Assessment of HER2 Asn deamidation and Asp isomerization using accelerated degradation conditions and quantitative UPLC-MS (Procedure B).

Relative quantification (in %) was conducted by specific ion current chromatogram analysis of proteolytic LysC peptides using the quantification software GRAMS/32™ (n = 2, mean ± S.D). HER2 charge variants were monitored by cation-exchange chromatography (CEC). Formation of fragments and aggregates was monitored by size-exclusion chromatography (SEC) and target binding activity was assessed by SPR-analysis. deamid, total Asp/iso-Asp; n.q., not quantifiable; RM, Reference material.