Development and validation of a novel ELISA for accurate and precise pharmacokinetic analysis of Antibody drug conjugate Sacituzumab Govitecan; Presented at the Festival of Biologics 2024 San Diego

ADCs have quickly gained popularity in biologics and cancer therapy due to their ability to deliver potent cytotoxic drugs directly to cancer cells while sparing healthy tissues, thereby minimizing systemic toxicity and improving patient outcomes. Sacituzumab govitecan is one such ADC, comprising sacituzumab, a linker, and cytotoxic drug payload SN-38, targeting Trop-2 - a surface antigen over-expressed in certain cancer cells.

Krishgen Biosystems report that the KRIBIOLISA Sacituzumab Govitecan ELISA kit successfully and accurately detected the ADC with high accuracy in both human sample and plasma samples. It demonstrates significant promise in treating refractory metastatic triple-negative breast cancer (FDA approved in 2020) and remains in variousphases of research for metastatic urothelial cancers and other indications. Quantifying sacituzumab govitecan is crucial for optimizing dosing,assessing pharmacokinetics, and establishing exposure-response relationships.

Traditionally, LCMS techniques are used to quantify the ADC, but it is complex to set up, may lack precision in complex matrices and have higher sample volume requirements. Comparatively, ELISA is readilyavailable method, being widely and extensively applied in almost every laboratory, and can be easily optimised to offer accuracy and precision incomplex matrices.In this study, we developed an immunoassay for the accurate and sensitive quantification of Sacituzumab govitecan concentrations in biologicalsamples, a first-of-its-kind, standardised ELISA available commercially worldwide.

The ELISA employs an optimised sandwich protocol. Trop-2protein is coated on the microwells, followed by sample incubation and a subsequent enzyme-based detection system. We optimised variousparameters, including antibody concentration, blocking conditions, and incubation time, to enhance assay sensitivity, dynamic range, and reproducibility.

The ELISA was validated as per EMA/FDA guidelines in line with ICH M10 Code, and we validated the assay's specificity, precision,accuracy, and linearity with extensive analytical characterization and comparison to standard methods. Our results demonstrate excellent performance, with an assay range of 0-640 ng/ml and low limits of detection (4.8 ng/ml). The unique immunoassay presented in this study offersa valuable tool for PK analysis of Sacituzumab govitecan, facilitating clinical development and optimization, and enabling a deeper understanding of antibody drug conjugates’ pharmacokinetic properties and additional therapeutic possibilities.