Firms’ Shares Drop on Tysabri Illness Report

Shares of Elan Corp. and Biogen Idec Inc. tumbled after a fourth possible case of a rare and often fatal nerve disorder was reported in a patient taking the companies’ withdrawn Tysabri multiple sclerosis drug.

Biogen and Elan are investigating the newest report of a patient who took Tysabri and has symptoms consistent with the disorder, Lenore Gelb, a Food and Drug Administration spokeswoman, said Thursday.

Elan shares fell $1.14, or 14.3%, to $6.85. Biogen lost $1.70, or 4.3%, to $38.07.

The case hasn’t been confirmed to be the disease, called progressive multifocal leukoencephalopathy, as have three other cases, Gelb said. Biogen and Elan withdrew Tysabri on Feb. 28 after the potential $1-billion drug was linked to the disorder. Two of three patients who developed the disease have died.

“We just don’t know what’s going on behind the scenes,” said Mike Booth, an analyst at Canaccord. “The efficacy data is impressive, but the safety data is frankly worrying. If it is a compound that kills people, I don’t think the FDA will allow it back on the market.”

Biogen spokeswoman Amy Brockelman declined to confirm the fourth case of PML, saying only that the person was still alive.

Shares of Dublin-based Elan had climbed 77% since April 28 on optimism that the FDA would let Tysabri sales resume. Shares of Cambridge, Mass.-based Biogen had risen 11% in that period. Thursday’s report on a possible fourth case of PML tied to Tysabri raised concerns about whether the information should have been disclosed sooner.

Tysabri was the first new type of MS treatment in eight years when it was approved in the U.S. in November based on partial results of a two-year study.