Integrated Glyco-Analytical Strategy for Comprehensive Characterization of a Complex Therapeutic Glycoprotein:...

Fabrazyme (agalsidase beta) is a therapeutic enzyme whose clinical efficacy is contingent upon its complex N-glycosylation patterns. Nevertheless, comprehensive glycosylation profiling remains challenging due to high site-specific heterogeneity. To address this, three orthogonal liquid chromatography-mass spectrometry (LC-MS) approaches were employed: (1) released N-glycan analysis with fluorescence detection and MS annotation, (2) site-specific glycopeptide mapping, and (3) intact protein MS. The released glycan profiling method was validated for reproducibility, intermediate precision, and inter-laboratory transferability, thereby enabling reliable separation and quantification of neutral, phosphorylated, and sialylated species. Glycopeptide mapping revealed distinct site-specific distributions: N108 was found to predominantly carry sialylated complex glycans; N161 was enriched in phosphorylated oligomannose structures; and N184 displayed the highest heterogeneity, including bisphosphorylated and sialylated glycans. Intact protein analysis was performed on both intact and desialylated Fabrazyme, thereby enabling confirmation of glycan assignments. Desialylation reduced spectral complexity, thereby facilitating accurate mass matching with a combinatorial library generated from glycopeptide-level data. The complementary use of these three analytical levels provides a comprehensive view of Fabrazyme glycosylation, offering a robust reference for quality control and biosimilar development.