The information is readily available on line. For example, from the manufacturer’s website:
“…The detection of anti-JCV antibodies may provide a means to segment, or stratify, multiple sclerosis (MS) patients considering or receiving treatment with TYSABRI(R) (natalizumab) and assess their risk for developing progressive multifocal leukoencephalopathy (PML), a rare, but serious, brain infection…”
From the NIH: “…The detection of anti-JCV antibodies may provide a means to segment, or stratify, multiple sclerosis (MS) patients considering or receiving treatment with TYSABRI(R) (natalizumab) and assess their risk for developing progressive multifocal leukoencephalopathy (PML), a rare, but serious, brain infection…”
“…Rituximab, sold under the trade names Rituxan and MabThera, is a chimeric monoclonal antibody against the protein CD20, which is primarily found on the surface of B cells. Rituximab is used in the treatment of many lymphomas, leukemias, transplant rejection and some autoimmune disorders….”
“…Natalizumab is a humanized monoclonal antibody against the cellular adhesion molecule α4-integrin. Natalizumab is used in the treatment of multiple sclerosis and Crohn’s disease. It is co-marketed by Biogen Idec and Élan as Tysabri, and was previously named Antegren. Natalizumab is administered by intravenous infusion every 28 days..”
Apparently there is a connection to the drugs ending in ‘mab.’
From the FDA website:
[I]”…Rituxan (rituximab) – PML
Audience: Rheumatological healthcare professionals
[Posted 10/23/2009] Genentech and FDA notified healthcare professionals about a third case of progressive multifocal leukoencephalopathy [PML], the first case of PML in a patient with rheumatoid arthritis [RA] treated with Rituxan who has not previously received treatment with a TNF antagonist. Information to date suggests that patients with RA who receive Rituxan have an increased risk of PML.
Physicians should consider PML in any patient being treated with Rituxan who presents with new onset neurologic manifestations. Consultation with a neurologist, brain MRI, and lumbar puncture should be considered as clinically indicated..[/I]..”
Yet another bit of data from Medscape [I]”…September 11, 2008 — The safety labeling for rituximab intravenous infusion (Rituxan, Genentech, Inc, comarketed with Biogen Idec, Inc) has been updated to reflect a fatal case of progressive multifocal leukoencephalopathy (PML) in a rheumatoid arthritis (RA) patient, the US Food and Drug Administration (FDA) announced today..[/I].”
This info from Wikipedia seems relevant: [I]”…The virus is very common in the general population, infecting 70 to 90 percent of humans;…Immunodeficiency or immunosuppression allows JCV to reactivate. In the brain it causes the usually fatal progressive multifocal leukoencephalopathy, or PML, by destroying oligodendrocytes. Whether this represents the reactivation of JCV within the CNS or seeding of newly reactivated JCV via blood or lymphatics is unknown. Several studies since 2000 have suggested that the virus is also linked to colorectal cancer, as JCV has been found in malignant colon tumors, but these findings are still controversial.[/I]…”
I found the most useful information here: [url]http://ms.about.com/od/treatments/a/How-Is-Pml-Diagnosed.htm[/url]
For example, [I]”…However, if the test is positive for the JC virus, that does not automatically confer a diagnosis of PML. The problem here is that a very large number of people in the general population will have these antibodies -– some estimate up to 70%…”[/I]
The key, for me, is that if your symptoms begin to noticeably worsen, notify your doctor immediately. The medicine should be stopped and other therapy methods discussed.