PML: Causes and Treatments

People with immune deficiencies, their doctors and their loved ones need to be aware of a serious and often fatal viral disease called progressive multifocal leukoencephalopathy (PML). PML is caused by the virus polyomavirus JC (also known as the JC virus). The majority of people carry the JC virus and it is usually harmless unless it contracted by a patient with a compromised immune system. It can be harmful for patients who have undergone an organ transplant, for AIDS patients, and for cancer patients, for example.

PML is an infection that affects the white matter in the brain. The white matter is often destroyed in multiple parts of the brain and leaves the nerve fibers unprotected. As a result, nerve signals are not properly received by the body.

Causes

While the JC virus is common, it typically only develops into PML in people with suppressed immune systems. There are a variety of legitimate medical reasons why a doctor might choose to suppress a patient's immune system depending on the patient's circumstances.

For example, a doctor might choose to put a patient on a drug that blocks certain immune cells if the patient has moderate or severe psoriasis. Since its FDA approval in 2003, many patients have taken the prescription drug Raptiva to block white blood cells known as T cells. In patients with psoriasis, T cells are not properly recognized by the body and can lead to inflammation, lesions, and other immune responses. Accordingly, many doctors have prescribed Raptiva to prevent the T cells from being activating and causing psoriasis symptoms.

However, according to the FDA, there have been three confirmed and one potential report of patients taking Raptiva developing PML and dying as a result. All of the patients took Raptiva for three or more years to treat psoriasis. In October 2008, the FDA advised the public of the potential link between Raptiva and PML and in April 2009 Genentech, the manufacturer of Raptiva, issued a voluntary Raptiva recall because of the possibility of potentially dangerous Raptiva side effects.

Symptoms

It is difficult to attribute specific symptoms to PML because the virus can affect any part of the brain and it is the loss of white matter in specific parts of the brain that cause symptoms. Depending on the part of the brain affected, early symptoms can include weakness, lack of coordination, speech or vision impairments, and even changes in personality.

Doctors often conduct a brain biopsy, use MRI imaging, and test for the JV virus in a patient's spinal fluid in order to make a PML diagnosis. PML is almost always fatal and death can occur swiftly, often within weeks of developing symptoms.

Treatments

PML is a difficult condition to treat because it affects patients with compromised immune systems who have other serious medical needs.

Often, treatment requires reversing the patient's immune deficiency. For cancer patients that might mean a change in chemotherapy, which could affect a patient's cancer. For organ transplant patients, that might mean discontinuing immunosuppressant drugs which can allow a body to reject a transplanted organ. For AIDS patients, it is typically recommended that anti-retroviral therapy be provided. However, none of these treatments is known to effectively and consistently treat PML.

For most patients with suppressed immune systems, PML remains a scary risk. However, psoriasis is a condition that does have other treatment options. Alternative psoriasis treatments include other pharmaceutical drugs and ultraviolet light therapy; these options that do not suppress the immune system, and therefore do not increase a patient's risk of developing PML. Many experts recommend a rotation of therapies for psoriasis patients, which can reduce the risk of side effects from any one treatment.