03:51 AM EST, 11/21/2025 (MT Newswires) -- GSK (GSK) subsidiary Tesaro said late Thursday it filed a lawsuit in Delaware Chancery Court accusing AnaptysBio ( ANAB ) of breaching their license agreement for cancer drug Jemperli.

The company said that the breach enables Tesaro to terminate the current deal, obtain a perpetual and irrevocable license to dostarlimab, and reduce royalty and milestone payments to AnaptysBio ( ANAB ) by 50%.

The legal action comes after AnaptysBio ( ANAB ) alleged that Tesaro failed to meet certain obligations under their 2014 agreement and attempted to revoke Tesaro's license.

GSK and its unit said they view the allegations as being "entirely without merit."

AnaptysBio ( ANAB ) didn't immediately respond to a request for comment from MT Newswires.

AnaptysBio ( ANAB ) shares were over 3% lower in premarket trade Friday.