Summit Therapeutics Inc.

This Quarterly Report on Form 10-Q contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), regarding the future financial performance, business prospects and growth of Summit Therapeutics Inc., that involve substantial risks and uncertainties. All statements contained in this Quarterly Report on Form 10-Q, other than statements of historical fact, including statements regarding our strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward-looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. The forward-looking statements in this Quarterly Report on Form 10-Q include, among other things, statements about:

•the ability to develop a successful product candidate under the License Agreement (as defined in Part I, Item 1 Financial Statements, Note 1 Organization);

•our ability to raise sufficient additional funds to make payments under the License Agreement, and fund ongoing operations and capital needs;

•the timing of and the ability to effectively execute clinical development of ivonescimab;

•the timing, costs, conduct and outcomes of clinical trials for any product candidates, including ivonescimab;

•our plans with respect to possible future collaborations and partnering arrangements;

•the potential benefits of possible future acquisitions or investments in other businesses, products or technologies;

•our plans to pursue research and development of other future product candidates;

•our estimates regarding the potential market opportunity and patient population for commercializing our product candidates, if approved for commercial use;

•our sales, marketing and distribution capabilities and strategy;

•our ability to establish and maintain arrangements with third parties, such as contract research organizations, contract manufacturing organizations, suppliers and distributors;

•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 estimates regarding expenses, future revenues, capital requirements and needs for additional financing;

•the impact of government laws and regulations in the United States and in foreign countries;

•the timing and likelihood of regulatory filings and approvals for our product candidates;

•whether regulatory authorities determine that additional trials or data are necessary in order to accept a new drug application for review and/or approval;

•our competitive position;

•our ability to attract and retain key scientific or management personnel;

•the impact of public health epidemics, such as the novel coronavirus pandemic, natural disasters or geopolitical instability, the response to such events and the potential effects of such events on our business, financial results, supply chain and market;

•the outcome of pending, threatened, and future legal proceedings;

•our expectations regarding the anticipated timeline and our planned use of our cash, cash equivalents and short-term investments, future financial performance and our ability to continue as a going concern;

•estimates regarding stock-based compensation;

•general economic conditions, including economic slowdowns or other adverse economic conditions, such as periods of increased or prolonged inflation; and

•other risks and uncertainties, including those described under the heading “Risk Factors” included in our most recent Annual Report on Form 10-K for the year ended December 31, 2025, filed with the U.S. Securities and Exchange Commission (“SEC”) on February 23, 2026 (the “Annual Report”).

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have included important factors in the cautionary statements included in this Quarterly Report on Form 10-Q, particularly in the “Risk Factors” and

"Management's Discussion and Analysis of Financial Condition and Results of Operations" sections in this Quarterly Report on Form 10-Q, that we believe could cause actual results or events to differ materially from the forward-looking statements that we make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make.

You should read this Quarterly Report on Form 10-Q and the documents that we have filed as exhibits to this Quarterly Report on Form 10-Q completely and with the understanding that our actual future results may be materially different from what we expect. We do not assume any obligation to update any forward-looking statements.