biosimilars, intact mass method was used for the glycosylation similarity
evaluation between biosimilar candidates and the reference
products.However,unexpectedantibody variants were observedin
some biosimilar candidates of mAb-X and mAb-Y when conducting
intact mass glycosylation similarity analysis. Through middle-up
and bottom-up MS comparative approaches, we have characterized
rapidly and unambiguously an unexpected leucine to glutamine
sequence error at the N-terminal 402 site of heavy chain in mAbX
biosimilar candidate and a low level interchain trisulfide bond
modification between the light and heavy chains in mAb-Y biosimilar
candidate. In summary, these two examples demonstrated that
mass spectrometry comparability analysis plays a crucial role for
the characterization of antibody variants, and biosimilar developers
should start with a comprehensive structural assessment and
comparative exercise to decrease the risk of biosimilar process
development.