Can a test for progressive multifocal leukoencephalopathy or PML provide better safety and comfort for patients taking Tysabri, Raptiva and other powerful immunosuppressant drugs? The manufacturer of Tysabri is betting that it will, the company recently announced that it is working on a new test to detect the virus that causes PML. The test could not only be a breakthrough for Tysabri patients but patients taking all powerful immunosuppressant drugs that can lead to PML and other opportunistic infections.



While Tysabri is probably the drug most associated with PML, it is not the only drug that can cause the disease. Recently, the FDA warned that the psoriasis drug Raptiva was responsible for several cases of PML. When Tysabri was first linked to PML the drug was removed from the market, but later returned to the delight of thousands of MS patients who swear by the drug.

There are very few treatment options available for patients diagnosed with PML. However, this is in a large part due to the fact that the disease is usually not discovered until it's very far advanced. If PML could be detected earlier it is believed that patients might benefit from plasma exchange. It is not clear how successful this treatment would be in PML patients or how early the disease would need to be detected.

When Tysabri returned to the market, Biogen and Elan worked with the FDA to implement one of the most thorough patient warnings ever. After being provided extensive information about the drug's risks, patients are required to sign a document acknowledging that they are aware of the potential risks of the drug. Unfortunately, the other manufacturers of powerful immunosuppressant drugs have not added such detailed warnings to their drugs.

The question of risk/reward has also surfaced with respect to PML and these powerful drugs. Many multiple sclerosis patients demanded the availability of Tysabri arguing that their daily lives were full of extreme pain and Tysabri was their only hope for relief. They were aware of the risks of the drug, but they were willing to take the risk in order to relieve their pain. However, a drug like Raptiva treats psoriasis which is generally not considered to be nearly as serious as multiple sclerosis. With other psoriasis treatments available and the fact that the disease itself is usually not as serious as MS, is it worth taking a risky drug to treat it?

It is also important to realize that Progressive Multifocal Leukoencephalopathy PML is just one of the many serious infections that can develop when medication is intentionally suppressing your immune system. As these drugs gain popularity, it would not be surprising to learn of patients taking these drugs being diagnosed with other opportunistic infections.