Biogen: 10 More Infections, 4 More Deaths In Tysabri Patients
Biogen Idec Inc. (BIIB) disclosed 10 more cases of a rare brain
infection among multiple sclerosis patients taking Tysabri, a
medication it sells with Elan Corp. (ELN, ELN.DB), bringing the
total number of affected patients to 95 as of Feb. 2.
The Weston, Mass., biotech company reported that four more of
those patients have died, bringing the total to 20.
The cases of the infection--known as progressive multifocal
leukoencephalopathy, or PML--are closely watched as the MS market
becomes increasingly competitive.
The drug is generally regarded as highly effective, but mostly
used for patients that have stopped responding to other drugs or
have aggressive cases of the disease. Sales rose 16% in 2010 to
$1.2 billion and 56,600 patients were on the drug at the end of
Regulators have said that they watch the cases of PML, but have
concluded that the benefits of the medicine to MS patients outweigh
the risks. Tysabri was withdrawn from the market in 2005 and
relaunched in 2006 with a strict access plan that monitors
There is hope that the development of a blood test may better
determine the chances of patients contracting PML. Although the
overall risk of the infection remains small, it can have
devastating and permanent effects, so a test may make patients and
physicians more comfortable with using the drug. Biogen and Elan
have filed with the Food and Drug Administration to update the
label of Tysabri to include information about certain antibodies in
the blood being a PML risk factor.
The overall global PML rate is now at 1.16 per 1,000 patients.
Although that is above the typical one-in-1,000 rate commonly cited
from clinical trials of the drug, a Biogen spokeswoman said the
current PML figure falls within that seen in the trials' confidence
interval, a statistical tool that helps show the precision of a
The rate is about 1.64 cases per 1,000 patients on the drug for
between two and three years. The incidence is about 0.41 case per
1,000 patients in those using it for one to two years, and it is
essentially nonexistent in patients using it for less than a year.
The rate drops to 1.06 per 1,000 patients for those on the drug
between three and four years.
-By Thomas Gryta, Dow Jones Newswires; 212-416-2169;
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