European panel reviewing infections linked to Tysabri

By Robert Weisman
Globe Staff / October 24, 2009

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Shares of transatlantic biotechnology partners Biogen Idec Inc. and Elan Corp. tumbled yesterday after European regulators said they were examining 23 cases of patients who developed potentially fatal brain infections after taking the companies’ multiple sclerosis drug Tysabri. That is twice as many cases as previously reported.

The European Medicines Agency, which regulates drugs in Europe, said it will review the risks and benefits of Tysabri and discuss whether added measures are needed to assure safety.

The move sent the stock of Biogen Idec, based in Cambridge, down $3.42, or 7.2 percent, to $43.81 on the Nasdaq exchange. Shares of Elan, an Irish drug maker that markets Tysabri in Europe, plunged $1.13, or 17.5 percent, to $5.31 on the New York Stock Exchange.

Biogen Idec spokeswoman Jennifer Neiman said the incidents of the brain infection, progressive multifocal leukoencephalopathy, remain extremely rare - well within the range of one in 1,000 cases noted on the drug’s label.

“Tysabri is a very compelling option for the treatment of multiple sclerosis,’’ Neiman said, “and overall, the benefit-risk profile for the product continues to be very favorable.’’ She said Tysabri is the only MS therapy that has been shown to stop - and in some cases reverse - the progression of the disease.

Al Sandrock, senior vice president and head of neurology research and development at Biogen Idec, said the company was discussing with global regulators a change to the wording on Tysabri’s label that would reflect an increased risk the longer patients took the drug.

Robert Weisman can be reached at