Another Tysabri patient has developed progressive multifocal leukoencephalopathy or PML. Ten cases of the often-fatal brain infection have now been associated with Tysabri since it was reintroduced in 2006. Of those patients, at least 3 have died. According to a report in the Boston Business Journal, Biogen Idec disclosed the latest case on Friday, and a total of three have been reported this month alone.
In the U.S. Tysabri was taken off the market in 2005 after three patients in clinical trials developed PML. But the drug was reapproved in 2006, although it was subject to restrictions. Tysabri is now available only to patients with relapsing multiple sclerosis (MS) or Crohn’s disease (CD) who are enrolled in the risk minimization plan called the TOUCH Prescribing Program. Under the TOUCH Prescribing Program, every Tysabri-treated patient is closely monitored and followed for the occurrence of PML and other serious opportunistic infections.
As we reported previously, Biogen Idec posts an Tysabri update on its website every Friday, which includes reports of PML. PML attacks the brain and central nervous system and is usually fatal. It is caused by a polyomavirus, called the JC virus. The JC virus is often acquired during childhood. Most adults have been infected with the JC virus but do not develop PML. The virus appears to remain inactive until something (such as a weakened immune system) allows it to be reactivated and start to multiply. Symptoms include vision problems, loss of coordination, and memory loss. Patients who survive the disease are often permanently disabled.
People with a weakened immune system or people taking drugs that suppress their immune system (immunosuppressants) are most likely to get the disease. Earlier this month, we reported that the Food & Drug Administration (FDA) was looking into a link between the lymphoma drug, Rituxan, and the disease. In April, the psoriasis drug Raptiva was voluntary withdrawn from the market after three patients died from PML.
According to The Wall Street Journal, Biogen Idec stock has taken a hit because of the latest Tysabri news. On Monday, the company’s stock dropped 5.5% to close at $47.32 on the Nasdaq Stock Market.
According to the Boston Business Journal, the 10th Tysabri PML case occurred overseas, in a patient who had been taking the drug for 30 months. Some have begun to theorize that long-term treatment with Tysabri may increase PML risks, and according to the Business Journal, some doctors have begun having patients take a “holiday” from the drug.
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