In a deal worth up to $1.15 billion, GSK is acquiring precision medicine biotech IDRx and its phase 3-ready gastrointestinal cancer asset.
“We really became impressed with what IDRx had achieved,” GSK Chief Commercial Officer Luke Miels told Fierce Biotech in an interview ahead of the J.P. Morgan Healthcare Conference. “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.”
GSK is doling out $1 billion in cash for the Boston-based biotech, tacking on the potential for an additional $150 million regulatory approval milestone payment, according to a Jan. 13 release.
The Big Pharma will also assume responsibility for milestone payments and potential royalties for the cancer candidate—dubbed IDRX-42—that are owed to Merck KGaA, from which IDRx licensed it in 2022.
The tyrosine kinase inhibitor (TKI) is designed to be a first- and second-line therapy for gastrointestinal stromal tumors (GIST) by hitting all key KIT mutations, something that gives the asset best-in-class potential.
Given IDRx’s status as a private company that holds almost all its value in the singular asset, it made sense to acquire the whole portfolio versus striking a licensing deal, according to Miels.
The Big Pharma will bring over “key members” from IDRx to help run the clinical program, with Miels saying the intent is to try to retain as many people from the biotech as possible.
The Boston company emerged in 2022 with $122 million and secured a similar $120 million in August 2024, with investors including Andreessen Horowitz (a16z), Blackstone, RA Capital and Merck KGaA, among others.
The biotech’s IDRX-42 is currently being evaluated in a phase 1/1b trial among GIST patients who have received second-line or more treatment. Data from the study, dubbed StrateGIST 1, demonstrate a manageable safety profile and favorable durability, according to GSK.
Across 87 evaluable patients of all KIT mutation subsets, the objective response rate (ORR) was 29%, including one complete response (CR) and 24 partial responses (PRs). For 15 patients who only had one prior line of treatment, the ORR was 53%, including one CR and seven PRs.
About 80% of GIST cases are driven by KIT gene mutations that prompt tumor cell growth and survival. What’s more, most patients who receive first-line therapy develop new KIT mutations that often lead to relapse and limit treatment options.
At this time, there aren’t any approved TKIs that stop the full range of relevant KIT mutations, according to the release.
The current standard of care for GIST includes Novartis’ TKI Gleevec (imatinib). But Miels said the toxicity levels associated with the drug, which leads to about 43% of patients experiencing grade 3 or greater toxicity, are a driving part of GSK’s interest in IDRx.
The pharma was looking for a candidate that doesn’t have the “off-target effects which were driving the toxicity of the other TKIs in the class, and we found that with IDRx's molecules,” Miels explained.
IDRX-42 has snagged FDA fast-track designation for treating patients with GIST after disease progression on or intolerance to imatinib, plus an orphan drug tag for GIST.
“It’s a phase 3-ready asset,” Miels said. “Our intent is to move it into second-line as quickly as we can, and then subsequently follow up with the first line.”
“There's a pathway to a best-in-class drug here that can improve upon the results that are achieved with Gleevec, and certainly a lot stronger than what you see with the second-, third- and fourth-line drugs,” the CCO said.
The deal is a continuation of GSK’s M&A strategy: acquiring assets designed to treat validated targets with unmet need, according to Miels, who cited the pharma’s $2 billion Bellus Health buyout and $1.9 billion takeover of Sierra Oncology.
“Hopefully we can identify more opportunities like IDRx and subsequently execute those deals in the future,” Miels concluded.