Biossil Labs acquires Theriva's antibiotic-degrader portfolio in up to $91 million deal

Biossil Labs, a Canadian biotech backed by OpenAI, announced a deal to acquire Theriva Biologics' early- to mid-stage portfolio of antibiotic‑degrading enzymes for a total potential value of up to $91 million.

The agreement includes an upfront payment of $350,000, with the possibility of $3 million in regulatory milestones and up to $88 million tied to worldwide net sales. Theriva could also earn up to $250 million in royalties at a low single‑digit rate.

The portfolio is led by the prophylactic therapy SYN-004, known as ribaxamase, which completed a phase 2b trial showing gut microbiome preservation and reduced Clostridioides difficile infection in patients receiving antibiotics. Two additional preclinical candidates, a ribaxamase reformulation (SYN-007) and an enzyme called carbenemase (SYN-006), are also part of the transfer.

The acquisition follows Biossil's recent $70 million investment from OpenAI and underscores its strategy to expand an AI‑driven pipeline focused on novel infection‑control therapies.