Pertuzumab Charge Variant Analysis and Complementarity-Determining Region Stability Assessment to Deamidation

Area of Science:

• Biochemistry
• Protein Chemistry
• Analytical Chemistry

Background:

• Pertuzumab is a monoclonal antibody for HER2-positive breast cancer treatment.
• Charge heterogeneity of pertuzumab is not well understood, unlike trastuzumab.

Purpose of the Study:

• To investigate the charge heterogeneity of pertuzumab under stress conditions.
• To characterize the main contributors to pertuzumab's charge variants.
• To assess if in vitro stress studies can predict in vivo modifications.

Main Methods:

• Pertuzumab was subjected to pH and temperature stress.
• Ion-exchange chromatography was used to analyze charge variants.
• Peptide mapping characterized isolated charge variants.
• Surface plasmon resonance assessed receptor binding affinity.

Main Results:

• Deamidation in the Fc domain and N-terminal pyroglutamate formation in the heavy chain were identified as primary sources of charge heterogeneity.
• Heavy chain CDR2 showed resistance to deamidation.
• Pertuzumab's affinity for HER2 remained unchanged under stress.
• In vitro findings correlated with peptide mapping analysis of clinical samples.

Conclusions:

• In vitro stress studies effectively predict in vivo modifications of pertuzumab.
• Deamidation and N-terminal pyroglutamate formation are key drivers of pertuzumab charge heterogeneity.
• Pertuzumab's therapeutic efficacy is unlikely to be affected by observed charge variants.