EMEA links 24th PML case to Tysabri

European regulators offer yet another update on Tysabri-linked cases of progressive multifocal leukoencephalopathy: The grand total is now 24, up from 23 last week and just 13 some six weeks ago. Of those 24 patients, four died.

The numbers are coming thick and fast now because the European Union is reviewing the safety of Tysabri, the top-selling multiple sclerosis drug marketed by Elan and Biogen Idec. And as the EMEA and U.S. FDA consider whether they need to take further measures to maximize patient safety, the companies are looking for ways to somehow mitigate the PML risk, either with prevention, quick diagnosis, treatment, or all of the above.

Tysabri hit the market in 2005, but was withdrawn just a few months later when a few patients developed PML. It was reintroduced in 2006 in the U.S. under a strict risk-management program; in Europe, the drug comes under varying levels of restriction and oversight. Company executives always warned that PML probably would resurface, so it's not an enormous surprise that it did. And many MS patients obviously believe the risk of PML is worth the drug's benefits, or they wouldn't be using Tysabri.

But analysts say the fact that 10 previously unknown cases were identified just in the last six weeks is "of particular concern," Pharmalot reports, quoting UBS analysts Guillaume van Renterghem and Martin Wales. And that was before case No. 24 was announced. We'll have to wait and see if the numbers continue rising--and how patients and markets respond.

- read the Pharmalot post
- check out the Reuters news