Treatment of Systemic Mastocytosis with an Imatinib-Sensitive KIT Mutation or Unknown KIT Mutational Status
A molecularly defined subset of systemic mastocytosis patients carries transmembrane KIT mutations — such as F522C or K509I — that confer sensitivity to a specific oral targeted agent, or lacks the KIT D816V mutation altogether. This scenario also encompasses aggressive systemic mastocytosis with unknown KIT mutational status. Recognising this molecular profile is essential before selecting a treatment path.
This protocol targets patients with systemic mastocytosis who harbour an imatinib-sensitive transmembrane KIT mutation (e.g., F522C or K509I) and are negative for KIT D816V, or those with aggressive systemic mastocytosis who lack KIT D816V or have unknown KIT mutational status. In these rare cases, dramatic clinical responses to targeted oral therapy have been observed — in contrast to the broader SM population, in whom this approach has limited utility.
The regimen involves an oral KIT-targeting agent. The full dosing strategy, titration approach, maintenance criteria, and patient-selection details are available in the complete protocol.
Clinical targets include improvement in urticaria pigmentosa skin lesions and reduction in bone marrow mast cell burden.
References
DOI: 10.1002/ajh.26962
- For the rare SM patient with a transmembrane KIT mutation (e.g., F522C or K509I), dramatic clinical responses to imatinib therapy can be observed.
- While IM is currently approved by the FDA (specific indication is treatment of adult patients with ASM without the KITD816V mutation or with unknown KIT mutational status), it has a limited role in the treatment of unselected adult SM patients, the majority of whom likely harbor KITD816V.
- Such rare SM cases that harbor an IM-sensitive KIT mutation, or those that are KITD816-unmutated may be appropriate candidates for IM treatment.
- Responses included improvement in UP and decrease in the BM MC burden.