A new treatment, bezuclastinib, has shown promise in improving health for people with non-advanced systemic mastocytosis (SM), based on results from a phase 2 clinical trial called SUMMIT.
The findings were recently reported in a press release from Cogent Biosciences, the company developing the treatment.
In the trial, people taking bezuclastinib felt noticeably better, with a bigger drop in their symptom scores after 24 weeks compared to those taking a placebo. Most people on bezuclastinib (about 87%) also had their levels of a blood protein called tryptase cut in half or more. High tryptase levels are linked to the abnormal immune cells that cause the disease.
Bezuclastinib was generally safe and well-tolerated. Most side effects were mild or moderate, such as changes in hair color, taste changes, nausea and changes in liver enzyme levels. Serious side effects were rare (occurring in 4.2% of patients on bezuclastinib compared to 5.0% in the placebo group).
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Bezuclastinib is a tyrosine kinase inhibitor designed to block the KIT D816V mutation that drives most cases of SM.
The study included people taking either bezuclastinib or a placebo for 24 weeks. Researchers measured symptoms, blood markers like tryptase levels and changes in mast cells in the bone marrow. Bezuclastinib showed clear benefits over the placebo in all these areas.
Cogent Biosciences plans to submit a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for bezuclastinib in patients with non-advanced SM by the end of 2025, aiming to make the treatment available as soon as possible.
“People living with [non-advanced SM] experience debilitating symptoms with enormous impact on their physical and psychological quality of life,” said Dr. Nathan Boggs, allergy division director at Walter Reed National Military Medical Center. “It is extremely encouraging to see the results of the SUMMIT trial, which match my own experience treating patients with bezuclastinib, as these results suggest there will soon be a new standard of care available for this patient population with significant unmet medical need.”
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