Biogen, Elan announce clinical utility data of two-step ELISA to detect anti-JCV antibodies

Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN) today announced data further supporting the potential clinical utility of an investigational assay that detects anti-JC virus (JCV) antibodies in human plasma or serum. The detection of anti-JCV antibodies may provide a means to segment, or stratify, multiple sclerosis (MS) patients considering or receiving treatment with TYSABRI^® (natalizumab) and assess their risk for developing progressive multifocal leukoencephalopathy (PML), a rare, but serious, brain infection. These data have been presented at the 26^th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Gothenburg, Sweden.

“When treating a debilitating, chronic disease such as MS, patient safety is of the utmost importance. At Biogen Idec, we are committed to improving the lives of people with MS. Understanding and mitigating potential treatment risk factors further support our commitment”

This two-step, analytically-validated, enzyme-linked immunosorbant assay (ELISA) to detect anti-JCV antibodies is currently being evaluated in large-scale, prospective clinical studies (>10,000 patients) to determine the utility of the assay in stratifying the risk of PML in TYSABRI-treated patients. Infection with JCV is one of a number of factors required for the development of PML. Detection of anti-JCV antibodies may be a useful tool to identify prior or ongoing JCV infection, helping physicians better assess a patient's potential risk for developing PML.

"When treating a debilitating, chronic disease such as MS, patient safety is of the utmost importance. At Biogen Idec, we are committed to improving the lives of people with MS. Understanding and mitigating potential treatment risk factors further support our commitment," said Alfred Sandrock, M.D., Ph.D., Senior Vice President of Neurology Research and Development at Biogen Idec. "We are committed to better understanding PML and have embarked on a number of risk mitigation efforts. The anti-JCV antibody assay is one of our most advanced initiatives and has the potential to provide physicians a tool to help them assess patients' risk for developing PML."

Overview of Data

Late Breaking News - Factors associated with anti-JCV antibody prevalence in a large cohort of natalizumab-treated MS patients - Platform Presentation 138

The two-step ELISA was used to detect anti-JCV antibodies in blood from patients enrolled in the TYSABRI Global Observation Study (TYGRIS), Safety of TYSABRI Re-dosing and Treatment (STRATA) study, and JCV Antibody Program in Patients with Relapsing Multiple Sclerosis Receiving or Considering Treatment with TYSABRI (STRATIFY-1) study. A chi-square test was used to assess associations between factors and prevalence of anti-JCV antibodies. Together, these data represent one of the largest cohorts of MS patients evaluated for the presence of anti-JCV antibodies, demonstrating an overall prevalence of anti-JCV antibodies of approximately 50 to 60 percent and delineating the prevalence by factors such as age and gender. There was an increasing prevalence of anti-JCV antibodies in men compared to women. There was also an increasing prevalence with age, regardless of gender. TYSABRI use and prior treatment with immunosuppressants did not appear to affect the prevalence of anti-JCV antibodies in this cohort.

Assessment of the incidence of anti-JCV antibodies in a cohort of natalizumab-treated patients with multiple sclerosis - Poster P873

This study, which used the ELISA to evaluate more than 800 serum samples, was designed to assess the prevalence of anti-JCV antibodies in TYSABRI-treated MS patients and evaluate the possible utility of anti-JCV antibodies as a means to segment, or stratify, MS patients and assess their risk for developing PML. Of the more than 800 patients evaluated, 54 percent tested positive for anti-JCV antibodies.

Additionally, anti-JCV antibodies were detected in 20 out of 20 (100 percent) of TYSABRI-treated PML patients at least six months prior to the diagnosis of PML. Further clinical studies are being conducted to determine whether the presence or absence of anti-JCV antibodies may be useful to stratify PML risk.

Late Breaking News - Multi-site cross-validation of the assay to detect anti-JCV antibodies in human serum and plasma - Poster P992

In this study, cross-validation of the ELISA was performed by three laboratories (Focus Diagnostics, Quintiles Laboratories, and Biogen Idec) by evaluating intra- and inter-assay precision, including specificity, sensitivity, selectivity and matrix interference, robustness, and reagent stability. A panel of 100 serum and plasma samples was evaluated at each laboratory. The ability of the ELISA to detect anti-JCV antibodies in human serum and plasma was robust and cross-validated by all three laboratories. The assay is now being used in two global clinical trials to evaluate the potential clinical utility of anti-JCV antibody status for stratifying PML risk.

Late Breaking News - Anti-JCV antibody prevalence in a Swedish cohort of MS patients and non-MS controls - Poster P983

In this study from Sweden, the ELISA was used to detect anti-JCV antibodies in plasma from 2772 untreated or treated MS patients, as well as non-MS controls. A chi-square test was used to assess the association between demographic factors and prevalence of anti-JCV antibodies. Based on the data analyzed to date, it is estimated that the prevalence of anti-JCV antibodies in the Swedish MS population to be 61 percent, which is lower than the prevalence observed in the non-MS control population (67 percent) in the study.