Initial results from Cogent Biosciences’ phase 2 Summit trial of bezuclastinib in patients with non-advanced systemic mastocytosis were presented recently at the 12th Annual Meeting of the Society of Hematologic Oncology, held in Houston, TX from Sept. 4 to 7.
The findings showed treatment with bezuclastinib resulted in an overall improvement of quality of life for patients, along with a reduced symptom burden. No serious adverse events were reported.
Early results from Part 1 of a phase 2 trial of bezuclastinib in patients with advanced SM have reported that the agent is associated with encouraging clinical activity and is well tolerated. Of note, treatment with bezuclastinib in patients with advanced SM was associated with meaningful reductions in bone marrow mast cell burden, serum tryptase levels and KIT D816V variant allele fraction.
Read more about SM therapies
Findings from the analysis of bezuclastinib in patients with advanced SM supported investigation of the agent as a possible treatment for individuals with non-advanced SM. Summit is intended to evaluate bezuclastinib therapy in patients with non-advanced SM. who exhibit inadequate symptom control in spite of treatment with best supportive care. Treatment effect on symptoms are being evaluated with the use of patient-reported outcome measures, including Mastocytosis Quality of Life and Mastocytosis Activity Score.
Study details and enrollment
In Part 1a of the Summit trial, a total of 20 participants were enrolled—18 of whom had indolent SM and two of whom had smoldering SM. The mean patient age was 54 years. Overall, 75% of the participants were female.
100% of patients used H1 blockers, 95% used H2 blockers and 40% used leukotriene receptor antagonists. Additionally, 75% of the patients were KIT D816V positive.
When MAS was utilized to evaluate baseline disease severity, a majority of patients self-reported severe disease. On the MC-QoL, participants self-reported a mean score of 56+/19–, which was indicative of a moderate impact of the disease on their quality of life.
“The patients enrolled in Part 1a of the Summit trial are generally representative of the population of patients with moderate to severe [NonAdvSM] based on number of supportive care medications, symptom severity, and disease impact on [quality of life],” the authors noted.
Findings show improvement in quality of life, symptom burden
Results from part 1b of the phase 2 trial showed a 51% reduction in symptom severity, along with a 49% improvement in health-related quality of life. Additionally, 70% saw an improvement in symptom severity of greater than or equal to 50%, compared with an 8% reduction for those taking the placebo.
The safety and tolerability of bezuclastinib was overall consistent with those on placebo, and there were no serious adverse events reported.
Cogent Biosciences is currently actively enrolling patients for part two of the trial.
