title: Auristatin antibody drug conjugate physical instability and the role of drug payload.
abstract: The conjugation of hydrophobic cytotoxic agents such as monomethyl auristatin E (MMAE) to the interchain sulfhydryl groups of monoclonal antibodies (Mabs) through a protease-labile linker generates a heterogeneous drug load distribution. The conjugation process can generate high-drug-load species that can affect the physical stability of antibody-drug conjugates (ADCs). In this study, the mechanism of physical instability of ADCs was investigated by formulating the ADC pool as well as isolated drug load species in high and low ionic strength buffers to understand the effect of ionic strength on the stability of drug-conjugated Mabs. The results showed that the presence of high ionic strength buffer led to time-dependent aggregate and fragment formation of ADCs, predominantly ADCs with high-drug-load species under stress conditions. In addition, differential scanning calorimetry (DSC) results confirmed that there is a direct correlation between thermal unfolding and drug payload and that specific changes in the DSC thermogram profiles can be assigned to modifications by MMAE.
authors.affiliation: Early Stage Pharmaceutical Development and ‡Purification Development Department, Genentech , 1 DNA Way, South San Francisco, California 94080, United States.
authors.forename: Yilma T
authors.initials: YT
authors.lastname: Adem
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Schwarz
authors.forename: Eileen
authors.initials: E
authors.lastname: Duenas
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Patapoff
authors.forename: William J
authors.initials: WJ
authors.lastname: Galush
authors.forename: Osigwe
authors.initials: O
authors.lastname: Esue
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D016466:CHO Cells; D002152:Calorimetry, Differential Scanning; D003412:Cricetulus; D004355:Drug Stability; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry*; D009842:Oligopeptides / Q000737:chemistry*; D009994:Osmolar Concentration; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D018796:Immunoconjugates; D009842:Oligopeptides; C495575:monomethyl auristatin E