The deal covers an ultra-rare pediatric IL-18-driven disorder tied to NLRC4 and XIAP mutations, with AB2 Bio still eligible for up to $600 million in milestones and royalties.
AB2 Bio said Nippon Shinyaku has exercised its exclusive U.S. commercialization option for Tadekinig alfa under the companies' 2025 option and license agreement, triggering a $30 million payment to the Swiss biotechnology company. The license covers Primary Monogenic IL-18-Driven Hyperinflammatory Syndrome in patients with NLRC4 and XIAP mutations, an ultra-rare pediatric disease with no FDA-approved treatments. AB2 Bio said it remains eligible for up to $100 million in development milestones and up to $500 million in commercial milestone and royalty payments. It had already received a $6 million option fee last year. Nippon Shinyaku now holds exclusive U.S. commercialization rights for the licensed indication, while AB2 Bio retains exclusive rights for all other U.S. indications and all indications outside the United States. AB2 Bio will continue leading Biologics License Application (BLA) preparation and other U.S. regulatory work. The company said the option exercise followed positive interactions with the FDA (U.S. drug regulator). Closing may require clearance under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, depending on the circumstances at the time of exercise. Tadekinig alfa is a recombinant human interleukin-18 binding protein, or IL-18BP, designed to neutralize excess free IL-18, which AB2 Bio describes as a driver of hyperinflammation. The company said it has completed its Phase 3 program in the lead indication and shown clinical proof of concept in three additional life-threatening orphan diseases. Tadekinig alfa has received Orphan Drug Designation in the United States and Europe, as well as Breakthrough Therapy and Rare Pediatric Disease designations from the FDA, which could make it eligible for a Priority Review Voucher upon approval. AB2 Bio said the disease primarily affects infants and young children with genetically confirmed NLRC4 or XIAP mutations who continue to suffer severe hyperinflammation despite supportive care. The company said Tadekinig alfa is designed to target the underlying disease mechanism rather than symptoms, positioning it as a potential first targeted treatment option.