GSK Acquires IDRx for $1B+, Targeting Rare Gastrointestinal Cancer

GSK has kicked off the 2025 JP Morgan Healthcare Conference with a significant acquisition, purchasing precision therapy specialist IDRx in a deal worth up to $1.15 billion. The move gives GSK ownership of IDRX-42, a promising small molecule drug candidate for gastrointestinal stromal tumors (GIST), a rare cancer affecting the digestive tract.

Acquisition Details and Strategic Rationale

GSK will make an upfront payment of $1 billion to acquire 100% of IDRx's outstanding equity interests, with an additional $150 million tied to regulatory approval milestones. The acquisition is subject to antitrust review and other customary closing conditions.

Luke Miels, GSK's Chief Commercial Officer, expressed enthusiasm for the deal, stating, "We really became impressed with what IDRx had achieved. I think we have an opportunity to develop a best-in-class product here for patients and move the standard of care ahead after 20 years."

The acquisition aligns with GSK's M&A strategy of targeting assets designed to treat validated targets with unmet needs. This approach is evident in their recent $2 billion Bellus Health buyout and $1.9 billion takeover of Sierra Oncology.

IDRX-42: A Potential Game-Changer for GIST Treatment

IDRX-42 is a tyrosine kinase inhibitor (TKI) designed as a first- and second-line therapy for GIST. The drug candidate stands out for its ability to target all clinically relevant KIT mutations present in GIST, addressing a major gap in the current standard of care.

Key features of IDRX-42 include:

• Oral administration
• Selective TKI that strongly inhibits both "activating mutations" and "resistance mutations"
• FDA Orphan Drug designation
• Fast Track designation for treating patients with GIST after disease progression on or intolerance to imatinib

Early clinical data from the Phase I/Ib StrateGIST 1 trial have shown promising results:

• 29% objective response rate across all treated patients
• 53% objective response rate in the second-line setting
• Estimated median progression-free survival of 12.9 months for third-line patients
• Manageable safety profile and favorable durability

Tony Wood, GSK's CSO, highlighted the drug's potential, saying, "We are excited by IDRX-42's early data, emphasizing the candidate's unique ability to target all clinically relevant KIT mutations present in GIST."

Market Impact and Future Plans

GIST affects approximately 4,000 to 6,000 people in the U.S., with about 80% of cases linked to alterations in the KIT gene. The current standard of care, including Novartis' Gleevec (imatinib), has limitations due to toxicity and the development of resistance mutations.

GSK plans to accelerate IDRX-42's development in 2025, with intentions to launch a second-line study within the year, followed shortly by a first-line trial. The company aims to redefine GIST treatment and potentially establish a new standard of care.

As part of the acquisition, GSK will bring over key members from IDRx to assist with the clinical program, aiming to retain as much expertise as possible from the biotech company.