How do you approach management of a patient with mast cell leukemia?

Mast cell leukemia (MCL) is a rare and aggressive subtype of systemic mastocytosis defined by ≥20% mast cells in the bone marrow aspirate. A recent multicenter analysis of 92 patients with MCL had a median overall survival (OS) of 1.6 years. Midostaurin was the most common first-line therapy (45% of patients) and was associated with improved OS on multivariate analysis (Kennedy et al., PMID 36094848). The dose of midostaurin is 100 mg BID for advanced systemic mastocytosis (ASM) with a response rate of 60% and median OS of 28.7 months in the pivotal study (Gotlib et al., PMID 27355533).

Avapritinib has been studied in ASM at a dose of 200 mg daily in the PATHFINDER study (Gotlib et al., PMID 34873345). A recent publication focused on the lo...