Glycan Profiles of FDA-Approved Therapeutic Antibodies: Insights from Regulatory Submissions

Glycosylation is a critical quality attribute of certain therapeutic proteins, influencing efficacy, safety, and pharmacokinetics. This study analyzed glycan characterization data and drug substance release specifications from 209 Biologics License Applications (BLAs) approved by the U.S. Food and Drug Administration (FDA) through May 2025. Ten predominant Fc N-glycans were identified across IgG antibodies expressed by CHO, NS0, and Sp2/0 cell lines, with six glycans common to all systems. Five low-abundance afucosylated glycans (< 10%) were tightly controlled within drug substance release specifications for antibodies with Fc effector functions, although acceptance criteria varied across products. Glycan profiles were strongly dependent on the expression system: CHO-derived antibodies predominantly contained human-compatible glycan structures, whereas NS0 and Sp2/0 antibodies introduced non-human epitopes. Fc fusion proteins exhibited higher branching and sialylation compared with conventional IgG antibodies. Notably, analysis of product labels revealed that Fc effector functions were described exclusively as in vitro observations or proposed mechanisms, with limited clinical validation. Overall, these findings establish a comprehensive benchmark for glycan profiles of FDA-approved therapeutic antibodies and underscore the need for harmonized control strategies and stronger correlation between in vitro Fc assays and clinical outcomes.