Phase 2 Midostaurin in Aggressive Systemic Mastocytosis and Mast Cell Leukemia

Inclusion criteria * At least 18 years of age. * Karnofsky performance status (KPS) of \> 30% (equivalent to ECOG 0 to 3) * Mast cell disease, histologically confirmed and documented to be * Aggressive systemic mastocytosis (ASM) OR * Mast cell leukemia (MCL) meeting the following criteria * Meets criteria for systemic mastocytosis * Biopsy indicates diffuse infiltration by atypical, immature mast cells * Bone marrow aspirate smears show at least 20% mast cells * Confirmed availability of tissue sample within 6 months prior to entry into study, for evaluation of KIT mutation status of the tumor cells. Subjects who have systemic mastocytosis PLUS eosinophilia AND known positivity for FIP1L1-PDGFR-alpha fusion are eligible only if they have demonstrated relapse or disease progression on prior imatinib therapy * Blood levels of liver enzymes within normal limits (EXCEPTION: If the sole cause of elevated blood levels of liver enzymes is ASM/MCL, then AST and ALT ≤ 4X upper limit of normal (ULN), and/or bilirubin ≤ 4X ULN) * Serum creatinine \< 2.0 mg/dL * If ANC \< 1500/mm3; Hb \< 10 g/dL; platelets \< 75,000/mm3; AND/OR other blood values are \> grade 2, then the relationship of these cytopenia(s) should be established as related to ASM or MCL on the basis of presence of mast cell infiltrate in the screening bone marrow exam and/or the presence of disease-related hypersplenism * Prior use of glucocorticoids must be tapered off within 14 days of Day 1 of midost…