Ridinilazole Shows Superior Efficacy for Treatment of C. diff in Phase 2 Study

Dr. Richard Vickers, chief scientific officer of R&D at Summit Therapeutics, discusses how ridinilazole showed superior efficacy for the treatment of C. diff when compared with vancomycin in a phase 2 study.

Interview Transcript (modified slightly for readability):

“We have recently completed a phase 2 proof-of-concept clinical trial in Clostridium difficile infection (CDI); this was the CoDiFY study, and we recently published this in the Lancet Infectious Diseases. I encourage you to go and look at the data in more detail, but this was a 100-patient study run in North America and Canada, a two-arm study comparing ridinilazole with vancomycin, which is probably our accepted standard of care.

The primary endpoint for the study was sustained clinical response and this is an endpoint that’s becoming very well-established in the field of C. diff clinical trials; it is defined as cure at the end of therapy and no recurrence in the 30 days post end of therapy. And so, it’s a really neat endpoint; it captures the course of the disease, the initial infection, and addresses if we see a recurrence in that high-risk 30-day window after we’ve completed treatment. It really tells you if you’ve got a drug that treats CDI and reduces the recurrence of CDI.

The data that we generated was extremely encouraging. Around 67% of the ridinilazole-treated patients had a sustained clinical response, so they were cured with no recurrence, whereas only 42% of the vancomycin-treated patients had a sustained cure. That’s really an absolute difference of almost 25%, which is a very significant improvement and actually genuinely clinically meaningful in terms of minimizing recurrences. This is what we wanted to do; we want to have sustained clinical response, sustained cures for patients. What drove this improvement in sustained clinical response was the reduction in the rates of recurrent disease. Around 33%, of the vancomycin-treated patients who were cured at the end of therapy, went on to have a recurrence compared with only around 14% of the ridinilazole-treated patients—so a relative reduction of around 60% in rates of recurrent disease. We saw good cures and we reduced rates of recurrent disease, which is exactly what we’re aiming for with ridinilazole.”