Update on Experience with Natalizumab Use, JCV Antibody Testing & Treatment Decisions at the University of Southern California MS Center – Including Sex Differences (P01.213)

OBJECTIVE: The JCV antibody test is a tool utilized in evaluating potential risks of therapy, specifically in relation to the use of natalizumab - we interpreted sex differences in the results of early testing via clinical trial, prompting us to evaluate whether males tested positive at a higher rate than females and to ask if this might be reflected in treatment decisions. BACKGROUND: A positive antibody status indicates prior exposure to JC virus and a detectable immune response to an otherwise asymptomatic virus. Patients who are anti-JCV antibody positive are thought to have a higher risk for developing PML. The risks and benefits of continuing treatment with natalizumab are carefully considered in the context of other potential risk factors. DESIGN/METHODS: Over 220 JCV Ab tests were done on over 175 unique patients at our center, noting greater than 120 patients were on natalizumab at the time of initial antibody testing, and more than 50 were not. We separated the patients based on sex, male or female, and categorized the testing and whether patients were subsequently treated with natalizumab. RESULTS: At time of abstract submission, over 50% of patients were noted to test positive for JCV antibodies upon initial test and we saw a greater percentage of males than females test positive, while noting fewer were tested or treated with natalizumab. CONCLUSIONS: How to utilize this test and how it may be most effectively used may be different for individual patients, potentially with regards to sex - we believe the presentation of this data and our interpretation of it may help others as they make complex treatment decisions. Disclosure: Dr. Williamson has received personal compensation for activities with Genzyme as an advisory board member. Dr. Williamson has received research support from the National MS Society and Biogen Idec. Dr. Aparicio has nothing to disclose. Dr. Buckbinder has nothing to disclose. Dr. Burnett has received personal compensation for activities with Bayer Pharmaceuticals, Biogen Idec, Genzyme Corporation, Novartis, Serono, and Teva Neuroscience.