(T0930-09-54) A Generic Approach to Monkey Anti-drug Antibodies Assay Development for Antibody Therapeutic Preclinical Studies

Purpose: Antibody therapeutics represent a major modality of biologics in development pipelines. Preclinical studies of antibody therapeutics frequently require anti-drug antibody (ADA) analysis. A generic assay platform would facilitate such analysis. Using custom-made antibody reagents, a simple platform assay is developed and qualified for ADA analysis following antibody therapeutic administration in monkeys.

Methods: The assay utilizes streptavidin-conjugated magnetic beads as capture reagent. Biotinylated drug is loaded to these beads, prior to incubating with ADA samples in monkey serum. Bound monkey ADA are detected with monkey IgG-specific antibody-HRP conjugate and TMB (Figure 1). Monkey anti-human polyclonal antibodies, which are generated by immunizing cynomolgus monkeys with a mix of humanized antibody therapeutics, are used as positive control in the platform assay. Method performance is evaluated in terms of relative sensitivity and drug tolerance of the assay.

Results: The platform assay has been evaluated for a monoclonal antibody therapeutic against PD-1 target, a monoclonal antibody therapeutic against HER2, and a bispecific antibody targeting at both PD-L1 and TIGIT. Using the monkey polyclonal antibody as the positive control, all assays exhibited relative sensitivity in the range of 25-50 ng/mL of ADA in monkey serum (Table 2). Drug tolerance were universally above 2 mg/mL when tested at 250 ng/mL concentration level of ADA (Table 1). These data demonstrated acceptable assay performance for the detection of ADA in monkey serum.

Conclusion: An innovative assay platform has been established for monkey ADA analysis in preclinical studies involving exposure to a human antibody therapeutic. Due to the use of monkey IgG-specific antibody reagent as a universal detection reagent, the assay platform avoids the need of labelled drug as the detection reagent in traditional bridging assay format, allowing a significantly reduced effort in assay development, while the detected ADA is still drug-specific.


Figure 1 Assay Design


Table 1 Drug tolerance test results


Table 2 Assay sensitivity test results