Overview
- AnaptysBio filed a verified complaint alleging Tesaro breached exclusivity and commercialization obligations and that GSK tortiously interfered with the 2014 agreement.
- Tesaro sued first in Delaware, claiming AnaptysBio breached the license and seeking termination, a perpetual license to dostarlimab, and a 50% reduction in royalties and milestones.
- Both companies assert the other’s claims lack merit, and the filings are under seal with public versions expected within about a week, according to AnaptysBio.
- Royalty and milestone obligations continue during the proceedings, and AnaptysBio expects a one-time $75 million payment if 2025 Jemperli sales reach $1 billion under its tiered royalty structure.
- Jemperli recorded about £600 million in sales in the first nine months of 2025, and AnaptysBio shares fell roughly 12% in early trading after the litigation disclosure.