SMMT Summit Therapeutics Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of September 2020.

Commission File Number 001-36866

SUMMIT THERAPEUTICS PLC

(Translation of registrant’s name into English)

136a Eastern Avenue

Milton Park, Abingdon

Oxfordshire OX14 4SB

United Kingdom

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F  ☒                Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

On September 17, 2020, Summit Therapeutics plc (the “Company”) issued a press release announcing that the High Court of Justice in England and Wales has sanctioned the scheme of arrangement under Part 26 of the Companies Act 2006. The Scheme is expected to become effective, and therefore complete, on September 18, 2020. The full text of the related press release is attached hereto as Exhibit 99.1.

This Report on Form 6-K, including Exhibit 99.1, is hereby incorporated by reference into the Company’s Registration Statement on Form F-3 (File No. 333-232074).