https://ansm.sante.fr/informations-de-securite/tecfidera-et-risque-de-leucoencephalopathie-multifocale-progressive-actualisation-des-recommandations 2020 false false false France French guidelines for drug use pharmacovigilance note leukoencephalopathy, progressive multifocal Dimethyl Fumarate Dimethyl Fumarate lymphopenia drug monitoring dimethyl fumarate lymphocytes