A case study application of AQbD to the re-development and validation of an affinity chromatography analytical procedure for mAb titer quantitation

Protein A (ProA) high-performance liquid chromatography (HPLC) is a common analytical procedure for measuring monoclonal antibody (mAb) titers due to its high specificity and efficiency. Accurate and reliable results of this procedure are imperative, as the quantitation of the total mAb present for in-process samples directly impacts downstream purification steps related to the removal of process-related impurities. This study aimed to improve a platform ProA HPLC analytical procedure which was previously developed using traditional approaches and was not always reliable. By retrospectively applying Analytical Quality by Design (AQbD) principles and statistical assessments of performance, a bias in the calibration standard due to protein-adsorption to common sample vial materials was identified. The inclusion of Tween® 20 into the mobile phase used as sample diluent was optimized to ensure procedure performance and improve analytical range. The resulting procedure robustness was evaluated using Design of Experiment (DoE) approaches and performance was verified against Analytical Target Profile (ATP) criteria as recommended by regulatory agencies. The resulting linearity displayed R² values of 1.00 with intercept biases of 1.2 % (analyst 1) and 0.8 % (analyst 2), accuracy across all levels was reported at 99.2 % recovery, and intermediate precision was reported as 3.0 % RSD. Application of this new platform procedure has since reduced development timelines for new mAb products by 50 % and allowed for accurate titer determination to support >5 early phase product-specific process decisions without requiring extensive analytical procedure development. This work demonstrates the utility and relative ease of adopting AQbD concepts, even for established procedures, and supporting them with a lifecycle approach to managing procedure performance.