Treatment of Mastocytosis: A Literature Review

Abstract

The term “mastocytosis” refers to a group of rare heterogeneous disorders resulting from proliferation and accumulation of neoplastic mast cells in various organs. The World Health Organization (WHO) classifies these diseases into three types: cutaneous mastocytosis, systemic mastocytosis (SM), and mast cell sarcoma (MCS). Depending on the degree of aggressiveness SM can be indolent, smoldering, aggressive (ASM), or associated with another proliferative hematological disease of non-mast cell line (SM-AHD). SM also includes mast cell leukemia (MCL). Numerous studies confirm the prognostic value of the WHO classification. All mastocytosis patients require treatment aimed at reducing the symptoms of mast cell activation. In case of prognostically unfavorable types of mastocytosis, such as ASM, SM-AHD, MCL, and MCS, more intensive treatment methods should come into consideration, which include allogeneic hematopoietic stem cell transplantation, cytoreductive therapy with tyrosine kinase inhibitors (TKI), interferon-α, and cladribine. In the pathogenesis of mastocytosis, mutations in different KIT gene exons have a dominating role. Most common is KITD816V activating mutation (80-90 % of SM cases). Some of TKIs (imatinib mesylate and midostaurin) had been successfully used in clinical trials and were approved for treating prognostically unfavorable mastocytosis. However, in some patients exclusive TKI treatment does not result in long-lasting remission due to therapy resistance induced by KIT activating mutations as well as other additional somatic mutations and molecular changes. For the purpose of comparative analysis, the review provides the results of major clinical trials dealing with various methods of mastocytosis treatment.