The first major deal of JPM 2025 will give GSK a promising small molecule drug for gastrointestinal stromal tumors.
GSK fired the opening gun for the 2025 JP Morgan Healthcare Conference on Monday with a front-loaded acquisition agreement, moving to buy precision therapy specialist IDRx and its rare cancer drug candidate.
To purchase 100% of IDRx’s outstanding equity interests, GSK will make a $1 billion upfront payment plus the promise of up to $150 million in a success-based regulatory approval milestone. In exchange, the pharma will gain ownership over IDRX-42, a small molecule asset being developed as a first- and second-line treatment for gastrointestinal stromal tumors (GIST).
The buyout is subject to an antitrust review and other customary closing conditions.
Affecting somewhere around 4,000 to 6,000 people in the U.S., GIST is a rare cancer that originates in the digestive tract, according to IDRx’s website. Around 80% of GIST diagnoses can be linked to alterations in the KIT gene, which encodes a protein involved in transmitting signals across the cell membrane.
Approximately 90% of GIST patients who undergo first-line treatment develop novel KIT mutations that give their cancers resistance to therapies and lead to relapse. There are currently no approved tyrosine kinase inhibitors (TKI) that can address the known clinically relevant KIT mutations in GIST.
IDRX-42 has the potential to address that gap. Designed to be taken orally, IDRX-42 is a selective TKI that can strongly inhibit both the “activating mutations” responsible for GIST progression and the “resistance mutations” that blunt the response to existing treatments. According to GSK’s news release on Monday, IDRX-42’s broad activity against known KIT mutations “provides potential for a best-in-class profile.”
The asset, which has won the FDA’s Orphan Drug designation, is currently in a Phase I/Ib study in advanced GIST. Data revealed in November 2024 indicate that IDRX-42 has potent antitumor activity, eliciting a 29% objective response rate across all treated patients. This response estimate jumped to 53% when focusing on the second-line setting. Estimated median progression-free survival for third-line patients was 12.9 months.
IDRx obtained the right to develop IDRX-42 when it launched in August 2022, licensing the asset from Merck KGaA. As per Monday’s acquisition agreement, GSK will assume responsibility over the milestones and royalties owed to the German company in connection with IDRX-42.
GSK is “excited” by IDRX-42’s early data, CSO Tony Wood said in a statement, emphasizing the candidate’s “unique ability to target all clinically relevant KIT Mutations present in GIST,” which according to him remains a “major gap in current standard of care.” The pharma will accelerate the development of IDRX-42 this year “to redefine treatment,” Wood said.
According to reporting by Endpoints News, GSK plans on launching a second-line study of IDRX-42 within the year, with a first-line trial coming shortly after.
