Last week, the U.S. Food & Drug Administration (FDA) announced it was updating the label of <"http://www.yourlawyer.com/topics/overview/tysabri">Tysabri (natalizumab) to include additional information about the risk of progressive multifocal leukoencephalopathy (PML), a rare but serious brain infection. According to a Drug Safety Communication issued by the FDA, the Tysabri label will also now include safety information about patients who have taken other drugs that suppress the immune system, who may be at a higher risk for PML.
Tysabri, marketed by Biogen Idec Inc. and Elan Corp., is approved for the treatment of multiple sclerosis (MS) and Crohn’s disease. PML attacks the brain and central nervous system and is usually fatal. Symptoms include vision problems, loss of coordination, and memory loss. Patients who survive the disease are often permanently disabled. Because of the PML risk, Tysabri was actually removed from the market briefly in 2005, after three patients in a Tysabri clinical trial developed the disease.
Though considered one of the most effective multiple sclerosis treatments available, Tysabri is generally only used in people who have not responded to other treatments. Because of its association with PML, Tysabri is now available to patients only through a restricted distribution program called the Tysabri Outreach Unified Commitment to Health (the TOUCH Prescribing Program).
As weâ€™ve reported in the past, Biogen Idec and Elan provide monthly updates on the number of PML cases associated with Tysabri. As of early March, 102 cases of the infection were confirmed in Tysabri patients, including 21 deaths.
According to the FDA’s Drug Safety Communication, the revised Tysabri drug label includes:
â€¢ A table summarizing rates of PML with Tysabri use according to the number of infusions (how long the drug is taken or duration of exposure).
â€¢ Information on a newly identified PML risk factor. Patients who took an immune system suppressing medication (e.g., mitoxantrone, azathioprine, methotrexate, cyclophosphamide, mycophenolate) prior to taking Tysabri have been shown to be at an increased risk for developing PML. The Tysabri label already warned that using immune system suppressing medications at the same time as Tysabri may increase the risk of developing PML.
Data from the past year have confirmed that the risk of developing PML is greater in patients who have received more than 24 Tysabri infusions (corresponding to two years of continuous treatment) compared to patients who have received fewer than 24 infusions, the FDA said in its Drug Safety Communication.
The FDA said it anticipates that the new PML information in the Tysabri label will aid healthcare professionals in assessing the risk for PML and in discussing that risk with their patients.
The FDA continues to advise patients to discuss any questions or concerns about Tysabri and the risk of PML with their healthcare professional. Patients should report any Tysabri side effects they experience to their healthcare professional.