Tysabri Patient Dies of Brain Infection, First Death Since Drug Re-Introduced

12/19/08Follow @xconomy

A patient taking Biogen Idec’s fastest-growing multiple sclerosis drug has died from a rare brain infection. The patient, a woman in the U.S., was diagnosed in October with the PML brain infection after taking natalizumab (Tysabri) for her neurodegenerative disease, said Naomi Aoki, a spokeswoman for the Cambridge, MA-based biotech company.

The death represents the first fatality from PML (progressive multifocal leukoencephalopathy) for a patient taking the drug since it was re-introduced to the market in July 2006, Aoki says. But it’s not an isolated case. Two patients in Europe were diagnosed with the infection in late July, and another European patient was diagnosed earlier this week. The two people who got the brain infection in July are still alive, and “have seen improvement,” Aoki says.

The product, an antibody drug designed to block cells of the immune system from attacking otherwise healthy nerves, has a history of also making patients susceptible to infection. Biogen Idec (NASDAQ: BIIB) and its partner, Irish drugmaker Elan, yanked it off the market in February 2005 after two cases of the brain disease were confirmed among patients taking the drug; a month later, a third case was confirmed. The FDA allowed natalizumab to return to the market in July 2006 after determining the drug’s benefits outweighed the risks, since it is the most effective medicine yet at reducing the risk of multiple sclerosis flare-ups. It is administered now under a strict patient monitoring system that looks for signs of PML.

By the end of September, the drug was being taken by more than 35,000 patients worldwide, and it is Biogen’s fastest-growing product. Since 2006, the prescribing information included with the drug has stated that about one in 1,000 patients who take Tysabri run the risk of getting PML.

So it may not be a surprise that a patient died—but any news of this death could still be harmful to Biogen, said Christopher James, an analyst with Rodman & Renshaw in New York, in a note to clients today. After the news, shares of Biogen Idec dropped 2.3 percent to $46.88 at 1:22 pm Eastern time today.

“Given the expected negative attention that this death will attract in the medical literature and media, we believe there is an increased risk to owning shares of both Biogen Idec and Elan,” James said.

The patient’s medical history will surely be analyzed and discussed by doctors seeking ways to best manage PML. The patient had taken 14 infusions of natalizumab over a little more than a year before she was diagnosed with the disease, as I reported back in October. About 18,000 patients have taken Tysabri for more than a year, 9,500 have been on the medicine for more than 18 months, and 3,700 have been using it for two years or more, James said. Based on those numbers, “we believe the risk of PML remains below the rate of 1 in 1,000 indicated in the label.”

He predicts the drug will generate $1.8 billion in worldwide sales in 2012.

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