January 9, 2020
The U.S. FDA has approved Ayvakit™ (avapritinib), manufactured by Blueprint Medicines Corporation, to treat adult patients who have unresectable or metastatic gastrointestinal stromal tumors (GIST) with a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations. Ayvakit is the first FDA-approved targeted therapy for GISTs with this rare mutation.
A form of cancer, GISTs occur due to mutations in the nerve cells of the gastrointestinal (GI) tract. More than 50% of these tumors begin in the stomach, though they can develop anywhere along the GI tract. In approximately 10% of cases, PDGFRA exon 18 mutations associated with a lack of response to standard GIST therapies are present.
Ayvakit delivered an overall response rate (ORR) of 84% in a clinical trial, with 7% of patients having a complete response and 77% having a partial response. A subgroup of patients who had PDGFRA D842V mutations experienced an ORR of 89%, with 8% having a complete response and 82% having a partial response. The median duration of response (DOR) has not yet been determined, though 61% of patients who responded to treatment have had a DOR of at least six months.
Recommended dosing is 300mg taken by mouth once daily on an empty stomach at least one hour before and two hours after a meal. The daily dose should be decreased to 200mg after one adverse event, and 100mg if a second adverse event occurs. Treatment should continue until disease progression or unacceptable toxicity.
Ayvakit is available at a wholesale acquisition cost (WAC) of $32,000 per 30-count bottle of 300mg tablets.