X0609 4 2026-06-12 0 0001599298 Summit Therapeutics Inc. SMMT 0001055919 DUGGAN ROBERT W false C/O SUMMIT THERAPEUTICS INC. 601 BRICKELL KEY DRIVE SUITE 1000 MIAMI FL 33131 1 1 1 0 Co-Chief Executive Officer 0 Common Stock 2026-06-12 4 P 0 3810000 13.12 A 573883879 D Common Stock 25824474 I By the Mahkam Zanganeh Revocable Trust, with the Spouse of Reporting Person as Trustee Common Stock 76680 I Immediate family member of Spouse Common Stock 31000 I By Spouse Common Stock 10199776 I By the Shaun Zanganeh Irrevocable Trust, with the Spouse of Reporting Person as Trustee The Reporting Person disclaims beneficial ownership of these securities, except to the extent of his pecuniary interest therein, if any, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the reported securities for purposes of Section 16 or for any other purpose. /s/ Robert W. Duggan 2026-06-12