Summit Therapeutics Inc. (NASDAQ:SMMT) today announced it has signed an agreement with Toronto-based Biossil, Inc. for the sale of ridinilazole, an investigational Phase III precision antibiotic owned by Summit. Biossil is an artificial intelligence (AI)-native biopharma company focused on advancing late-stage programs in life-threatening indications with urgent unmet medical needs.

Previously, ridinilazole was evaluated in Summit’s Phase III Ri-CoDIFy study for the treatment of patients suffering from C. difficile infection (C. diff. infection or CDI), an area of high unmet need. The study showed that ridinilazole resulted in a higher observed Sustained Clinical Response (SCR) rate than vancomycin but did not meet the study’s primary endpoint for superiority within the established time boundaries. SCR is defined as Clinical Response of the treated episode of CDI and no recurrence of the infection through 30 days after the end of treatment. These results were announced by Summit in December 2021 and subsequently published in the journal Clinical Infectious Diseases.1 Ri-CoDIFy, as well as earlier-stage clinical studies of ridinilazole, demonstrated its ability to spare the gut microbiome compared to vancomycin, the standard of care in C. difficile infection, which is believed to impact recurrence of the disease. The gut microbiome and its homeostasis have been linked to overall quality of human health across several recent studies.