Generation of assay positive controls for detection of isotype anti-drug antibodies for immunogenicity monitoring

Aim: Development of drug-related surrogate positive controls for isotype anti-drug antibodies assay remains challenging. Efforts on antibody engineering or chemical crosslinking have been made. However, multiple epitope recognition, purity and stability are often of concern. To tackle these challenges, we used LC-SPDP/SMPB crosslinking to conjugate polyclonal anti-drug IgG and human immunoglobulin isotype (hIgE, hIgA, hIgM or hIgG4) with optimized conditions. Results: The final product was a hybrid of anti-drug IgG cross-linked to human isotype immunoglobulin through stable thioether bond. The characteristics of the hybrids and their performance as assay positive controls were further evaluated. Conclusion: The results demonstrate that LC-SPDP/SMPB chemical crosslinking method is suitable for generating stable hybrids to be used as assay positive controls in isotype anti-drug antibodies assay.