MALDI-MS: a Rapid and Reliable Method for Drug-to-Antibody Ratio Determination of Antibody-Drug Conjugates

Mehri Abedi,Reza Ahangari Cohan,Fereidoun Mahboudi,Mehdi Shafiee Ardestani,Fatemeh Davami

doi:10.29252/ibj.23.6.395

Abstract

Background:It is believed that the loading value of anticancer drug conjugated to the monoclonal antibody, called drug-to-antibody ratio (DAR), is the main quality feature of antibody-drug conjugates. Methods:In this study, matrix assisted laser desorption/ionization mass spectrometry was used to determine the average molecular weight of trastuzumab and its three conjugated forms. The differences in the measured masses for each conjugate and unconjugated trastuzumab were compared to the expected mass change through the conjugation of one mole of related drug-linker, in order to measure DAR.Results:There was a consistency between the loading results of mass spectrometry and the measurements of UV spectrometry in most cases. Conclusion: According to our findings, the MALDI-MS method for determining the loading values can be used rapidly and reliably to estimate the covalently bound drugs conjugated to antibodies when ESI-TOF-MS is unavailable.

Highlights

Monoclonal antibodies have actively been used to deliver the anticancer drugs to the sites of tumors
Comparison of the results indicated a logical correlation between the loading results obtained by mass spectrometry and the measurements acquired by UV spectrometry
Molecular weight analysis Kadcyla®, trastuzumab, and the conjugates were subjected to 12% sodium dodecyl polyacrylamide gel electrophoresis (Fig. 2)

Summary

Introduction

Monoclonal antibodies have actively been used to deliver the anticancer drugs to the sites of tumors. The loading value of a drug on the conjugate is defined as the average number of moles of that drug attached to a monoclonal antibody. The maximum absorbance values of the UV/VIS spectra of the drug and the antibody should be different to implement this procedure. It is believed that the loading value of anticancer drug conjugated to the monoclonal antibody, called drug-to-antibody ratio (DAR), is the main quality feature of antibody-drug conjugates. Conclusion: According to our findings, the MALDI-MS method for determining the loading values can be used rapidly and reliably to estimate the covalently bound drugs conjugated to antibodies when ESI-TOF-MS is unavailable.

Objectives

Methods

Results

Conclusion