The Multiple Sclerosis (MS) drug Tysabri (natalizumab) has been linked to Progressive Multifocal Leukoencephalopathy (PML), a rare but severe brain infection that can cause permanent disability or death. Our law firm is now evaluating potential Tysabri lawsuits on behalf of people who were injured by this side effect.
UPDATE: At least 6 Tysabri PML Lawsuits Filed Against Biogen Idec, Inc.
September 18, 2013 — The FDA has received 395 reports of PML in Tysabri patients, including 92 deaths. At least six people who had PML after using Tysabri have filed lawsuits alleging that Biogen Idec Inc. did not warn about the risk. Click here to read more.
May 17, 2012 — In a new study, researchers have confirmed that Tysabri patients who tested negative for the JC-virus had essentially zero risk of developing PML during treatment. Furthermore, experts determined that Tysabri patients who had the highest risk for PML had three risk factors: a history of using immunosuppressant medications, testing positive for the JC-virus, and long duration of Tysabri treatment. The new information will help physicians more safely prescribe Tysabri to new patients.
FDA Drug Safety Communication
The U.S. Food and Drug Administration has issued a new Drug Safety Communication to inform the public that they have identified a way to determine whether Tysabri patients are at higher risk of developing Progressive Multifocal Leukoencephalopathy (PML), a rare but serious type of brain infection.
What is PML? PML occurs in the part of the brain called the “myelin,” which covers and protects nerves in the white matter. The myelin is a layer of protein and fatty matter that helps nerve impulses travel quickly and efficiently in the brain. PML is caused by a virus that attacks the myelin, and can quickly cause severe damage to the central nervous system, disability, and death.
Researchers already suspected that a risk factor for PML was the John Cunningham (JC) virus, which is thought to be latent and harmless in 40-80% of the adult U.S. population. It can be reactivated when patients take certain medications, including Tysabri. It often causes problems for people with weakened immune systems. Once a patient develops PML, there is no way to cure the infection.
The link between Tysabri and PML was well-known. Tysabri weakens a person’s immune system, making them more susceptible to PML and other infections. Because of the risk of PML, Tysabri was pulled off the market in 2005, and then re-introduced in 2006 with new warnings. Meanwhile, the drug-company kept public records about the rate of PML, and funded research to screen patients who have a latent JC virus.
The drug-company recently gained FDA-approval for a diagnostic test that can identify people who have a latent JC virus and would be at a higher risk of developing PML if they took Tysabri. The test is called the Stratify JCV Antibody ELISA test.
The FDA also announced updates to the safety labeling for Tysabri that will include information that testing positive for the JC virus has been identified as a risk factor for developing PML.
Risk Factors for PML
The FDA identified three risk factors that increase a person’s risk of developing PML. Patients with all three risk factors have an estimated risk of 11/1,000 for developing PML.
- The presence of anti-JC virus antibodies, which can now be tested for using a blood test
- Longer Tysabri treatment, especially more than 2 years.
- Prior treatment with an immunosuppressant medication (for example: mitoxantrone, azathioprine, methotrexate, cyclophosphamide, or mycophenolate mofetil)
Tysabri Overview
Tysabri (natalizumab) is a medication used to treat people with multiple sclerosis or Crohn’s disease. It belongs to a class of medications called “immunomodulators,” which works by preventing certain immune cells from causing damage to a person’s nerves and spinal cord.
Multiple sclerosis (MS) is a disease in which nerves in the body degenerate over time. People with MS may experience weakness, numbness, gradual loss of muscle control, incontinence, and problems with speech and vision. Tysabri is used in patients who experience “flare-ups” of symptoms, and it is used to prevent these episodes. It is also used to slow the worsening of disability.
Crohn’s Disease is a condition in which the body’s immune system attacks the lining of a person’s intestinal tract. It causes pain, diarrhea, weight loss, and fever. It is caused by an over-reaction of a person’s immune system, in which the body can’t tell the difference between normal tissue and foreign substances. As a result, a person with Crohn’s disease suffers from chronic inflammation. Crohn’s disease may affect the small intestine, large intestine, rectum, or mouth.
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