Assessment of physical stability of an antibody drug conjugate by higher order structure analysis: impact of thiol- maleimide chemistry.
OBJECTIVE
To provide a systematic biophysical approach towards a better understanding of impact of conjugation chemistry on higher order structure and physical stability of an antibody drug conjugate (ADC).


METHODS
ADC was prepared using thiol-maleimide chemistry. Physical stabilities of ADC and its parent IgG1 mAb were compared using calorimetric, spectroscopic and molecular modeling techniques.


RESULTS
ADC and mAb respond differently to thermal stress. Both the melting temperatures and heat capacities are substantially lower for the ADC. Spectroscopic experiments show that ADC and mAb have similar secondary and tertiary structures, but these are more easily destabilized by thermal stress on the ADC indicating reduced conformational stability. Molecular modeling calculations suggest a substantial decrease in the conformational energy of the mAb upon conjugation. The local surface around the conjugation sites also becomes more hydrophobic in the ADC, explaining the lower colloidal stability and greater tendency of the ADC to aggregate.


CONCLUSIONS
Computational and biophysical analyses of an ADC and its parent mAb have provided insights into impact of conjugation on physical stability and pinpointed reasons behind lower structural stability and increased aggregation propensity of the ADC. This knowledge can be used to design appropriate formulations to stabilize the ADC.
Biotherapeutics Pharmaceutical Sciences, Pharmaceutical R&D, Pfizer Inc., 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA.
Jianxin
J
Guo
Sandeep
S
Kumar
Amarnauth
A
Prashad
Jason
J
Starkey
Satish K
SK
Singh
D000911:Antibodies, Monoclonal / Q000737:chemistry*; D004355:Drug Stability; D018796:Immunoconjugates / Q000737:chemistry*; D007074:Immunoglobulin G / Q000737:chemistry*; D008301:Maleimides / Q000737:chemistry*; D008958:Models, Molecular; D066329:Protein Aggregates; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D000911:Antibodies, Monoclonal; D018796:Immunoconjugates; D007074:Immunoglobulin G; D008301:Maleimides; D066329:Protein Aggregates; D013438:Sulfhydryl Compounds; C043592:maleimide