GSK’s Tesaro unit and AnaptysBio entered reciprocal litigation over a decade‑old license tied to the cancer drug Jemperli, with GSK seeking contract enforcement and Anaptys alleging breach by Tesaro. The dispute centers on collaboration terms that affect royalty flows tied to Jemperli sales and future testing rights. Amid the legal fight, AnaptysBio authorized an amended $100 million stock repurchase program. The company said the buyback complements its cash position and noted an anticipated $75 million milestone tied to Jemperli reaching $1 billion in sales, underscoring the commercial stakes behind the licensing dispute.