Holding(s) in Company

TR-1: Standard form for notification of major holdings

NOTIFICATION OF MAJOR HOLDINGS (to be sent to the relevant issuer and to the FCA in Microsoft Word format if possible)i
1a. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attachedii:			Summit Therapeutics PLC Sedol BN40HZ0
1b. Please indicate if the issuer is a non-UK issuer  (please mark with an “X” if appropriate)
Non-UK issuer
2. Reason for the notification (please mark the appropriate box or boxes with an “X”)
An acquisition or disposal of voting rights						X
An acquisition or disposal of financial instruments
An event changing the breakdown of voting rights
Other (please specify)iii:
3. Details of person subject to the notification obligationiv
Name
City and country of registered office (if applicable)
4. Full name of shareholder(s) (if different from 3.)v
Name			Robert W. Duggan
City and country of registered office (if applicable)
5. Date on which the threshold was crossed or reachedvi:			14/01/2020
6. Date on which issuer notified (DD/MM/YYYY):			17/01//2020
7. Total positions of person(s) subject to the notification obligation
	% of voting rights attached to shares (total of 8. A)	% of voting rights through financial instruments (total of 8.B 1 + 8.B 2)		Total of both in % (8.A + 8.B)	Total number of voting rights of issuervii
Resulting situation on the date on which threshold was crossed or reached	39.55%	23.31%		62.86%	335,873,208
Position of previous notification (if applicable)	49.47%	23.31%		72.78%