Annual General Meeting

18 July 2012

www.summitplc.com2 | Annual General Meeting | 18 July 2012

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FORWARD-LOOKING STATEMENTS

This Document contains forward-looking statements. These statements relate to, among other things, analysis and other information that are based on forecasts of future results and estimates of amounts not yet determinable. These statements also relate to the Company’s future prospects, developments and business strategies. Forward-looking statements are identified by their use of terms and phrases such as “believe”, “could”, “envisage”, “estimate”, “expect”, “intend”, “may”, “plan”, “will” or the negative of those, variations or comparable expressions, including references to assumptions. The forward-looking statements in this Document are based on current expectations and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by those statements. Given the risks and uncertainties associated with a company of this nature, potential investors should not place reliance on forward-looking statements. These forward-looking statements speak only as at the date of this Document. The Company does not undertake any obligation to update forward-looking statements or risk factors other than as required by any relevant regulations, whether as a result of newinformation, future events or otherwise.

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Focus on Key Programmes

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• Immediate priority is the development of leading programmes through to important development milestone over the next 12 months

SMT 19969Clostridium difficile Infection

SMT C1100Duchenne Muscular Dystrophy

TauopathiesAlzheimer’s disease & other rare dementias

www.summitplc.com4 | Annual General Meeting | 18 July 2012

Utrophin

upregulator

•Dystrophin replaced with naturally occurring protein called utrophin

•Restores and maintains healthy muscle function in non-clinical efficacy studies

Competitive

advantage

•Only disease modifying drug candidate in clinical trials to benefit all patients

•Oral administration

De-risked

development

•$1.5m agreement with US organisations to fund Phase I clinical trial

• Independent due diligence endorses scientific approach

Orphan

drug•Designated as orphan drug status in Europe and the US

Status•Phase I trial initiated in May 2012

•Results expected by the end of 2012

Disease modifying drug with >$1bn p.a. sales potential

SMT C1100Duchenne Muscular Dystrophy

www.summitplc.com

► Phase 1 ready antibiotic programme for the treatment of CDI

► Front-line treatment for initial infection & prevention of recurrent disease

► Excellent profile in all key differentiating areas:

Summary Profile SMT19969 Comments

Potent C. difficile growth inhibitor ���� Active against all ribotypes

Extremely narrow spectrum of activity ���� No impact on human gut flora

Very low propensity for resistance development ���� Extends clinical utility

Oral delivery ���� Twice daily dosing likely

Retained in GI tract ���� No systemic exposure

Excellent safety profile ���� No in vivo toxicity issues

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► Phase I human trials expected to start in H2 2012

SMT 19969Clostridium difficile Infection

www.summitplc.com

• Neurodegenerative diseases characterised by the formation in the brain of neurofibrillary tangles

• Inhibition of the enzyme OGA has emerged as a drug target by preventing formation of the NFTs through reduction in tau phosphorylation

• Summit is developing potent, selective OGA inhibitors using Seglin™ technology

• Encouraging in vivo and in vitro data shows:

– In vitro efficacy in human cell disease models

– Able to penetrate through the blood brain barrier into the central nervous system

– Reduction in tau phosphorylation in in vivo studies

• Further development and evaluation of OGA inhibitors on-going to establish in vivo

proof of concept and identify a lead candidate

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TauopathiesAlzheimer’s disease & other rare dementias

www.summitplc.com

Outlook

• Opportunity to achieve key development milestones in lead programmes within the next 12 months

– Completion of Phase I trial in DMD

– Completion of Phase I clinical trial in C. difficile programme

– Advance OGA / tauopathies programme through to in vivo proof of concept

• Achieving these milestones is expected to act as a catalyst for realising the value of programme assets through a commercial deal

• Potential for significant near-term value growth from current market cap

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