AIM Delisting Reminder

Summit Therapeutics plc
(“Summit Therapeutics” or the “Company”)

AIM Delisting Reminder

Oxford, UK, and Cambridge, MA, US, 11 February 2020 - Summit Therapeutics (AIM: SUMM, NASDAQ: SMMT), a leader in antibiotic innovation, issues a reminder that, as previously announced and pursuant to AIM Rule 41, the Company’s ordinary shares of one penny nominal value (“Ordinary Shares”) will cease to be admitted to trading on AIM at 7.00 am on 24 February 2020. Accordingly, the final day of trading on AIM of the Company’s Ordinary Shares will be 21 February 2020.

The Company’s American Depositary Shares (“ADSs”) will remain listed on the Nasdaq Global Market and all public trading of shares in the Company after that date will take place on that exchange; one ADS is represented by five Ordinary Shares. Thereafter, Ordinary Shares will continue to be capable of being held and transferred in certificated form, but there will be no public market in the UK on which the shareholders of the Company will be able to trade Ordinary Shares.

Shareholder are able to convert Ordinary Shares into ADSs and by doing, are able to trade such ADSs on Nasdaq. Further information can be found on the Company’s website at https://www.summitplc.com/investors/investor-centre/ under the heading “AIM Delisting FAQs”.

About Summit Therapeutics
Summit Therapeutics is a leader in antibiotic innovation. Our new mechanism antibiotics are designed to become the new standards of care for the benefit of patients and create value for payors and healthcare providers. We are currently developing new mechanism antibiotics to treat infections caused by C. difficile, Enterobacteriaceae and N. gonorrhoeae, and are using our proprietary Discuva Platform to expand our pipeline. For more information, visit www.summitplc.com and follow us on Twitter @summitplc.

For more information, please contact:

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