This Friday, I will receive my 24th infusion of what many call the most effective treatment for Multiple Sclerosis currently on the market: Tysabri. Despite its effectiveness, the risk of PML (progressive multifocal leukoencephalopathy) continues to haunt neurologists who prescribe the treatment. The only people haunted more are the 67,000+ patients who currently turn to Tysabri as their monthly hope for a halt to the progression of M.S. and its effect on their brains and central nervous systems. Now that Tysabri has been on the market for several years, researchers are able to study PML a little more effectively and it seems that the longer a patient is on Tysabri, the risk of PML increases — from just under one in one-thousand (for those on Tysabri under two years) to a solid one in one-thousand (for those on Tysabri for over two years).
Last week I met with my neurologist to make that all-important decision — to stay on Tysabri or not. Surprisingly, despite the positive results from my treatment, the decision didn’t come easy. I have spent the last several months looking strongly at the benefits and risks of the treatment (and the limited other options currently available to me should I decide to cease treatment). For now we plan to stay the course, continuing treatments at least for another six months or so. And in the meantime, we wait (for oral treatments to finish clinical trials) and we watch (for changes in symptoms or behaviors that could be associated with PML). Below is the most recent news on PML cases resulting from the use of Tysabri in Multiple Sclerosis.
Republished from the National Multiple Sclerosis Society — updated April 29, 2010:
According to information released by Biogen Idec, as of April 6, 2010 there have been 46 confirmed cases of progressive multifocal leukoencephalopathy (PML, a viral infection of the brain that usually leads to death or severe disability) among people who have used Tysabri® (natalizumab, Biogen Idec and Elan Pharmaceuticals) after it became available for prescription in July 2006. The U.S. Food and Drug Administration provides post-marketing safety warnings on Tysabri at this link.
On February 5, 2010, the FDA alerted the public that the risk of developing PML increases with the number of Tysabri infusions received. This new safety information is now included in the Tysabri drug label and patient Medication Guide. Based on the available information, the FDA has stated that the clinical benefits of Tysabri continue to outweigh the potential risks. Revisions to the drug label and patient Medication Guide, with the continued use of the TOUCH Prescribing Program, are intended to maximize the safe use of Tysabri and the identification of new PML cases.
As of the end of March 2010, 67,700 people worldwide have used Tysabri since it was marketed. Although the absolute risk for PML in patients treated with Tysabri cannot be precisely determined, the U.S. FDA and the sponsor have released data suggesting that the risk increases with increasing time on therapy, starting out lower than the one-in-one thousand level that was estimated at the time of Tysabri’s re-approval in 2006, and rising after two years of infusions to about one in one thousand. According to the FDA, the cumulative rate of PML in the U.S. in patients treated with 24 to 36 infusions is similar to the rate seen during clinical trials (about 1 case per 1,000 patients treated), and outside the U.S. the cumulative rate is about 2 cases per 1,000 patients treated. The reasons for this difference are not known. There is insufficient information to determine the risk of PML in those who have been on therapy for three years or more.
Read more, including information on PML by clicking here, being redirected to Kim’s Blog
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