Systemic Mastocytosis with c-KITD816VMutation Treated with Dasatinib.

Objectives: Systemic mastocytosis (SM) is mainly a clonal disease with a variable clinical outcome. Prognosis is very much related to additional symptoms. If so called c-findings are present, survival is often limited to months. Until recently only Interferon and Cladribine could show some effect on the disease progression. With the introduction of Imatinib some hope grew to treat the disease by acting on c-KIT (CD 117; stem cell factor receptor). However, the substitution of valine for aspartic acid at position 816 in c-KIT (D816V) leads to prolonged mast cell survival and increased proliferation because of constitutive activation of the tyrosine kinase of c-KIT. Between 31% and 100% of patients with SM harbour the c-KIT D816V mutation which is invariably related to Imatinib resistance. Fortunately, the new tyrosinkinase inhibitor Dasatinib (BMS-354825) could show a much higher inhibition of the c-KIT D816V mutated receptor in vitro. Therefore we treated a patient with systemic mastocytosis with associated hematologic clonal non mast cell lineage disease (SM-AHNMD) and c-findings with Dasatinib.