Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion and analysis of our financial condition and results of operations is for the year ended December 31, 2025 compared with the year ended December 31, 2024. This comparison should be read in conjunction with our consolidated financial statements and related notes appearing elsewhere in this Annual Report on Form 10-K. This discussion contains forward-looking statements based upon current expectations that involve risks and uncertainties. Our actual results may differ materially from those anticipated in these forward-looking statements as a result of various factors, including those set forth under “Risk Factors” included in Part I, Item 1A or in other parts of this Annual Report on Form 10-K. For a discussion and analysis of our financial condition and results of operations for the year ended December 31, 2024 compared to December 31, 2023, see Part II, Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations” included in the 2024 Annual Report on Form 10-K, filed with the Securities and Exchange Commission on February 24, 2025.

The Management’s Discussion and Analysis of Financial Condition and Results of Operations, or MD&A, describes principal factors affecting the results of our operations, financial condition and liquidity, as well as our critical accounting policies and estimates that require significant judgment and thus have the most significant potential impact on our Consolidated Financial Statements. This section provides an analysis of our financial results for the year ended December 31, 2025 compared to the same period in the prior year.

Company Overview

Summit Therapeutics Inc. (“we”, “Summit” or the “Company”) is a biopharmaceutical company focused on the discovery, development, and commercialization of patient-, physician-, caregiver- and societal-friendly medicinal therapies intended to improve quality of life, increase potential duration of life, and resolve serious unmet medical needs. The Company’s pipeline of product candidates is designed with the goal to become the patient-friendly, new-era standard-of-care medicines, in the therapeutic area of oncology.

The Company’s current lead development candidate is ivonescimab, a novel, potential first-in-class bispecific antibody intending to combine the effects of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects of an anti-VEGF compound into a single molecule. On December 5, 2022, the Company entered into the License Agreement with Akeso pursuant to which the Company has in-licensed intellectual property rights related to ivonescimab (as amended, the “License Agreement”). Through the License Agreement, the Company obtained the rights to develop and commercialize ivonescimab in the United States, Canada, Europe, and Japan. The License Agreement and transaction closed in January 2023 following customary waiting periods. On June 3, 2024, the Company entered into the Second Amendment with Akeso to expand its territories covered under the License Agreement to also include Latin America, including Mexico and all countries in Central America and South America, the Middle East and Africa. The Company’s operations are focused on the development of ivonescimab and other future activities, as the Company determines.

The Company is developing ivonescimab in NSCLC and CRC, specifically conducting Phase III clinical trials in the following proposed indications:

(a) ivonescimab combined with chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who were previously treated with a third-generation EGFR TKI (“HARMONi”);

(b) ivonescimab combined with chemotherapy in patients with first-line metastatic NSCLC (including separate statistical analyses planned for patients with squamous NSCLC and non-squamous NSCLC) (“HARMONi-3”);

(c) ivonescimab monotherapy in patients with first-line metastatic NSCLC whose tumors have high PD-L1 expression (“HARMONi-7”); and

(d) ivonescimab combined with chemotherapy in patients with first-line unresectable metastatic CRC (“HARMONi-GI3”).

In October 2024, the Company completed enrollment in its HARMONi clinical trial. In May 2025, we announced topline results from our multiregional, double-blinded, placebo-controlled, Phase III study HARMONi. At the prespecified primary data analysis, ivonescimab in combination with chemotherapy demonstrated a statistically significant improvement in PFS, the magnitude of which we believe to be clinically meaningful, with a hazard ratio of 0.52 (95% CI: 0.41 – 0.66; p<0.00001) compared to placebo in combination with chemotherapy; median PFS was 6.8 months for those patients receiving ivonescimab plus chemotherapy compared to 4.4 months for those receiving chemotherapy. PFS was assessed by BICR.

We believe the PFS hazard ratio that was observed in both Asian and Western sub-populations to be clinically meaningful. The primary analysis demonstrated the consistency of the magnitude of the PFS benefit between patients randomized in Asian and Western territories, as well as the consistency in a single-region study (HARMONi-A) with this multiregional study.

In a longer-term follow-up of PFS, which included all Western patients and at least six months of follow-up time for all patients, ivonescimab plus chemotherapy demonstrated a consistent hazard ratio in PFS as the primary PFS analysis observed HR = 0.57; 95% CI: 0.46 – 0.71). With the longer-term follow-up analysis, consistency of the magnitude of PFS benefit was demonstrated between patients randomized in Asia and Western patients when measured by hazard ratio. This longer-term follow-up analysis of PFS was performed at the time of the primary OS analysis.

Ivonescimab in combination with chemotherapy showed a positive trend in OS in the primary analysis without achieving a statistically significant benefit with a hazard ratio of 0.79 (95% CI: 0.62 – 1.01; p=0.057). This trend provides further support for its use in EGFRm NSCLC post-TKI therapy, a setting where high unmet need continues to exist with limited approved options in the United States and other western territories. Currently there are no FDA-approved regimens that have demonstrated a statistically significant OS benefit in this patient setting. Both Asian and North American patients demonstrated a positive trend in OS. The results of the primary analysis in this multiregional study were consistent with that of the single-region randomized Phase III HARMONi-A study, which demonstrated a statistically significant OS benefit with a hazard ratio of 0.74 in the primary OS analysis in a similar patient population.

In September 2025, an additional ad hoc OS analysis was performed for the HARMONi study, whereby the Western patients were followed for a longer period of time (Asian patients were locked at the time of the primary analysis). In this analysis that included longer-term follow-up of Western patients (median follow-up time of Western patients of 13.7 months), a hazard ratio consistent with the primary analysis was observed with an improved nominal p-value (HR=0.78; 95% CI: 0.62 – 0.98; nominal p=0.0332). Median OS for this analysis remained the same in both arms as was observed in the primary analysis. Median OS in Western patients receiving ivonescimab was 17.0 months compared to 14.0 months for those receiving placebo (HR=0.84); median OS in North American patients, specifically, had not yet been reached in the ivonescimab arm compared to 14.0 months in the placebo arm (HR=0.70). The hazard ratios for Western patients in totality, as well as patients from the North American and European regions individually, improved from the primary OS analysis to the analysis with longer-term follow-up of Western patients. Consistent benefit was observed across pre-defined subgroups.

The dual primary endpoints were allocated separate alpha levels and tested individually. The alpha was recycled from the PFS to the OS analysis upon the successful achievement of the PFS endpoint.

Based on the results of the HARMONi clinical trial, we submitted a BLA in the fourth quarter of 2025 in order to seek approval for ivonescimab plus chemotherapy for this proposed indication. The positive results of the multiregional Phase III study are detailed further under “Product Pipeline” below. As previously disclosed, the FDA noted that a statistically significant OS benefit is necessary to support marketing authorization in this setting. After careful consideration of the safety and efficacy profile of the current FDA-approved options for patients in this setting, the positive results of the Phase III multiregional study, including regional consistency, as well as discussions with key opinion leaders and those physicians who have administered ivonescimab to patients in a clinical study setting, we believe that the safety and efficacy data generated in the HARMONi study demonstrates that the ivonescimab regimen offers a potential treatment option for patients impacted by EGFR-mutant NSCLC in this setting with a favorable benefit-risk profile despite the lack of a statistically significant OS benefit. Summit announced in January 2026 that the FDA accepted for filing the BLA seeking approval for ivonescimab in combination with chemotherapy for this proposed indication. The FDA noted it intends to perform a complete review of the accepted and filed BLA, including planned mid-cycle and wrap-up meetings, and, subject to major deficiencies not being identified during the FDA’s review, proposed labeling, prior to the Prescription Drug User Fee Act goal action date of November 14, 2026.

Key Components of our Results of Operations

Research and Development Expenses

Research and development expenses consist of all costs associated with our research and development activities.

These include:

•costs incurred in conducting our preclinical studies and clinical trials through contract research and development organizations, including, but not limited to, preclinical toxicology, pharmacology, formulation and manufacturing work, as well as regulatory, operational, drug supply and treatment costs related to conducting the study;

•laboratory and vendor expenses incurred in relation to our preclinical, non-clinical and clinical studies;

•costs incurred in supply chain development and scale up activities to support product registration;

•employee related expenses, which include salary, benefits and stock-based compensation, for our research and development staff;

•costs incurred in development and conduct of training and education related our development candidates; and

•facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies.

We utilize our employee and infrastructure resources across multiple research projects. We track expenses related to our clinical programs and certain preclinical programs on a per project basis. We expect our research and development expenses to continue to be significant as we initiate our planned clinical trials of ivonescimab, and continue our activities to initiate preclinical programs for future product candidates. The timing and amount of these expenses will depend upon the outcome of our clinical trials and the associated costs. The timing and amount of these expenses will also depend on the costs associated with potential future clinical trials of our product candidates and the related expansion of our research and development organization, regulatory requirements, advancement of our preclinical programs and product candidate manufacturing costs.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and benefits related to our executive, finance, business development, human resources, legal and other support functions. Other general and administrative expenses include stock-based compensation expenses, market research costs, facility-related costs, consulting costs and expenses associated with the requirements of being a publicly traded company in the United States, including insurance, legal, audit and taxation services fees.

We anticipate that our general and administrative expenses will continue to increase in the future as we increase our headcount to support our planned clinical trials of ivonescimab, continued research and development and potential commercialization of our product candidates. We also anticipate continued accounting, audit, regulatory, compliance, insurance and investor and public relations expenses associated with being a publicly traded company in the United States.

Other Income, Net

Other income, net primarily consists of foreign currency net gains and losses and investment income related to investments in money market funds and U.S. treasury securities. All highly liquid investments with a maturity date of 90 days or less at the date of purchase are considered to be cash equivalents and the related investment income is recognized in net loss. The appropriate classification of investments in securities is determined by the Company at the time of purchase.

Interest Expense

Interest expense consists of cash and imputed interest expense incurred related to our promissory notes to related parties. Imputed interest is calculated as the difference between the expected interest payable and the deemed market rate of interest and is recorded as a debt discount at inception of the note payable with a credit to additional paid-in capital for notes payable to related parties. The debt discount is amortized to interest expense using an effective interest rate method.

Taxation

As a U.S. tax resident trading entity, we are subject to U.S. corporate taxation. Our U.K. resident trading subsidiaries are individually subject to U.K. corporate taxation. Due to the nature of our business, we have generated losses since inception. We

have recorded a full valuation allowance against the deferred tax assets with respect to these tax losses in excess of our deferred tax liabilities in each jurisdiction because we do not consider it more likely than not that there will be suitable taxable profits in the foreseeable future based on the evidence available against which to offset these losses.

Results of Operations

For a discussion and analysis of our financial condition and results of operations for the year ended December 31, 2024 compared to December 31, 2023, please refer to Item 7 of Part II, “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on February 24, 2025, and is available on the SEC’s website at www.sec.gov and our Investor Relations website at www.smmttx.com/investor-information.

Amounts reported in millions within this Annual Report on Form 10-K are computed based on the amounts in thousands, and therefore, the sum of components may not equal the total amount reported in millions due to rounding.

Comparison of the Year Ended December 31, 2025 to the Year Ended December 31, 2024

Year Ended December 31,

Operating expenses:

Acquired in-process research and development — 15.0 (15.0)

Interest expense — (8.7) 8.7

Research and Development Expenses

The table below summarizes our research and development expenses by category for the year ended December 31, 2025 and 2024, respectively.

Year Ended December 31,

Oncology clinical trial related costs $ 266.4 $ 100.9 $ 165.5

Acquired in-process research and development — 15.0 (15.0)

Compensation related costs, excluding stock-based compensation 52.7 33.9 18.8

The entry into the License Agreement represents a significant change in our strategy from anti-infectives to the therapeutic area of oncology. We invested our resources in the clinical development of ivonescimab in the periods presented.

Oncology clinical trial related costs represent our investment in the clinical development of ivonescimab, known as SMT112 in the Licensed Territory.

Research and development expenses increased by $371.9 million during the year ended December 31, 2025, compared to the same period in the prior year. This increase was in part due to the increase in stock-based compensation expense of $202.6 million for the year ended December 31, 2025, as a result of the modification to our performance-based stock option awards during the second quarter of 2025. In addition, our continued investment in oncology expenses for ivonescimab, known as SMT112 in our Licensed Territory, resulted in an increase of $165.5 million for the year ended December 31, 2025, primarily due to adding new clinical trials and expanding current clinical trials from last year. We expect oncology-related research and development costs to continue to increase as we progress with the development of ivonescimab.

In June 2024, we entered into a second amendment (the “Second Amendment”) to the License Agreement with Akeso to expand the Licensed Territory to include Latin America, Middle East and Africa regions. Considered an extension of the original License Agreement, we agreed to make an upfront payment to Akeso in the amount of $15.0 million for these expanded territories which we paid in the third quarter of 2024. This was recorded in our consolidated statement of operations and comprehensive loss as acquired in process research and development expenses for the year ended December 31, 2024.

General and Administrative Expenses

The table below summarizes our general and administrative expenses by category for the year ended December 31, 2025 and 2024, respectively.

Year Ended December 31,

Legal fees and professional services 11.2 4.8 6.4

Other general and administrative expenses 8.8 5.7 3.1

General and administrative expenses increased by $496.5 million for the year ended December 31, 2025, compared to the same period in the prior year. The increase was primarily due to the increase in stock-based compensation expense of $478.8 million for the year ended December 31, 2025, as a result of the modification to our performance-based stock option awards during the second quarter of 2025. In addition, compensation related costs, excluding stock-based compensation, increased by $8.2 million, for the year ended December 31, 2025, compared to the same period in the prior year, as the Company is focused on building its executive management team and legal fees and professional services increased by $6.4 million for the year ended December 31, 2025, compared to the same period in the prior year to continue supporting the development of ivonescimab. We expect general and administrative expenses to continue to increase as we scale our infrastructure and management to support development of ivonescimab.

Other Income, Net

The table below summarizes our other income, net by category for the year ended December 31, 2025 and 2024, respectively.

Year Ended December 31,

Foreign currency loss $ (0.6) $ (0.1) $ (0.5)

Other income, net increased by $1.4 million for the year ended December 31, 2025, compared to the same period in the prior year, primarily due to an increase of $2.0 million in interest income due to the higher cash equivalents and short-term investments balance.

Interest Expense

Interest expense decreased for the year ending December 31, 2025 compared to the same period in the prior year, due to the repayment in full of the promissory note in October 2024.

Liquidity and Capital Resources

Sources of Liquidity

To date, we have financed our operations primarily through issuances of our common stock, including our most recent private placements issued in October 2025 and September 2024 for gross proceeds of $500.0 million and $235.0 million, respectively,

and the raise of $150.7 million gross proceeds from our ATM Agreement since inception, issuance of debt, and receipt of payments to us under license and collaboration arrangements.

We have devoted substantially all of our efforts to research and development, including clinical trials. We have not completed the development of any drugs. We expect to continue to incur significant expenses and increasing operating losses for at least the next few years. The net losses we incur may fluctuate significantly from quarter to quarter and year to year, due to the nature and timing of our research and development activities. We expect that our research and development and general and administrative expenses will continue to be significant in connection with our ongoing research and development efforts. In addition, if we obtain marketing approval for any of our product candidates in the United States or other jurisdictions where we retain commercial rights, and if we choose to retain those rights, we would expect to incur significant sales, marketing, distribution and outsourced manufacturing expenses, as well as ongoing research and development expenses. In addition, our expenses will increase if and as we:

•invest in clinical development of ivonescimab in our Licensed Territory;

•conduct research and continue development of additional product candidates;

•maintain and augment our intellectual property portfolio and opportunistically acquire complimentary intellectual property;

•seek further regulatory advancement for ivonescimab;

•invest in our manufacturing capabilities for ivonescimab and any other products for which we may obtain regulatory approval;

•seek marketing approvals for any product candidates that successfully complete clinical development;

•ultimately establish a sales, marketing and distribution infrastructure in jurisdictions where we have retained commercialization rights and scale up external manufacturing capabilities to commercialize any product candidates for which we receive marketing approval;

•perform our obligations under our collaboration agreements;

•pursue business development opportunities, including investing in other businesses, products and technologies;

•experience any delays or encounter any issues with any of the above, including but not limited to failed studies, complex results, safety issues or other regulatory challenges;

•hire additional clinical, regulatory, scientific and administrative personnel;

•expand our physical presence;

•add operational, financial and management information systems and personnel, including personnel to support our product development and planned future commercialization efforts; and

•borrow capital to fund our resources and have to pay interest expenses on such borrowings.

During the year ended December 31, 2025, we incurred a net loss of $1,079.6 million, and cash flows used in operating activities was $322.9 million. As of December 31, 2025 we had an accumulated deficit of $2,294.2 million, cash and cash equivalents and short-term investments of $713.4 million. We expect to continue to generate operating losses for the foreseeable future.

During the year ended December 31, 2025, the Company raised gross proceeds of $500,037 from a private placement and $106,498 from the Company’s at-the-market sales agreement. With these recent financings, the Company has evaluated and concluded that its cash, cash equivalents and short-term investments provide sufficient cash to fund its operating cash needs for at least the next 12 months from the date of issuance of these consolidated financial statements.

From time to time, we may raise additional equity or debt capital through both registered offerings off of a shelf registration, including ATM offerings, and private offerings of securities. On February 20, 2024, we filed a shelf registration statement on Form S-3 with the SEC, which the SEC declared effective on February 27, 2024. Through our shelf registration statement we may, from time to time, sell up to an aggregate of $450.0 million of our common stock, preferred stock, debt securities, depository shares, warrants, subscription rights, purchase contracts, or units. Of the $450.0 million of liquidity available to us under this shelf registration statement, on May 13, 2024, we had established an ATM offering program with J.P. Morgan Securities LLC, as sales agent, in the amount of up to $90.0 million.

On August 11, 2025, we entered into an amendment (the “Amendment”) to the distribution agreement, which amended that certain distribution agreement, dated May 13, 2024, by and between us and sales agent (the “Original Distribution Agreement” and, as amended by the Amendment, the “Distribution Agreement”). Pursuant to the Amendment, the Original Distribution Agreement was amended to, among other things, increase the aggregate offering price of shares of the Company’s common stock, par value $0.01 per share, from time to time, through the sales agent, by up to an additional $360.0 million. The remaining gross proceeds available under the Distribution Agreement as of December 31, 2025 was approximately $299.3 million.

In addition to the payments already made to Akeso, under the License Agreement and Second Amendment, there are additional potential milestone payments of $4.56 billion, as Akeso will be eligible to receive regulatory milestones of up to $1.05 billion and commercial milestones of up to $3.51 billion. In addition, Akeso will be eligible to receive low double-digit royalties on net sales. Until we can generate substantial revenue and achieve profitability, we will need to raise additional capital to fund ongoing operations and capital needs, including the payment of the milestone payments referenced above.

We have based the foregoing estimate on assumptions that may prove to be wrong, and we could use our capital resources sooner than we currently expect. This estimate assumes, among other things, that we do not obtain any additional funding through grants and clinical trial support or through new collaboration arrangements. Our future capital requirements will depend on many factors, including:

•the costs, timing and outcome of clinical trials required for clinical development of ivonescimab;

•the number and development requirements of other future product candidates that we pursue;

•the costs, timing and outcome of regulatory review of ivonescimab and/or our other product candidates we develop;

•the costs and timing of commercialization activities, including product sales, marketing, distribution and manufacturing, for any of our product candidates that receive marketing approval;

•the extent to which we become liable for milestone payments under the License Agreement and Second Amendment for ivonescimab;

•subject to receipt of marketing approval, revenue received from commercial sales of any product candidates;

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

•our ability to establish and maintain collaborations, licensing or other arrangements and the financial terms of such arrangements;

•the extent to which we acquire or invest in other businesses, products and technologies;

•the rate of the expansion of our physical presence; and

•the extent to which we change our physical presence.

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through a combination of some, or all, of the following: equity and debt offerings, collaborations, strategic alliances, grants and clinical trial support from government entities, philanthropic, non-government and not-for-profit organizations, and marketing, distribution or licensing arrangements.

We will need to seek additional funding in the future to fund operations. Additional capital, when needed, may not be available to us on acceptable terms, or at all. To the extent that we raise additional capital through the sale of equity or convertible debt securities, the ownership interest of our existing stockholders may be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our existing stockholders. Additional debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends or other distributions. If we raise additional funds through collaborations, strategic alliances or marketing, distribution, or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to us.

If we are unable to raise additional funds through equity or debt financings or other arrangements when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves, which could materially adversely affect our business, operating results and financial condition and our ability to continue operations.

Cash Flows

The following table summarizes our cash flows for the years ended December 31, 2025 and 2024.

Year Ended December 31,

Net cash used in operating activities $ (322.9) $ (142.1)

Net cash used in investing activities $ (174.3) $ (205.3)

Net cash provided by financing activities $ 617.5 $ 381.2

Operating Activities

Net cash used in operating activities for the year ended December 31, 2025 was $322.9 million and primarily consisted of net loss of $1,079.6 million and a $31.4 million net change in operating assets and liabilities, partially offset by non-cash charges of $725.2 million. The non-cash charges primarily consisted of $732.4 million of stock-based compensation driven by the modification to outstanding performance-based stock option awards which removed the performance-based vesting criteria, partially offset by $7.0 million relating to amortization of the discount on short-term investments in U.S. Treasury securities. The net change in working capital is primarily due to a $15.3 million increase in accounts payable, a $12.9 million increase in accrued liabilities and other current liabilities, a $4.9 million decrease in prepaid expenses and other current assets, a $2.9 million increase in accrued compensation, partially offset by a $4.9 million increase in other assets.

Net cash used in operating activities for the year ended December 31, 2024 was $142.1 million and primarily resulted from a net loss of $221.3 million, which included an adjustment of $15.0 million in cash payments related to investing activities for the purchase of in-process research and development from Akeso under the terms of the License Agreement and the associated direct transaction costs, non-cash charges of $48.7 million and a net change in operating assets and liabilities of $15.5 million. Non-cash charges primarily include $51.0 million of stock-based compensation, partially offset by $2.6 million related to the amortization of discount on short-term investments. The net change in operating assets and liabilities is primarily due to an $11.9 million increase in accrued liabilities and other current liabilities, a $6.6 million increase in accrued compensation, a $2.5 million decrease in other assets, and a $2.0 million increase in accounts payable, partially offset by a $7.4 million increase in prepaid expenses and other current assets.

Investing Activities

Net cash used in investing activities for the years ended December 31, 2025 was $174.3 million and primarily consisted of net purchases of short-term investments of $173.7 million.

Net cash used in investing activities for the years ended December 31, 2024 was $205.3 million and was primarily due to $190.2 million of net purchases of short-term investments and $15.0 million of cash payments made to Akeso pursuant to the License Agreement.

Financing Activities

Net cash provided by financing activities for the year ended December 31, 2025 was $617.5 million and primarily consisted of proceeds from a private placement of $500.0 million, $104.5 million net proceeds from our current Distribution Agreement, $7.3 million of proceeds received related to the exercise of warrants and proceeds received of $5.7 million related to employee stock awards and purchase plans.

Net cash provided by financing activities for the year ended December 31, 2024 was $381.2 million and was primarily due to $434.9 million of proceeds from various private placements, $43.0 million net proceeds from our current ATM Agreement, and proceeds received of $2.7 million related to employee stock awards, partially offset by a $100.0 million early principal payment on promissory notes payable to a related party.

Contractual Obligations and Commitments

Fixed asset purchase commitments

At December 31, 2025 and 2024, we had no capital commitments.

Lease commitments

The following table summarizes our lease contractual obligations as of December 31, 2025:

Payment due by period

Operating lease obligations (1) $ 27.3 $ 3.5 $ 8.2 $ 6.4 $ 9.2

(1) For additional information, please see Note 11 to our consolidated financial statements contained in this Annual Report on Form 10-K.

Debt commitments

On December 6, 2022, we entered into a Note Purchase Agreement (the “Note Purchase Agreement”), with Mr. Duggan and Dr. Zanganeh, pursuant to which we agreed to sell to each of Mr. Duggan and Dr. Zanganeh unsecured promissory notes in the aggregate amount of $520 million. Pursuant to the Note Purchase Agreement, we issued to Mr. Duggan and Dr. Zanganeh unsecured promissory notes in the amount of $400 million (the “Duggan February Note”) and $20 million (the “Zanganeh Note”), respectively, which matured and became due on February 15, 2023 and an unsecured promissory note to Mr. Duggan in the amount of $100 million (the “Duggan September Note” and together with the Duggan February Note and the Zanganeh Note, the “December 2022 Notes”), which was originally due on September 15, 2023. The maturity dates of the December 2022 Notes could have been extended one or more times at our election, but in no event to a date later than September 6, 2024. In addition, if we consummated a public offering, then upon the later to occur of (i) five business days after we receive the net cash proceeds therefrom or (ii) May 15, 2023, the Duggan February Note and the Zanganeh Note were to be prepaid by an amount equal to the lesser of (a) 100% of the amount of the net proceeds of such offering and (b) the outstanding principal amount on such Notes. On January 19, 2023, we provided notice to extend the term of the Duggan February Note and Duggan September Note to a maturity date of September 6, 2024.

Furthermore, on January 19, 2023, we and Mr. Duggan rectified the Duggan February Note and Duggan September Note in order to correctly reflect the parties’ intent that we may only prepay (i) the Duggan February Note following the completion of a public rights offering to be conducted by us in the approximate amount of $500 million, or a similar capital raise, in an amount equal to the lesser of (x) the net proceeds of the 2023 Rights Offering or such capital raise or (y) the full amount outstanding of the Duggan February Note, and (ii) the Duggan September Note following the completion of a capital raising transaction subsequent to the 2023 Rights Offering (as defined in Note 17 Stockholders’ Equity to the consolidated financial statements included under Item 15 Exhibits, Financial Statement Schedules) in an amount equal to the lesser of (A) the net proceeds of such capital raise or (B) the full amount outstanding of the Duggan September Note. Following the issuance of the two new Promissory Notes (the “Duggan Promissory Notes”), the Duggan February Note and Duggan September Note were marked as “cancelled” on their face and replaced in their entirety by the Duggan Promissory Notes (together with the Zanganeh Note, the “Notes”). The Notes accrued interest at an initial rate of 7.5%. All interest on the Notes was paid on the date of signing for the period through February 15, 2023. Such prepaid interest was paid in a number of shares of our common stock, par value $0.01 (“Common Stock”) equal to the dollar amount of such prepaid interest, divided by $0.7913 (the consolidated closing bid price immediately preceding the time we entered into the Note Purchase Agreement, plus $.01), which was 9,720,291 shares. For all applicable periods following February 15, 2023, interest accrued on the outstanding principal balance of the Notes at the US prime interest rate, as reported in the Wall Street Journal, plus 50 basis points, as adjusted monthly, for three months immediately following February 15, 2023, and thereafter at the US prime rate plus 300 basis points, as adjusted monthly. Accrued interest was paid in cash, quarterly in arrears, on each of March 31, June 30, September 30 and December 31.

On February 15, 2023, the $20 million Zanganeh Note matured and we repaid the outstanding principal balance. In connection with the closing of the 2023 Rights Offering, the $400 million Duggan Promissory Note matured and became due, and we satisfied all principal and accrued interest thereunder using a combination of a portion of the cash proceeds from the 2023 Rights Offering and the extinguishment of a portion of the amount due equal to the subscription price of shares subscribed by Mr. Duggan in the 2023 Rights Offering.

On February 17, 2024 the Duggan February Note was amended to extend the maturity date from September 6, 2024 to April 1, 2025. For all applicable periods commencing February 17, 2024, interest accrued on the outstanding principal balance at the greater of 12% or the US prime interest rate, as reported in the Wall Street Journal plus 350 basis points, as adjusted monthly, compounded quarterly. Interest was paid upon maturity of the loan.

As of October 1, 2024, the Company repaid the Duggan September Note in full, resulting in principal payments in the aggregate amount of $100.0 million and accrued cash interest of $7.3 million.

Other commitments

We enter into contracts in the normal course of business with various third parties for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. Most contracts provide for termination upon notice, and therefore are cancellable contracts. As of December 31, 2025, total unconditional purchase obligations, excluding lease commitments, are estimated to be approximately $18.0 million.

We have certain commitments under our agreements with Akeso. The License Agreement with Akeso also contains certain manufacturing and purchase commitments. As of December 31, 2025, we are unable to estimate the amount, timing or likelihood of achieving the milestones, making future product sales or assessing estimated forecasts for manufacturing and supplied materials which these contingent payment obligations relate to. For additional information about the License Agreement with Akeso, refer to Note 4, “Akeso License and Collaboration Agreement” to the Consolidated Financial Statements included under Item 15, “Exhibits, Financial Statement Schedules.”

Legal Proceedings

Litigation Relating to the December 2022 Notes Entered into in Connection with the License Agreement

On March 17, 2025, Rainaldi Revocable Trust, a purported stockholder of the Company, filed a derivative lawsuit in the Delaware Court of Chancery against certain of the Company’s current and former directors and the Company, solely as a nominal defendant, concerning the December 2022 Notes entered into by the Company, Mr. Duggan and Dr. Zanganeh in connection with the License Agreement. The suit asserts claims for breach of fiduciary duty and unjust enrichment and seeks, among other things, unspecified damages, rescission of the shares that Mr. Duggan and Dr. Zanganeh received as part of prepaid interest payments under the December 2022 Notes, as well as attorneys’ fees and costs.

Pursuant to the December 2022 Notes, the Company obtained $520 million in bridge financing through three unsecured promissory notes: (1) a $400 million note issued to Mr. Duggan due on February 15, 2023; (2) a $20 million note issued to Dr. Zanganeh due on February 15, 2023; and (3) a $100 million note issued to Mr. Duggan due on September 15, 2023 (the “$100 Million Note”). The notes had an interest rate of 7.5% through February 15, 2023, with prepaid interest through that date paid in shares valued at $0.7913 per share. For periods after February 15, 2023, interest would accrue at the U.S. prime interest rate plus 50 basis points for three months, and thereafter at the U.S. prime rate plus 300 basis points. The notes contained no warrant coverage and no security interests. The Company announced the 2023 Rights Offering on December 6, 2022, which ran from February 7 through March 1, 2023. The 2023 Rights Offering was fully subscribed, with stockholders purchasing 476,190,471 shares of the Company’s common stock at $1.05 per share, raising $500 million in gross proceeds. Mr. Duggan and Dr. Zanganeh fully subscribed to their basic subscription rights, with Mr. Duggan participating by purchasing 376,489,880 shares for approximately $395.31 million. Following the Company’s fully subscribed $500 million 2023 Rights Offering, Dr. Zanganeh’s $20 million note was repaid on February 15, 2023, and Mr. Duggan's $400 million note was repaid. In the interest of minimizing stockholders dilution, the $100 Million Note was extended, and eventually the $75.5 million repayment was funded through the proceeds of the September 2024 Private Placement in which Mr. Duggan purchased 3,325,991 shares for an aggregate purchase price of $75.5 million as a participant in the September 2024 Private Placement at a purchase price of $22.70 per share, and the remaining $24.5 million was repaid in full on October 1, 2024, along with $7.3 million in accrued interest. Defendants’ motion to dismiss the complaint was filed on May 16, 2025 (the “Motion to Dismiss”). Plaintiff filed a motion to certify certain constitutional questions to the Delaware Supreme Court on May 29, 2025 (the “Motion to Certify”). Defendants agreed to a stipulation staying briefing on the Motion to Certify and the Motion to Dismiss pending the Delaware Supreme Court’s decision in another case involving substantially the same constitutional questions. On June 18, 2025, the Court granted such stipulation.

European Patent Opposition

On June 18, 2025, an unknown third party filed a notice of opposition against the Company’s in-licensed EP3882275B1 patent (the “’275 patent”) in the European Opposition Division of the European Patent Office (“EPO”). The ’275 patent covers Ivonescimab. The notice primarily asserts that the 275 patent lacks inventive step. The Company contests these assertions and worked with its collaboration partner, Akeso, to timely file a response before the European Opposition Division of the EPO on January 2, 2026.

Critical Accounting Policies and Significant Judgments and Estimates

Our management’s discussion and analysis of our financial condition and results of operations are based on our consolidated financial statements, which have been prepared in accordance with United States generally accepted accounting principles. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, and expenses and the disclosure of contingent assets and liabilities in our financial statements. On an ongoing basis, we evaluate our estimates and judgments, including those related to accrued research and development expenses, stock-based compensation and income taxes. We base our estimates on historical experience, known trends and events, and various other factors 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 from these estimates under different assumptions or conditions.

We believe the following critical accounting policies affect the most significant judgments, assumptions and estimates we use in preparing the consolidated financial statements:

Acquired In-Process Research and Development

The Company may enter into agreements with collaboration partners for the development and commercialization of its products. These arrangements may include payments contingent on the occurrence of certain events such as development, regulatory or sales-based milestones. The Company considers the unique nature, terms and facts and circumstances of each transaction. The Company considers whether or not the assets acquired have a future alternative use.

The fair value associated with acquired in-process research and development which does not have an alternative future use is expensed and is recorded as research and development expense. Any development or commercial milestone payments are recognized when the achievement of the associated milestone becomes probable and will either be expensed or capitalized depending upon whether or not regulatory approval has been obtained.

Research and Development Costs

Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred to discover, research and develop product candidates, including personnel expenses, stock-based compensation expense, allocated facility-related and depreciation expenses, third-party license fees and external costs of outside vendors engaged to conduct preclinical and clinical development activities and clinical trials as well as to manufacture clinical trial materials. Non- refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered, or the services rendered. The significant estimates in our accrued research and development expenses include the costs incurred for services performed by our vendors in connection with research and development activities for which we have not yet been invoiced. Milestone and other payments made to third-parties with respect to in-process research and development, in accordance with the Company’s license, acquisition and other similar agreements are expensed when determined to be probable and estimable.

The Company has entered into various research and development contracts with other companies. These agreements are generally cancellable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs or prepaid expenses where the payments made exceed the estimated costs. These amounts are determined based on the estimated costs to complete each study or activity, the estimation of the current stage of completion and the invoices received, as well as predetermined milestones which are not reflective of the current stage of development for prepaid expenses. Actual results could differ from the Company’s estimates. In all cases, the full cost of each study or activity is expensed by the time the final report or where applicable, product, has been received. The Company’s historical estimates have not been materially different from the actual costs.

Stock-Based Compensation

The Company measures and recognizes compensation expense for all stock option and restricted stock unit awards based on the estimated fair value of the award on the grant date. The Company uses the Black-Scholes option pricing model to estimate the fair value of stock option awards. Additionally, the Company uses a Monte Carlo simulation model to calculate the estimated fair value on the date of grant related to awards with market-based service conditions. The fair value is recognized as expense, over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis for each separately vesting portion of the award when the only condition to vesting is continued service. If vesting is subject to a market or performance condition, recognition is based on the derived service period of the award. Expense for awards with performance conditions is estimated and adjusted on a quarterly basis based upon the assessment of the probability that the performance condition will be met. Use of the Black-Scholes option-pricing model requires management to apply judgment under subjective assumptions. These assumptions include:

•Expected term—The expected term of stock options represents the weighted-average period the stock options are expected to be outstanding. The Company uses the simplified method for estimating the expected term as provided by the Securities and Exchange Commission. The simplified method calculates the expected term as the average of the time-to-vesting and the contractual life of the options.

•Expected volatility—The expected volatility is calculated based on historical volatility of the Company’s share price.

•Risk-free interest rate—The risk-free rate assumption is based on the U.S. Treasury instruments, the terms of which were consistent with the expected term of the Company’s stock options.

•Expected dividend—The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has not paid and does not intend to pay dividends.

The Company uses a Monte Carlo simulation model to estimate the fair value of Performance and Market-based Stock Options at the date of grant. Key assumptions used in the model include the risk-free interest rate, which reflects the US Treasury Constant Maturity Yield with a term commensurate with the contractual term of the award, and stock price volatility, which is derived based on the historical volatility of the Company’s stock.

The Company estimates expected forfeitures at the time of grant instead of accounting for forfeitures as they occur. Stock option awards have been granted at fair value to non-employees, in connection with research and consulting services provided to the Company, to non-employees in connection with corporate activities, and to employees, in connection with Stock Purchase and Restriction Agreements. Equity awards generally vest over terms of 3 or 4 years.

The Company classifies stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified.

Income Taxes

The provision for income taxes is determined using the asset and liability approach. Tax laws may require items to be included in tax filings at different times than the items are reflected in the financial statements. A current asset or liability is recognized for the estimated taxes receivable or payable for the current year. Deferred taxes represent the future tax consequences expected to occur when the reported amounts of assets and liabilities are recovered or paid. Deferred taxes are initially recognized at enacted tax rates in force at the time of initial recognition and are subsequently adjusted for any enacted changes in tax rates and tax laws. Subsequent changes to deferred taxes originally recognized in equity are recognized in income. Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized. The Company has recorded a full valuation allowance against the deferred tax assets in excess of its deferred tax liabilities, as the deferred tax liability represents future reversals of existing taxable temporary differences. The Company records interest and penalties related to income tax matters as part of income tax expense.

The Company accounts for uncertain tax positions taken in its tax filings by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities having full knowledge of the facts and applicable tax rules. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed as the amount of benefit to recognize in the consolidated financial statements. The amount of benefits that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate, as well as the related net interest and penalties. At December 31, 2025, 2024, and 2023 the Company had unrecognized tax positions of $3.9 million, $2.1 million, and $1.1 million, respectively. Due to the Company’s full valuation allowance, the unrecognized tax benefits are not expected to materially impact the Company’s effective tax rate when recognized or significantly increase or decrease in the next 12 months. In addition, the Company’s policy is to recognize interest and penalties related to uncertain tax positions as part of its income tax provision.

Recent Accounting Pronouncements

For a discussion of recent accounting pronouncements, please see Note 2 to our consolidated financial statements contained in this Annual Report on Form 10-K.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Our primary exposures to market risk are liquidity risk and foreign currency risk.

Liquidity Risk

We have funded our operations since inception primarily through the issuance of equity and debt securities. We have also received funding from our license and collaboration arrangements. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity or debt financings or other sources. Adequate additional financing may not be available to us on acceptable terms, or at all. Our inability to raise capital as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy.

Foreign Currency Exchange Rate Risk

Foreign currency exchange rate risk refers to the risk that the value of a financial commitment or recognized asset or liability will fluctuate due to changes in foreign currency rates. Our net loss and financial position, as expressed in U.S. dollars, are exposed to movements in foreign exchange rates against the pound sterling and the euro. The main trading currencies are the pound sterling, the U.S. dollar, Japanese Yen, and the euro. We are exposed to foreign currency exchange rate risk as a result of entering into operating transactions denominated in currencies other than the functional currency of our subsidiaries, particularly in relation to our monetary assets and liabilities relating to intercompany transactions, supplier liabilities and the translation of foreign cash balances. Operating transaction foreign currency gains and losses are included in the determination of net loss in our statements of operations and comprehensive loss. We monitor our exposure to foreign currency exchange rate risk. Exposures are generally managed through natural hedging via the currency denomination of cash balances and any impact currently is not material to us.

Interest Rate Risk

We hold our cash, cash equivalents and short-term investments for working capital purposes. Some of the securities we invest in are subject to market risk. This means that a change in prevailing interest rates may cause the principal amount of such investments to fluctuate. To minimize this risk, we maintain our portfolio of cash, cash equivalents and short-term investments which are invested in a variety of short term securities, including money market funds, certificates of deposit and U.S. treasury securities. Due to the short-term nature of these instruments, we believe that we do not have any material exposure to changes in the fair value of our investment portfolio as a result of changes in interest rates. Declines in interest rates, however, would reduce future interest income. The effect of a hypothetical 10% increase or decrease in overall interest rates would not have had a material impact on our operating results or the total fair value of our portfolio.

Credit Risk

We consider all of our material counterparties to be creditworthy. We consider the credit risk for each of our counterparties to be low and do not have a significant concentration of credit risk at any of our counterparties. We have $0.9 million of research and development tax credits outstanding at December 31, 2025. Given that these receivables relate to U.K. research and development tax credit cash rebate regimes and given our history of collection, it is highly unlikely that these amounts will not be collected.

Item 8. Financial Statements and Supplementary Data

The financial statements required to be filed pursuant to this Item 8 are included in this Annual Report on Form 10-K. An index of those financial statements is found in Item 15, “Exhibits, Financial Statement Schedules.”

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

None.

Item 9A. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

We have performed an evaluation of the effectiveness of our disclosure controls and procedures under the supervision and the participation of the company’s management, including our Co-Chief Executive Officers (our Principal Executive Officers) and our Chief Operating Officer and Chief Financial Officer (our Principal Financial Officer). The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the company’s management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure. There are inherent limitations to the effectiveness of any system of disclosure controls and procedures, including the possibility of human error and the circumvention or overriding of the controls and procedures. Accordingly, even effective disclosure controls and procedures can only provide reasonable assurance of achieving their control objectives. Based upon our evaluation of our disclosure controls and procedures as of December 31, 2025, our Co-Chief Executive Officer and Executive Chairman and our Co-Chief Executive Officer, President and Director (our Principal Executive Officers), and our Chief Operating Officer, Chief Financial Officer and Director (our Principal Financial Officer) concluded that, as of such date, our disclosure controls and procedures were effective at a reasonable level of assurance.

Management’s Report on Internal Control Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Our internal control over financial reporting is a process designed, under the supervision of the Co-Chief Executive Officers (our Principal Executive Officers), and our Chief Operating Officer and Chief Financial Officer (our Principal Financial Officer), to provide reasonable assurance regarding the reliability of financial reporting and the preparation of our financial statements for external reporting purposes in accordance with generally accepted accounting principles.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of the effectiveness of internal control to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Our management has assessed the effectiveness of internal control over financial reporting as of December 31, 2025, based on the “Internal Control—Integrated Framework” issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in 2013. Based on this assessment, management concluded that, as of December 31, 2025, our internal control over financial reporting is effective based on the COSO internal control criteria.

The effectiveness of the Company’s internal control over financial reporting as of December 31, 2025 has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in its report included in Item 15, “Exhibits, Financial Statement Schedules” of this Annual Report on Form 10-K.

Changes in Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting (as defined in Rules 13a‐15(f) and 15d‐15(f) under the Exchange Act) during the quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information

Rule 10b5-1 Trading Plans.

None.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Not applicable.

PART IIIs

Item 10. Directors, Executive Officers and Corporate Governance

The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference.

Item 11. Executive Compensation

The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference.

Item 13. Certain Relationships and Related Party Transactions

The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference.

Item 14. Principal Accounting Fees and Services

The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference.

PART IV

Item 15. Exhibits, Financial Statement Schedules

(1) Financial Statements

As part of this Annual Report on Form 10-K, the consolidated financial statements are listed in the accompanying index to financial statements on page 92.

(2) Financial Statement Schedules

All financial statement schedules have been omitted because they are not applicable, not required, or the information required is shown in the consolidated financial statements or the notes thereto.

(3) Exhibits

The exhibits filed as part of this Annual Report on Form 10-K are listed below.

Exhibit No. Description

14.1* Code of Business Conduct and Ethics of Summit Therapeutics Inc.

19.1 Insider Trading Policy

21.1* List of Significant Subsidiaries

101.SCH* Inline XBRL Taxonomy Extension Schema Document

101.CAL* Inline XBRL Taxonomy Extension Calculation Linkbase Document

Exhibit No. Description

101.DEF* Inline XBRL Taxonomy Extension Definition Linkbase Document

101.LAB* Inline XBRL Taxonomy Extension Label Linkbase Document

101.PRE* Inline XBRL Taxonomy Extension Presentation Linkbase Document

* Filed herewith.

** Furnished herewith.

# Indicates management contract or compensatory plan or arrangement.

Item 16. Report Summary

None.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

SUMMIT THERAPEUTICS INC.

By: /s/ Robert W. Duggan

By: /s/ Mahkam Zanganeh

By: /s/ Manmeet S. Soni

Date: February 23, 2026

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Report has been signed below by the following persons on behalf of the Registrant in the capacities and on the dates indicated.

Name Title Date

Robert W. Duggan

Dr. Mahkam Zanganeh

Manmeet S. Soni

Bhaskar Anand

/s/ Robert F. Booth Director February 23, 2026

Dr. Robert F. Booth

/s/ Alessandra Cesano Director February 23, 2026

Dr. Alessandra Cesano

/s/ Kenneth Clark Director February 23, 2026

Kenneth Clark

/s/ Jeff Huber Director February 23, 2026

Jeff Huber

/s/ Mostafa Ronaghi Director February 23, 2026

Mostafa Ronaghi

/s/ Yu Xia Director February 23, 2026

Dr. Yu Xia

SUMMIT THERAPEUTICS INC. Page

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Report of Independent Registered Public Accounting Firm (PCAOB ID: 238) 93

Consolidated Balance Sheets 95

Consolidated Statements of Operations and Comprehensive Loss 96

Consolidated Statements of Stockholders' Equity 97

Consolidated Statements of Cash Flows 98

Notes to Consolidated Financial Statements 99

Report of Independent Registered Public Accounting Firm

To theBoard of Directors and Stockholders of Summit Therapeutics Inc.

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of Summit Therapeutics Inc. and its subsidiaries (the "Company") as of December 31, 2025 and 2024, and the related consolidated statements of operations and comprehensive loss, of stockholders’ equity and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes (collectively referred to as the "consolidated financial statements"). We also have audited the Company's internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO.

Basis for Opinions

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

Emphasis of Matter

As discussed in Note 1 to the consolidated financial statements, the Company has incurred net losses from operations and cash outflows from operating activities. Management’s evaluation of the events and conditions and management’s plans to mitigate these matters are also described in Note 1.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and

expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

External Research and Development Costs

The Company’s research and development expense for the year ended December 31, 2025 was $537.7 million, of which a portion relates to external research and development costs. As described in Note 2 to the consolidated financial statements, research and development costs are expensed as incurred. Research and development expenses consist of costs incurred to discover, research and develop product candidates, including third-party license fees and external costs of outside vendors engaged to conduct preclinical and clinical development activities and clinical trials as well as to manufacture clinical trial materials. Management has entered into various research and development contracts with other companies. These agreements are generally cancellable, and related payments are recorded as research and development expenses as incurred.

The principal consideration for our determination that performing procedures relating to external research and development costs is a critical audit matter is a high degree of auditor effort in performing procedures related to the Company’s external research and development costs.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls related to the research and development costs process. These procedures also included, among others, testing external research and development costs on a sample basis by (i) evaluating costs incurred to underlying agreements with outside vendors, invoices received, and underlying payments made for costs incurred on the contract; and (ii) evaluating the classification as research and development costs.

/s/ PricewaterhouseCoopers LLP

San Jose, California

February 23, 2026

We have served as the Company’s auditor since 2021.

Summit Therapeutics Inc.

Consolidated Balance Sheets

(in thousands, except share and per share data)

Assets

Current assets:

Prepaid expenses and other current assets 6,537 11,076

Non-current assets:

Property and equipment, net 1,059 254

Operating lease right-of-use assets 20,616 7,144

Liabilities and stockholders’ equity

Current liabilities:

Operating lease liabilities, current portion 3,388 3,765

Non-current liabilities:

Operating lease liabilities, net of current portion 17,502 3,453

Other non-current liabilities 1,832 1,630

Commitments and contingencies (Note 16)

Stockholders’ equity:

Accumulated other comprehensive loss (2,540) (2,285)

Total liabilities and stockholders' equity $ 751,182 $ 435,560

The accompanying notes are an integral part of the consolidated financial statements

Summit Therapeutics Inc.

Consolidated Statements of Operations and Comprehensive Loss

(in thousands, except share and per share data)

Year Ended December 31,

Operating expenses:

Acquired in-process research and development — 15,007 520,915

Net loss per share:

Weighted average common shares outstanding:

Other comprehensive income (loss):

Foreign currency translation adjustments (327) 60 (172)

Unrealized gain on short-term investments 72 100 36

(1)Refer to Note 15 – Related Party Transactions for expenses incurred.

The accompanying notes are an integral part of the consolidated financial statements.

Summit Therapeutics Inc.

Consolidated Statements of Stockholders’ Equity

(in thousands, except share data)

Shares Amount

Net other comprehensive loss — — — (555) — (555)

Net other comprehensive gain — — — 163 — 163

Net other comprehensive loss — — — (255) — (255)

(2)Refer to Note 13 – Stockholders’ Equity for related party transactions.

The accompanying notes are an integral part of the consolidated financial statements.

Summit Therapeutics Inc.

Consolidated Statements of Cash Flows

(in thousands)

Year Ended December 31,

Cash flows used in operating activities:

Adjustments to reconcile net loss to net cash used in operating activities:

Non-cash interest expense — — 6,253

Amortization of discount on short-term investments (7,006) (2,576) (1,924)

Unrealized foreign exchange loss (gain) (320) 229 (812)

Reclassification of currency translation gain — — (419)

Impairment of fixed assets — — 474

Loss on disposal of assets — — (109)

Acquired in-process research and development expense — 15,007 520,915

Changes in operating assets and liabilities:

Prepaid expenses and other current assets 4,866 (7,370) 3,613

Accrued liabilities and other current liabilities 12,930 11,879 (2,377)

Other long-term liabilities 80 95 —

Operating lease right-of-use assets and lease liabilities, net 203 (167) (359)

Cash flows used in investing activities:

Purchase of property and equipment (657) (139) (128)

Proceeds from sale of property, plant and equipment — — 226

Cash flows provided by financing activities:

Proceeds from the issuance of common stock for rights offering (2) — — 104,686

Re-payment of related party promissory notes — (100,000) (24,686)

Effect of exchange rates on cash and cash equivalents 102 (18) 839

Supplemental Disclosure of Cash Flow Information:

Cash paid for interest on related party promissory note $ — $ 8,806 $ 10,650

Cash paid for income taxes $ — $ — $ 52

Supplemental Disclosure of Non-Cash Investing and Financing Activities:

(2)Refer to Note 13 – Stockholders’ Equity for related party transactions.

The accompanying notes are an integral part of the consolidated financial statements.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

1. Organization

The Company’s current lead development candidate is ivonescimab, a novel, potential first-in-class bispecific antibody intending to combine the effects of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects of an anti-VEGF compound into a single molecule. On December 5, 2022, the Company entered into the License Agreement with Akeso, Inc. and its affiliates (collectively, “Akeso”) pursuant to which the Company has in-licensed intellectual property rights related to ivonescimab (as amended, the “License Agreement”), as further described in Note 4. Through the License Agreement, the Company obtained the rights to develop and commercialize ivonescimab in the United States, Canada, Europe, and Japan. The License Agreement and transaction closed in January 2023 following customary waiting periods. On June 3, 2024, the Company entered into an amendment to the License Agreement (the “Second Amendment”) with Akeso to expand its territories covered under the License Agreement to also include Latin America, including Mexico and all countries in Central America and South America, the Middle East and Africa (collectively, and as expanded, the “Licensed Territory“) . The Company’s operations are focused on the development of ivonescimab and other future activities, as the Company determines.

Basis of Presentation

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).Certain reclassifications have been made to the prior years’ financial statements to conform to current year presentation.

Use of Estimates

The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of income and expenses during the reporting period. On an on-going basis, management evaluates its estimates and judgments, including those related to accrued research and development expenses, stock-based compensation, and income taxes. Management bases its estimates and judgments on historical experience and on various other factors that are believed 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 from these estimates under different assumptions or conditions.

Liquidity and Capital Resources

During the year ended December 31, 2025, the Company incurred a net loss of $1,079,586 and cash used in operating activities was $322,930. As of December 31, 2025, the Company had an accumulated deficit of $2,294,159, and cash and cash equivalents of $225,266 and short-term investments of $488,182. The Company expects to continue to generate operating losses for the foreseeable future.

During the year ended December 31, 2025, the Company raised gross proceeds of $500,037 from a private placement and $106,498 from the Company’s at-the-market sales agreement, both described further in Note 13. With these recent financings, the Company has evaluated and concluded that its cash, cash equivalents and short-term investments provide sufficient cash to fund its operating cash needs for at least the next 12 months from the date of issuance of these consolidated financial statements.

Until the Company can generate substantial revenue and achieve profitability, the Company will need to raise additional capital to fund its ongoing operations and capital needs. The Company continues to evaluate options to further finance its operating

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

cash needs for its product candidates through a combination of some, or all, of the following: equity and debt offerings, collaborations, strategic alliances, grants and clinical trial support from government entities, philanthropic, non-government and not-for-profit organizations, and marketing, distribution or licensing arrangements. There is no assurance, however, that additional financing will be available when needed or that management of the Company will be able to obtain financing on terms acceptable to the Company. If the Company is unable to obtain funding when required in the future, the Company could be required to delay, reduce, or eliminate research and development programs, product portfolio expansion, or future commercialization efforts, which could adversely affect its business prospects.

2. Summary of Significant Accounting Policies and Recent Accounting Pronouncements

The significant accounting policies adopted by the Company in the preparation of these consolidated financial statements are set out below. These policies have been consistently applied to all the years presented, unless otherwise stated.

Principles of Consolidation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. GAAP and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. The consolidated financial statements reflect the accounts of Summit Therapeutics Inc. and its wholly owned subsidiaries. Intercompany balances and transactions are eliminated in consolidation.

Foreign Currency Translation

The financial statements of the Company’s subsidiaries with functional currencies other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates for operating results. Translation gains and losses are included in accumulated other comprehensive (loss) income in stockholders’ equity. Foreign currency transaction gains and losses are included in other income, net in the consolidated statements of operations and comprehensive loss. The Company recorded realized and unrealized foreign currency transaction (loss) gain of ($610), $(97) and $613 for the years ended December 31, 2025, 2024 and 2023, respectively, which is included in other income, net in the consolidated statements of operations and comprehensive loss.

Net Loss Per Share

Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per share is computed by dividing the diluted net loss by the weighted-average number of common shares outstanding for the period, including potentially dilutive common shares. The dilutive effect of share options and warrants are determined under the treasury stock method using the average market price for the period.In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options and warrants that are in-the-money.

Goodwill

Goodwill represents the excess of the consideration transferred over the fair value of net assets acquired. Goodwill is assigned to reporting units at the time of acquisition or when there is a change in the reporting structure and bases that allocation on which reporting units will benefit from the acquired assets and liabilities. Reporting units are defined as operating segments or one level below an operating segment, referred to as a component. Typically acquisitions related to a single reporting unit do not require the allocation of goodwill to multiple reporting units. If the net assets obtained in an acquisition are assigned to multiple reporting units, the goodwill is distributed to the respective reporting units as part of the purchase price allocation process.

The Company assesses goodwill for impairment on an annual basis as of December 31 or more frequently when events and circumstances occur indicating that the recorded goodwill may be impaired. The Company regularly monitors current business conditions and other factors including, but not limited to, adverse industry or economic trends and lower projections of

100

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

profitability that may impact future operating results. The process of evaluating the potential impairment of goodwill requires significant judgment. In performing the Company’s annual goodwill impairment test, the Company is permitted to first assess qualitative factors to determine whether it is more likely than not that the fair value of the Company’s reporting unit is less than its carrying amount, including goodwill. In performing the qualitative assessment, the Company considers certain events and circumstances specific to the reporting unit and to the entity as a whole, such as macroeconomic conditions, industry and market considerations, overall financial performance and cost factors when evaluating whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. The Company is also permitted to bypass the qualitative assessment and proceed directly to the quantitative test. If the Company chooses to undertake the qualitative assessment and concludes that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the Company would then proceed to the quantitative impairment test. In the quantitative assessment, the Company compares the fair value of the reporting unit to its carrying amount, which includes goodwill. If the fair value exceeds the carrying value, no impairment loss exists. If the fair value is less than the carrying amount, a goodwill impairment loss is measured and recorded.

Leases

The Company has operating leases for real estate. The Company does not have any finance leases. A contract is or contains a lease when the lessee has the right to control the use of an identified asset. The Company determines if an arrangement is a lease at inception of the contract, which is the date on which the terms of the contract are agreed to and the agreement creates enforceable rights and obligations. The lease term used to calculate the lease liability include options to extend or terminate the lease when it is reasonably certain that the option will be exercised.

At the lease commencement date, the Company measures and recognizes a lease liability and a right-of-use asset in the financial statements. Lease liabilities are recognized based on the present value of the future lease payments over the lease term at commencement date. The right-of use asset is measured by taking the present value of future lease payments, plus any incremental direct costs incurred, less any lease incentives received. As most of the Company’s leases do not provide an implicit rate, the Company uses an estimated incremental borrowing rate based on the lease term and the economic environment of the lease at the lease commencement date, which is then utilized to determine the present value of future lease payments. Lease expense for minimum lease payments are recognized on a straight-line basis over the lease term, with variable lease payments recognized in the periods in which they are incurred.

The Company has existing lease agreements with lease and non-lease components, has elected to account for the lease and non-lease components as a single lease component, and has allocated all of the contract consideration to the lease component only.

Leases with an initial lease term of 12 months or less are not recorded on the balance sheet. The Company recognizes lease expense for its short-term leases on a straight-line basis over the lease term.

Acquired In-Process Research and Development

Research and Development Costs

101

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered, or the services rendered. Milestone and other payments made to third-parties with respect to in-process research and development, in accordance with the Company’s license, acquisition and other similar agreements are expensed when determined to be probable and estimable.

Stock-Based Compensation

The Company measures and recognizes compensation expense for all stock option awards based on the estimated fair value of the award on the grant date. The Company uses the Black-Scholes option pricing model to estimate the fair value of stock option awards. Additionally, the Company uses a Monte Carlo simulation model to calculate the estimated fair value on the date of grant related to awards with market-based service conditions. The fair value is recognized as expense, over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis for each separately vesting portion of the award when the only condition to vesting is continued service. If vesting is subject to a market or performance condition, recognition is based on the derived service period of the award. Expense for awards with performance conditions is estimated and adjusted on a quarterly basis based upon the assessment of the probability that the performance condition will be met. Use of the Black-Scholes option-pricing model requires management to apply judgment under subjective assumptions. These assumptions include:

•Expected term—The expected term of stock options represents the weighted-average period the stock options are expected to be outstanding. The Company uses the simplified method for estimating the expected term as provided by the SEC. The simplified method calculates the expected term as the average of the time-to-vesting and the contractual life of the options.

•Expected volatility—The expected volatility is calculated based on historical volatility of the Company’s share price.

•Risk-free interest rate—The risk-free rate assumption is based on the U.S. Treasury instruments, the terms of which were consistent with the expected term of the Company’s stock options.

•Expected dividend—The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has not paid and does not intend to pay dividends.

The Company uses a Monte Carlo simulation model to estimate the fair value of Performance and Market-based Stock Options at the date of grant which utilizes multiple input variables to estimate the probability that the market condition will be achieved. Key assumptions used in the model include the risk-free interest rate, which reflects the US Treasury Constant Maturity Yield with a term commensurate with the contractual term of the award, and stock price volatility, which is derived based on the historical volatility of the Company’s stock.

Income Taxes

102

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

for the estimated taxes receivable or payable for the current year. Deferred taxes represent the future tax consequences expected to occur when the reported amounts of assets and liabilities are recovered or paid. Deferred taxes are initially recognized at enacted tax rates in force at the time of initial recognition and are subsequently adjusted for any enacted changes in tax rates and tax laws. Subsequent changes to deferred taxes originally recognized in equity are recognized in income. Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized. The Company has recorded a full valuation allowance against the deferred tax assets in excess of its deferred tax liabilities, as the deferred tax liabilities represent future reversals of existing taxable temporary differences. The Company records interest and penalties related to income tax matters as part of income tax expense.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash and short-term investments. The Company’s cash is comprised of short-term cash deposits at a variety of financial institutions which the Company believes are of high credit ratings in amounts that may exceed federally insured limits. The Company has not experienced any losses on such accounts. Cash balances maintained during the year have been principally held with U.S.-based and U.K.-based banks. The Company does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

The Company relies, and expects to continue to rely, on a number of vendors to conduct its clinical trials and preclinical studies, manufacture drug product and supply clinical trial and preclinical study materials for its development programs. These programs could be adversely affected by a significant interruption in these services or the availability of materials.

Fair Value Measurements

In accordance with the provisions of fair value accounting, a fair value measurement assumes that the transaction to sell an asset or transfer a liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability and defines fair value based on the exit price model.

The fair value measurement guidance establishes a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The guidance describes three levels of inputs that may be used to measure fair value:

Level 1

Quoted prices in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2

Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets and liabilities include debt securities with quoted prices that are traded less frequently than exchange-traded instruments or securities or derivative contracts that are valued using a pricing model with inputs that are observable in the market or can be derived principally from or corroborated by observable market data.

Level 3

Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation.

In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the Company categorizes such assets and liabilities based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset.

103

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Cash and Cash Equivalents

The Company considers only those investments that are highly liquid, readily convertible to cash and that mature within 90 days or less from date of purchase to be cash equivalents. As of December 31, 2025, cash equivalents were comprised of money market funds and U.S. treasury securities. As of December 31,2024, cash equivalents were comprised of money market funds.

Restricted Cash

Restricted cash represents amounts which are legally restricted to withdrawal or usage and is presented in the consolidated balance sheet as restricted cash. As of December 31, 2025 the Company has $316 of restricted cash associated with an irrevocable letter of credit required by the landlord to enter into the lease for Company’s corporate office.

The Company’s total cash, cash equivalents and restricted cash balances were as follows:

Year Ended December 31,

Short-term Investments

Short-term investments consist of marketable securities with original maturities greater than ninety days from the date of acquisition. The Company classifies marketable securities with original maturities of greater than 90 days and less than one year as short-term, based on the liquid nature of the marketable securities and because such marketable securities represent the investment of cash that is available for current operations. The Company considers its investment portfolio of marketable securities as available-for-sale. Accordingly, these investments are recorded at fair value, which is based on quoted market prices or other observable inputs. Unrealized gains and losses are recorded as a component of other comprehensive income (loss). Realized gains and losses are determined on a specific identification basis and are included in other income, net. Amortization and accretion of discounts and premiums are also recorded in other income, net.

When the fair value is below the amortized cost of the asset, an estimate of expected credit losses is made. This estimate is limited to the amount by which fair value is less than amortized cost. The credit-related impairment amount is recognized in the consolidated statements of operations and comprehensive loss and the remaining impairment amount and unrealized gains are reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Credit losses are recognized through the use of an allowance for credit losses account and subsequent improvements in expected credit losses are recognized as a reversal of the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis the allowance for credit loss is written off and the excess of the amortized cost basis of the asset over its fair value is recorded in the consolidated statements of operations and comprehensive loss.

Recently Issued Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update “ASU” 2023-09, “Improvements to Income Tax Disclosures”, which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company adopted ASU 2023-09 for the year ended December 31, 2025 using a retrospective approach. The adoption of ASU-2023-09 did not have a material impact on the Company’s consolidated financial statements and related disclosures.

104

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

In November 2024, the FASB issued ASU 2024-03, “Disaggregation of Income Statement Expenses”, which requires disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures. The guidance is to be applied prospectively, with the option for retrospective application and is effective for public business entities for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of this standard on the Company’s consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-11, “Narrow-Scope Improvements”, which is intended to improve the navigability of the guidance in ASC 270 and clarify when the guidance is applicable. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of this standard on the Company’s consolidated financial statements and related disclosures.

Other recent authoritative guidance issued by the FASB (including technical corrections to the FASB ASC), the American Institute of Certified Public Accountants, and the SEC did not or are not expected to have a material impact on the Company’s consolidated financial statements and related disclosures.

3. Segment Reporting

The Company’s chief operating decision makers (the “CODM function”), which are the Company’s Co-Chief Executive Officers, Mr. Duggan and Dr. Zanganeh, and Chief Operating Officer and Chief Financial Officer, Mr. Soni, utilize consolidated net loss that is reported on the consolidated statement of operations and comprehensive loss to make decisions about allocating resources and assessing performance for the entire Company. The CODM function approves of key operating and strategic decisions, including key decisions in clinical development and clinical operating activities, entering into significant contracts, such as revenue contracts and collaboration agreements and approves the Company’s consolidated operating budget. The CODM function views the Company's operations and manages its business on a consolidated basis and as a single reportable operating segment. The CODM function is regularly provided with the following significant segment expenses:

Year Ended December 31,

Acquired in-process research and development — 15,007 520,915

(1) Other expenses include general and administrative expenses excluding compensation and stock-based compensation.

As of December 31, 2025 and 2024, substantially all of our long-lived assets are located in the United States.

4. Akeso License and Collaboration Agreement

On December 5, 2022, the Company entered into the License Agreement with Akeso pursuant to which the Company is in-licensing its breakthrough bispecific antibody, ivonescimab. The License Agreement and transaction closed in January 2023 following customary waiting periods.

105

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Ivonescimab, known as AK112 in China and Australia, and also as SMT112 in the United States, Canada, Europe, and Japan, is a novel, potential first-in-class bispecific antibody intending to combine the effect of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects of an anti-VEGF into a single molecule. Ivonescimab was engineered to bring two well established oncology targeted mechanisms together. Ivonescimab is currently in clinical development and, pursuant to the terms of the License Agreement, Summit will design and conduct the clinical trial activities to support regulatory filings in the Licensed Territory that Summit will submit.

Pursuant to the terms of the License Agreement, Summit will have final decision making authority with respect to clinical development strategy and execution in the Licensed Territory. For co-joined studies in which both Summit and Akeso participate, mutual agreement is required for material decisions; Summit retains the exclusive decision making with respect to participating in, and continuing its participation in, co-joined studies. Pursuant to the terms of the License Agreement, Summit will have final decision-making authority with respect to commercial strategy, pricing and reimbursement and other commercialization matters in the Licensed Territory. In connection with the License Agreement, the Company agreed to purchase a certain portion of drug substance and/or drug product for clinical and commercial supply and to enter into a supply agreement with Akeso. Summit is not assuming any liabilities (including contingent liabilities), acquiring any physical assets or trade names, or hiring or acquiring any employees from Akeso in connection with the License Agreement. Through the License Agreement, the Company obtained the rights to develop and commercialize ivonescimab in the United States, Canada, Europe, and Japan.

In exchange for the rights obtained, the Company made an upfront payment of $500,000 to Akeso, of which $274,900 was paid in cash and, pursuant to the License Agreement and Issuance Agreement, Akeso elected to receive 10,000,000 shares of the Company’s common stock, par value $0.01 per share (“common stock”) in lieu of $25,100 in cash. The remaining $200,000 amount of the upfront payment was paid on March 6, 2023.

Effective June 3, 2024, the Company and Akeso entered into the Second Amendment to the License Agreement to expand the Company’s territories covered under the License Agreement to include the Latin America, Middle East and Africa regions. Pursuant to the Second Amendment, the Company paid an upfront payment to Akeso of $15,000 in the third quarter of 2024. Akeso will also be eligible to receive up to an additional $55,000 upon the achievement of certain commercial milestones. Except as specifically modified by the Second Amendment, the terms and conditions of the License Agreement remain in full force and effect.

The Company has accounted for the License Agreement and Second Amendment to acquire the rights to develop and commercialize ivonescimab as the acquisition of an asset. All of the consideration relates to ivonescimab and technological feasibility of the asset has not yet been established since ivonescimab is in clinical development. As such, the Company has expensed the consideration as acquired in-process research and development upon closing of the transaction in the consolidated statement of operations and comprehensive loss. Acquired in-process research and development expense for the year ended December 31, 2025 was nil. Acquired in-process research and development expense for the year ended December 31, 2024, was $15,007 which is comprised of the upfront payment and immaterial transaction costs. For the year ended December 31, 2023, acquired in-process research and development expense totaled $520,915 pursuant to the License Agreement, which was comprised of the $474,900 paid in cash, the fair value of the 10,000,000 shares of common stock on the date of closing the transaction of $45,900, and $115 of direct transactions costs incurred.

In addition to the payments already made to Akeso, under the License Agreement and Second Amendment, there are additional potential milestone payments of up to $4,555,000, as Akeso will be eligible to receive regulatory milestones of up to $1,050,000 and commercial milestones of up to $3,505,000. In addition, Akeso will be eligible to receive low double-digit royalties on net sales.

106

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

5. Other Income, Net

The following table sets forth the components of other income, net:

Year Ended December 31,

Foreign currency (loss) gain $ (610) $ (97) $ 613

Reclassification of cumulative currency translation gain (2) — — 419

Other expense, net (53) — (252)

(1) Investment income relates to the Company’s money market funds and short-term investments in U.S. treasury securities. Refer to Note 9 for details.

(2) The reclassification of cumulative currency translation gain related to the reclassification of cumulative foreign currency translation gains from accumulated other comprehensive loss due to the dissolution of certain dormant entities.

6. Income Tax

The Company is primarily subject to corporation taxes in the U.S. and the U.K. The calculation of the Company’s tax provision involves the application of both U.S. and U.K. tax law and requires judgment and estimates. The Company has also assessed the applicability of the OECD/G20 Inclusive Framework on Base Erosion and Profit Shifting (BEPS) Pillar 2 rules, which establish a global minimum tax rate. Based on the Company’s current financial position and revenue it does not meet the thresholds for Pillar 2 to apply. Therefore, the provisions and requirements under Pillar 2 do not impact our financial statements for the reporting period.

Deferred taxes represent the future tax consequences expected to occur when the reported amounts of assets and liabilities are recovered or paid. Deferred taxes are initially recognized at enacted tax rates in force at the time of initial recognition and are subsequently adjusted for any enacted changes in tax rates and tax laws. Subsequent changes to deferred taxes originally recognized in equity are recognized in income.

Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized. The Company has recorded a full valuation allowance against the deferred tax assets in excess of its deferred tax liabilities, as the deferred tax liabilities represent future reversals of existing taxable temporary differences. The Company records interest and penalties related to income tax matters as part of income tax expense.

Uncertain Tax Positions

Due to the Company’s full valuation allowance, the unrecognized tax benefits are not expected to materially impact the Company’s effective tax rate when recognized or significantly increase or decrease in the next 12 months. In addition, the

107

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Company’s policy is to recognize interest and penalties related to uncertain tax positions as part of its income tax provision. However, for the years ended December 31, 2025 and 2024, the Company had no interest or penalties related to unrecognized tax benefits because any potential disallowance would not result in current tax but only result in a reduction to the Company’s net operating loss carryforwards.

Loss Before Income Taxes

The components of the Company’s loss before income taxes are as follows:

Year Ended December 31,

Deferred Income Taxes

The Company has not recognized a current or deferred provision for federal, state or non-United States income taxes in either of the years ending December 31, 2025 or December 31, 2024.

Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes.

The major components of deferred tax assets and liabilities are as follows:

Year Ended December 31,

Deferred tax assets:

Research and development credit carryforward 16,092 7,869

Deferred tax liabilities:

Total deferred tax liabilities (417) (337)

Net deferred tax assets before valuation allowance 133,161 95,588

Deferred tax, net $ — $ —

For the year ended December 31, 2025 and 2024, the Company recorded a deferred tax asset of $133,578 and $95,925, respectively.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize its deferred tax assets, which are comprised primarily of net operating loss carryforwards, research and development credits, stock-based compensation expense, and research and development costs capitalized for tax purposes. Management has considered the Company’s history of cumulative net losses in each taxing jurisdiction, estimated future taxable income, as well as prudent and feasible tax planning strategies, and has concluded that it is more likely than not that the Company will not realize the tax benefits in each

108

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

jurisdiction. Accordingly, a full valuation allowance has been established against these net deferred tax assets as of December 31, 2025 and 2024, respectively. The Company reevaluates the positive and negative evidence at each reporting period.

The changes in the valuation allowance during the years ended December 31, 2025, 2024 and 2023 primarily related to net operating loss carryforwards and capitalized research and development expenses.

The change in the valuation allowance was as follows:

Year Ended December 31,

Valuation allowance as of beginning of year $ (95,588) $ (84,751) $ (64,016)

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2025 and 2024, the Company had U.S. Federal gross operating loss carryforwards of approximately $93,210 and $44,270, respectively, which may be available to offset future income tax liabilities. The 2017 Tax Cuts and Jobs Act (“TCJA”) will generally allow losses incurred after 2017 to be carried over indefinitely but generally limits the net operating loss deduction to the lesser of the net operating loss carryover or 80% of a corporation’s taxable income (subject to Section 382 of the Internal Revenue Code of 1986, as amended). In addition, the Company has approximately $21,335 in U.S. State gross loss carryforwards which expire through various dates through 2044.

As of December 31, 2025, the Company had an estimated U.S. federal and state research and development tax credit carryforwards of $15,565 and $5,002, respectively, which may be available to offset future tax liabilities, and each begin to expire in 2041 and 2037, respectively.

As of December 31, 2025 and 2024, the Company had U.K. gross operating loss carryforwards of approximately $211,096 and $198,653 respectively, which may be available to offset future income tax liabilities. To the extent that U.K. taxable profits exceed £5,000 in each year, the loss available to utilize against profits in excess of £5,000 will be restricted to 50%. The U.K. loss carryforwards do not lapse and therefore, the full amount will be relieved over time provided there are sufficient profits against which the losses can be utilized.

Utilization of the U.S. net operating loss carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986 due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of carryforwards that can be utilized annually to offset future taxable income. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period. The Company has not completed a study to assess whether a change of ownership has occurred, or whether there have been multiple ownership changes since its formation. Any limitation may result in the loss of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization.

U.K. tax losses are subject to additional restrictions where there is a change in ownership in the business and certain other conditions are met. An ownership change of a U.K. tax resident company would occur where (directly or indirectly) a single person acquires more than half of the ordinary share capital of a company, or two or more persons each acquire a holding of at least 5% of the ordinary share capital of a company and these holdings together amount to more than half the ordinary share capital of a company. Where a change in ownership has occurred, and within three years prior to that change in ownership and five years afterwards, there is a major change in the nature and conduct of trade of that company or the trade of that business becomes small or negligible, any losses carried forward will be extinguished from the point of the change in ownership. In addition, losses accrued subsequent to April 1, 2017 will be extinguished on a change of ownership when there is a major change in the nature or conduct of a company’s business, or where there is a major change in the scale of that business, or a company ceases to carry on a particular trade or business. The Company has not completed a study to assess whether a change of ownership has occurred since its formation, or whether there has been a major change in the Company’s business that would

109

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

restrict the U.K. tax losses. Any limitation may result in the loss of a portion of the net operating loss carryforwards before utilization.

Deemed U.S. Income Inclusions

The TCJA created a requirement that US corporations include in income earnings of certain controlled foreign corporations under the global intangible low taxed income (“GILTI”) regime. Pursuant to the FASB Staff Q&A, Topic 740 No.5. Accounting for Global Intangible Low-taxed Income, the Company is allowed to make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as period expense only. The Company has elected to account for GILTI in the year the tax is incurred and include the current tax impact of GILTI in the effective tax rate. Given the Company’s loss position in the U.S. and the valuation allowance recorded against its U.S. net deferred tax assets, these provisions have not had a material impact on the Company’s consolidated financial statements.

Annual Effective Tax Rate Reconciliation

A reconciliation of the Company’s effective tax rate to the U.S. federal statutory rate is as follows:

Year Ended December 31,

State income tax, net of federal tax benefit — — % (17) — % — — %

Nontaxable or nondeductible Items

Foreign Tax Effects

Total $ — — % $ — — % $ — — %

Unrecognized Tax Benefit Reconciliation

The Company records unrecognized tax benefits in accordance with ASC 740-10, Income Taxes. ASC 740-10 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s income tax return and also provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition. As of December 31, 2025, 2024, and 2023, the Company had total unrecognized tax benefits of $3,903, $2,122, and $1,064, respectively.

A reconciliation of unrecognized tax benefits from continuing operations is as follows:

Year Ended December 31,

Unrecognized tax benefits, beginning of year $ 2,122 $ 1,064 $ —

Increases related to prior year tax positions 592 122 610

Increases related to current year tax positions 1,189 936 454

Unrecognized tax benefits, end of year $ 3,903 $ 2,122 $ 1,064

110

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Audit Examinations

In the U.S., the Company files a Federal consolidated income tax return and income tax returns in various states. In the U.S., the filings for tax years from 2020 remain subject to examination by the U.S. Internal Revenue Service and state tax authorities. The Company is not currently under examination by the Internal Revenue Service or any other jurisdiction for years 2020 through present. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period. In the U.K., tax returns for the year ended December 31, 2023 remains subject to examination by HMRC.

SMMT US Equity

SMMT · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

Item 9A. Controls and Procedures

Item 9B. Other Information

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Item 10. Directors, Executive Officers and Corporate Governance

Item 11. Executive Compensation

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Item 13. Certain Relationships and Related Party Transactions

Item 14. Principal Accounting Fees and Services

Item 15. Exhibits, Financial Statement Schedules

Item 16. Report Summary

SMMT US Equity☆

SMMT · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

Item 9A. Controls and Procedures

Item 9B. Other Information

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Item 10. Directors, Executive Officers and Corporate Governance

Item 11. Executive Compensation

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Item 13. Certain Relationships and Related Party Transactions

Item 14. Principal Accounting Fees and Services

Item 15. Exhibits, Financial Statement Schedules

Item 16. Report Summary

SMMT US Equity