Biopharmaceutical oncology company Summit Therapeutics Inc (NASDAQ:SMMT) on Tuesday announced an agreement to sell ridinilazole, an investigational Phase III precision antibiotic, to Toronto-based Biossil Inc, an AI-native biopharma company focused on late-stage programs for life-threatening conditions.

The transaction includes a USD500,000 upfront payment, up to USD104.5m in regulatory and commercial milestones, and tiered royalties on net sales.

Ridinilazole was previously evaluated in Summit's Phase III Ri-CoDIFy study for C. difficile infection, where it showed a higher observed Sustained Clinical Response rate than vancomycin but did not achieve the study's primary superiority endpoint. The program demonstrated potential microbiome-sparing benefits compared with vancomycin, the standard of care for C. difficile infection.

Ridinilazole remains an investigational asset and has not been approved or evaluated for safety and efficacy by regulatory authorities, including the US Food and Drug Administration.