The USA Federal Drug Administration (FDA) is investigating a case of progressive multifocal leukoencephalopathy (PML) in a 46 year old European person with suspected MS who was treated with fingolimod (Gilenya).
PML is a rare and potentially fatal viral brain infection characterised by progressive damage to the white matter of the brain. It is caused by the JC virus, which is present in about half of the general population, but symptoms only manifest in people whose immune system has been suppressed, including those on immunosuppressive medication. PML in people with MS is known to be a relatively rare safety risk of natalizumab treatment with most cases of PML occurring after more than two years of natalizumab treatment.
The case appears to be a complex and unusual case of suspected MS, in which a range of treatments (Interferon beta 1a, azathiaprine and several courses of steroids) had been utilised prior to fingolimod. The FDA investigation will determine whether the patient had MS, what might have predisposed the patient to PML, whether the patient had been appropriately tested for the JC virus before treatment was commenced and if PML was in any way related to the fingolimod treatment. The FDA investigation is a normal and cautious approach to any serious adverse event experienced during drug treatments.
The FDA has advised that patients should not stop taking fingolimod without first discussing any questions or concerns with their health care professionals.
The pharmaceutical sponsor of fingolimod, Novartis, reports that approximately 71,000 patients worldwide have been treated with fingolimod.
View the FDA statement here