Miami — Summit Therapeutics has signed an agreement to sell its investigational Phase 3 antibiotic ridinilazole to Toronto-based Biossil, Inc.
Under the agreement, Summit will receive $500,000 upfront and could receive up to $104.5 million in regulatory and commercial milestone payments. The company will also be eligible for tiered royalties on net sales.
Biossil is an artificial intelligence-native biopharmaceutical company focused on advancing late-stage drug candidates for life-threatening conditions with significant unmet medical needs.
Ridinilazole was previously evaluated in Summit’s Phase 3 Ri-CoDIFy trial as a treatment for Clostridioides difficile infection, also known as C. difficile infection or CDI.
The study showed a higher observed sustained clinical response rate with ridinilazole than with vancomycin, but it did not meet its primary endpoint of demonstrating superiority within the established time frame.
Sustained clinical response was defined as a clinical response to the treated CDI episode without a recurrence through 30 days after treatment ended. Summit announced the trial results in December 2021, and they were later published in the journal Clinical Infectious Diseases.
Summit said the Phase 3 study and earlier clinical trials showed that ridinilazole preserved more of the gut microbiome than vancomycin, a standard treatment for C. difficile infection. Disruption of the gut microbiome is believed to contribute to disease recurrence.
“Ridinilazole has long represented a scientifically differentiated approach to addressing Clostridioides difficile infection, a serious disease that continues to place a substantial burden on patients, caregivers, and healthcare systems,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit. “We believe Biossil’s AI-native development capabilities and focus on urgent unmet medical needs make them well positioned to advance this program, while allowing Summit to continue prioritizing our core oncology strategy and the development of ivonescimab.”
Duggan said exploratory findings from previous clinical trials showed numerical differences favoring ridinilazole over vancomycin in areas including microbiome preservation, recurrence rates, toxin production, dosing convenience and tolerability. He noted that the findings require further study.
“Introduction of novel, microbiome-sparing antibiotics has lagged the growing global need,” said Alexander Mosa, MD, PhD, Chief Scientific Officer and Chair of Biossil. “Recurrent C. difficile infection, selection of antibiotic-resistant genes, and gut dysbiosis are common, burdensome, and in need of new approaches. We thank Summit for entrusting us with continued development of ridinilazole, and we will advance this program with urgency and focus.”
Summit said the transaction will allow it to concentrate on its oncology strategy and the development of ivonescimab, while Biossil plans to continue the clinical development of ridinilazole.
Ridinilazole has not been approved, and its safety and efficacy have not been evaluated by regulatory authorities, including the U.S. Food and Drug Administration.
