The British pharmaceutical giant has made the acquisition to complement its portfolio of drugs to combat gastrointestinal cancers. 

British pharmaceutical giant GSK has said that it will buy clinical-stage biopharmaceutical company IDRx for up to $1.15 billion (£940 million). The Boston-based firm is developing precision therapeutics to treat gastrointestinal stromal tumours. 

GSK will pay $1 billion upfront, with potential for an additional $150 million if the company hits various regulatory milestones. The acquisition includes lead molecule, IDRX-42, a highly selective KIT TKI being developed as a first- and second-line therapy for the treatment of gastrointestinal stromal tumours.

“IDRX-42 complements our growing portfolio in gastrointestinal cancers,” said GSK chief commercial officer Luke Miels. “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.”

Gastrointestinal stromal tumours

Gastrointestinal stromal tumours are the most common subtype of soft tissue sarcoma, with about 80,000 to 120,000 patients diagnosed every year worldwide. The tumours typically present in the gastrointestinal tract with 80% of cases driven by mutations in the KIT gene that lead to the growth, proliferation, and survival of tumour cells (primary or activating mutations in exons 9 and 11). Additionally, about 90% of patients treated in the first-line develop new KIT mutations (secondary or resistance mutations in exons 13 and 17) that typically lead to relapse with limited therapeutic options. There are no approved TKIs that inhibit the full spectrum of clinically relevant primary and secondary mutations in KIT.

IDRx was set up in 2021 to address the limitations of today’s precision cancer medicines with highly potent and selective targeted therapies to stop key tumour escape mechanisms and prolong patients’ response to therapy.

GSK will be responsible for success-based milestone payments as well as tiered royalties for IDRX