Bioanalytical challenges and solutions for immunogenicity evaluation of bispecific antibody therapeutics.

Bispecific antibodies (bsAbs) represent a rapidly expanding class of biotherapeutics that enable novel mechanisms of action beyond the conventional monoclonal antibodies (mAbs). While their clinical success continues to grow, the increased structural complexity, non-native architecture, and dual-targeting mechanisms introduce unique immunogenicity risks and sophisticated bioanalytical challenges. In this review, we examine the clinical immunogenicity profiles of approved and selected investigational bsAbs, highlighting key determinants that drive immunogenicity risk. We also discuss critical hurdles, considerations and emerging solutions in immunogenicity evaluation for bsAbs, including limitations of widely used anti-drug antibody (ADA) assay format, matrix interference, domain-specific characterization, and functional neutralization assessment. Finally, we propose an integrated immunogenicity assessment framework that combines predictive tools, clinical bioanalytical data, and reverse-translational investigations to refine therapeutic platforms and reduce immunogenicity risk in next-generation bsAb development. To support this evolution, we advocate enhanced industry transparency and the publication of immunogenicity results in detail, especially for programs terminated due to high immunogenicity. Together, these approaches aim to support more informed decision-making and enable the safe and effective advancement of complex bispecific antibody therapeutics.