Blueprint Medicines has secured the US Food and Drug Administration (FDA) approval for Ayvakit (avapritinib) for treating unresectable or metastatic gastrointestinal stromal tumour among adults (GIST).

Ayvakit, a kinase inhibitor, is the first precision therapy to be approved to treat GIST harbouring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation. The approval also extends to GIST with PDGFRA D842V mutation.

GIST is a genomically driven sarcoma of the gastrointestinal (GI) tract that usually develops in the stomach or small intestine. Around 6% of GIST patients exhibit PDGFRA exon 18 mutations.

The FDA approved Ayvakit for GIST based on the results of Phase I NAVIGATOR clinical trial. The trial included 43 patients with GIST harbouring a PDGFRA exon 18 mutation and 38 patients with PDGFRA D842V mutation.

Ayvakit demonstrated an overall response rate (ORR) of 84% in patients with PDGFRA exon 18 mutant GIST.

Common side effects among patients included oedema, nausea, fatigue / asthenia, vomiting, decreased appetite and diarrhoea.

NAVIGATOR trial investigator Michael Heinrich said: “Today’s approval of AYVAKIT brings forward a new standard of care for patients with PDGFRA exon 18 mutant GIST, a genomically defined population that previously had very limited treatment options.

“For the first time, we can offer these patients a highly effective treatment that targets the underlying genetic cause of their disease.”

Blueprint Medicines plans to distribute Ayvakit in the US within a week.

Blueprint Medicines CEO Jeff Albers said: “The full approval of AYVAKIT based on robust data from our Phase I NAVIGATOR clinical trial is an incredibly exciting milestone for our company and, more importantly, for GIST patients with a PDGFRA exon 18 mutation, who have been waiting for a new treatment option.”