Summit Therapeutics plc
(“Summit Therapeutics” or the “Company”)

Notification of Transactions of Persons Discharging Managerial Responsibilities

Oxford, UK, and Cambridge, MA, US, 15 January 2020 – Summit Therapeutics (AIM: SUMM, NASDAQ: SMMT), a leader in antibiotic innovation, announces that it has received notification that on 14 January 2020, Mr Robert W. Duggan, a Non-Executive Director of the Company, sold a total of 33,321,870 ordinary shares and transferred a total of 4,998,279 warrants to various trusts as detailed below.

Name of Trust	Number of Ordinary Shares Sold	Sale Price per Ordinary Share*	Number of Warrants Transferred
Daniel Douglas Duggan Trust	1,753,780	22.1 pence	263,067
Dante Eon Duggan Trust	1,753,780	22.1 pence	263,067
David Michael Duggan Trust	1,753,780	22.1 pence	263,067
Diamond Augustus Duggan Trust	1,753,780	22.1 pence	263,067
Diana Star Duggan Trust	1,753,780	22.1 pence	263,067
Dsara Ann Duggan Trust	1,753,780	22.1 pence	263,067
Dylan Duke Duggan Trust	1,753,780	22.1 pence	263,067
Mahkam Zanganeh Revocable Trust	10,522,705	22.1 pence	1,578,405
Shaun Zanganeh Irrevocable Trust	10,522,705	22.1 pence	1,578,405
Total	33,321,870		4,998,279

* The sale price per ordinary share has been converted from US Dollars at an exchange rate of $1.2900 to £1.00.

Following the completion of these dealings, Mr Duggan has the following interest in the Company’s ordinary shares and warrants, respectively:

		Shareholding	% of Issued Share Capital	Warrants
Robert W. Duggan	Non-Executive Director	211,123,385	62.85%	19,925,276

This announcement contains inside information for the purposes of Article 7 of EU Regulation 596/2014. The person responsible for arranging for the release of this announcement on behalf of the Company is Richard Pye, Vice President, Investor Relations and Corporate Affairs.

About Summit Therapeutics
Summit Therapeutics is a leader in antibiotic innovation. Our new mechanism antibiotics are designed to become the new standards of care for the benefit of patients and create value for payors and healthcare providers. We are currently developing new mechanism antibiotics to treat infections caused by C. difficile, N. gonorrhoeae and Enterobacteriaceae and are using our proprietary Discuva Platform to expand our pipeline. For more information, visit www.summitplc.com and follow us on Twitter @summitplc.

For more information, please contact:

Summit
Glyn Edwards / Richard Pye (UK office)	Tel:	44 (0)1235 443 951
Michelle Avery (US office)		+1 617 225 4455
Cairn Financial Advisers LLP (Nominated Adviser)	Tel:	+44 (0)20 7213 0880
Liam Murray / Tony Rawlinson / Ludovico Lazzaretti
N+1 Singer (Joint Broker)	Tel:	+44 (0)20 7496 3000
Aubrey Powell / George Tzimas, Corporate Finance Tom Salvesen, Corporate Broking
Bryan Garnier & Co Limited (Joint Broker)	Tel:	+44 (0)20 7332 2500
Phil Walker / Dominic Wilson
MSL Group (US)	Tel:	+1 781 684 6552
Erin Anthoine		summit@mslgroup.com
Consilium Strategic Communications (UK)	Tel:	+44 (0)20 3709 5700
Mary-Jane Elliott / Sue Stuart / Sukaina Virji / Lindsey Neville		summit@consilium-comms.com

The information set out below is provided in accordance with the requirements of Article 19(3) of the Market Abuse Regulation (EU) No 596/2014.

1	Details of the persons discharging managerial responsibilities/person closely associated
a)	Name	(i)  Robert W. Duggan
2	Reason for the notification
a)	Position / status	(i)  Non-Executive Director
b)	Initial notification / Amendment	Initial notification
3	Details of the issuer, emission allowance market participant, auction platform, auctioneer or auction monitor
a)	Name	Summit Therapeutics plc
b)	LEI	213800NRW8AOMYMTBD89
4	Details of the transaction(s): section to be repeated for (i) each type of instrument; (ii) each type of transaction; (iii) each date; and (iv) each place where transactions have been conducted
a)	Description of the financial instrument, type of instrument	Ordinary shares of 1 penny each
	Identification code	GB00BN40HZ01
b)	Nature of the transactions	Sale of ordinary shares of one penny nominal value
c)	Price(s) and volume(s)		Price(s)	Volume(s)
			(i) 22.1p (exercise price)	(i)  33,321,870
d)	Aggregated information   – Aggregated volume   – Price	33,321,870 ordinary shares   22.1 pence
e)	Date of the transactions	14 January 2020
f)	Place of the transactions	Outside a trading venue

1	Details of the persons discharging managerial responsibilities/person closely associated
a)	Name	(ii)  Robert W. Duggan
2	Reason for the notification
a)	Position / status	(ii)  Non-Executive Director
b)	Initial notification / Amendment	Initial notification
3	Details of the issuer, emission allowance market participant, auction platform, auctioneer or auction monitor
a)	Name	Summit Therapeutics plc
b)	LEI	213800NRW8AOMYMTBD89
4	Details of the transaction(s): section to be repeated for (i) each type of instrument; (ii) each type of transaction; (iii) each date; and (iv) each place where transactions have been conducted
a)	Description of the financial instrument, type of instrument	Ordinary shares of 1 penny each
	Identification code	GB00BN40HZ01
b)	Nature of the transactions	Transfer of warrants to subscribe for ordinary shares of one penny nominal value
c)	Price(s) and volume(s)		Price(s)	Volume(s)
			(i) n/a	(ii)  4,998,279
d)	Aggregated information   – Aggregated volume   – Price	4,998,279 warrants to subscribe for ordinary shares   n/a
e)	Date of the transactions	14 January 2020
f)	Place of the transactions	Outside a trading venue

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