Simultaneous quantification of monoclonal antibodies using LC-MS/MS

A new LC–MS/MS method has been developed to simultaneously quantify monoclonal antibodies in a cassette-dosing setting using rat plasma.

Due to the major limitations of ligand binding assays for the therapeutic quantification of monoclonal antibodies in biological samples, Hangyam Li (Amgen Inc, CA, USA) and colleagues have recently developed a general LC–MS/MS method that employs a uniformly heavy isotope labelled common whole monoclonal antibody internal standard and a common immunocapture for sample processing. The new method was developed to overcome limitations such as the need for a new internal standard to be produced for each sample and to reduce time and resources need for preclinical studies.

This initial approach has been applied to eight monoclonal antibodies. A more recent paper published by the same group has demonstrated the development of a multiplex LC–MS/MS method for the simultaneous quantification of multiple monoclonal antibodies. The authors detail how they have increased the ability of the method to simultaneously quantify four monoclonal antibodies and have also assessed the feasibility of applying this technique to a cassette-dosing study. This use of this technique in a cassette dosing situation would save on animal use and costs.

In the paper the method was qualified for the simultaneous quantification of the four monoclonal antibodies in rat plasma and the method was also applied to samples from discrete and cassette-dosed rats. The author were able to demonstrate that this method gave comparable pharmacological parameters for the four monoclonal antibodies to those produced from discrete dosing and enzyme linked immunosorbent assay results. The authors revealed that the study demonstrated ‘a robust performance’ of the multi analyte LC–MS/MS method following cassette dosing. This method would enable improved efficiency and reduce costs in preclinical trials. However, the authors have warned about the limitations and special considerations that need to be taken into account regarding cassette dosing. For example, for large molecule biotherapeutic candidates in preclinical studies, non human primates are often used and so new ways of using animals need to be discovered.

Sources: Li H, Ortiz R, Tran LT et al. Simultaneous analysis of multiple monoclonal antibody biotherapeutics by LC–MS/MS method in rat plasma following cassette-dosing. APPS J. doi:10.1208/s12248-012-9435-5 (2012) (Epub ahead of print); Li H, Ortiz R, Tran L et al. General LC–MS/MS method approach to quantify therapeutic monoclonal antibodies using a common whole antibody internal standard with application to preclinical studies. Anal Chem. 84(3) 1267–1273 (2012).