GSK announced that they have entered into an agreement under which GSK will acquire IDRx, a Boston-based, clinical-stage biopharmaceutical company dedicated to developing precision therapeutics for treating GIST. As part of the agreement, GSK will pay $1 billion upfront, with the potential for an additional $150 million success-based regulatory approval milestone payment. This acquisition includes lead molecule IDRX-42, a highly selective KIT TKI being developed as a first- and second-line therapy for treating GIST.
GIST usually presents in the GI tract, with 80% of cases driven by mutations in the KIT gene that lead to tumor cells’ growth, proliferation, and survival (primary or activating mutations). And 90% of patients treated in the first line develop new KIT mutations (secondary or resistance mutations) that typically lead to relapse with limited therapeutic options. Currently, no approved TKIs inhibit the full spectrum of clinically relevant primary and secondary mutations in KIT.
IDRX-42 has shown activity against all key primary and secondary KIT mutations, designed to improve outcomes for patients with GIST. This depth of mutational coverage and high selectivity, which could enhance tolerability, provides the potential for a best-in-class profile.
The updated clinical data from StrateGIST 1, an ongoing phase I/Ib trial of IDRX-42 in patients with advanced GIST, were presented in an oral presentation at the Connective Tissue Oncology Society (CTOS) 2024 Annual Meeting. And the data shows the promising anti-tumor activity of IDRX-42 in patients with advanced GIST with a manageable safety profile.
Across patients with second-line or greater GIST, and amongst all KIT mutation subsets, the objective response rate (ORR) by modified RECIST v1.1 in the total efficacy evaluable population was 29% (n=87), including one complete response (CR) and 24 partial responses (PRs). Among patients with one prior line of therapy, the ORR was 53% (n=15), including one CR and 7 PRs.
Across all patients, two of the PRs were awaiting confirmation at the time of the data cut, of which both were subsequently confirmed. And the emerging durability data from StrateGIST 1 was also favorable. IDRX-42 was generally well-tolerated, and treatment-related adverse events (TRAEs) were mainly low-grade at the recommended phase Ib dose.
GSK has a growing portfolio in development targeting the significant medical need in GI cancers, such as ongoing trials with dostarlimab and GSK5764227 (GSK’227), a B7-H3-targeted antibody-drug conjugate. And this agreement reflects GSK’s portfolio approach of identifying potentially best-in-class molecules with targeted mechanisms of action. The transaction supports GSK’s ambitions for growth through 2031 and beyond.
IDRx was launched in 2021 to address the limitations of today’s precision cancer medicines with highly potent and selective targeted therapies to stop key tumor escape mechanisms and prolong patients’ response to treatment. And IDRx investors include Andreessen Horowitz (a16z), Casdin Capital, Nextech Invest, Forge Life Science Partners, RA Capital Management, Commodore Capital, Blackstone Multi-Asset Investing, and Rock Springs Capital. IDRx co-founders include George Demetri, M.D., FACP, FASCO, FAACR, Nicholas Lydon, Ph.D., Alexis Borisy, Robert Forrester, and Ben Auspitz.
Under the terms of the agreement, GSK will buy 100% of the outstanding equity interests (including all options and other incentive equity) in IDRx for up to $1.15 billion of total cash consideration, comprising an upfront payment of $1 billion with potential for an additional $150 million success-based regulatory approval milestone payment. And GSK will also be responsible for success-based milestone payments and tiered royalties for IDRX-42 owed to Merck KGaA, Darmstadt, Germany.
For IDRx, Centerview Partners is acting as the exclusive financial advisor and Goodwin Procter as legal counsel. And for GSK, Leerink Partners LLC is acting as the exclusive financial advisor.
This deal is subject to customary conditions, including applicable regulatory agency clearances.
KEY QUOTES:
“IDRX-42 complements our growing portfolio in gastrointestinal cancers. This acquisition is consistent with our approach of acquiring assets that address validated targets and where there is clear unmet medical need, despite existing approved products.”
– Luke Miels, Chief Commercial Officer, GSK
“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.”
– Tony Wood, Chief Scientific Officer, GSK
“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.”
– Tim Clackson, CEO, IDRx
