Labeling Changes For Tysabri Sought By FDA

The Federal Drug Administration has recently issued an alert to health care providers in the US about two new European cases of progressive multifocal leukoencephalopathy or PML that has been linked to the drug Tysabri. The FDA is currently trying to work with the US manufacturers of the said drug, namely Elan and Biogen Idec for a possible amendment to the current product labeling in order to inform patients using the said drug about the cases of PML linked to the use of Tysabri as monotherapy.

Tysabri, also known as natalizumab, is a known FDA approved treatment for multiple sclerosis and Crohn’s Disease. Tysabri is taken intravenously in specified doses every 28 days as treatment. The drug is believed to be effective by reducing the ability of the body’s inflammatory immune cells to pass through the blood-brain barrier and the cell layers lining the intestines and cause damage to nerve cells. The use of Tysabri has proven to be effective in treating the symptoms of multiple sclerosis as well as help prevent relapse of the diseases and offer MS patients with a better quality of life.

The use of Tysabri was first approved for use in the US in 2004 by the United States Food and Drug Administration for treatment of MS. But in 2005, the drug was immediately pulled out of the market by the manufacturers in light of three cases of the rare neurological condition known as PML that was linked to treatment using the drug administered in combination with interferon beta-1a, another known treatment for MS.

After further reviews which resulted in no cases of deaths reported, Tysabri was once again re-approved for use in 2006 but subject to restrictions. The use of the drug was only given to multiple sclerosis patients who have chosen to be enrolled in the TOUCH Prescribing Program. Under this program aimed to reduce the risk associated with the use of Tysabri, patients are closely monitored for any occurrence of PML or any other similar infections.

PML is a fatal infection caused by a polyomavirus called the JC virus. This infection attacks the brains and the central nervous system. The JC virus is often acquired during childhood with most adults having them without developing PML. The virus appears to remain inactive until a weakened immune system triggers it to start multiplying. Tysabri and drugs like interferon beta affect or suppress the body’s immune system, allowing it to weaken and likely cause the infection.

It was once thought that taking Tysabri as monotherapy (used alone)will lessen the risk of MS patients from developing PML. But the two recent European cases of PML developing on Tysabri patients have used the said drug for treating their multiple sclerosis and have not been using any other therapy. The recent incidents have prompted FDA to issue the alert and consider the product labeling of Tysabri to be amended to inform future patients and doctors of the risk.


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