Development and characterization of a non-cell-based assay to assess the presence of neutralizing antibodies to interferon-beta in clinical samples.

Assessment of immunogenicity is an integral part of product development and involves evaluation of binding and neutralizing antibodies. The use of cell-based assays for detection of neutralizing antibodies (NAbs) is usually a regulatory expectation. Different cell-based assay formats are available for detection of anti-interferon-beta (IFN-β) NAbs but all present technical difficulties and limitations. In this paper, a non-cell-based NAb assay which overcomes the limitations of cell-based assays is described. This NAb assay utilizes an electrochemiluminescence detection platform and is based on the first step involved in all IFN-β-induced biological activities, namely the binding of IFN-β to its receptor, which is inhibited when NAbs are present. Using this approach, NAb titers in clinical samples from multiple sclerosis patients treated with IFN-β were determined and compared with those obtained using existing cell-based NAb assays. The sensitivity of the assays was not comparable, the cell-based approach having superior sensitivity. However a good correlation between the two approaches was observed. This study illustrates the practicality and feasibility of non-cell-based neutralization assays in the context of immunogenicity, however the utility of this approach would need to be assessed on a case-by-case basis for each therapeutic.