AnaptysBio files lawsuit against Tesaro and GSK over collaboration agreement

AnaptysBio, Inc. (NASDAQ:ANAB) announced Thursday that it has filed a verified complaint in Delaware Chancery Court, alleging that TESARO, Inc. and its parent company, GlaxoSmithKline (NYSE:GSK), breached the parties’ Collaboration and Exclusive License Agreement.

According to a statement based on the company’s SEC filing, AnaptysBio claims that Tesaro violated exclusivity provisions by participating in clinical trials with PD-1 antagonists that compete with Jemperli, a drug covered under the agreement, including trials involving Keytruda. The filing also alleges that Tesaro and GSK failed to use commercially reasonable efforts to achieve optimum commercial returns for Jemperli, instead favoring GSK’s antibody-drug conjugate candidates by pairing them with competing PD-1 antagonists.

AnaptysBio is seeking a court declaration affirming its rights and remedies under the collaboration agreement. The company contends that GSK induced Tesaro to breach the agreement and interfered with its terms.

The filing notes that in 2020, AnaptysBio previously filed a complaint against GSK for similar alleged breaches, which was settled with a cash payment and increased royalties on Jemperli sales.

On Thursday, Tesaro responded by initiating its own lawsuit against AnaptysBio, seeking injunctive relief and alleging that AnaptysBio breached the collaboration agreement by making improper breach claims. AnaptysBio has stated that it believes Tesaro’s claims lack merit and intends to seek dismissal and pursue further legal remedies.

Both parties have agreed to request an expedited schedule from the Delaware Chancery Court, with a trial anticipated in July 2026. During the legal proceedings, milestone and royalty payment obligations to AnaptysBio under the agreement remain in effect.

This information is based on statements made in a press release and the company’s SEC filing.

In other recent news, AnaptysBio has been involved in a legal dispute with TESARO, a subsidiary of GSK, over their collaboration on the oncology drug Jemperli. TESARO has filed a lawsuit against AnaptysBio, alleging a breach of the license agreement, which could lead to a termination of the agreement and a reduction in royalties and milestone payments. In response, AnaptysBio has countersued, claiming TESARO violated exclusivity obligations and did not make sufficient efforts to maximize commercial returns for Jemperli. Additionally, AnaptysBio has announced the discontinuation of its Phase 2 trial for rosnilimab, a treatment for ulcerative colitis, after the drug failed to meet primary and secondary efficacy endpoints. Despite the drug’s acceptable safety profile, the company decided to halt the trial, anticipating a cost saving of at least $10 million. Meanwhile, AnaptysBio’s Board of Directors has approved an expansion of its stock repurchase program by $100 million, adding to the remaining $6.4 million from its existing $75 million plan. The company has already repurchased over 3.4 million shares, representing 11.2% of its outstanding shares prior to the initial buyback.

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