August 7, 2025
Content
Why Glycans Matter in Antibody Therapy
Glycosylation: The Antibody Game-Changer
Tuning Sugar Chains to Boost Antibody Power
Precision Fucose Editing Made Easy
Mastering Glycan Control in Antibody Production
Glycoengineered Antibodies: From Lab to Market
Conclusion: The Future of Antibodies Is Sugar-Engineered
When it comes to developing antibody therapeutics, most discussions center around binding specificity, affinity, and half-life. But beneath the surface, something smaller—and often overlooked—plays a critical role in efficacy: glycans.
According to Dr. Volker Sandig, Chief Scientific Officer at ProBioGen and one of the leading experts in glycoengineering,
“Glycans are not just decorative sugar chains – they fundamentally shape how antibodies interact with the immune system.”
His work has helped redefine how we understand the role of glycosylation in therapeutic design.
Glycosylation—the enzymatic attachment of sugar molecules to proteins—is the most structurally and functionally flexible post-translational modification (PTM) in antibody production. These small sugar chains may not seem like much, but they shape nearly every aspect of an antibody’s performance: from immune activation to pharmacokinetics to manufacturability.
In collaboration with Dr. Volker Sandig, this article explores how glycan structures influence antibody activity, how glycoengineering can unlock their therapeutic potential, and why the next generation of antibody biologics will be built with sugar in mind.
Why Glycans Matter in Antibody Therapy
Unlike amino acid sequences, glycan profiles aren’t encoded in the genome. Instead, they depend on cellular conditions like glycosyltransferase activity, intracellular sugar-nucleotide pools, and media composition. The most functionally important glycan in monoclonal antibodies is located at Asn297 on the Fc region, where its structure directly governs interaction with immune effectors such as FcγRIIIa on natural killer (NK) cells.
Depending on its composition, the Asn297 Fc glycan can:
Glycosylation: The Antibody Game-Changer
The role of glycosylation in antibody function became evident through a series of pivotal studies. In 1995, Lifely et al. demonstrated that monoclonal antibodies expressed in CHO versus rat cells exhibited dramatically different potencies due to glycan variation—particularly the absence of fucose and the presence of bisecting GlcNAc. These modifications enhanced antibody-dependent cellular cytotoxicity (ADCC) more than 100-fold, highlighting how sugar architecture directly impacts immune recruitment (1).
Further reinforcing these findings, a comprehensive evaluation showed that removal of core fucose from IgG Fc N-glycans significantly enhances FcγRIIIa binding and ADCC activity both in vitro and in vivo. Structural studies suggest fucose absence induces subtle conformational changes in the Fc region, acting like “unlatching a molecular gate”—enabling tighter, more dynamic engagement with FcγRIIIa (2).
Clinical evidence supports these mechanistic insights: polymorphisms in FcγRIIIa affect binding strength, and patients homozygous for the high-affinity variant respond better to therapeutic IgG1 antibodies against a target on the tumor cell surface. Hence, if glycoengineering can impact affinity to FcγRIIIa, it has therapeutic relevance.
Tuning Sugar Chains to Boost Antibody Power
Glycan profiles can be modulated in various ways during antibody development:For example, galactosylation enhances complement-dependent cytotoxicity (CDC) by promoting stronger C1q binding, while sialylation can reduce proinflammatory activity by modulating Fc receptor interactions and may help reduce rapid clearance by masking galactose residues recognized by the asialoglycoprotein receptor (ASGP-R), effectively extending antibody half-life.
However, eliminating fucose—a key to boosting antibody-dependent cellular cytotoxicity (ADCC)—has proven harder. While a knockout of the enzyme for GDP-fucose attachment Fut8 is effective at removing core fucose, it comes at a cost: lower viability, reduced productivity, and inflexibility. Once you knock it out, you can’t tune it back.
“We did not choose to knock out the gene – we did something else instead.”
Dr. Volker Sandig
Precision Fucose Editing Made Easy
To overcome these challenges, ProBioGen developed GlymaxX®, a metabolic engineering platform that removes fucose through a smart, non-disruptive mechanism. Rather than altering or knocking out genes, GlymaxX redirects the fucose synthesis pathway using a bacterial enzyme: RMD (GDP-4-keto-6-deoxymannose reductase).
RMD converts GDP-KDM, a key metabolic intermediate, into GDP-rhamnose—a sugar not incorporated into mammalian glycans. This effectively blocks the internal fucose pathway without producing unwanted byproducts. Since mammalian cells lack a rhamnosyltransferase, there’s no risk of rhamnose incorporation.
What Sets GlymaxX Apart?
“Natural antibodies are never absolutely afucosylated – so tuning would be something that would be desired – and it is possible.”
Dr. Volker Sandig
Mastering Glycan Control in Antibody Production
With GlymaxX, developers don’t have to commit to a particular glycoform too early. They can produce both fucosylated and afucosylated antibodies from the same cell line and decide which profile to advance later—ideal for biosimilar comparability, T-cell engager tuning, or balancing effector function in bispecifics.
Moreover, this technology can be combined with other glycoengineering techniques like hypergalactosylation or Fc mutations for enhanced ADCC or CDC. It offers not only potent afucosylation but also the option to fine-tune immune responses across immune cell types.
Glycoengineered Antibodies: From Lab to Market
GlymaxX has been licensed by over half of the top 10 global pharma companies. Its clinical relevance is underscored by success stories such as:
Zenocutuzumab-zbco (Merus): A bispecific HER2/HER3 antibody approved for NRG1+ NSCLC and pancreatic cancer. GlymaxX-enabled afucosylation ensured strong ADCC regardless of FcγRIIIa genotype.
Zanidatamab-hrii (Zymeworks): HER2-targeted bispecific antibody for biliary tract cancer, with tuned afucosylation levels allowing an optimal balance of potency and safety.
These antibodies have received regulatory recognition for their clinical impact, including priority review and accelerated approval. These aren’t just antibodies—they’re precision-tuned immune tools, made possible by advanced glycoengineering.
“So if you have any doubts this tuning approach can be taken to the market – here is the proof.”
Dr. Volker Sandig
Conclusion: The Future of Antibodies Is Sugar-Engineered
Glycosylation is no longer a side effect of production—it’s a central design parameter in next-generation biologics. These small sugar chains shape many aspects of an antibody’s function, from immune activation to manufacturability and half-life.
With GlymaxX, developers gain full control over one of the most powerful levers of therapeutic antibody function. The technology allows for efficient, tunable afucosylation—without compromising cell viability or process flexibility. Whether optimizing ADCC, tuning effector function in bispecifics, or maintaining flexibility for late-stage decisions, GlymaxX supports smarter, faster development.
Want to learn more? Connect with our scientists or visit our technology page:
https://www.probiogen.de/technologies-for-proteins/adcc-enhancement-glycoengineering
Webinar Tip:
Dr. Volker Sandig has presented a deep-dive webinar on this exact topic, exploring the science and application of precision glycoengineering.
References:
(1) Lifely MR, Hale C, Boyce S, Keen MJ, Phillips J. Glycosylation and biological activity of CAMPATH-1H expressed in different cell lines and grown under different culture conditions. Glycobiology. 1995 Dec;5(8):813-22. doi: 10.1093/glycob/5.8.813. PMID: 8720080.
(2) Chung S, Quarmby V, Gao X, Ying Y, Lin L, Reed C, Fong C, Lau W, Qiu ZJ, Shen A, Vanderlaan M, Song A. Quantitative evaluation of fucose reducing effects in a humanized antibody on Fcγ receptor binding and antibody-dependent cell-mediated cytotoxicity activities. MAbs. 2012 May-Jun;4(3):326-40. doi: 10.4161/mabs.19941. Epub 2012 Apr 26. PMID: 22531441; PMCID: PMC3355491.