A robust reporter assay for the determination of the bioactivity of IL-4R-targeted therapeutic antibodies

•HEK-293 cells stably expressing hSTAT6 controlled luciferase were established.•The optimal dose-response curve was demonstrated after assay parameter optimization.•Validation according to ICH-Q2 proved the excellent assay performance characteristics.•The established RGA is suitable for the bioactivity determination of anti-IL-4R mAbs.