NCT04910685

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

A Randomized, Double-Blind, Placebo-Controlled Phase 2/3 Study of BLU-263 in Indolent Systemic Mastocytosis

• Status: Recruiting
• Phase: Phase 2 / Phase 3
• Study type: Interventional
• Enrollment: 534 (estimated)
• Sponsor: Blueprint Medicines Corporation · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

This is a randomized, double-blind, placebo-controlled, Phase 2/3 study comparing the efficacy and safety of elenestinib (BLU-263) + symptom directed therapy (SDT) with placebo + SDT in participants with indolent systemic mastocytosis (ISM) whose symptoms are not adequately controlled by SDT. Parts 1 and 2 will enroll participants with ISM. Participants enrolled in Part 2 will roll over onto Part 3 to receive treatment with elenestinib in an open-label fashion following completion of the earlier Part. Part K will enroll participants with ISM who have previously received an approved selective KIT inhibitor. The study also includes pharmacokinetic (PK) groups that will enroll participants with ISM.

Conditions

• Indolent Systemic Mastocytosis
• Smoldering Systemic Mastocytosis

Interventions

Type	Name	Description
DRUG	Elenestinib	Elenestinib oral tablet
DRUG	Placebo	Placebo oral tablet

Timeline

• Start date: 2021-11-30
• Primary completion: 2032-09-30
• Completion: 2032-09-30
• First posted: 2021-06-02
• Last updated: 2026-04-06

Locations

63 sites across 18 countries: United States, Argentina, Australia, Austria, Belgium, Czechia, France, Germany, Greece, Italy, Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland, United Kingdom

Regulatory

• FDA-regulated drug study