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

Aggressive Systemic Mastocytosis (ASM) with C-Findings: What to Do When Initial Cytoreductive Therapy Has Not Achieved Adequate Response

This protocol addresses the management of aggressive systemic mastocytosis (ASM) in patients with one or more C-findings who did not achieve — or could not sustain — an adequate response to their initial line of cytoreductive treatment.

Clinical Scenario

Aggressive systemic mastocytosis (ASM) defined by the presence of one or more C-findings per WHO criteria, or eligible organ damage findings per IWG-MRT-ECNM criteria. The diagnosis does not meet criteria for mast cell leukemia (MCL).

Prior Treatment — Failure Condition

An initial cytoreductive regimen — which may have included agents such as midostaurin, cladribine, imatinib, or interferons, or allogeneic hematopoietic cell transplant (HCT) — was previously used. That treatment is considered to have not achieved adequate response: resolution of organ damage findings, reduction in bone marrow mast cell burden, and reduction in serum tryptase level, maintained for at least 12 weeks, were not attained. The protocol below represents the structured next clinical step.

Next-Line Approach (Partial Overview)

The approach centres on re-staging and switching to an alternate cytoreductive strategy not previously used; the specific options and eligibility considerations are detailed in the full protocol.

Instant Access to Structured Evidence-Based Regimens

References

DOI: 10.6004/jnccn.2018.0088

The diagnosis of ASM requires the presence of one or more C-findings, but does not meet the criteria for MCL.

Patients with advanced SM with inadequate response or loss of response should be treated with alternate cytoreductive therapy not previously received.

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.

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