News Summit Utrophin Update 29.03.2017 Please see below a synopsis of the clinical update from Summit Therapeutics Plc on their progress with the utrophin modulation program: PhaseOut DMD is a Phase 2 clinical trial evaluating ezutromid in patients with DMD. This 48-week open-label trial is ongoing in the UK and the US. Enrolment of approximately 40 patients continues, and we expect to complete trial enrolment in the second quarter of 2017. DMD is characterised by high levels of muscle degeneration caused by the absence of functional dystrophin. Muscle fibres consequently enter into a cycle of repair and degeneration that over time leads to fat infiltrating into muscle and loss of ambulation and other functional abilities. Ezutromid aims to maintain production of utrophin so that it can substitute for the missing dystrophin. This has potential to allow muscle fibres to mature and so reduce the level of muscle degeneration, reduce the rate of fat infiltration and reduce the rate of decline in functional abilities. PhaseOut DMD is assessing all of these factors through various techniques including use of muscle biopsy to evaluate utrophin distribution and muscle fibre regeneration and maturity; magnetic resonance imaging to measure fat infiltration; and various functional tests including the North Star Ambulatory Assessment and the six minute walk test. We expect to report the analysis of 24-week biopsy data for all patients providing a 24-week biopsy sample in PhaseOut DMD in the first quarter of 2018, in lieu of reporting an earlier interim 24-week biopsy analysis from a subset of these patients in 2017. In addition, at the time we report the full 24-week biopsy data, we expect to announce the 24-week analysis of MRI and functional data from all patients in the trial. We believe that this revised approach of analyzing the full 24-week dataset will provide a more complete picture of ezutromid’s potential by evaluating a larger number of patients. Recently, we applied to the MHRA and FDA regulatory authorities to proceed with the planned extension of PhaseOut DMD for patients currently enrolled in the trial. The applications followed support for our plan from the trial’s independent Data Monitoring Committee upon an interim review of the safety and tolerability data from the ongoing trial. The extension phase is expected to last until ezutromid either receives marketing approval in relevant countries or its development is discontinued. In addition to PhaseOut DMD, we plan to conduct a randomised, placebo controlled trial designed with the potential to support accelerated and conditional approvals for ezutromid in the US and Europe, respectively. It is anticipated that this trial would start after positive interim data from PhaseOut DMD, and we would plan to provide timing guidance following the release of the 24-week dataset. Summit Therapeutics Plc is registered in England and Wales, Company number 05197494. Registered address 85b Park Drive, Milton Park, Abingdon, Oxfordshire. UK. OX14 4RY. The VAT registration number is 876 331 407.