27 April 2026

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GSK plc (LSE/NYSE: GSK) subsidiary, TESARO, Inc., confirms that the Delaware Chancery Court has granted the motion to dismiss filed by AnaptysBio, Inc. against TESARO’s claim for anticipatory breach. The court’s ruling does not address the merits of the principal contractual dispute between the parties and has no impact on TESARO’s remaining claim against AnaptysBio for declaratory judgment. GSK and TESARO are firmly of the view that these allegations are entirely without merit and remain focused on pursuing that claim at trial.

TESARO initiated this litigation following allegations made by AnaptysBio that TESARO has not fulfilled certain requirements of the license agreement entered in March 2014 between the parties and that AnaptysBio intends to revoke TESARO’s licence for dostarlimab.

Jemperli, which is the brand name for dostarlimab, is currently approved in over 35 countries for use in certain endometrial cancers, the most common gynaecologic cancer in the United States. GSK and TESARO have reported significant growth for Jemperli driven by label expansions in endometrial cancer, including in the US and EU. 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.

GSK is a global biopharma company with a purpose to unite science, technology, and talent to get ahead of disease together. Find out more at www.gsk.com.

GSK cautions investors that any forward-looking statements or projections made by GSK, including those made in this announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Such factors include, but are not limited to, those described in the “Risk Factors” section in GSK’s Annual Report on Form 20-F for 2025.