GSK Enters Agreement to Acquire IDRx for $1.15 Billion To Strengthen Cancer Portfolio

GSK Enters Agreement to Acquire IDRx for $1.15 Billion To Strengthen Cancer Portfolio

UK pharmaceutical giant GSK has confirmed that it has signed an agreement to acquire the privately-held biotechnology company IDRx.

Under the terms of the agreement, GSK will make an upfront payment of $1 billion, with an additional $150 million in milestone payments contingent upon the successful progression of IDRx’s pipeline.

The acquisition includes IDRx’s experimental targeted therapy for a rare gastrointestinal cancer, which aligns with GSK’s expanding portfolio in gastrointestinal oncology.

According to Luke Miels, GSK’s Chief Commercial Officer, the drug complements their existing portfolio, which includes Jemperli (dostarlimab), an anti-PD-1 antibody in mid-to-late-stage development for colorectal cancer, and GSK5764227, a B7-H3-directed antibody-drug conjugate.

GSK highlighted that IDRX-42, the targeted therapy, addresses key KIT mutations that drive tumor growth and progression in gastrointestinal stromal tumors (GIST), affecting an estimated 4,000 to 6,000 people in the US annually.

Approximately 80% of GIST cases are driven by KIT gene mutations, with 90% of patients treated in the first line developing new KIT mutations leading to relapse and limited therapeutic options.

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

GSK’s Chief Scientific Officer, Tony Wood, expressed optimism about accelerating the development of IDRX-42 in 2025, citing 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, a major gap in the current standard of care.”

“We look forward to accelerating its development in 2025 to redefine treatment,” he added.

Tim Clackson, chief executive of IDRx, said “We are looking forward to working with GSK to advance IDRX-42 for patients with GIST given there have been no major advances to the standard of care for almost 20 years. Combining our experience to date with GSK’s expertise in GI cancers, global clinical development capability, and strong commercial presence in oncology will help to accelerate the development of this novel medicine for patients”.

This acquisition agreement continues GSK’s strategy of enhancing its oncology pipeline, following its $1.9 billion acquisition of Sierra Oncology in 2022 and additional deals with Hansoh Pharma, Rgenta Therapeutics, and Duality Biologics.

GSK is also preparing for upcoming patent expirations, including that of its top-selling HIV drug dolutegravir in 2027, and competition to its shingles vaccine Shingrix from Pfizer/BioNTech and Modernav.
IDR-x was launched in Plymouth, near Boston, in August 2022 by entrepreneurs Ben Auspitz, who serves as chief executive, and Alexis Borisy, to develop precision cancer medicines.
Christoph Lengauer acts as scientific adviser.
The first financing round was led by the Californian venture capital firm Andreessen Horowitz and New York-based Casdin Capital.