TYSABRI, THE multiple sclerosis drug developed by Elan, carries an increased risk of triggering a potentially fatal brain disease over time, according to the company’s US partner in the drug.
Biogen Idec executives said yesterday that the company had now determined that the risk of patients contracting progressive multifocal leukoencephalopathy (PML) does increase with time. It said it was in contact with the US regulator, the Food and Drug Administration (FDA), on changing the label on the drug’s prescribing information to reflect the new conclusion.
As recently as last month, Biogen said it would be premature to draw such a conclusion.
The admission came in a conference call by Biogen following publication of its third-quarter figures yesterday. Those figures showed that the number of people signing up for Tysabri had slowed again in the third quarter following a stronger performance earlier in the year.
According to Geoffrey Meacham, an analyst at JP Morgan, only 223 net new patients were added per week in the latest quarter, down from 262 a week in the second quarter.
A total of 46,200 people are now on Tysabri worldwide, up from 43,300 at the end of June and 40,000 six months ago.
Shares in both Elan, which reports its third-quarter numbers today, and Biogen were down over 2 per cent yesterday following the news.
Biogen chief executive Jim Mullen blamed the impact of European summer holidays for the lower patient additions during the quarter.
Tysabri was temporarily withdrawn from the market in 2005 after being linked with PML, a rare condition. It was reintroduced in 2006 following a safety review and strong support from MS patients. Since then, 13 cases of PML have been reported.
Biogen ceased announcing new cases of the disease earlier this year, saying it wanted to focus on the benefits of the drug rather than its risks.
The company declined to say whether the label change was requested by the FDA or offered voluntarily.
Nor did it say what new information led the company to reach its latest conclusion. Biogen said the rate of infection was still within the range of 1-in-1,000 listed on the drug’s prescribing information.
In an update last month, the FDA wrote: “The risk for developing PML appears to increase with the number of Tysabri infusions received. The number of monthly infusions of Tysabri in the 13 patients who developed PML [since it returned to market in 2006] ranged from 12 to 35 infusions. The average number of infusions received before the diagnosis of PML was 25.
“There is minimal experience in patients who have received more than 35 infusions of Tysabri.”
However, the FDA said that it was not at this time requiring changes to Tysabri’s prescribing information regarding PML. – (Additional reporting, Reuters)
