Fit-for-Purpose Validation of a Ligand Binding Assay for Toxicokinetic Study Using Mouse Serial Sampling

Purpose: The purpose of this study was to validate a ligand binding assay for the quantitation of a monoclonal antibody-based biotherapeutics (PF-57781346) in samples collected via capillary microsampling to support a regulated mouse toxicity study.

Method: A quantitative ligand binding assay on the Gyrolab platform was developed to quantify PF-57781346 in blood samples derived from capillary mouse serial sampling. The method validation evaluated assay characteristics including accuracy and precision, influence of sample processing on drug quantitation, whole blood matrix selectivity, dilution linearity and the stability of the drug in the study sample matrix.

Results: The method validation demonstrated acceptable analytical characteristics. The whole blood selectivity testing demonstrated accuracy between -4.8% and 13.9% in 10 out of 10 individual whole blood samples, suggesting that drug quantitation from whole blood is not impacted by the serial sampling procedure. Short-term and long-term drug stability in study sample matrix were established to cover required stability for sample storage and analysis (accuracy between -7.3% and 6.1%).

Conclusion: We reported a successful validation of a bioanalytical method that quantifies PF-55781346 in samples collected via capillary microsampling. The experience shared in this study could serve as a model process for bioanalytical method validation when capillary microsampling is used.