Effective midostaurin treatment in a patient with aggressive systemic mastocytosis

Abstract

Systemic mastocytosis (SM) is a rare neoplastic disease of the hematopoietic system characterized by the presence of a somatic mutation in the KIT gene, leading to excessive proliferation of pathological mast cells. This results in abnormal growth of mast cells in the skin and other organs. There are following variants of SM: SM with an associated hematological neoplasm (SM-AHN), aggressive SM (ASM) and mast cell leukemia (MCL), they all are referred to as advanced SM (AdvSM). The drug of choice in the treatment of ASM in Poland is cladribine, which, however, is not approved in this indication, unlike the multikinase inhibitor — midostaurin and imatinib. The latter drug can be used when c-KIT D816V mutation remains negative or unknown. A 61-year-old female with ASM, accompanied by pancytopenia, hepatosplenomegaly and bone marrow fibrosis with sclerotic bone lesions was reported. The patient was initially treated with cladribine, but due to lack of efficacy after 3 cycles, midostaurin was used as a second option. Initially, the patient developed neutropenia, which led to dose reduction. Treatment continuation resulted in improvement of blood counts and regression of organ changes. Finally, the patient achieved a partial response and the drug was well tolerated. Midostaurin remains a promising treatment option in a patient with ASM and cladribine ineffectiveness.