Summit Highlights Microbiome Preservation During Ridinilazole Treatment in Exploratory Phase 2 Clinical Trial at ID Week 2017

OXFORD, United Kingdom, Oct. 09, 2017 (GLOBE NEWSWIRE) -- Summit Therapeutics plc (NASDAQ:SMMT) (AIM:SUMM), the drug discovery and development company advancing therapies for Duchenne muscular dystrophy and Clostridium difficile infection (‘CDI’), announces that at ID Week 2017, it presented further positive gut microbiome data of ridinilazole from its exploratory Phase 2 clinical trial. As was previously reported, the Company’s novel and highly selective antibiotic, ridinilazole, was more preserving of patients’ gut microbiomes during a ten-day treatment period of the Phase 2 clinical trial than the marketed narrow-spectrum antibiotic, fidaxomicin.

“The impressive level of microbiome detail afforded by our clinical analyses shows the low impact of ridinilazole treatment on the gut microbiomes of patients while they are being treated for CDI,” said Dr David Roblin, Chief Medical and Operating Officer of Summit. “We believe ridinilazole is a precision antibiotic that combines low impact on the gut microbiome with high potency in killing C. difficile and that, with this profile, and its consequent potential to reduce recurrent disease, it could become a future front-line treatment option in CDI.”

Ridinilazole’s antimicrobial activity was limited to two bacterial families, one including C. difficile and the other a closely related family. Fidaxomicin reduced the abundancy of these families as well, but also reduced the abundancy of additional bacterial families, including reductions to bacteria belonging to the Firmicutes phylum that are thought to have direct functional roles in protecting against CDI. Another important measure of microbiome health is alpha-diversity. In this measure, ridinilazole treatment resulted in no loss in median alpha diversity, whereas fidaxomicin treatment was associated with loss of alpha diversity during dosing.

The poster, “Preservation of Gut Microbiome Following Ridinilazole versus Fidaxomicin Treatment of Clostridium difficile Infection,” was authored by S. Mitra, C. Chilton, J. Freeman, M. Taylor, P. Quirke, H. Wood and MH Wilcox of Leeds Teaching Hospitals and RJ Vickers of Summit. It is available for download on the Publications page of Summit’s website, www.summitplc.com.

About C. difficile Infection

C. difficile infection is a serious healthcare threat in hospitals, long-term care homes and increasingly the wider community with over one million estimated cases of CDI each year in the United States and Europe. It is caused by an infection of the colon by the bacterium C. difficile, which produces toxins that cause inflammation and 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 predominantly broad spectrum antibiotics, and these cause further damage to the gut flora and are associated with high rates of recurrent disease. Reducing disease recurrence is the key clinical issue in CDI 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 the Exploratory Phase 2 Clinical Trial

The exploratory open-label Phase 2 clinical trial enrolled 27 patients aged between 18 and 90 years at trial sites in the US, the UK and the Czech Republic. Patients were randomly assigned to receive either ridinilazole (200mg, twice a day) or fidaxomicin (200mg, twice a day) for ten days.

About Ridinilazole

Ridinilazole is a small molecule antibiotic that Summit is developing for the treatment of CDI. In preclinical efficacy studies, ridinilazole exhibited a targeted spectrum of activity that combined a potent bactericidal effect against all clinical isolates of C. difficile tested with minimal impact on other bacteria that are typically found in the gut microbiome. In a Phase 2 proof of concept trial in CDI patients, ridinilazole showed statistical superiority in sustained clinical response ('SCR') rates compared to the standard of care, vancomycin. In that trial, SCR was defined as clinical cure at end of treatment and no recurrence of CDI within 30 days of the end of therapy. Ridinilazole was also shown to be highly preserving of the gut microbiome in the Phase 2 proof of concept trial, which was believed to be the reason for the improved clinical outcome for the ridinilazole-treated patients. In addition, ridinilazole preserved the gut microbiome to a greater extent than the marketed narrow-spectrum antibiotic fidaxomicin in an exploratory Phase 2 clinical trial. Ridinilazole, an orally administered small molecule, has received Qualified Infectious Disease Product ('QIDP') designation and has been granted Fast Track designation by the US Food and Drug Administration. The QIDP incentives are provided through the US GAIN Act and include an extension of marketing exclusivity for an additional five years upon FDA approval.

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
Any statements in this press release about Summit’s future expectations, plans and prospects, including but not limited to, statements about the clinical and preclinical development of Summit’s product candidates, the therapeutic potential of Summit’s product candidates, and the timing of initiation, completion and availability of data from clinical trials, and other statements containing the words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "would," and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: the uncertainties inherent in the initiation of future clinical trials, availability and timing of data from on-going and future clinical trials and the results of such trials, whether preliminary results from a clinical trial will be predictive of the final results of that trial or whether results of early clinical trials or preclinical studies will be indicative of the results of later clinical trials, expectations for regulatory approvals, availability of funding sufficient for Summit’s foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the "Risk Factors" section of filings that Summit makes with the Securities and Exchange Commission, including Summit’s Annual Report on Form 20-F for the fiscal year ended January 31, 2017. Accordingly, readers should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this press release represent Summit’s views only as of the date of this release and should not be relied upon as representing Summit’s views as of any subsequent date. Summit specifically disclaims any obligation to update any forward-looking statements included in this press release.

This announcement contains inside information for the purposes of Article 7 of EU Regulation 596/2014 (MAR).

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