Glycosylation of recombinant anticancer therapeutics in different expression systems with emerging technologies

Abstract

Glycosylation, a posttranslational modification, has a major role in recombinant anticancer therapeutic proteins, as most of the approved recombinant therapeutics are glycoproteins. The constant amino acid sequence of therapeutics determines the enzymatic activity, while the presence of glycans influences their pharmacokinetics, solubility, distribution, serum half-life, effector function, and binding to receptors. Glycoproteins expressed in different expression systems acquire their own oligosaccharides, which increases the protein diversity. The heterogeneity of glycans creates hurdles in downstream processing, ultimately leading to variable anticancer therapeutic efficacy. Therefore, glycoproteins require an appropriate expression system to obtain structurally and functionally identical glycans, as in humans. In many expression systems, the N-glycosylation pathway remains conserved in the endoplasmic reticulum, but divergence is observed when the protein enters the Golgi complex. Hence, in recent decades, numerous approaches have been adopted to engineer the Golgi's N-glycosylation pathway to attain human-like glycans. Several researchers have tried to engineer the N-glycosylation pathway of expression systems. In this review, we examine the glycosylation pattern in various expression systems, along with emerging technologies for glycosylation engineering of anticancer therapeutic drugs.