Biogen Idec Inc. (NASDAQ: BIIB) just came out with an SEC filing showing that on December 11, 2008, regulatory agencies were notified of a confirmed case of progressive multifocal leukoencephalopathy.  In other words, it found another PML case in a multiple sclerosis patient treated with TYSABRI. This is also affecting shares of its partner Elan Corp. plc (NYSE: ELN).

This was in the commercial setting in the European Union as part ofTYGRIS: TYSABRI Global Observational Program in Safety — ROW.Additional notes issued are as follows:

• The diagnosis was made based upon the detection of JC Virus (JCV) DNAin the cerebrospinal fluid (CSF) in the setting of clinical signs,symptoms and magnetic resonance imaging (MRI) findings consistent withthe diagnosis of PML.
• Patient Background: Patient has a history of MS and prior diseasemodifying therapies, including beta-interferons; Patient receivedapproximately 26 months of TYSABRI monotherapy; Clinical vigilance ledto early identification of signs and symptoms of possible PML andclinical evaluation which included MRI scanning and CSF testing;Patient is under the care of patient’s treating physician.

Shares are now trading down 8% pre-market at $43.05, but this is onvery thin trading volume and the spread appears to be very wide.  As a reminder, these PML risks have been associated with TYSABRI and the company sees this from time to time now.  To see how much this stock bounced off of lows after the dust settles, the 52-week trading range $37.21 to $73.59.

Elan Corp. plc (NYSE: ELN) is its partner, and its shares are down 6% pre-market at $6.74.

Jon C. Ogg
December 15, 2008

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