On June 2, 2026, the Audit Committee and all independent directors of the Board of Directors of Summit Therapeutics Inc. (the "Company") approved one or more Company affiliates to purchase shares of the Company's common stock under the previously disclosed at-the-market offering with JP Morgan Securities LLC acting as Sales Agent (the "ATM").
Separately, Mr. Robert Duggan, the Company's Co-Chief Executive Officer and Chairman of the Board of Directors, Dr. Mahkam Zanganeh, the Company's Co-Chief Executive Officer, President and Director, and Mr. Manmeet Soni, Chief Operating Officer, Chief Financial Officer and Director, have indicated that they are likely to purchase shares under the ATM in the near term, but they have not indicated the number of shares they intend to purchase nor have they made any formal binding commitments to do so. Any purchases of shares by these individuals would be at the prevailing market bid price or better.