Effect of ADCC-enhancing mutations on N-glycan profiles of human IgG1 antibodies

Human antibody-based therapeutics display characteristic N-glycan profiles that are critical determinants of developability, safety, pharmacokinetics, and efficacy. Although fragment crystallizable (Fc) engineering strategies to modulate effector functions are well established, comparatively less is known about how Fc mutations designed to enhance Fc effector functions, such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity, influence Fc glycosylation. In the present study, we evaluated the impact of several ADC-enhancing Fc mutations (S239D/I332E, D280H/K290S, S239D/A330L/I332E, S298A/E333A/K334A, F243L/R292P/Y300L/V305I/P396L) on N-glycan composition and Fc-mediated activity. These mutations are spatially distinct from the N297 glycosylation site. Among the variants examined, antibodies containing the F243L/R292P/Y300L/V305I/P396L (LPLIL) mutations exhibited elevated levels of high-mannose glycans (Man5-9) when expressed in either CHO (Chinese hamster ovary) or HEK293 (human embryonic kidney 293) mammalian cells. Comparative glycan profiling revealed that differences in galactosylation and mannosylation between CHO- and HEK293-derived antibodies influenced CD16A binding affinity and ADCC activity across Fc variants. Notably, LPLIL-containing antibodies consistently demonstrated altered glycosylation patterns associated with enhanced effector function. Collectively, our findings demonstrated that ADCC-enhancing Fc mutations could substantially modify N-glycan composition, which in turn modulated Fc receptor engagement and downstream effector functions. These results highlighted the importance of evaluating glycosylation changes during Fc engineering to ensure optimal therapeutic performance.