What is Progressive Multifocal Leukoencephalopathy?
Progressive multifocal leukoencephalopathy (PML) is caused by the reactivation of a common virus in the central nervous system of immune-compromised individuals. Polyomavirus JC (often called JC virus) is carried by a majority of people and is harmless except among those with lowered immune defenses. The disease occurs, rarely, in organ transplant patients; people undergoing chronic corticosteroid or immunosuppressive therapy; and individuals with cancer, such as Hodgkin's disease, lymphoma, and sarcoidosis. PML is most common among individuals with acquired immune deficiency syndrome (AIDS). Studies estimate that prior to effective antiretroviral therapy, as many as 5 percent of people with AIDS eventually developed PML. For them, the disease was most often rapidly fatal.
With current HIV therapy, which effectively restores immune system function, as many as half of all HIV-PML patients survive, although they sometimes have an inflammatory reaction in the regions affected by PML. The symptoms of PML are the result of an infection that causes the loss of white matter (which is made up of myelin, a substance the surrounds and protects nerve fibers) in multiple areas of the brain. Without the protection of myelin, nerve signals can't travel successfully from the brain to the rest of the body. Typical symptoms associated with PML are diverse, since they are related to the location and amount of damage in the brain, and evolve over the course of several days to several weeks. The most prominent symptoms are clumsiness; progressive weakness; and visual, speech, and sometimes, personality changes. The progression of deficits leads to life-threatening disability and death over weeks to months. A positive diagnosis of PML can be made on brain biopsy, or by combining observation of a progressive course of the disease, consistent white matter lesions visible on a magnetic resonance image (MRI) scan, and the detection of the JC virus in spinal fluid. (PML Symptoms)
Is there any treatment for PML?
Currently, the best available therapy is reversal of the immune-deficient state. This can sometimes be accomplished by alteration of chemotherapy or immunosuppression (even if it means losing non-vital transplanted organs). In the case of HIV-associated PML, immediately beginning anti-retroviral therapy will benefit most individuals.
What is the prognosis for PML
The mortality rates for those with HIV-PML have fallen dramatically from approximately 90 percent to around 50 percent according to most reports. For non-AIDS individuals with PML, the prognosis remains grim; the disease usually lasts for months and 80 percent die within the first 6 months, although spontaneous improvement has been reported. Those who survive PML can be left with severe neurological disabilities.
Raptiva and PML Progressive Multifocal Leukoencephalopathy
In October 2008, the product labeling for Raptiva was revised to highlight in a boxed warning the risks of life-threatening infections, including PML. At that time, the FDA directed Genentech, the manufacturer, to develop a risk evaluation and mitigation strategy (REMS) to include a medication guide to educate patients about the drug's risks.
The FDA strongly recommends that health care professionals carefully monitor patients on Raptiva, as well as those who have discontinued the drug, for any signs or symptoms of neurologic disease, and that they periodically reassess the benefits of continued treatment. Patients should be aware of the symptoms of PML and contact their health care professionals immediately if they experience any such symptoms.
Raptiva is a once-weekly injection approved for adults with moderate to severe plaque psoriasis who are candidates for systemic (whole body) therapy or phototherapy. The drug works by suppressing T-cells (blood cells that help fight infection) in the immune system. These cells, when activated, migrate to the skin and cause inflammation which results in the red, inflamed and scaly patches of skin, which is associated with psoriasis. By suppressing T-cells, Raptiva decreases the function of the immune system which increases a patient's susceptibility to infections.
Health care professionals and consumers may report serious adverse events (side effects) or product quality problems with the use of this product to the FDA's MedWatch Adverse Event Reporting program online, by regular mail, fax or phone.
