Avapritinib effectively reduces indolent systemic mastocytosis severity: NEJM

The key findings of this study were:

Avapritinib-treated individuals saw a drop in TSS of 15.6 points (95% CI, 18.6 to 12.6) from baseline to week 24, as opposed to a fall of 9.2 points (13.1 to 5.2) in the placebo group; P = 0.003.

A 50% decrease in blood tryptase level was attained from baseline to Week 24 in 76/141 patients (54%; 45% to 62%) in the avapritinib group as opposed to 0/71 patients in the placebo group; P 0.001.

Avapritinib caused greater edema and alkaline phosphatase elevations than the placebo; nonetheless, there were few cases of therapy termination due to side effects.

Avapritinib exhibited superiority to placebo in treating symptoms in patients with mild to severe symptomatic ISM on BSC during this 24-week blinded phase of the PIONEER study. Overall AE incidence was comparable amongst the groups, and discontinuation rates were low. The current 5-year open-label extension is intended to assess the durability of avapritinib's effectiveness and safety.

Reference:

Gotlib, J., Castells, M., Elberink, H. O., Siebenhaar, F., Hartmann, K., Broesby-Olsen, S., George, T. I., Panse, J., Alvarez-Twose, I., Radia, D. H., Tashi, T., Bulai Livideanu, C., Sabato, V., Reiter, A., Pongdee, T., … Maurer, M. (2023). Avapritinib versus Placebo in Indolent Systemic Mastocytosis. In NEJM Evidence (Vol. 2, Issue 6). Massachusetts Medical Society. https://doi.org/10.1056/evidoa2200339