Tysabri has been implicated in two more cases of a deadly brain infection, raising new concerns about the safety of the multiple sclerosis drug. Tysabri was taken off the market once already after three patients developed the brain infection, known as progressive multifocal leukoencephalopathy, or PML. However, the drug was returned to the market a year later under severe restrictions.
PML attacks the brain and central nervous system and is usually fatal. Symptoms include vision problems, loss of coordination, and memory loss. Patients who survive the disease are often permanently disabled.
According to Elan and Biogen Idec, the makers of Tysabri, two European patients have developed the disease. At this time, one is ambulatory and the other is hospitalized. One patient had been taking Tysabri for 14 months and the other for 17.
The most disturbing aspect of these latest PML cases, however, is that both patients had been taking Tysabri as monotherapy – with no other drugs. It had been theorized that patients contracting PML had done so because of exposure to multiple medications and that monotherapy with Tysabri was less risky.
In 2005, the law firm Parker Waichman Alonso LLP was retained by the estate of Anita Smith, a patient who died from a confirmed case of PML while taking Tysabri. In February 2000, Smith was diagnosed with MS. By April 2002, she was enrolled in a clinical trial involving the MS drug, Tysabri along with 1,200 other patients. In November 2004, while Anita Smith’s health was rapidly deteriorating and she was experiencing severe neurological problems, Tysabri gained a coveted “fast-track” approval from the Food & Drug Administration (FDA). Anita Smith took her last IV infusion of Tysabri in January 2005. On February 24, 2005 she died of the brain infection known as PML; the same disease that killed other Tysabri patients. Four days later, Tysabri sales were halted.
In its 2005 Annual Report, Elan Inc. informed shareholders that it had entered into settlement talks with the lawyers representing Anita Smith’s estate. When contacted, Jerry Parker, the managing partner of Parker Waichman Alonso LLP said the Anita Smith Tysabri case had been resolved, but that the case was confidential.
About 31,800 people take Tysabri, which is also used to treat Crohn’s disease, a digestive condition. The company has forecast 100,000 patients would be on it by 2010, with quarterly sales hitting a $1 billion annual rate by the end of this year. However, these new PML reports could endanger that forecast.
For now, Biogen has said it has no plans to take Tysabri off the market or restrict its use despite the renewed concerns over PML.
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