BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is associated with natalizumab treatment. Biogen-Idec quantified the risk of PML in MSers, according to the presence or absence of three risk factors: positive status with respect to anti-JC virus antibodies, prior use of immunosuppressants, and increasing duration of natalizumab treatment.
METHODS: Data from postmarketing sources, clinical studies, and an independent Swedish registry were used to estimate the incidence of PML among natalizumab-treated MSers, according to positive or negative status with respect to anti-JC virus antibodies, prior or no prior use of immunosuppressants, and duration of treatment (1 to 24 months vs. 25 to 48 months). Blood samples were available for anti-JC virus antibody testing from 5896 MSers and from 54 MSers who were treated with natalizumab and in whom PML later developed.
RESULTS: As of February 29, 2012, there were 212 confirmed cases of PML among 99,571 MSers treated with natalizumab (2.1 cases per 1000 patients). All 54 MSers with PML for whom samples were available before the diagnosis were positive for anti-JC virus antibodies. When the risk of PML was stratified according to three risk factors, the risk of PML was lowest among the MSers who were negative for anti-JC virus antibodies, with the incidence estimated to be 0.09 cases or less per 1000 patients (95% confidence interval [CI], 0 to 0.48). MSers who were positive for anti-JC virus antibodies, had taken immunosuppressants before the initiation of natalizumab therapy, and had received 25 to 48 months of natalizumab treatment had the highest estimated risk (incidence, 11.1 cases per 1000 patients [95% CI, 8.3 to 14.5]).
CONCLUSIONS: Positive status with respect to anti-JC virus antibodies, prior use of immunosuppressants, and increased duration of natalizumab treatment, alone or in combination, were associated with distinct levels of PML risk in natalizumab-treated MSers.
Multiple Sclerosis Research: Research: DMT and JC-PML Virus
21 hours ago
Background: Natalizumab-associated progressive multifocal leukoencephalopathy (PML) in MS occurred in two individuals also treated with interferon β1a, raising concerns about the interaction of these disease-modifying …
Multiple Sclerosis Research: Natalizumab PML Safety Update
27 Apr 2012
2 comments: Anonymous said… Any ideas why the number of people diagnosed with PML has increased from around 7-8 per month to 20 in March ? Friday, April 27, 2012 5:51:00 PM · Gavin Giovannoni said… Re: “Any ideas …
Multiple Sclerosis Research: News: first case of PML on fingolimod
14 Apr 2012
As you are aware natalizumab is strongly associated with PML. Therefore it is difficult to point a finger at, or blame, fingolimod as the cause of the PML in this specific case. However, fingolimod is likely to have contributed to …
Multiple Sclerosis Research: Research: Tysabri and PML
14 Mar 2012
We then divided patients into groups according to their PML risk. Treatment indication was reassessed. Of the patients, 64 (61.5%) were JCV seropositive. Amongst seropositive patients on natalizumab for 2 years or more, …