Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN) today announced data has been published in the Annals of Neurology on an investigational, two-step assay to detect anti-JC virus (JCV) antibodies in human serum and plasma. This assay is currently being evaluated in clinical studies as a potential tool for risk stratification in TYSABRI® (natalizumab)-treated patients. Data from this preliminary analysis have been released online and will be published in the journal’s September issue. Detection of anti-JCV antibodies may provide a means to segment patients into groups at higher risk or lower risk for developing progressive multifocal leukoencephalopathy (PML), a rare but serious brain infection. In order to develop PML, it is believed that a person must experience a convergence of viral and environmental factors, one of which is being anti-JCV antibody positive. The publication describes the development and validation efforts undertaken to date, as well as preliminary findings on the prevalence of anti-JCV antibodies in multiple sclerosis (MS) patients from the Safety of TYSABRI Redosing and Treatment (STRATA) study. Plasma and serum samples were also analyzed from 17 TYSABRI-treated patients who were later diagnosed with PML. These data showed that all 17 patients were anti-JCV antibody positive prior to the onset of PML. “We believe an assay with the ability to detect anti-JCV antibodies will be useful in our efforts to stratify patients for the risk of developing PML. It also has the potential to change the clinical management of MS patients,” said Alfred Sandrock, M.D., Ph.D., senior vice president of neurology research and development at Biogen Idec. “These data support our ongoing clinical studies to assess the clinical utility of this assay and our commitment to further mitigating the rare risk of PML in TYSABRI-treated patients.” About the study The study was undertaken to develop an enzyme-linked immunosorbent assay (ELISA) to detect JCV-specific antibodies in MS patients and to evaluate its potential utility in identifying patients at higher or lower risk of developing PML.
A two-step assay for detecting and confirming the presence of anti-JCV antibodies in human serum and plasma was developed and demonstrated to be both sensitive and specific. ELISA cutpoints were statistically established using plasma and serum samples obtained from a total of 831 patients with relapsing MS from the STRATA study. STRATA is an open-label, single-arm, multinational study in which all patients receive TYSABRI every four weeks for 48 weeks. Subsequently, the assay was used to determine the presence of anti-JCV antibodies in TYSABRI-treated PML patients where serum samples were collected 16-180 months prior to the diagnosis of PML.In the evaluation, 53.6 percent of MS patients in the STRATA study tested positive for anti-JCV antibodies, with a 95 percent confidence interval of 49.9 to 57.3 percent. The false-negative rate was calculated as 2.5 percent. Notably, all pre-PML serum samples from 17 TYSABRI-treated patients who were later diagnosed with PML were anti-JCV antibody positive. This was significantly different from the 53.6 percent seropositivity observed in the analysis of the STRATA study (p<0.001). The article, entitled “Anti-JC Virus Antibodies: Implications for PML Risk Stratification,” can be found online and will be published in the Annals of Neurology September print issue, Volume 68, Issue 3. About TYSABRI TYSABRI is approved in more than 45 countries. In the U.S., it is approved for relapsing forms of MS and in the European Union for relapsing-remitting MS. Data from the Phase III AFFIRM trial highlights TYSABRI’s powerful efficacy. According to that data, which was published in the New England Journal of Medicine, after two years, TYSABRI treatment led to a 68 percent relative reduction ( p<0.001) in the annualized relapse rate when compared with placebo and reduced the relative risk of disability progression by 42-54 percent ( p<0.001). TYSABRI increases the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability. The risk of PML increases with increasing duration of treatment. The risk of PML also increases with immunosuppressant use prior to TYSABRI therapy, and this increased risk is independent of treatment duration. Other serious adverse events that have occurred in TYSABRI-treated patients include hypersensitivity reactions (e.g., anaphylaxis) and infections, including opportunistic and other atypical infections. Clinically significant liver injury has been reported in patients treated with TYSABRI in the post-marketing setting. Common adverse events reported in TYSABRI-treated MS patients include headache, fatigue, infusion reactions, urinary tract infections, joint and limb pain and rash.