Sec Form 3 Filing - Stefanov Ventzislav @ Summit Therapeutics Inc. - 2020-09-18

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Stefanov Ventzislav 2. Issuer Name and Ticker or Trading Symbol Summit Therapeutics Inc. [ SMMT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) See Remarks (Last) (First) (Middle) C/O SUMMIT THERAPEUTICS INC.,, ONE BROADWAY, 14TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/18/2020 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 14,900 ( 1 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (right to buy) $ 1.37 ( 2 ) 12/23/2029 Common Stock 200,000 D Stock Option (right to buy) $ 3.3 ( 3 ) 05/01/2030 Common Stock 1,000,000 D Stock Option (right to buy) $ 3.3 ( 4 ) 05/01/2030 Common Stock 27,273 D Stock Option (right to buy) $ 3.31 ( 5 ) 07/08/2030 Common Stock 200,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Stefanov Ventzislav C/O SUMMIT THERAPEUTICS INC., ONE BROADWAY, 14TH FLOOR CAMBRIDGE, MA02142 X See Remarks Signatures /s/ Michael Paul Donaldson, Attorney-in-Fact 09/18/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Reflects the beneficial ownership of the reporting person following the succession pursuant to Rule 12g-3(a) of the Securities Exchange Act of 1934, as amended, of Summit Therapeutics Inc., a Delaware corporation ("New Summit") to the attributes of Summit Therapeutics plc, a public limited company incorporated in England and Wales ("Old Summit"), the predecessor issuer. The succession occurred following the effectiveness, on September 18, 2020, of a United Kingdom court-approved scheme of arrangement in which every five ordinary shares, 0.01 pound sterling par value per share, of Old Summit were exchanged for one share of common stock, $0.01 par value per share, of New Summit, which resulted in New Summit becoming the holding company of Old Summit and its subsidiaries. ( 2 )The option was granted on December 23, 2019. The shares underlying the option are scheduled to vest in four equal annual installments with the first installment occurring on the one year anniversary of the grant date, or sooner on the happening of certain corporate events reflecting the achievement of the company's long-term objectives. ( 3 )The option was granted on May 1, 2020. The shares underlying the option are scheduled to vest quarterly over a four year period subject to the satisfaction of certain performance targets. ( 4 )The option was granted on May 1, 2020. The shares underlying the option are scheduled to vest in full on May 1, 2021. ( 5 )The option was granted on July 8, 2020. The shares underlying the option are scheduled to vest in four equal annual installments with the first installment occurring on the one year anniversary of the grant date subject to the satisfaction of certain performance targets.

Remarks: Executive Vice President and President of DiscuvaExhibit List: Exhibit 24 - Power of Attorney

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