By Thomas Gryta
Of DOW JONES NEWSWIRES
NEW YORK (Dow Jones)--Biogen Idec Inc., Elan Corp. Plc and Roche are planning to form a research consortium dedicated to a rare brain infection that has emerged in patients taking a number of their drugs.

The move comes as cases of progressive multifocal leukoencephalopathy, or PML, have risen sharply in patients taking multiple sclerosis treatment Tysabri, sold by Biogen and Elan, prompting a panel of European regulators to review the drug. The infection, also found in users of several other immune system-suppressing therapies, is often deadly, and its emergence has perplexed physicians and researchers as they balance the risk and reward of these drugs.

It has appeared in patients taking some drugs used after organ transplants, as well as arthritis treatment Rituxan, sold by Biogen and Roche, and Raptiva, a psoriasis drug that Roche's Genentech unit pulled from the market earlier this year because of the issue.
Before these drugs, the condition hadn't shown up in patients with MS, or psoriasis, and was most common in patients with AIDS. There have been some reports in cases of arthritis patients, according to a Roche spokeswoman who declined to provide additional details about the consortium because formal agreements haven't been signed.

PML has been most frequent in users of Tysabri, with 24 confirmed cases since its re-launch in 2006, but generally consistent with the 1-in-1,000 patient rate implied by its label. The drug is subject to a rigorous risk management plan and the companies have been researching PML since its emergence in 2005, which led to Tysabri's temporary withdrawal from the market.

Mariska Kooijmans-Coutinho, Biogen's senior director of clinical trial safety and risk management, detailed the plans for the consortium at a meeting covering various aspects of the infection at the New York Academy of Sciences on Tuesday.
The group plans to pool resources related to PML, including the formation of a global database of cases in an effort to predict, prevent and treat the condition, she said.
The effort will also include non-profit organizations and academic institutions, and she invited other drug companies to join the effort. She noted that the consortium will seek financial and time commitments from companies to ensure stability in the group.

PML is caused when JC virus, which most people carry, attacks the central nervous system in people with weakened immune systems, often leading to an irreversible decline in neurologic function and death.
A higher number of Tysabri patients with PML have survived the infection, with only four dying since 2006, because of close patient monitoring and quick removal of the drug from the body. Regardless, the infection's nature often leaves survivors with varying degrees of disability.

Eugene Major, who runs the Laboratory of Molecular Medicine and Neuroscience at the National Institutes of Health, believes that the risk of PML in Tysabri is generally known, but he warns that the condition may be more common than thought in areas not related to Tysabri.
"It is pretty clear that it is underreported," Major said, noting that the NIH and Centers for Disease Control are forming a collaboration to increase the monitoring of PML in the broader population with the hope of gaining a better understanding of its scope.