Summit Therapeutics plc, a drug discovery and development company advancing therapies for Duchenne muscular dystrophy and Clostridium difficile infection (CDI), announced that the European Patent Office (EPO) has granted a key patent covering the novel antibiotic, ridinilazole, and that the opposition period has expired with the patent having faced no challenge. The patent covers the use of ridinilazole for the treatment of infections caused by the bacterium Clostridium difficile.

“This is a key patent protecting the use of ridinilazole for the treatment of CDI and its grant and emergence from the period of opposition means this patent is now effective in Europe, in addition to the other major commercial markets including the United States and Japan,” commented Glyn Edwards, chief executive officer of Summit. “The robust patent portfolio for ridinilazole, together with the strong phase 2 clinical data showing statistical superiority over vancomycin, the current standard of care, further strengthens the potential commercial value of this novel product candidate in the treatment of CDI.”

The patent (European patent number EP2373631) is entitled “Antibacterial Compounds” and will provide a period of exclusivity for the use of ridinilazole in the treatment of CDI through until December 1, 2029, with the possibility of patent term extension through to June 1, 2035 subject to the obtaining of Supplementary Protection Certificates and a paediatric investigation plan on marketing approval. The patent has also been validated in all available contracting countries to the European Patent Convention, and so is now in force in over 30 European states including the United Kingdom, Germany, France, Spain, Italy, Switzerland and Norway. Patent protection has previously been granted for ridinilazole for the treatment of CDI in other countries including the United States, Australia, New Zealand, Japan, Russia and China, in addition to other territories.

Ridinilazole is a novel class small molecule antibiotic that Summit is developing for the treatment of CDI. Top-line results from a Phase 2 proof of concept trial reported in late 2015 showed that ridinilazole was statistically superior to vancomycin, the current standard of care, in the endpoint of sustained clinical response (SCR). SCR was measured as cure at the end of treatment and no recurrence of CDI within 30 days of the end of treatment.

C. difficile infection is a serious healthcare threat in hospitals, long-term care homes and increasingly the wider community with between 450,000 and 700,000 cases of CDI in the US annually. It is caused by an infection of the colon by the bacterium 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 predominantly broad spectrum antibiotics, and these cause further damage to the gut flora and are associated with high rates of recurrent disease. Recurrent disease 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.