Biopharmaceutical company GSK plc (LSE: GSK) (NYSE: GSK) announced on Monday that it has finalised the acquisition of IDRx Inc, a Boston-based clinical-stage biopharmaceutical company focused on precision therapeutics for gastrointestinal stromal tumours (GIST).

The deal, valued at up to USD1.15bn, includes an upfront payment of USD1bn and a potential USD150m milestone payment tied to regulatory approval. GSK will also pay tiered royalties to Merck KGaA, Darmstadt, Germany.

IDRX-42, the lead asset in the acquisition, is an investigational tyrosine kinase inhibitor (TKI) designed to target all clinically relevant KIT mutations in GIST, addressing a significant unmet medical need. GIST affects 80,000 to 120,000 patients globally each year, with around 80% of cases driven by KIT gene mutations. Nearly 90% of patients develop secondary resistance mutations, leading to disease relapse and limited treatment options.

The US Food and Drug Administration has granted IDRX-42 Fast Track designation for patients with GIST who have progressed on or cannot tolerate imatinib, along with Orphan Drug designation. The acquisition strengthens GSK's oncology pipeline and reinforces its strategy to advance precision therapies in high-need cancer indications.