Neutralizing antibodies (NAbs) to biological drugs may cause loss of therapeutic effi cacy and in some cases, loss of endogenous protein function as well. Standard immunoassays can detect anti-drug antibodies, but cannot differentiate neutralizing antibodies, so cell-based assays are often required by the regulatory agencies to identify NAbs. Therefore, a key step in the development of a biotherapeutic is the selection and development of an appropriate cell-based bioassay for NAbs, which has traditionally posed significant challenges, especially regarding serum/matrix tolerance, sensitivity and specificity.
Here, we describe the development, validation and application of PathHunter® cell-based assays, a novel technology platform to create simple cell-based assays for the detection of NAbs to biological drugs. This technology relies on cells expressing full length, native receptors to create assays that are highly specifi c, robust and have a homogenous mix-and-read protocol. This enables accurate and sensitive detection of neutralizing antibodies even in high concentrations (up to 100%) of human serum through a simple chemiluminescent output. The assays are developed in thaw-and-use format to increase convenience and minimize assay variability due to cell culture and handling. The cell preparation, bioassay protocol and reagents have been optimized to provide superior bioassay performance with high reproducibility (<7% RSD). A case study will be presented on the GLP1 receptor assay, as an example of the multitude of assays available for bioinnovator and biosimilar drugs.