Biogen has announced 4 new PML cases in MS patients on Tysabri, and one new death. From Reuters, December 16, 2010:

Quote:Biogen reports four more Tysabri cases, one death

* 79 confirmed PML cases as of Dec. 2, with 16 deaths

* Estimated incidence of PML per 1000 patients is 1.0

NEW YORK Dec 16 (Reuters) - Four more patients taking Biogen Idec's (BIIB.O) multiple sclerosis drug Tysabri have developed the serious brain infection known as PML and one of them died, according to the biotechnology company's monthly update.

The four new confirmed cases of potentially fatal progressive multifocal leukoencephalopathy, or PML, were detected between Nov. 2 and Dec. 2, the company said. That brought the total number of confirmed cases as of Dec. 2 to 79, with 16 deaths.

Biogen, which markets the drug with Ireland-based partner Elan Corp Plc (ELN.I), said the rate of PML cases per 1,000 patients has edged slightly higher to 1.0 from 0.96 and is likely due to more patients being on the drug for more than two years.

The chances of contracting PML tend to increase the longer a patient is on the drug, which is considered the most important growth driver for Biogen and Elan. The incidence of PML cases per 1,000 patients who have received between 1 to 12 infusions of Tysabri is just 0.01, but that rises to 2.05 at more than 24 infusions, according to Biogen's statistics.

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(Reporting by Bill Berkrot. Editing by Robert MacMillan)



The entire article can be seen here.