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Biogen Idec Inc. has identified high-risk patients taking its multiple sclerosis drug Tysabri who have a 1 in 100 chance of developing a potentially deadly brain infection from the medicine.

By analyzing risk factors including the length of time taking Tysabri, previous treatments and results of a blood test for antibodies to the virus that causes the infection, doctors may also spot patients with less than a 1 in 10,000 chance of developing the disease known as progressive multifocal leukoencephalopathy, or PML, a study showed. The drug’s U.S. label says the risk of PML is about 1 in 1,000 after two years of treatment.

The test for the JC virus should boost use of Tysabri over time, with peak sales of as much as $3 billion, said Corey Davis, an analyst at Jefferies & Co. in New York.... Read More - http://www.msrc.co.uk/index.cfm/fuseact ... ageid/1768

Squiff...you just keep coming up with all these reports...great stuff..thanks.

While this report paints a brighter picture for potential Tysabri users, there is couple of items I would like to point out.

One is that they say this is not yet a proven test. Well, that certainly doesn't give one a lot of confidence.

Another is that there is a 4% false negative result. Small but nonetheless it exists.

I also read previously that having a negative JC virus test does not guarantee you won't get the virus and then PML.

One last comment...after two years of use Biogen stated that 37% of Tysabri users experienced relapse/progression free results as compared to 7% of those on placebo. And there we go again with that approx 30% benefit for those using a DMD over nothing. Sound familiar.

Harry