Summit Therapeutics Presents Data From Phase I Clinical Programme Of Ezutromid At The EPNS Congress

Summit Therapeutics plc

(‘Summit’, or ‘the Company’)

SUMMIT PRESENTS DATA FROM PHASE 1 CLINICAL PROGRAMME OF EZUTROMID AT THE EUROPEAN PAEDIATRIC NEUROLOGY SOCIETY CONGRESS

Oxford, UK, 22 June 2017 - Summit Therapeutics plc (NASDAQ: SMMT, AIM: SUMM), the drug discovery and development company advancing therapies for Duchenne muscular dystrophy (‘DMD’) and Clostridium difficile infection, today announces the presentation of clinical data from two Phase 1 clinical trials of ezutromid, Summit’s lead utrophin modulator, at the European Paediatric Neurology Society Congress in Lyon, France. The oral presentation focussed on the Company’s positive efforts to improve absorption and increase exposure of ezutromid in patients with DMD, as evidenced by the results of both the modified diet and new formulation Phase 1 clinical trials. The presentation took place today, 22 June 2017, during the Neuromuscular Pathologies 2 session.

“Our Phase 1 clinical development programme has identified ways to improve the pharmacokinetic profile of ezutromid. Through both formulation development and dietary advice, ezutromid achieves exposures which we believe have the potential to sustain utrophin production in patients with DMD,” commented Dr David Roblin, President of R&D of Summit. “We are now utilising both methods in our ongoing Phase 2 clinical trial, PhaseOut DMD, where we have the chance to see the impact of ezutromid drug exposure on pharmacology, safety and efficacy with longer term dosing of patients with DMD.”

The presentation is available on the Publications page of Summit’s website, www.summitplc.com.

About Utrophin Modulation in DMD

DMD is a progressive muscle wasting disease that affects around 50,000 boys and young men in the developed world. The disease is caused by different genetic faults in the gene that encodes dystrophin, a protein that is essential for the healthy function of all muscles. There is currently no cure for DMD and life expectancy is into the late twenties. Utrophin protein is functionally and structurally similar to dystrophin. In preclinical studies, the continued expression of utrophin has a meaningful, positive effect on muscle performance. Summit believes that utrophin modulation has the potential to slow down or even stop the progression of DMD, regardless of the underlying dystrophin gene mutation. Summit also believes that utrophin modulation could potentially be complementary to other therapeutic approaches for DMD. The Company’s lead utrophin modulator, ezutromid, is an orally administered, small molecule. DMD is an orphan disease, and the US Food and Drug Administration (‘FDA’) and the European Medicines Agency have granted orphan drug status to ezutromid. Orphan drugs receive a number of benefits including additional regulatory support and a period of market exclusivity following approval. In addition, ezutromid has been granted Fast Track designation and Rare Pediatric Disease designation by the FDA.

About Summit Therapeutics

Summit is a biopharmaceutical company focused on the discovery, development and commercialisation of novel medicines for indications for which there are no existing or only inadequate therapies. Summit is conducting clinical programs focused on the genetic disease Duchenne muscular dystrophy and the infectious disease C. difficile infection. Further information is available at www.summitplc.com and Summit can be followed on Twitter (@summitplc).

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Forward-looking Statements

Any statements in this press release about Summit’s future expectations, plans and prospects, including but not limited to, statements about the clinical and preclinical development of Summit’s product candidates, the therapeutic potential of Summit’s product candidates, and the timing of initiation, completion and availability of data from clinical trials, and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” and similar expressions, constitute forward looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: the uncertainties inherent in the initiation of future clinical trials, availability and timing of data from on-going and future clinical trials and the results of such trials, whether preliminary results from a clinical trial will be predictive of the final results of that trial or whether results of early clinical trials or preclinical studies will be indicative of the results of later clinical trials, expectations for regulatory approvals, availability of funding sufficient for Summit’s foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the “Risk Factors” section of filings that Summit makes with the Securities and Exchange Commission including Summit’s Annual Report on Form 20-F for the fiscal year ended January 31, 2017. Accordingly, readers should not place undue reliance on forward looking statements or information. In addition, any forward-looking statements included in this press release represent Summit’s views only as of the date of this release and should not be relied upon as representing Summit’s views as of any subsequent date. Summit specifically disclaims any obligation to update any forward-looking statements included in this press release.

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