Study of BLU-263 Elenestinib Compared to Placebo with Symptom Therapy in Adults With Indolent Systemic Mastocytosis

What this Trial Is About

Researchers are evaluating the safety and effectiveness of elenestinib BLU-263 combined with symptom directed therapy SDT compared to placebo plus SDT in adults with indolent systemic mastocytosis ISM whose symptoms are not well controlled by SDT alone. This randomized, double-blind, placebo-controlled Phase 23 study includes multiple parts to assess different doses and durations of elenestinib treatment, including an open-label extension for participants finishing earlier phases. The study also enrolls participants who have previously received an approved selective KIT inhibitor and includes pharmacokinetic groups. Participants receive oral elenestinib or placebo once daily alongside SDT, which is personalized based on individual symptom management needs. Part 1 focuses on short-term treatment lasting up to 12 weeks, while Part 2 extends treatment to approximately 48 weeks. Part 3 and other parts allow treatment for up to about 5 years. The study monitors participants through these phases to evaluate how elenestinib affects symptoms, disease markers, and safety over time. During the study, participants undergo regular assessments of symptoms using the ISM-Symptom Assessment Form ISM-SAF, laboratory tests including serum tryptase and KIT D816V allele levels, bone marrow evaluations, and quality of life measures. Researchers track adverse events and changes in disease-related factors at various points up to 5 years. This thorough monitoring helps measure treatment effects and safety over both short and long-term periods, with total participation lasting several years depending on the study part.

(HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic Mastocytosis