Abstract: The present invention relates to methods and pharmaceutical compositions for the treatment of systemic mastocytosis. The inventors showed the effect of KPT-251 treatment on SCF-dependent human Mast cell (MC) line without KIT mutation (WT ROSA) and on two factor-independent MC lines with KIT mutations : ROSA ? 417-419 insY and ROSA D816V. KPT is a Selective Inhibitor of Nuclear Export (SINE) that specifically inhibits the activity of the exportin-1 (XPO1). KPT-251 treatment induces minimal toxicity in non-cancerous hematopoietic cells both in vitro and in vivo. In particular, the present invention relates a method of treating systemic mastocytosis in patient in need thereof comprising administering to the patient a therapeutically effective amount of a XPO1 inhibitor.