GSK Plc is to pay $1 billion upfront and potentially $150 million in milestone payments for IDRx Inc of the US which has an early clinical stage product for the treatment of gastrointestinal stromal tumours (GIST). The deal was announced at the start of the JP Morgan Healthcare Conference in San Francisco, US, on 13 January. It marks a significant expansion of the UK company’s portfolio.
GISTs are uncommon cancers that start in special cells in the wall of the gastrointestinal tract and can grow or spread to other parts of the body. The tyrosine kinase receptor KIT plays a major role in GIST. An estimated 95% of these tumours express the KIT protein and about 70% are said to show activating mutations of the KIT gene.
IDRx has developed a kinase inhibitor, IDRX-42, for GIST which is currently in a Phase 1/1b study in patients living with the disease. The small molecule drug is designed to target the most prevalent KIT mutations that either drive the growth, proliferation and survival of tumour cells or confer resistance to currently available therapies. Specifically, the targets are exons nine and 11 to stop tumour growth, and exons 13 and 17 to prevent resistance to therapies. According to GSK, there are currently no approved therapies that inhibit the full spectrum of clinically relevant primary and secondary mutations in KIT.
Data from the ongoing Phase 1/1b study has shown an objective response rate of 29% across all patients and a rate of 53% in second-line patients. IDRx has received a ‘fast track’ designation from the US Food and Drug Administration as well as an orphan designation for the treatment of GIST.
GSK has a number of prospective drugs for gastrointestinal cancers including a novel antibody-drug conjugate, dostarlimab, which is being investigated for mismatch repair deficient endometrial cancers and solid tumours with no alternative treatment options.
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