Summit Therapeutics Presents New Positive Preclinical Data On Novel C. difficile Antibiotic SMT19969 At ICAAC 2015

OXFORD, United Kingdom, Sept. 18, 2015 (GLOBE NEWSWIRE) -- Summit (NASDAQ:SMMT) (AIM:SUMM), the drug discovery and development company advancing therapies for Duchenne Muscular Dystrophy and C. difficile infection ('CDI'), announces new preclinical data on SMT19969, a novel and selective oral antibiotic for the treatment of CDI, will be presented at the 55th Interscience Conference on Antimicrobial Agents and Chemotherapy ('ICAAC 2015') being held in San Diego, USA from September 17-21, 2015.

The data being presented are from preclinical in vitro studies that provide further evidence to support SMT19969's profile as a potential treatment for CDI and ability to reduce the high rates of recurrence currently associated with the disease. SMT19969 was shown to have high potency against 107 clinical isolates of C. difficile selected to maximise the diversity of their resistance to common classes of antibiotics, and SMT19969 also continues to display a low resistance development profile.

"These new data further illustrate the promise of SMT19969 as a differentiated antibiotic to treat CDI and, through its selective antibiotic profile, potential to leave the healthy gut microbiome unharmed, and so address the key clinical issue of disease recurrence," commented Glyn Edwards, Chief Executive Officer of Summit . "It is an exciting time in the development of SMT19969 as we look forward to reporting top-line data from our Phase 2 proof of concept trial during the fourth quarter of this year."

The results will be detailed in two poster presentations to be given by Summit's collaborators: Professor Mark Wilcox (Leeds Teaching Hospitals and University of Leeds, UK) and Dr Joseph Blondeau (Royal University Hospital and the University of Saskatchewan, Canada). The details of the presentations are as follows:

SMT19969 has good activity against prevalent Clostridium difficile ribotypes with varying antimicrobial resistance

J Freeman, J Vernon, R Vickers and M.H. Wilcox (Poster C-618)

This study assessed SMT19969 against 107 clinical isolates of C. difficile that had been selected to maximise the diversity of the isolates resistance to key classes of commonly used antibiotics. The results show that SMT19969 was highly active against all C. difficile clinical isolates, displayed superior potency against C. difficile isolates compared to vancomycin and metronidazole, and comparable potency to fidaxomicin. SMT19969 displayed no evidence of cross-resistance with other classes of antibiotics in routine clinical use.

Mutant Prevention Concentration values of SMT19969 against Clostridium difficile isolates using a modified microbroth dilution method

J.M. Blondeau, S Shebelski, R. Vickers (Poster D-212)

The study evaluated the mutant prevention concentration ('MPC') of SMT19969 to determine the drug concentration threshold that blocks the growth of the least susceptible cells present in bacterial populations. The results show that SMT19969 had low MPC values against clinical isolates of C. difficile and provide further evidence supporting its low resistance development profile.

Copies of the presentations given at ICAAC 2015 will be available from the 'Programmes' section of Summit's website, www.summitplc.com from 20 September 2015.

The development of SMT19969 is being supported by a Wellcome Trust Translational Award.

Notes to Editors

About C. difficile Infection

C. difficile infection is a serious healthcare threat in hospitals, long-term care homes and increasingly the wider community. It is a serious illness caused by infection of the colon by the bacteria C. difficile, which produces toxins that cause inflammation, severe diarrhoea and in the most serious cases can be fatal. Patients typically develop CDI following the use of broad-spectrum antibiotics that can cause widespread damage to the natural gastrointestinal (gut) flora and allow overgrowth of C. difficile bacteria. Existing CDI treatments are broad spectrum antibiotics and these cause further damage to the gut flora and are associated with high rates of recurrent disease. Disease recurrence is the key clinical issue as repeat episodes are typically more severe and associated with an increase in mortality rates and healthcare costs. The economic impact of CDI is significant with one study estimating annual acute care costs at $4.8 billion in the US.

About SMT19969

SMT19969 is an orally administered small molecule antibiotic that is being developed specifically for the treatment of CDI. Results from preclincial efficacy studies showed that SMT19969 displayed a potent bactericidal effect against all clinical isolates of C. difficile tested with high levels of antibacterial selectivity. A Phase 1 trial conducted in healthy volunteers showed SMT19969 to be well tolerated at all doses tested. In addition, SMT19969 was highly selective for total Clostridia whilst having a minimal impact on other bacterial groups comprising the gut flora. SMT19969 has received Qualified Infectious Disease Product designation ('QIDP') and Fast Track status from the US Food and Drug Administration.

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

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