With or Without Sugar? (A)glycosylation of Therapeutic Antibodies

Abstract

Antibodies and antibody-based drugs are currently the fastest-growing class of therapeutics. Over the last three decades, more than 30 therapeutic monoclonal antibodies and derivatives thereof have been approved for and successfully applied in diverse indication areas including cancer, organ transplants, autoimmune/inflammatory disorders, and cardiovascular disease. The isotype of choice for antibody therapeutics is human IgG, whose Fc region contains a ubiquitous asparagine residue (N297) that acts as an acceptor site for N-linked glycans. The nature of these glycans can decisively influence the therapeutic performance of a recombinant antibody, and their absence or modification can lead to the loss of Fc effector functions, greater immunogenicity, and unfavorable pharmacokinetic profiles. However, recent studies have shown that aglycosylated antibodies can be genetically engineered to display novel or enhanced effector functions and that favorable pharmacokinetic properties can be preserved. Furthermore, the ability to produce aglycosylated antibodies in lower eukaryotes and bacteria offers the potential to broaden and simplify the production platforms and avoid the problem of antibody heterogeneity, which occurs when mammalian cells are used for production. In this review, we discuss the importance of Fc glycosylation focusing on the use of aglycosylated and glyco-engineered antibodies as therapeutic proteins.

Preclinical Pharmacokinetics, Tolerability, and Pharmacodynamics of Metuzumab, a Novel CD147 Human–Mouse Chimeric and Glycoengineered Antibody

“…ADCC efficacy of IgG antibodies is significantly dependent on Fc glycosylation patterns (34). The absence of fucose on N297 of mAbs can results in conformational changes in the Fc region and increase ADCC by increasing the affinity between the Fc region and Fcg receptors (27,(35)(36)(37)(38).…”

Engineering an IgG Scaffold Lacking Effector Function with Optimized Developability

“…A recent study examined the Asn to Gly (N297G) variant, along with Asn to Ala (N297A), impact on Fc␥R binding and pharmacokinetics for the first time and concluded that N297G and N297A variants have similar pharmacokinetics (PK) to that of the wild type antibodies (14). Aglycosylated antibodies have a very low levelof binding to Fc␥Rs (15,16). The advantage with this approach is that it requires a single mutation in the constant domain (CH2), thus minimizing the risk of immunogenicity via the formation of new epitopes.…”

Rational design of therapeutic mAbs against aggregation through protein engineering and incorporation of glycosylation motifs applied to bevacizumab

“…Carbohydrate groups participate in the integrity of most biologics by reducing aggregation propensity, increasing solubility, stabilizing the native conformation, protecting against various degradation pathways (hydrolysis, oxidation) and overall stabilizing the macromolecules. 28,55 This functionality is particularly relevant for antibodies as all IgGs are naturally N-glycosylated at position N297 in each of the CH2 chains of the Fc domain. It has been demonstrated on several occasions that this N-glycan participates in the stabilization of mAbs against aggregation caused by various stresses.…”

“…8,24,26,27,56,57 Natural IgGs present in human serum are all glycosylated in the Fc domain whereas only less than a third are glycosylated in the Fab domain. 55 N-glycans are found attached to the variable region of the LC, the HC or both. It is estimated that »20% of the variable region of mAbs bear an N-glycosylation site motif.…”