Fingolimod (FTY720) phosphate, approved for treatment of highly active relapsing-remitting (RR) MS, acts as a functional antagonist of the sphingosine 1-phosphate (S1P) receptor subtypes and its binding to S1P1, mainly expressed on the lymphocyte surface, results in inhibition of lymphocyte leakage from lymph nodes thus determining a reversible redistribution of pathogenic lymphocytes as well as reducing their recirculation into the central nervous system (CNS)4. The gene discussed is S1PR1; the disease is myeloid sarcoma.