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

Aggressive Systemic Mastocytosis with KIT D816V Mutation: Treatment When Avapritinib Has Not Achieved Remission

This page covers the next treatment step for patients with aggressive systemic mastocytosis (ASM) harbouring a KIT D816V (c-KIT gene) mutation whose disease has not adequately responded to a first-line regimen — specifically when the goals of reversing organ damage and substantially reducing bone marrow mast cell burden have not been met.

Aggressive systemic mastocytosis with KIT D816V mutation is a form of advanced SM characterised by one or more C-findings indicating organ dysfunction. Patients with advanced SM frequently need mast cell cytoreductive therapy to reverse disease-related organ dysfunction.
Prior therapy: Avapritinib (first-line).
Failure condition: Insufficient reversion of disease-related organ damage and inadequate decrease in bone marrow mast cell burden — the goals that, if not achieved, indicate the need to escalate to the protocol described here.
After Avapritinib has not achieved the required disease control in ASM with KIT D816V mutation, cytoreductive therapy options are available. The structured regimen involves specific agents for mast cell debulking — the complete protocol, including which agents apply to this scenario and their evidence base, is accessible below.
References

DOI: 10.1002/ajh.26962

Patients with advanced SM frequently need MC cytoreductive therapy to reverse disease-related organ dysfunction.

ASM is characterized by one or more C-findings (Table 5); of note, the definition of C-findings has undergone revision in the 2022 WHO classification.

patients were treated with midostaurin at 100 mg BID.

Dose: 5 mg/m2 IV 5 days every 4–8 weeks

We favor 2-CdA as first-line treatment in cases where rapid MC debulking is indicated, or as salvage treatment in patients progressing after interferon-α, TKI, or other cytoreductive therapy.

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