Inhibitor can improve symptoms of systemic mastocytosis

Among the 32 evaluable patients, there was a 41% reduction in TSS from baseline (P=0.043). Among the 16 most symptomatic patients, there was a 46% reduction in TSS from baseline (P=0.038).

In all 32 evaluable patients, there was a 58% reduction from baseline in the score for most bothersome symptom domain (gastrointestinal or skin; P=0.0034). In the 16 most symptomatic patients, there was 63% reduction from baseline (P=0.0038).

“This is the first advanced SM-specific PRO to demonstrate significant improvements in total symptom score,” Dr. Gotlib said. “The clinical activity and initial PRO data do support further evaluation of avapritinib in both advanced and indolent disease.”

Dr. Gotlib noted that the PATHFINDER trial (NCT03580655), a study of avapritinib in advanced SM, is now enrolling. And the PIONEER trial (NCT03731260), a study of avapritinib in patients with indolent or smoldering SM, is scheduled to begin at the end of the year.

The EXPLORER trial was sponsored by Blueprint Medicines Corporation. Dr. Gotlib reported relationships with Blueprint Medicines, Celgene, Incyte, Novartis, Deciphera, Gilead, Promedior, and Kartos.