FRIDAY, Jan. 10, 2020 -- The kinase inhibitor Ayvakit (avapritinib) has been approved to treat adults with unresectable or metastatic gastrointestinal stromal tumors (GISTs) with a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, the U.S. Food and Drug Administration announced Thursday.
The approval includes GISTs harboring a PDGFRA D842V mutation, the most common exon 18 mutation, and marks the first time a drug is specifically approved for GISTs harboring the PDGFRA exon 18 mutation, which is involved in about 10 percent of GIST cases.
Approval was based on clinical data from the phase 1 NAVIGATOR trial of 43 patients with GISTs harboring a PDGFRA exon 18 mutation. Thirty-eight patients had a PDGFRA D842V mutation. Patients received 300 or 400 mg of Ayvakit orally once daily until disease progression or unacceptable toxicity. Researchers determined the recommended dose was 300 mg once daily. Patients with a PDGFRA exon 18 mutation had an overall response rate of 84 percent; 7 and 77 percent of patients had a complete and partial response, respectively. Among patients with a PDGFRA D842V mutation, the overall response rate was 89 percent; 8 and 82 percent of patients had a complete and partial response, respectively. Patients did not reach the median duration of response; 61 percent of responding patients with exon mutations had a response that lasted six months or longer.
Commonly reported side effects with Ayvakit include edema, nausea, fatigue/asthenia, cognitive impairment, vomiting, decreased appetite, diarrhea, hair color changes, increased lacrimation, abdominal pain, constipation, rash, and dizziness. The FDA noted that Ayvakit can cause intracranial hemorrhage and central nervous system effects, including cognitive impairment, dizziness, sleep and mood disorders, speech disorders, and hallucinations.
Approval was granted to Blueprint Medicines Corporation.