The drug previously received breakthrough therapy, fast track, and orphan drug designations.
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.
Efficacy of Ayvakit was established from 43 patients in the NAVIGATOR trial with unresectable or metastatic GIST with those particular mutations. Approximately 6 percent of patients with newly diagnosed GIST have PDGFRA exon 18 mutations. In the subgroup, the ORR was 89% (95% CI, 75%-97%), with 8% CRs and 82% PRs.
In the 204 evaluated patients, there were no safety contradictions observed with avapritinib.
Median duration of response was not reached, but 61% of the patients had responses that lasted 6 months or beyond - 31% had ongoing responses but were followed for less than 6 months.
Common side effects included edema, nausea, fatigue/asthenia, cognitive impairment, vomiting, decreased appetite, diarrhea, hair color changes, increased lacrimation, abdominal pain, constipation, rash, and dizziness.
In its approval notice, FDA called for dose reductions or treatment cessation if intracranial hemorrhage occurs and for dose interruptions or cessation if severe central nervous system effects develop (i.e., cognitive impairment, dizziness, hallucinations, or sleep, mood, or speech disorders). Embryo-fetal toxicity is also possible while on Ayvakit, so pregnant women and men and women of reproductive potential should be warned of this risk.
"For the first time, we can offer these patients a highly effective treatment that targets the underlying genetic cause of their disease", said Michael Heinrich, MD, Professor of Medicine at Oregon Health & Science University and an investigator on the NAVIGATOR trial, in a prepared statement.
The FDA has approved Ayvakit for the treatment of GISTs with platelet-derived growth factor receptor alpha mutations, following 84 percent response rate in clinical trials.
The tiny trial indicates just how rare this type of cancer is, and Blueprint has priced its product accordingly, at $32,000 for a 30-day supply, regardless of the dose needed by the patient.
Blueprint plans to make Ayvakit available through certain specialist pharmacies in the USA within the week, with a list price of $32,000 for a 30-day supply regardless of dosage.
Fourth-line GISTBlueprint also announced that the FDA split avapritinib's proposed indications into 2 new drug applications: (1) PDGFRA exon 18 mutant GIST and (2) fourth-line GIST.