Systemic mastocytosis in adults: a review on prognosis and treatment based on 342 Mayo Clinic patients and current literature

Purpose of review Systemic mastocytosis is a neoplastic disease of mast cells that often harbors a KIT mutation and involves the bone marrow. The current review provides an update on prognosis and treatment of systemic mastocytosis, including investigational drug therapy. Recent findings We have recently examined survival data and treatment outcome in 342 adult patients with systemic mastocytosis seen at our institution. Life expectancy in indolent systemic mastocytosis was not significantly different than that of the control population; however, prognosis was not as good in the WHO indolent systemic mastocytosis variant of smoldering mastocytosis. Prognosis in systemic mastocytosis associated with another myeloid malignancy was significantly better in the absence of morphological features of myelodysplasia or monocytosis. On the contrary, although prevalent, eosinophilia had little prognostic impact. Cladribine and interferon alpha were therapeutically the most effective drugs. Current experience suggests limited treatment success with either imatinib mesylate or other anti-KIT D816V kinase inhibitors. TET2 mutations have recently been described in approximately 29% of patients with systemic mastocytosis, but their pathogenetic or treatment relevance is unknown. Summary Primary data from a large series of patients have enabled delineation of well defined prognostic groups in systemic mastocytosis and clarification of the merits of conventional drugs for aggressive systemic mastocytosis.