A recent study published in Experimental Hematology and Oncology found that allogeneic hematopoietic cell transplantation significantly improved overall survival in patients with systemic mastocytosis with associated acute myeloid leukemia (SM-AML), but not in patients with other forms of advanced SMAdvanced SM In these subtypes of SM, mast cells begin to damage organs. Advanced SM includes the subtypes aggressive SM, mast cell leukemia and SM with an associated hematological neoplasm..
SM-AML is a form of SM with an associated hematological neoplasmSM with an associated hematological neoplasm A form of advanced SM and the second-most common subtype of SM overall. In this subtype, SM occurs alongside another blood disorder. Also called SM with an associated myeloid neoplasm. (SM-AHN), the second-most common subtype of SM. In SM-AHN, SM occurs alongside another blood disorder. In the case of SM-AML that’s acute myeloid leukemia, a quickly moving cancer of the blood and bone marrow.
Learn more about this systemic mastocytosisMastocytosis Rare disease caused by the buildup of mast cells. Cutaneous mastocytosis primarily affects the skin and is more common in children, while systemic mastocytosis affects internal organs and is more common in adults. subtype: “Subtypes explained: What is SM-AHN?“
Allogeneic hematopoietic cell transplantation works by replacing the patient’s bone marrow with blood stem cells from a donor. The procedure is a potential curative option for some individuals living with advanced forms of SM, but how effective it is for different types of advanced SM is unclear.
The study included 631 individuals with advanced SM from the European Competence Network on Mastocytosis registry. Of these, 69 (11%) received an allogeneic hematopoietic cell transplant.
Across the entire study sample, transplant showed no improvement in overall survival. Similarly, subtype-specific analysis showed no benefits for aggressive SMAggressive SM A subtype of advanced SM marked by a high mast cell burden that leads to organ damage. Aggressive SM accounts for less than 10% of SM cases., mast cell leukemiaMast cell leukemia The most severe subtype of SM, caused by the rapid buildup of immature mast cells in the bone marrow and blood. Mast cell leukemia accounts for less than 5% of SM cases and has a poor prognosis. or forms of SM-AHN besides SM-AML.
Sign up here to get the latest news, perspectives, and information about SM sent directly to your inbox. Registration is free and only takes a minute.
Patients with SM-AML who received a transplant, though, had an 80% lower risk of death at any given point during the follow-up period.
“Given the limited size of the SM-AML subgroup, this estimate must be regarded as exploratory,” the authors wrote. “These findings nonetheless support subtype-specific patient selection.”
The study did find, however, that tyrosine kinase inhibitorTyrosine kinase inhibitor Targeted therapies designed to block the KIT D816V mutation that drives most cases of SM. Includes avapritinib, midostaurin and imatinib. use was associated with a 58% lower risk of death at any given point during the follow-up period across all participants. Subtype-specific analysis showed significant benefits for individuals with aggressive SM and mast cell leukemia.
Among the 69 transplant recipients, higher International Prognostic Scoring System for Mastocytosis (IPSM) score at the time of transplant predicted worse overall and progression-free survival.
Individuals with a favorable IPSM score had a two-year overall survival of 72% and progression-free survival of 60%. Those with an unfavorable IPSM score, on the other hand, had a two-year overall survival of 48% and progression-free survival of 32%. These findings suggest that IPSM scores may serve as a useful tool for predicting post-transplant outcomes and guiding transplant timing.
Read more about stem cell transplants: “What is a stem cell transplant for systemic mastocytosis?”
