GSK Acquires IDRx for $1.15 Billion to Boost Cancer Portfolio

GSK, the UK-based pharmaceutical giant, has announced that it has entered into an agreement to acquire the privately held biotechnology company IDRx.

As per the terms of the deal, GSK will make an upfront payment of $1 billion, with an additional $150 million in milestone payments contingent on the successful advancement of IDRx’s pipeline.

The acquisition includes IDRx’s experimental targeted therapy aimed at treating a rare gastrointestinal cancer, which complements GSK’s growing portfolio in gastrointestinal oncology.

Luke Miels, GSK’s Chief Commercial Officer, emphasized that the new drug aligns well with their existing portfolio, which features Jemperli (dostarlimab), an anti-PD-1 antibody currently in mid-to-late-stage development for colorectal cancer, and GSK5764227, an antibody-drug conjugate targeting B7-H3.

The targeted therapy, IDRX-42, specifically addresses key KIT mutations that drive tumor growth and progression in gastrointestinal stromal tumors (GIST), a rare cancer affecting approximately 4,000 to 6,000 people in the U.S. annually. Around 80% of GIST cases are caused by KIT gene mutations, and 90% of patients treated in the first line of therapy develop new KIT mutations that lead to relapse and limited treatment options.

Currently undergoing the phase 1/1b StrateGIST 1 trial, IDRX-42 has demonstrated a 29% overall objective response rate (ORR), which rises to 53% among patients who have received only one prior line of treatment.

Tony Wood, GSK’s Chief Scientific Officer, expressed optimism about accelerating the development of IDRX-42 in 2025, highlighting its potential to redefine treatment standards.

“We are excited by the early data from IDRX-42 and its unique ability to target all clinically relevant KIT mutations present in GIST, addressing a significant gap in current treatment options,” Wood said. “We look forward to advancing its development in 2025 to set new standards in care.”

Tim Clackson, CEO of IDRx, also shared his enthusiasm for the collaboration, stating, “We are eager to work with GSK to advance IDRX-42 for GIST patients, as there have been no major advancements in the standard of care for nearly 20 years. By combining our experience with GSK’s expertise in gastrointestinal cancers, global clinical development capabilities, and strong oncology presence, we aim to accelerate the development of this promising treatment for patients.”