From Cinderella story, to heartache, to back on the market, back to side-effect disaster, it's been one wild ride for multiple sclerosis drug Tysabri and the stocks of its owners, Biogen Idec
The drug increases the risk of developing progressive multifocal leukoencephalopathy, or PML, a serious brain infection. The infection is caused by the usually relatively harmless JC virus, which the immune system usually takes care of. Tysabri weakens the immune system -- multiple sclerosis is essentially the immune system attacking body's nervous system -- but in the process of trying to control the immune system, Tysabri can potentially allow infections to occur.
Just "potentially" because not everyone has the JC virus floating around their bloodstream, waiting for their host to take an immune-system weakening drug before launching its attack. And no virus means no PML.
The inclusion of the JC virus status as a risk factor for Tysabri patients developing PML is good news for Quest Diagnostics
Tysabri is arguably the best drug available to treat multiple sclerosis, but many of the JC-virus-negative patients haven't taken the drug for fear of the chance of developing PML, however small it may be. With the ability to determine the risk, patients who don't have the virus are more likely to switch from Teva Pharmaceuticals'
Tysabri and the JC virus test are just the sort of innovative thinking the analysts on the Fool's Rule Breakers newsletter look for. See what they think is the next rule-breaking multibagger. Grab a copy of their free report by clicking here.
Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of Teva Pharmaceutical Industries. Motley Fool newsletter services have recommended buying shares of Quest Diagnostics, Teva Pharmaceutical Industries, Pfizer, and Elan. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.