An estimated 14,000 patients across the globe are currently taking Elan and Biogen IDEC's multiple sclerosis treatment Tysabri, a year after the drug's return to market.
In the US, over 8,600 patients are on Tysabri and over 1,800 physicians have prescribed the therapy, the drug's marketers said. In the European Union, over 4,300 patients are on Tysabri therapy. An additional 1,000 patients are taking the drug in global clinical trials.
An FDA panel allowed Tysabri back on the market in June 2006 under a restricted distribution program. The agency ruled that Tysabri could only be prescribed, distributed and infused by healthcare providers registered with the “Tysabri Outreach: Unified Commitment to Health (TOUCH) prescribing program.” Before Tysabri treatment can start, patients must undergo a magnetic resonance imaging (MRI) scan. Then, patients on Tysabri are to be evaluated at three and six months after the first infusion, and every six months after that, with their status being reported directly to Biogen IDEC.
Tysabri was initially approved by the FDA in November 2004, but was withdrawn by Biogen Idec and Elan in February 2005, after three patients in the drug's clinical trials developed PML, a serious and rare viral infection of the brain. Based on this information, FDA put clinical trials of the drug on hold in February 2005.
FDA allowed a clinical trial of Tysabri to resume in February 2006, following a re-examination of the patients who had participated in the previous clinical trials, confirming that there were no additional cases of PML.