A new clinical trial aims to improve treatment options for individuals with indolent systemic mastocytosis (SM), a rare disorder that can cause severe allergic reactions, digestive issues and cardiovascular symptoms, according to trial details published recently at ClinicalTrials.gov.
The HARBOR study, a Phase 2/3 clinical trial, is testing elenestinib (BLU-263) in combination with best supportive care against a placebo to determine its safety and effectiveness. This study is currently enrolling participants.
Indolent SM is characterized by excessive mast cell activity, leading to symptoms such as skin flushing, gastrointestinal distress and life-threatening anaphylaxis. Current treatment primarily consists of medications such as antihistamines and corticosteroids, which may not provide sufficient relief. Elenestinib, an investigational oral drug, is designed to block a key mutation in the KIT gene that drives overactivation of mast cells.
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The HARBOR trial is divided into multiple parts. “Patients enrolled in Part 1 or Part 2 will roll over onto Part 3 to receive treatment with elenestinib in an open-label fashion following completion of the earlier Part,” explained the clinical trial’s webpage.
Parts 1 and 2 focus on patients with indolent SM whose symptoms remain uncontrolled despite standard therapies. These participants are randomly assigned to receive either elenestinib or a placebo for approximately 24 weeks. Part 3 allows all patients who complete the earlier phases, including those who initially received a placebo, to take elenestinib in an open-label extension.
Additional study segments include Part M, which enrolls patients with monoclonal mast cell activation syndrome, and Part S, which includes patients with smoldering SM.
Researchers are measuring several outcomes, including symptom reduction, changes in blood markers and improvements in quality of life. The study’s primary goal is to determine whether elenestinib can significantly reduce symptoms by at least 30% compared to baseline. Secondary measures include reductions in mast cell burden and the need for additional medications. Safety is also a key focus, with adverse events being closely monitored over the study period.
To qualify for the clinical trial, participants must have moderate to severe symptoms, meet specific diagnostic criteria, and have previously tried other supportive therapies without adequate relief. Patients with more aggressive forms of SM or certain other medical conditions are excluded.
If successful, this study could provide a much-needed alternative for patients struggling with indolent SM. By targeting the underlying genetic cause of the disease, elenestinib has the potential to offer more effective and lasting symptom control than existing treatments.
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