GSK Subsidiary Tesaro Files Lawsuit Against AnaptysBio Over Jemperli License Breach
Key Insights
GSK's subsidiary Tesaro has filed litigation in Delaware Chancery Court against AnaptysBio (search), alleging material breach of their 2014 license agreement for the cancer drug Jemperli (dostarlimab).
The lawsuit stems from AnaptysBio (search)'s attempt to revoke Tesaro's license, with Tesaro claiming this breach entitles it to secure a perpetual license and reduce royalties and milestone payments by 50%.
Jemperli is currently approved in over 35 countries for endometrial cancer (search) and is undergoing trials for additional cancers including rectal, colon, and head and neck cancers.
GSK's subsidiary Tesaro has initiated legal proceedings against AnaptysBio (search) in Delaware Chancery Court, alleging a material breach of their licensing agreement for the oncology drug Jemperli (dostarlimab). The lawsuit represents an escalation in a contractual dispute that could significantly impact the future development and commercialization of the cancer immunotherapy.
License Agreement Dispute
Tesaro claims that AnaptysBio (search)'s recent actions violate the 2014 license agreement that granted Tesaro rights to dostarlimab. According to the filing, AnaptysBio's attempt to revoke the license constitutes a material breach that entitles Tesaro to terminate the existing agreement, secure a perpetual and irrevocable license to dostarlimab, and reduce related royalties and milestone payments by 50%.
The legal action follows AnaptysBio (search)'s own allegations that Tesaro failed to meet certain contractual obligations under the original agreement. AnaptysBio has indicated its intention to revoke Tesaro's license based on these claimed failures. However, GSK and Tesaro maintain that AnaptysBio's allegations are "entirely without merit."
Jemperli's Commercial Success
Jemperli has achieved significant commercial success since its initial approval, with regulatory authorization in more than 35 countries for certain endometrial cancers. The drug has demonstrated strong growth driven by recent label expansions in both the United States and European Union markets.
Beyond its current indications, GSK and Tesaro continue to advance a broad clinical program evaluating dostarlimab in additional cancer types. Active trials are underway investigating the drug's efficacy in rectal, colon, and head and neck cancers, potentially expanding its therapeutic applications.
Market Impact
The legal dispute has had immediate market implications for both companies. GSK shares closed down 0.9% at 1,757.00 pence in London, while also trading 0.50% lower at $46.11 on the New York Stock Exchange. AnaptysBio (search)'s stock showed mixed performance, closing regular trading up 1.76% at $37.66 but declining in overnight trading.
The outcome of this litigation could have substantial implications for the future development and commercialization of Jemperli, particularly as both companies continue to invest in expanding the drug's clinical applications across multiple cancer indications.