NCT03731260 2025-09-23(PIONEER) Study to Evaluate Efficacy and Safety of Avapritinib (BLU-285), A Selective KIT Mutation-targeted Tyrosine Kinase Inhibitor, Versus Placebo in Patients With Indolent Systemic MastocytosisBlueprint Medicines CorporationPhase 2 Active not recruiting251 enrolled