Development and validation of a reporter gene assay for bioactivity determination of Anti-CGRP monoclonal antibodies

Calcitonin gene-related peptide (CGRP) is critical for the pathophysiology of migraine, and four therapeutic antibodies targeting CGRP and its corresponding receptors have been approved by the Food and Drug Administration (FDA), while many others are in the different stages of clinical trials. Bioactivity determination is essential for the quality control and clinical application of therapeutic monoclonal antibodies (mAbs). However, no bioassay has been reported to date. In this study, we developed a reporter gene assay (RGA) based on SK-N-MC cells stably expressing firefly luciferase driven by cAMP response element (CRE). The key assay parameters were optimized according to signal-to-noise (SNR), the response value, and the fitted dose-response curve. Validation of the RGA in accordance with ICH-Q2 guidelines showed that the method had good specificity, accuracy, linearity, and precision. The established RGA can be utilized as a reference method for release testing and stability studies of relevant antibodies.