Summit Outlines Clinical Development Plans for Utrophin Modulator Programme for Duchenne Muscular Dystrophy

Summit Corporation plc

(‘Summit’ or ‘the Company’)

SUMMIT OUTLINES CLINICAL DEVELOPMENT PLANS FOR UTROPHIN MODULATOR PROGRAMME FOR DUCHENNE MUSCULAR DYSTROPHY

• First patient clinical trials of SMT C1100 expected to start H2 2013
• Summit to showcase programme at international scientific conference

Oxford, UK, 21 March 2013 – Summit (AIM: SUMM), a drug discovery and development company advancing therapies for Duchenne Muscular Dystrophy (‘DMD’) and C. difficile infections, today outlines its future plans for the continued development of utrophin modulators for the treatment of DMD. Utrophin modulation is a disease modifying approach that has the potential to treat all genetic forms of DMD. Summit’s programme includes the lead candidate SMT C1100 that is expected to enter clinical trials in patients during H2 2013, and earlier-stage next generation utrophin modulators that are being developed to add further value to the programme. Summit is presenting its utrophin modulator programme at a major international conference being held later this Spring.

“Summit has a unique opportunity to develop a high-value franchise in utrophin modulation, an innovative therapeutic approach for DMD that targets all genetic forms of this devastating disease,” commented Glyn Edwards, Chief Executive Officer of Summit. “These clinical trials will be the first to evaluate utrophin modulation in patients, and they aim to quickly establish clinical proof of concept for SMT C1100 through the use of novel biomarkers developed to measure aspects of muscle health. The biomarker work, to be conducted side by side with our clinical development programme, will strengthen our DMD franchise and will enhance the commercial value of this asset.”

The proposed proof of concept patient trial will include two components: a dose-finding study in DMD patients to confirm translation of safety, tolerability and pharmacokinetics from an adult to a paediatric population, followed by a Phase 2 trial that will include clinical markers of muscle health as well as levels of utrophin expression and other novel biomarkers. The biomarker programme has commenced and includes the collaboration with Children’s National Medical Center of Washington DC, funded by the DMD organisation, The Foundation to Eradicate Duchenne, which was announced by Summit in February 2013. Summit is now engaged with the regulatory authorities and expects the dose finding study to start in H2 2013.

In preparation for the clinical studies, drug material manufacture and long-term regulatory toxicology studies will be commissioned. Summit has selected a specialist contractor capable of manufacturing and formulating GMP grade drug material for use in the long-term toxicology studies, the patient proof of concept trials, and ultimately any potential future registration trials and market use.

The Company will present its utrophin modulation programme and biomarker development at the Muscular Dystrophy Association Scientific Conference, 21-24 April 2013, Washington DC, US. A copy of the presentation will be made available on the Company website at that time.

About DMD and Utrophin Modulation

DMD is caused by genetic mutations that prevent patients from making the structural protein dystrophin, which leads to progressive muscle wasting and is ultimately fatal. Summit is pioneering utrophin modulation to stimulate production of utrophin, a functionally similar protein to dystrophin that is expressed in foetal and regenerating muscle, and which has the potential to restore and maintain healthy muscle function. This disease modifying approach would target all genetic forms of DMD. SMT C1100 is the Company’s leading utrophin modulator drug and it has successfully completed a Phase 1 healthy volunteer clinical trial in late 2012.

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