Biopharma company CStone Pharmaceuticals reported on Friday the receipt of approval from the National Medical Products Administration (NMPA) for the launch of a Phase III clinical trial in China for its partnered drug candidate avapritinib as a third-line treatment against KIT-driven gastrointestinal stromal tumours (GIST).

GIST, which is classed as a rare disease, is a form of sarcoma usually found in the walls of the stomach or the small intestine, and is typically diagnosed between the ages of 50 and 80. Approximately 90% of GIST cases are linked to mutations of KIT or PDGFRα.

Avapritinib is an orally available, potent and highly selective inhibitor of KIT and PDGFRα. Avapritinib is active across a broad spectrum of KIT and PDGFRα mutations, including KIT D816V, PDGFRα D842V and KIT exon 17 mutations, for which there are limited or no effective treatment options,added the company.

A part of the global VOYAGER Phase III trial, the new trial will compare avapritinib against the current standard of care regorafenib in GIST patients who have previously received imatinib and one or two additional tyrosine kinase inhibitors (TKIs).

The company stated that the study is designed to evaluate avapritinib's safety and efficacy, with progression-free survival as the primary efficacy endpoint and based on the NAVIGATOR Phase I clinical trial data, avapritinib was administered to 109 fourth-line or later GIST patients at doses of 300mg or 400mg.