AnaptysBio filed a verified complaint in Delaware Chancery Court claiming Tesaro (a GSK subsidiary) materially breached a 2014 collaboration and exclusive license agreement related to Jemperli and asserting GSK tortiously interfered with the contract. The litigation seeks a court declaration of Anaptys’ rights under the original agreement. Separately, Anaptys authorized an amended $100 million stock repurchase plan, increasing buyback capacity amid expected cash inflows and a one‑time commercial milestone tied to Jemperli sales. The dual moves — litigation and capital return action — signal Anaptys’ strategy to defend contractual value while managing shareholder returns.