In December 2014, important label changes were made to the prescribing information for Tecfidera® (dimethyl fumarate, Biogen Idec) including information regarding an individual who developed PML. Most recently, Biogen has confirmed report of a second case of PML (progressive multifocal leukoencephalopathy, a viral infection of the brain that often leads to death or severe disability) that occurred in a person taking Tecfidera. According to the company, the 64-year-old patient has primary progressive MS and experienced severe and prolonged lymphopenia (decreased white blood cells) during treatment with Tecfidera. Severe and prolonged lymphopenia is a known risk factor for PML and Consideration should be given to interrupting treatment if lymphocyte counts are low for more than six months. The patient is stable and is not hospitalized. Biogen has reported the case to the U.S. Food and Drug Administration (FDA).
PML is caused by the re-activation of a virus called the JC (John Cunningham) virus, a common virus to which many people have been exposed. PML has emerged in people using other medications, including the MS treatment Tysabri® (natalizumab, Biogen), and the MS treatment Gilenya® (fingolimod, Novartis AG).
It is not possible at this point to determine a person’s risk for developing PML because there have been so few cases in people taking Tecfidera. There have been two reported cases of PML in people with MS among the more than 155,000 individuals who have been treated with Tecfidera to date.
The symptoms of PML are diverse and can be similar to MS symptoms. For this reason, individuals should be alert to any new or worsening symptoms and report them promptly to their MS healthcare provider. Learn more about the risk factors and symptoms of PML from the web site of The PML Consortium. Individuals who have concerns about this report should discuss it with their MS healthcare providers.
If and when the FDA or Biogen provide additional information or recommendations for people taking Tecfidera or other MS medications, the National MS Society will share it as soon as possible.