REPEAT DOSING OF SMT C1100 FOR TREATMENT OF DUCHENNE MUSCULAR DYSTROPHY MEETS ENDPOINTS IN PHASE 1 CLINICAL TRIAL

•  New formulation delivers drug levels that are predicted to significantly increase utrophin production
•  Summit to progress utrophin upregulator into next stages of development

Oxford, UK, 7 November 2012

– Summit (AIM: SUMM), a UK drug discovery company, announces that the repeat dosing of the utrophin upregulator SMT C1100 for the treatment of the fatal muscle-wasting disease Duchenne Muscular Dystrophy (‘DMD’) has successfully met the endpoints as part of a Phase 1 clinical trial in healthy volunteers. The trial evaluated a new formulation of SMT C1100 and the results showed that upon repeat dosing, concentrations of the drug achieved in the blood plasma, stabilised at levels that from preclinical studies are expected to significantly increase utrophin protein production. The new formulation was also shown to be safe and well-tolerated in this Phase 1 trial.

SMT C1100 is a potential disease-modifying, oral small-molecule that works by upregulating (increasing) the amount of a naturally occurring protein called utrophin to maintain the healthy function of muscles. These data strongly support the progression of SMT C1100 into the next stages of development that includes biomarker and long-term safety studies, which will be required before a DMD patient efficacy trial could commence. The latest results will be presented at the 2012 Action Duchenne Conference, 9-10 November, London UK.

“Utrophin upregulation is a unique approach for treating DMD because it could benefit all DMD patients, regardless of their underlying genetic fault,”

commented Glyn Edwards, Chief Executive Officer of Summit. “We are highly encouraged by these results, as the new formulation achieves blood concentrations that have the potential to significantly increase utrophin levels, with the outcome of maintaining the healthy function of muscles in patients with DMD. The results therefore strongly support continuing clinical evaluation of SMT C1100.”

The double blind, placebo-controlled Phase 1 trial examined a new nanoparticle aqueous suspension of SMT C1100 in a total of 48 healthy volunteers. The previously reported results from the single ascending dose cohort showed SMT C1100 to be safe and well-tolerated at all doses. These new data are being reported from the repeat dosing cohort where the volunteers received 100mg/kg twice daily for nine days. These results show that in all volunteers the blood plasma concentration of SMT C1100 stabilised after four days of dosing above the required level expected to increase utrophin protein production by 50% for at least 14 hours a day in a preclinical model. The plasma levels achieved were equivalent to those that gave significant therapeutic benefit in the gold standard disease model of DMD.

A copy of the presentation being given at the Action Duchenne conference will be available on

Summit’s website after the event.

The Phase 1 trial has received funding from a group of US DMD foundations: the Muscular Dystrophy Association, Charley’s Fund, Cure Duchenne, the Foundation to Eradicate Duchenne, Nash Avery Foundation and Parent Project Muscular Dystrophy.

About SMT C1100 & Utrophin Upregulation

SMT C1100 is designed to upregulate and maintain the production of utrophin. Utrophin is a protein that is highly expressed in foetal and regenerating muscle but decreases as the muscle fibre mature and is eventually replaced by dystrophin, a similar protein that maintains the integrity and healthy function of muscles. Patients with DMD are unable to make dystrophin, resulting in muscle fibre

degeneration. However, if utrophin is continually expressed in the mature fibre, it can functionally replace dystrophin and is expected to overcome the deficit in patients with DMD. This approach is expected to be a universal treatment for all DMD patients regardless of whether the disease was caused by an inherited or spontaneous mutation. Summit has demonstrated in non-clinical efficacy studies that SMT C1100 is capable of switching utrophin production back-on to restore and maintain the healthy function of muscles including the heart and diaphragm. SMT C1100 has been granted orphan drug status in Europe and the US.

About Summit

Summit is an Oxford, UK based drug discovery and development company targeting high-value areas of unmet medical need including Duchenne Muscular Dystrophy and

C. difficile infection. Summit is listed on the AIM market of the London Stock Exchange and trades under the ticker symbol SUMM. Further information is available at www.summitplc.com and follow Summit on Twitter (@summitplc).

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