Summit Therapeutics Announces Timing of
Rights Offering for Up to $500 Million

Menlo Park, California, January 30, 2023 – Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit” or the “Company”) today announced that the Company’s Board of Directors has set the record date for the Company’s previously announced rights offering, which will be available to all holders of record of the Company’s common stock, par value $0.01 (the “Common Stock”), as of the close of the market on February 6, 2023 (the “Record Date”).

The Company intends to distribute to all holders of Common Stock as of the Record Date non-transferable subscription rights to purchase up to 476,190,476 shares of Common Stock at a price per share equal to the lesser of (i) $1.05 per share, or (ii) the volume weighted-average price of the Common Stock for the five consecutive trading days through and including the expiration date of the offering, currently contemplated to be March 1, 2023. Assuming that the rights offering is fully subscribed, the Company will receive gross proceeds of up to $500 million, less expenses related to the rights offering. As indicated below, please refer to the registration statement on Form S-3 for more complete information regarding the Company’s rights offering.

The rights offering will include an over-subscription right to permit each rights holder that exercises its basic subscription rights in full to purchase additional shares of Common Stock that remain unsubscribed at the expiration of the offering. The availability of the over-subscription right will be subject to certain terms and conditions to be set forth in the offering documents.

Robert W. Duggan, Chairman, Chief Executive Officer, and the beneficial owner of approximately 78.1% of Summit’s Common Stock prior to this rights offering, and Dr. Maky Zanganeh, Co-Chief Executive Officer, President, a member of the Board of Directors, and the beneficial owner of approximately 6.0% of the Company’s Common Stock prior to this rights offering, have each indicated that they intend to participate in the rights offering for at least the full amount of their basic subscription rights, but have not made any formal binding commitment to participate.

Summit has filed a registration statement (including a prospectus) on Form S-3 with the Securities and Exchange Commission (the “SEC”) on December 21, 2022, as amended on January 23, 2023, which has not yet become effective. The registration statement covers, among other things, the rights offering to which this communication relates. Such securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. Before you invest, you should read the final prospectus in that registration statement, together with any prospectus supplement, that we will file prior to commencing any rights offering, and the documents incorporated by reference in the prospectus (or any prospectus supplement), as well as the other documents Summit has filed with the SEC for more complete information about Summit and the rights offering. You may get these documents for free by visiting EDGAR on the SEC’s website at

This press release does not constitute an offer to sell or the solicitation of an offer to buy these securities, nor will there be any sale of these securities in any state or other jurisdiction in which such offer, solicitation, or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

Summit Therapeutics’ Mission Statement
To build a viable, long-lasting health care organization that assumes full responsibility for designing, developing,  trial  execution  and  enrollment,  regulatory  submission  and  approval,  and  successful commercialization of patient, physician, caregiver, and societal-friendly medicinal therapy intended to: improve quality of life, increase potential duration of life, and resolve serious medical healthcare needs. To identify and control promising product candidates based on exceptional scientific development and administrational expertise, develop our products in a rapid, cost-efficient manner, and to engage commercialization and/or development partners when appropriate.

We accomplish this by building a team of world class professional scientists and business administrators that apply their experience and knowledge to this mission. Team Summit exists to pose, strategize, and execute a path forward in medicinal therapeutic health care that places Summit in a well-deserved, top market share, leadership position. Team Summit assumes full responsibility for stimulating continuous expansion of knowledge, ability, capability, and well-being for all involved stakeholders and highly-valued shareholders.

About Summit Therapeutics
Summit was founded in 2003 and our shares are listed on the Nasdaq Global Market (symbol ‘SMMT’). We are headquartered in Menlo Park, California, and we have additional offices in Oxford, UK and Cambridge, UK. For more information, please visit and follow us on Twitter @summitplc.

Contact Summit Investor Relations:
Dave Gancarz
Head of Stakeholder Relations & Corporate Strategy

General Inquiries:

Rights Offering Information and Subscription Agent:
Broadridge Corporate Issuer Solutions, LLC
+1 855 793 5068

Summit Forward-looking Statements
Any statements in this press release about the Company’s future expectations, plans and prospects, including but not limited to, statements about the clinical and preclinical development of the Company’s product candidates, entry into and actions related to the Company’s partnership with Akeso Inc., the therapeutic potential of the Company’s product candidates, the potential commercialization of the Company’s product candidates, the timing of initiation, completion and availability of data from clinical trials, the potential submission of applications for marketing approvals, the impact of the COVID-19 pandemic on the Company’s operations and clinical trials, potential acquisitions and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including the results of our evaluation of the underlying data in connection with the development and commercialization activities for SMT112, the outcome of discussions with regulatory authorities, including the Food and Drug Administration, the uncertainties inherent in the initiation of future clinical trials, availability and timing of data from ongoing and future clinical trials, the results of such trials, and their success, and global public health crises, including the coronavirus COVID-19 outbreak, that may affect timing and status of our clinical trials and operations, whether preliminary results from a clinical trial will be predictive of the final results of that trial or whether results of early clinical trials or preclinical studies will be indicative of the results of later clinical trials, whether business development opportunities to expand the Company’s pipeline of drug candidates, including without limitation, through potential acquisitions of, and/or collaborations with, other entities occur, expectations for regulatory approvals, laws and regulations affecting government contracts and funding awards, availability of funding sufficient for the Company’s foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the “Risk Factors” section of filings that the Company makes with the Securities and Exchange Commission. Any change to our ongoing trials could cause delays, affect our future expenses, and add uncertainty to our commercialization efforts, as well as to affect the likelihood of the successful completion of clinical development of SMT112. Accordingly, readers should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this press release represent the Company’s views only as of the date of this release and should not be relied upon as representing the Company’s views as of any subsequent date. The Company specifically disclaims any obligation to update any forward-looking statements included in this press release.