The U.S. Food and Drug Administration approved Ayvakit™ (avapritinib) for adults with unresectable or metastatic gastrointestinal stromal tumor (GIST), including those with the PDGFRA D842V mutation.
The decision was based on results from the phase I NAVIGATOR trial that included 43 patients with GIST harboring a PDGFRA exon 18 mutation, including 38 patients with PDGFRA D842V mutation. Patients received avapritinib 300 mg or 400 mg orally once daily until disease progression or unacceptable toxicity. The recommended dose is 300 mg once daily.
Improved response with avapritinib
Among patients with PDGFRA exon 18 mutation, the overall response rate (ORR; primary endpoint) was 84%, with 7% achieving complete response (CR) and 77% achieving partial response (PR). Among patients with PDGFRA D842V mutations, the ORR was 89%, with 8% CR and 82% PR. The median duration of response was not reached, but 61% of responding patients with exon 18 mutations were still responding at six months of treatment.
The most common adverse events associated with avapritinib include edema, nausea, fatigue/asthenia, cognitive impairment, vomiting, decreased appetite, diarrhea, hair color changes, increased lacrimation, abdominal pain, constipation, rash, and dizziness. Avapritinib can cause intracranial hemorrhage and central nervous system effects, including cognitive impairment, dizziness, sleep disorders, mood disorders, speech disorders, and hallucinations.
Pregnant or breastfeeding patients should not receive avapritinib.