Friday, May 8, 2009

Risk of PML Associated with Tysabri Use Is Lower Than Previously Thought

Researchers have more information now on the potential link between PML (progressive multifocal leukoencephalopathy) and the drug Tysabri. It appears, that the risk of contracting PML from using Tysabri is less than was previously estimated. It was previously thought that the risk of PML was something like 1 in 1000 of Tysabri users, but, according to Carmen Bozic, VP and global head of drug saftey and risk management for Biogen Idec (maker of Tysabri), that stat is more like 1.2 per 10,000. It is welcomed news. Tysabri is approved in over 40 countries and, in the US, is even approved for use in some cases of Crohn's disease. It's an effective medication which works by preventing the white blood cells from entering the brain and attacking nerves. Hopefully, the new statistic will help quell fears multiple sclerosis patients have about potential treatment with Tysabri.

Tysabri Outreach: Unified Committment to Health is a mandatory program for patients, physicians and infusion centers throughout the US, and it is the group responsible for the new results on Tysabri. Its goal is to faciliate the "appropriate and informed use of Tysabri." It has a sister program called the Tysabri Global Observation Program in Saftey, which is a global program that monitors the long term saftey of Tysabri. The results of long term exposure to Tysabri have previously been unknown and, therefore, concerning to those who take the medication. But, says Dr. Bozic, "Of the 52,000 patients who have taken the drug, there have been 6 cases of PML, or an incidence of approximately 1.2 per 10,000 patients treated. It's trending lower than what we saw in the clinical-trial setting." Once again, more welcomed news. Helen Yates, Chief Executive of the Multiple Sclerosis Resource Centre said, "It is obviously good news to see that the incidence of PML looks much lower than was first supposed. We would still like to see more investigation into the potential causal links between Tysabri and PML and of course the potential to develop this life-threatening condition does still remain." There is some risk with all medications, but, Ms. Yates is right, if a 'causal link,' between the drug and the infection could be identified or dismissed, it would allow patients to know more accurately the risks associated with Tysabri use or researchers could hone in on the real cause of the PML infection. Nevertheless, the current data helps put to rest some unwarranted fears about Tysabri use.
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