Warning of Liver Injury for Biogen’s Tysabri

Tysabri, a multiple sclerosis drug has been linked to signs of liver injury within six days of taking their first dose.

According to FDA regulators, Biogen Idec Inc and Elan Corp Plc have warned doctors of significant liver injury suffered by some patients taking the drug Tysabri, a monoclonal antibody used to treat MS.

Biogen and its Irish partner Elan Corp. have issued a letter to the doctors saying Tysabri should not be used in patients suffering from jaundice or a liver injury. Patients also should be informed that taking the drug could harm their liver, the letter says.

Since its approval, Tysabri has been under various controversies. It first received FDA approval in November 2004, but was pulled from the market in 2005 after it was linked to a rare and fatal form of brain infection. However, FDA allowed its’ resale under a monitoring program in 2006 after they decided that the drug's effectiveness outweighed its risks.

``This is a drug with a cloud of risk hanging over it, and each additional risk is unwelcome,'' said Jason Kantor, an analyst with RBC Capital Markets in San Francisco. ``I don't think this will have a material impact on use of Tysabri, but if more of these things pile up it will become less compelling.''

According to estimates by Biogen, less than one in 1,000 patients taking the drug for either MS or Crohn's disease suffered from serious liver injury. As of the end of December last year, about 21,000 patients were taking the drug.

This data has been collected from the post-marketing reports, Biogen spokeswoman Shannon Altimari said.

Tysabri had fourth-quarter sales of $129 million. The company estimates that it expects 100,000 patients to be taking Tysabri by the end of 2010, which translates to about $2.8 billion in annual sales at current prices.

Biogen also markets Avonex, one of the world's best-selling MS treatments with sales of $500 million in the fourth-quarter.

Biogen shares fell almost $1.40, or 2.3 percent, to $60.13 in Nasdaq Stock Market composite trading. Elan's American depositary receipts fell $1.54, or 6.3 percent, to $22.77 in New York Stock Exchange composite trading.