Tackling Issues Observed during the Development of a Liquid Chromatography Method for Small Molecule Quantification in Antibody-Chelator Conjugate

In the context of targeted radionuclide therapy, antibody-chelator conjugates (ACCs) are an evolving class of antibody-related drugs with promising applications as tumor-targeted pharmaceuticals. Generally, a typical ACC consists of a recombinant monoclonal antibody (mAb) coupled to radionuclide via a chelating agent. Characterizing the ACC structure represents an analytical challenge since various impurities must be constantly monitored in the presence of formulation components during the quality control (QC) process. In this contribution, a reliable method devoted to the monitoring of an ACC sample, and its small molecule-related synthesis impurities, has been developed via liquid chromatography (LC). A problem-solving approach of common analytical issues was used to highlight some major issues encountered during method development. This included separation of poorly retained impurities (issue #1); interferences from the formulation components (issue #2); analysis of impurities in presence of ACC at high concentration (issue #3); and recovery of impurities during the whole analytical procedure (issue #4). To the best of our knowledge, this is the first time that a chromatographic method for the analysis of ACC synthesis impurities is presented. In addition, the developed approach has the potential to be more widely applied to the characterization of similar ACCs and other antibody-related drugs.

Automated summary

Antibody-chelator conjugates (ACCs) are a promising class of tumor-targeted pharmaceuticals in targeted radionuclide therapy. A reliable method using liquid chromatography (LC) has been developed to monitor ACC samples and their small molecule impurities. This method addresses common analytical issues such as separation of impurities, interferences from formulation components, analysis of impurities in high concentration samples, and impurity recovery during the entire analytical procedure. This chromatographic method can also be potentially applied to the characterization of similar ACCs and other antibody-related drugs.