March 2016 Dear Shareholder, Notification to shareholders regarding parent company financial statements: Adoption of Financial Reporting Standard ( FRS ) 101 Reduced Disclosure Framework The financial statements for the

Notification to shareholders regarding

parent company financial statements:

Adoption of Financial Reporting Standard ( FRS ) 101 Reduced Disclosure Framework

The financial statements for the year ended 31 January 2015 of the individual entity, Summit Therapeutics plc (the Company ), as set out on

pages 52 to 56 of the 2014/15 Annual Report and Accounts, were prepared in accordance with UK Generally Accepted Accounting Practice ( UK GAAP ).

A new UK GAAP accounting framework introduced by the Financial Reporting Council ( FRC ) became mandatorily effective for the financial statements

of UK companies in 2015. Under this new framework, the Company is required to prepare its parent company financial statements for its financial year ended 31 January 2016 on one of the new bases permitted by the FRC.

The Company therefore proposes to adopt FRS 101 Reduced Disclosure Framework, based on International Financial Reporting Standards

( IFRS ) as endorsed by the European Union and as issued by the International Accounting Standards Board ( IASB ). As a result of utilising possible disclosure exemptions permitted under FRS 101, disclosures are expected to be

the same as, or follow closely, those reported under current UK GAAP.

The Company s decision to adopt FRS 101 does not require shareholder approval.

However, due to the election to take advantage of the possible disclosure exemptions permitted under FRS 101, the Company is required to notify all shareholders of this election and any shareholder or shareholders holding in aggregate 5% or more of

the total allotted shares in the Company may object. Objections must be served in writing and delivered to Melissa Strange, the Company Secretary, at the Company s registered office (85b Park Drive, Milton Park, Abingdon, OX14 4RY) not later

This notification will apply on an ongoing basis until such time as the Company notifies its shareholders of any change to its

chosen accounting framework for the parent company financial statements.

The consolidated financial statements of the Group will continue to be prepared

in accordance with IFRS as endorsed by the European Union and as issued by the IASB, and are unaffected by this new accounting framework.

information, please contact Summit Therapeutics plc (+44 (0)1235 443939).