Fingolimod-associated PML in a patient with prior immunosuppression

Fingolimod, a sphingosine-1-phosphate receptor modulator, was the first oral disease-modifying drug approved for relapsing-remitting multiple sclerosis (RRMS).1 Fingolimod decreases multiple sclerosis disease activity through a presumed mechanism of sequestration of lymphocytes in lymph nodes, thereby reducing circulating lymphocytes available for entry into the CNS. Its lymphopenic effect has raised concern for predisposition to opportunistic infections.2 Recently, the US Food and Drug Administration (FDA) issued a new warning on labeling for fingolimod following reports of 2 cases of progressive multifocal leukoencephalopathy (PML) associated with fingolimod therapy.3