The safety of yet another FDA-approved prescription drug has been called into question. Biogen Idec and Elan Corporation have announced a voluntary suspension in the marketing of Tysabri, a treatment for multiple sclerosis (MS), following a fatal reaction to the drug.
The companies are suspending supply of Tysabri from commercial distribution and have advised physicians to suspend dosing of the drug until further notification. In addition, the companies have suspended dosing in all clinical trials.
In a joint statement, the two pharmaceutical companies said the decision is based on very recent reports of two serious adverse events that have occurred in patients treated with Tysabri in combination with Avonex in clinical trials.
These events involve one fatal, confirmed case and one suspected case of progressive multifocal leukoencephalopathy, a rare and frequently fatal demyelinating disease of the central nervous system. Both patients received more than two years of Tysabri therapy in combination with Avonex.
The companies said their actions have been taken in consultation with U.S. Food and Drug Administration (FDA). Worldwide regulatory agencies are also being kept informed.
The companies said they will work with clinical investigators to evaluate Tysabri-treated patients and will consult with leading experts to better understand the possible risk of PML. The outcome of these evaluations will be used to determine possible re-initiation of dosing in clinical trials and future commercial availability.
"Our ongoing commitment to MS patients has led us to take these steps," said Burt Adelman, MD, executive vice president, Development, Biogen Idec. "Because we believe in the promising therapeutic benefit of Tysabri, we are working to evaluate this situation thoroughly and expeditiously. While we work through this matter, we must place patient safety above all other considerations."
In total, approximately 3,000 patients have been treated with Tysabri in clinical trials of MS, Crohn's disease, and rheumatoid arthritis.
To date, the companies said they have received no reports of PML in MS patients receiving Tysabri monotherapy or in patients with Crohn's disease or rheumatoid arthritis in TYSABRI clinical trials. Biogen Idec has received no reports of PML in patients treated with AVONEX alone, a product that has been on the market since 1996.
