additionally, given the broad solid tumor expression profile of EpCAM, Varseta-M has the potential to be an innovative new treatment option in a wide range of solid tumors. High expression of EpCAM has been documented in other tumors such as gastric, gastroesophageal, pancreatic, ovarian, endometrial, non-small cell lung and triple negative breast cancers. We plan to potentially initiate development in indications outside of CRC inIn the secondthird halfquarter of 2026, we are initiating Varseta-M Phase 1 expansion cohorts in gastric and gastroesophageal junction (“GEJ”), EpCAM selected pancreatic ductal adenocarcinoma (“PDAC”), and EpCAM selected biliary tract cancer (“BTC”). Development of Varseta-M in multiple, EpCAM-expressing gastrointestinal (“GI”) cancers is aligned with the ultimatelong-term vision toof developpotentially commercializing Varseta-M as a pan-tumorpan-tumor, therapy.multi-indication ADC.

Varsetatug Masetecan DevelopmentMay 2025 Phase 1 Dose Escalation Data

In May 2025, we announced positive interim Phase 1 data as of an April 7, 2025 data cutoff in advanced metastatic CRC. The data encompassed results from 25 CRC patients treated with Varseta-M at 5 dose levels ranging from 2.4 mg/kg to 10 mg/kg, administered every three weeks (“Q3W”). The 2.4 mg/kg and 4.8 mg/kg doses were single patient dose escalation cohorts not anticipated to be therapeutically active. At the 7.2 mg/kg, 8.6 mg/kg, and 10 mg/kg doses, 23 patients were treated, 18 of whom were efficacy evaluable, having had at least one post-baseline tumor assessment as of the data cutoff. Patients enrolled in the study at the time of data cutoff had previously received a median of 4 prior lines of therapy and all patients had previously been treated with irinotecan. 64% of patients had liver metastases, 64% had disease with KRAS mutations, and 96% werehad disease that was microsatellite stable. Patients were not preselected based on EpCAM expression levels.

Based on the positive interim Phase 1 dose escalation data in May 2025, dose expansions were initiated at the dose levels of 7.2 mg/kg, 8.6 mg/kg, and 10 mg/kg, administered Q3W and are currently ongoing.Q3W.

In Phase 1 dose expansions starting in Q2 2025, prophylactic strategies for diarrhea management were investigated. In dose optimization starting in Q4 2025, an updated prophylaxis regimen of anti-motility medication (loperamide or diphenoxylate/atropine) plus budesonide was implemented.2 In the 20 patients receiving the updated prophylactic regimen at the Varseta-M expansion doses of 8.6 mg/kg and 10 mg/kg, Grade 3 diarrhea was 10%.3,410% after 2 months of follow up post treatment initiation.3,4 Overall, as of the January 16, 2026 data cutoff, in the 80 patients treated at expansion and optimization doses ranging between 7.2 mg/kg to 10 mg/kg, the most common TRAEs were diarrhea (68 pts, 19 Gr 3), nausea (44 pts, 4 Gr 3), vomiting (29 pts, 3 Gr 3), fatigue (32 pts, 2 Gr 3), hypokalemia (21 pts, 13 Gr 3+), and anemia (13 pts, 6 Gr 3). Serious treatment related adverse events (SAEs) in > 1 patient included diarrhea (4), vomiting (3), hypokalemia (3), dehydration (3), acute kidney injury (2), and colitis (2).

As of April 2026, enrollment into Varseta-M Dose Optimization cohorts is complete, having reached the goal of 40 total patients across the 8.6 mg/kg Q3W and 10 mg/kg Q3W doses. Additional Phase 1 Varseta-M data, including data from ongoing dose optimization, is anticipated to be presented at a medical meeting inby the second halfend of 2026. This update is expected to support monotherapy dose selection and a potential registrational trial design in late line CRC. FDA interactions are also planned in 2026 with the goal of aligning on potential first registrational study for Varseta-M monotherapy in advanced CRC to start in the first half of 2027.

A Phase 1 Varseta-M combination study with bevacizumab in CRC has commenced with an initial focus on determining combination dose(s) for later phase development, including in earlier lines of therapy. Varseta-M doses to be assessed in combination with bevacizumab will include Q2W and Q4W schedules to align with the approved bevacizumab CRC dose of 5 mg/kg Q2W. InitialThe study continues with initial clinical data arefrom the Varseta-M combination with bevacizumab anticipated by the first half of 2027.

Phase 1/2 combination study including Varseta-M administered with bevacizumab, 5-fluorouracil, and leucovorin is planned to start in the secondfourth halfquarter of 2026.

Initiation of initial Phase 1 expansion cohort(s) in non-CRC indications isincluding plannedGEJ, forEpCAM selected PDAC and EpCAM selected BTC are initiating in the secondthird halfquarter of 2026.

The IND for CX-801 was allowed to proceed by the FDA in January 2024, and in the third quarter of 2024 the first patient was dosed in the CX-801 Phase 1 dose escalation study in solid tumors. The Phase 1 dose escalation study is focused on patients with advanced melanoma. In Phase 1 dose escalation, the study will evaluate safety, translational biomarkers and signs of clinical activity for CX-801 monotherapy and in combination with KEYTRUDA®. In the second quarter of 2024, we announced a clinical collaboration with Merck to supply KEYTRUDA for evaluation of its combination with CX-801 in the Phase 1 study. The Phase 1 study is currently in the fourth monotherapy dose escalation cohort. In May 2025, Phase 1 dose escalation enrollment of CX-801 in combination with KEYTRUDA® (pembrolizumab) in advanced melanoma was initiated and is currently enrolling atand has cleared the third dose level.

Phase 1 CX-801 monotherapy translational data in melanoma patients was presented at the Society of Immunotherapy of Cancer (“SITC”) 2025 Annual Meeting in November 2025, providing evidence that the CX-801 mechanism of action was working as designed. As of the November 8, 2025 SITC presentation, CX-801 had been generally well tolerated and the translational data presented suggest consistently increased expression of interferon-stimulated genes in paired tumor biopsies. Upregulation of immune checkpoint genes, including PD-1 and PD-L1, and activation of immune cell populations, was also observed, providing a rationale for evaluating the combination of CX-801 and pembrolizumab. Pharmacokinetics (“PK”) analysis also demonstrated dose-proportional exposure of CX-801, which remained predominantly in its intact (masked) form in circulation. Phase 1 clinical data from the CX-801 and KEYTRUDA® combination dose escalation portion of the study are expected byin the endfirst half of 2026.2027.

We do not have any products approved for sale, and we continue to incur significant research and development as well as general and administrative expenses related to our operations. As of MarchJune 31,30, 2026 and December 31, 2025, we had an accumulated deficit of $730.2$750.9 million and $711.9 million, respectively.

The preparation of our Condensed Financial Statements requires us to make estimates and judgments that affect the reported amounts in the financial statements and related disclosures. On an ongoing basis, management evaluates its significant accounting policies and estimates. We base our estimates on historical experience and on various market-specific and other relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ significantly from these estimates. Estimates are assessed each period and updated to reflect current information. A summary of our critical accounting policies and estimates is presented in Part II, Item 7 of our Annual Report on Form 10-K for the year ended December 31, 2025. Except as noted in the revenue discussion below, there have been no material changes to our critical accounting policies and estimates from the Annual Report on Form 10-K for the three monthsyear ended MarchDecember 31, 2026.2025.

For the foreseeable future, we do not expect to generate any revenue from the sale of products unless and until such time as our product candidates have advanced through clinical development and obtained regulatory approval. We expect that any revenue we generate in the foreseeable future will fluctuate from year to year as a result of the timing and amount of milestones and other payments from our collaboration agreements with Astellas, Regeneron, Bristol Myers Squibb, Moderna and any other collaboration partners, and as a result of the fluctuations in the research and development expenses we incur in the performance of assigned activities under these agreements.

Our research and development expenses consist primarily of costs incurred to conduct research, such as the discovery and development of our product candidates, clinical development, including activities with third parties, such as contract research organizations (“CRO”) and contract development and manufacturing organizations (“CMO”), and the manufacture of drug products used in clinical trials, as well as the development of product candidates pursuant to our research, collaboration and license agreements. Research and development expenses include personnel costs, including stock-based compensation expense, contractor services, laboratory materials and supplies, depreciation and maintenance of research equipment, and an allocation of related facilities costs. We expense research and development costs as incurred.

The decrease in revenue of $40.7$17.2 million and $57.9 million for the three and six months ended MarchJune 31,30, 2026, respectively, compared to the corresponding periodperiods of 2025 was primarily due to:

A decrease in revenue under the Astellas Agreement primarily driven by a $5.0 million preclinical milestone payment and higher research activities in the first quarter of 2025 compared to the corresponding period of 2026, partially offset by a $7.1 million of accelerated revenue recognition in the first quarter of its deferred revenue2026 due to Astellas' notice of termination of the Astellas Agreement in the first quarter of 2026.collaboration. The completion of our performance obligationobligations under the Astellas Agreement ishave expectedbeen bycompleted as of the second quarter of 2026;

Research and development expenses increased by $0.4$4.3 million for the three months ended MarchJune 31,30, 2026, compared to the corresponding period of 2025 primarily due to a $3.5 millionan increase in externalmanufacturing costsactivities for Varseta-M manufacturing and clinical activities,activities partiallyfor offsetother byclinical aprograms, $2.3and millionan decreaseincrease in internal costs reflecting the absence of $1.7 million of restructuring expenses incurred in the first quarter of 2025. We expect program development expenses in future quartersdue to beincreased primarilypersonnel focusedrelated on Varseta-M with expected continued growth in Varseta-M development spend.expenses.

General and administrative expenses increased by $1.3$1.0 million for the three months ended MarchJune 31,30, 2026, compared to the corresponding period of 2025, primarily driven by increased consulting expenses and stockhigher basedrent compensationexpense expensesdue to termination of the partial sublease of the Company's headquarters in the first quarter of 2026, partially offset by $1.1 million of restructuring expenses incurred in the first quarter of 2025.2026.

Interest income increased by $0.5$2.0 million and $2.5 million during the three and six months ended MarchJune 31,30, 20262026, respectively, compared to the corresponding periodperiods of 2025. The increase was primarily driven by the increase in cash and cash equivalents and short-term investments position in the first quarter of 2026 as a result of the underwritten public offering in March 2026.

As of MarchJune 31,30, 2026, we had cash, cash equivalents andequivalents, short-term investments of $346.7$330.3 million and an accumulated deficit of $730.2$750.9 million, compared to cash, cash equivalents and short-term investments of $137.1 million and an accumulated deficit of $711.9 million as of December 31, 2025.

We also have an at-the-market offering program (“ATM Program”) pursuant to a sales agreement with Jefferies,Jefferies LLC (as amended on March 4, 2022 and August 9, 2024, the “Sales Agreement”). In 2025, we sold 4,872,861 shares at a weighted average price of $3.44 per share under our ATM offering for net proceeds of approximately $16.3 million after deducting sales commissions and related issuance costs. As of MarchJune 31,30, 2026, we had an aggregate of $39.4 million remaining for issuance under our ATM Program.

Based upon our current operating plan and liquidity requirements, we expect our existing capital resources will be sufficient to fund operations into at least the second half of 2028. However, if the anticipated operating results are not achieved in future periods, our planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund the operations. The amounts and timing of our actual expenditures depend on numerous factors, including the progress of our preclinical and clinical development efforts, the results of any clinical trials and other studies, our operating costs and expenditures and other factors described under the caption “Risk Factors” in this Quarterly Report on Form 10-Q. The cost and timing of developing our product candidates is highly uncertain and subject to substantial risks and changes. As such, we may alter our expenditures as a result of contingencies such as the failure of one or all of our product candidates currently in clinical development, the acceleration of one or all of our product candidates in clinical development, the initiatinginitiation of clinical trials for additional product candidates, the identification of more promising product candidates in our research efforts or unexpected operating costs and expenditures. We will need to raise additional capital to fund our operations in the future. There can be no assurance, however, that such efforts will be successful; or if they are successful, that the terms and conditions of such financing will be favorable to us.

Net cash used in operating activities of $25.5$43.6 million and $21.0$36.8 million for the threesix months ended MarchJune 31,30, 2026 and 2025, respectively, was largely due to ongoing research and development activities and general and administrative expenses to support those activities. Net loss for the threesix months ended MarchJune 31,30, 2026 and net income for the threesix months ended MarchJune 31,30, 2025 included, among other items, non-cash charges of stock-based compensation, non-cash lease expense, depreciation and amortization, partially offset by net accretion of discounts on short-term investments.

During the threesix months ended MarchJune 31,30, 2026, net cash used in investing activities was $192.8$186.8 million, primarily due to increased purchases of short-term investments following the funds received from our equity issuance via the underwritten public offering in March 2026. These purchases were partially offset by proceeds from the maturities of marketable securities.

During the threesix months ended MarchJune 31,30, 2026, net cash provided by financing activities of $234.5$235.0 million was primarily due to net proceeds from equity issuance via the underwritten public offering in March 2026.

During the three months ended MarchJune 31,30, 2026, there were no material changes in contractual obligations from the amounts disclosed in our Annual Report on Form 10-K for the year ended December 31, 2025.