Blueprint gets first approval as FDA backs stomach cancer drug

US biotech Blueprint Medicines has its first approved drug, after the FDA backed its oncology drug Ayvakit for a certain kind of stomach cancer.

The regulator approved Ayvakit (avapritinib) on the basis of high response rates seen in phase 1 trial results in gastrointestinal stromal tumour (GIST), with a platelet-driven growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations.

There are no approved drugs in this indication, and the FDA is also reviewing another set of data in fourth-line GIST, where a decision is due midway through next month.

This review is likely to be extended to allow Massachusetts-based Blueprint to submit top-line data from the phase 3 trial testing avapritinib against Bayer’s Stivarga (regorafenib).

Blueprint plans to make Ayvakit available through certain specialist pharmacies in the US within the week, with a list price of $32,000 for a 30-day supply regardless of dosage.

The price patients will pay will vary according to their individual insurance arrangements.

The FDA granted a full approval to Ayvakit based on efficacy results from the phase 1 NAVIGATOR clinical trial, as well as combined safety results from multiple clinical trials for avapritinib.

Efficacy of Ayvakit was established from 43 patients in the NAVIGATOR trial with unresectable or metastatic GIST with those particular mutations.

In patients with PDGFRA exon 18 mutant GIST, Ayvakit had an overall response rate (ORR) of 84% and a median duration of response (DOR) was not reached.

GIST is a rare, genomically driven sarcoma of the gastrointestinal (GI) tract. Approximately 6% of patients with newly diagnosed GIST have PDGFRA exon 18 mutations.

The most common PDGFRA exon 18 mutation is the D842V mutation, which is resistant to all other approved therapies.

A retrospective study showed that no patients whatsoever who harboured this mutation responded to Novartis’ Gleevec (imatinib), a standard therapy for stomach cancer.