GSK/Tesaro claim denied in Jemperli lawsuit with AnaptysBio
A court ruling in the US has delivered a setback for GSK and its Tesaro subsidiary in their dispute with AnaptysBio over cancer immunotherapy Jemperli.
GSK and Tesaro filed a lawsuit against AnaptysBio last year, claiming breach of contract and arguing that the agreement – dating back to 2014 – should be ended, with the issuance of a perpetual licence to PD-1 inhibitor Jemperli (dostarlimab) and a cut in royalty and milestone payments payable under the deal. AnaptysBio promptly filed a countersuit claiming that Tesaro, under pressure from GSK, had unlawfully modified the terms of the 2014 agreement.
The Delaware ruling is that AnaptysBio has not breached the contract and preserves the contracted royalty rate at the current level. The company said the decision "is an important validation of our efforts to protect our contractual rights to the Jemperli royalty stream for our shareholders."
GSK acknowledged the decision in a statement, but added that the ruling "does not address the merits of the principal contractual dispute between the parties." AnaptysBio is also contending that Tesaro has failed to meet the obligations of their agreement, including that it would not be involved in "research, development, manufacturing, or commercialisation" of any other PD-1 antagonist candidate.
The company's complaint is that trials of GSK/Tesaro drugs in combination with PD-1 inhibitors that compete with Jemperli, like MSD's Keytruda (pembrolizumab), contravene the agreement and mean that the Jemperli license should be revoked. It also claims that Tesaro has not made the required effort to make the most of Jemperli's commercial potential in markets, and has not met its obligations to inform AnaptysBio of clinical trial plans in advance.
GSK and Tesaro said they are "firmly of the view that these allegations are entirely without merit and remain focused on pursuing that claim at trial." They argue that "a robust and ambitious clinical trial programme to evaluate the potential use of dostarlimab in additional cancers, including rectal, colon, and head and neck, is ongoing." The trial has been scheduled for 14th to 17th July this year.
Jemperli was originally discovered by AnaptysBio and licensed to Tesaro before its merger with GSK in 2019 in a $5.1 billion deal. Last year, sales of the drug reached around $1.16 billion, up 86% on the prior year.
The PD-1 inhibitor was recently awarded a national priority review voucher in the US as a pre-surgery therapy for rectal cancer with dMMR/MSI-H alterations based on the results of the AZUR-1 trial, which could support accelerated approval.
GSK/Tesaro are also running a second trial (AZUR-2) comparing Jemperli to chemotherapy as first-line therapy for dMMR/MSI-H resectable colon cancer, with results due in 2028.
