The popular multiple sclerosis drug, Tysabri (natalizumab), appears to promote a rare brain infection and is linked to the death of another multiple sclerosis patient.
This would be the fourth such infection reported among Tysabri users in five months since the drug was re-introduced to the U.S. market in 2006, reports bizjournals.
It was pulled from the market in February 2005, after three patients contracted a brain infection, two fatally.
*New * The American patient’s death was reported to Cambridge, Mass-based Biogen Wednesday. The patient had been diagnosed with PML, or multifocal leukoencephalopathy. The virus invades the brain causing irreversible damage.
Four cases have been reported since the drug was introduced in 2006. Three have died. This patient had received 14 Tysabri infusions before falling ill.
Reuters reports that the fourth case of infection occurred in a European patient who had been taking Tysabri exclusively for 26 months.
The researchers, who conducted an autopsy on an MS patient, tell Reuters, that it may be possible to make the drug safer by giving patients treatment "holidays" from time to time to allow the brain's immune protection to recover.
Tysabri is the second-best selling drug for Biogen Idec and is co-owned by Elan Corp, a drug company in Ireland.
Severe brain infection is predicted by drug makers to occur in one in every 1,000 patients.
"Whether or not treatments other than prolonged, uninterrupted dosing may benefit patients with MS should be tested in controlled clinical trials," Dr. Olaf Stuve, a neurologist at the University of Texas Southwestern Medical School in Dallas, said in a statement.
43,000 people have reportedly taken the drug since 2006.
Fred Baron, a Democratic party fundraiser and well-known environmental trial lawyer, sought treatment with Tysabri for his multiple myeloma, a cancer of the bone marrow, though that was considered experimental.
His condition became known when his son, Andrew, fought with the Mayo Clinic to obtain permission to use the Tysabri. Baron died in October.#