A second case of progressive multifocal leukoencephalopathy (PML) has been reported in an MS patient taking Tecfidera (delayed-release dimethyl fumarate), an oral disease-modifying therapy approved to treat relapsing forms of multiple sclerosis.
Biogen reported the case to the Food and Drug Administration (FDA); however, details of the report are not available on the Drugs@FDA website nor on Biogen’s company website.
This case will not likely require any change to the prescription label. The FDA had already updated the Tecfidera label in December 2014 to warn of the risk of PML, following the death of a 54-year old woman with MS who had participated in the DEFINE clinical trial and experienced severe lymphopenia for 3.5 years.
Reports of the earlier case of PML, as well as another fatal case in a patient using a compounded version of dimethyl fumarate for the treatment of psoriasis, were published in an April edition of The New England Journal of Medicine. Surprisingly, the patient with psoriasis who died in August 2014 did not have two of the known risk factors for PML: severe lymphopenia and exposure to immunosuppressive therapy.
Biogen spokesperson Catherine Falcetti told MedPageToday that this most recent case of Tecfidera-related PML involved a patient diagnosed with primary progressive MS who had prolonged severe lymphopenia. Decreased lymphocyte counts (i.e., lymphopenia) is a known side effect of dimethyl fumarate, indicating a lowered immune system.