GSK

GSK

Market cap $96.6B

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AnaptysBio stock buckled Friday after the biotech company and GSK filed competing lawsuits against one another over a licensing deal.

Shares of AnaptysBio fell 14% in premarket trading on Friday after the U.S. drug developer and Tesaro, a unit of Britain's GSK , filed lawsuits against each other, with both claiming a breach in a partnership deal for a cancer drug.

GSK plc (NYSE: GSK) subsidiary, Tesaro Inc., has initiated litigation against AnaptysBio, Inc. (NASDAQ: ANAB) in the Delaware Chancery Court.

The companies accuse one another of breaching a licensing agreement for Jemperli, a drug used to treat some forms of endometrial cancer.

SAN DIEGO, Nov. 21, 2025 (GLOBE NEWSWIRE) -- AnaptysBio, Inc. (Nasdaq: ANAB), a clinical-stage biotechnology company focused on delivering innovative immunology therapeutics, announced it has filed a Verified Complaint in Delaware Chancery Court, requesting a court declaration that TESARO, Inc. (“Tesaro”) has materially breached the parties' Collaboration and Exclusive License Agreement (“Collaboration Agreement”) and that GSK (Tesaro's corporate parent) has tortiously interfered with the Collaboration Agreement. Anaptys has requested that the court declare that Anaptys is entitled to all rights and remedies under the Collaboration Agreement.

GSK PLC (LSE:GSK, NYSE:GSK) has stepped up a dispute over rights to its fast-growing cancer drug Jemperli by having its US subsidiary Tesaro sue AnaptysBio in the Delaware Court of Chancery. Tesaro is asking the court to confirm that alleged breaches of their 2014 licence deal allow it to end the current contract, keep a perpetual licence to the medicine and cut by half the royalty and milestone payments it owes AnaptysBio.

GSK plc ( GSK ) Jefferies London Healthcare Conference 2025 November 19, 2025 4:30 AM EST Company Participants Tony Wood - Chief Scientific Officer and Head of R&D Conference Call Participants Michael Leuchten - Jefferies LLC, Research Division Presentation Michael Leuchten Jefferies LLC, Research Division Good morning, everybody. My name is Michael Leuchten, covering analyst on Glaxo here at Jefferies.

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GlaxoSmithKline is now known simply as GSK. GSK stock trades for 13 times earnings and barely 11 times free cash flow.