Summit Therapeutics plc : Holding(s) in Company

For filings with the FCA include the annex
For filings with issuer exclude the annex

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESⁱ

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached: ⁱⁱ		Summit Therapeutics PLC Sedol BN40HZ0
2 Reason for the notification (please tick the appropriate box or boxes):
An acquisition or disposal of voting rights
An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached
An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments
An event changing the breakdown of voting rights			x
Other (please specify):
3. Full name of person(s) subject to the notification obligation: ⁱⁱⁱ	¹Lansdowne Partners International Limited ²Lansdowne Partners Limited ³Lansdowne Partners (UK) LLP
4. Full name of shareholder(s) (if different from 3.):iv	HSBC Client Holdings Nominee (UK) Ltd, HSBC Bank Plc Lansdowne Markets (Registered Shareholders)
5. Date of the transaction and date on which the threshold is crossed or reached: ^v	20/03/2015
6. Date on which issuer notified:	26/03/2015
7. Threshold(s) that is/are crossed or reached: ^{vi, vii}	26%

8. Notified details:

A: Voting rights attached to shares ^{viii, ix}

Class/type of
shares

if possible using
the ISIN CODE

Situation previous
to the triggering
transaction

Resulting situation after the triggering transaction

Number
of
Shares

Number
of
Voting
Rights

Number
of shares

Number of voting
rights

% of voting rights ^x

Direct

Direct ^xi

Indirect ^xii

Direct

Indirect

Ordinary Shares

11,077,170

18.17%

GB00BN40HZ01

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial
instrument

Expiration
date ^xiii

Exercise/
Conversion Period ^xiv

Number of voting
rights that may be
acquired if the
instrument is
exercised/ converted.

% of voting
rights

American Depositary Shares (ADS)

N/A

4,650,000

7.63%

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments ^{xv, xvi}

Resulting situation after the triggering transaction

Type of financial
instrument

Exercise price

Expiration date ^xvii

Exercise/
Conversion period ^xviii

Number of voting rights instrument refers to

% of voting rights ^{xix, xx}

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

15,727,170

25.80%

9. Chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held, if applicable: ^xxi
Lansdowne Partners International Limited is the parent undertaking of Lansdowne Partners Limited which is the First Corporate Member of Lansdowne Partners (UK) LLP

Proxy Voting:
10. Name of the proxy holder:
11. Number of voting rights proxy holder will cease to hold:
12. Date on which proxy holder will cease to hold voting rights:

13. Additional information:	Based on total voting rights of 60,955,197
14. Contact name:	Ruari Paton
15. Contact telephone number:	+44 020 7290 5500