Systemic mastocytosis
ICD-10 D47.0 · ICD-11 2A21.0

Systemic Mastocytosis with MCL: What to Do After Cytoreductive Therapy Has Not Achieved Adequate Response

This protocol covers patients diagnosed with mast cell leukemia (MCL) — characterised by ≥20% neoplastic mast cells on a bone marrow aspirate, with or without an associated hematologic neoplasm — who have already undergone first-line cytoreductive therapy and did not meet the defined response criteria.

Prior therapy — targets not met

First-line cytoreductive therapy — including clinical trial, midostaurin, or cladribine — aimed to achieve adequate response: resolution of organ damage findings, substantial reduction in bone marrow mast cell burden, and a sustained reduction in serum tryptase level maintained for at least 12 weeks. When these goals are not reached, escalation to the next protocol is indicated.

Next-line approach (partial overview)

The next step involves re-staging and evaluation for allogeneic hematopoietic cell transplant (HCT). In the setting of associated hematologic neoplasm progression or transformation, a distinct category of systemic therapy is considered alongside concurrent MCL management. The full decision algorithm, eligibility conditions, and sequencing are contained in the complete protocol.

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References

MCL is defined histopathologically by the presence of ≥20% neoplastic mast cells on a bone marrow aspirate.

Evaluation of allogeneic HCT should be considered for patients with advanced SM (ASM, SM-AHN, or MCL) with adequate response to cytoreductive therapy and with suitable donor(s) identified.

DOI: 10.6004/jnccn.2018.0088

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