European regulators said in a report published late last week that the number of cases of a rare brain infection linked to Biogen'sTysabri multiple sclerosis drug are much higher than previously disclosed. And so the European Medicines Agency is reviewing the benefits and risks of the med, which is already under tight regulatory supervision in the US, The Pink Sheet reports.
The EMEA counted 23 cases of the brain infection PML since Tysabri reentered the market in 2006 (here is the press release). Three more cases came to light during clinical trials, pushing the total to 26 out of more than 46,000 patients who have received the drug. The last count by the FDA was 13 cases given patients in the general population.
Tysabri was originally granted a fast-track approval by the FDA in late 2004 because it appeared much more effective at slowing the symptoms of multiple sclerosis than current treatments. Regulators will be weighing those benefits as they re-consider what seems to be a growing risk of PML, a potentially deadly brain infection caused by a common virus that only attacks people with compromised immune systems. The first clinical cases of PML knocked Tysabri off the market soon after launch.
The drug was removed from the market shortly after its 2005 launch over PML links and was back on the market in July 2006. But Biogen admitted in its quarterly earnings call last week that the risk of PML infection increases the longer a patient takes Tysabri. Biogen is working on a label change, just one month after the FDA released a safety alert. Biogen insists the overall risk of infection remains roughly 1 in 1,000.
In a research note today, Cowen & Co. analyst Ian Sanderson writes that the issue for the FDA and the EMEA is whether additional measures beyond the current REMS program are required to ensure safe use, although neither agency is considering removing Tysabri. "We believe physicians and patients will become incrementally cautious in their Tysabri use as the number of PML cases continues to rise, so we are cutting Tysabri patient estimates by 55 percent to 60 percent in 2015 - to 25,000 patients from our previous target of 59,000 patients - reflecting 10 percent average annual decline from today's 46,000 patient population," he concludes.
Disclosure: Ed Silverman is an editor at The Pink Sheet