Exploiting Carbohydrate–Receptor Interactions for Targeted Therapeutics
Targeted delivery represents one of the most promising strategies in modern medicine, with applications spanning oncology, autoimmune diseases, infectious diseases, vaccine development, and inflammatory conditions.1 Classical therapeutic approaches often lack the precision required for optimal efficacy while minimizing adverse effects. Conventional systemic administered drugs frequently cause broad systemic effects, leading to compromised immune function, autoimmune reactions, or inadequate therapeutic responses across diverse patient populations.
Active targeting enhances drug delivery to specific cells exploiting ligands that bind to unique cell-surface receptors, increasing payload concentration at the target site while minimizing off-target effects.2 A successful example is the use of antibody-drug conjugates (ADCs) to selectively target specific cells and deliver a drug payload, however, given their complex development and structure, this approach may not be optimal for every application.3
Carbohydrates on the other hand, through their ability to selectively interact with specific receptors, particularly on immune cells, offer an alternative opportunity for targeted delivery.4 Additionally, engaging these immune receptors can modulate the outcome of the immune response, either triggering pro-inflammatory or anti-inflammatory effects, a strategy widely exploited in cancer therapy, vaccine development, and autoimmune disease treatment.
This whitepaper explores how glycan-based strategies can offer an alternative to immune targeting across therapeutic applications, from enhancing vaccine responses and treating autoimmune diseases to combating infectious pathogens and modulating inflammatory responses.
Why Glycans?
Glycans are particularly effective, though not limited, to target immune cells, since these molecules are the natural ligand for many immune cell receptors. Immune cells act as expert sentinels, constantly patrolling the body to detect and respond to pathogens such as bacteria and viruses. Particularly, immune cells recognize specific glycan motifs displayed on the surface of different pathogens and recognize them as pathogen-associated molecular patterns (PAMPs), enabling their identification and subsequent phagocytosis.4 For example, C-type lectin receptors (CLRs) are a superfamily of more than 1000 proteins that are particularly expressed on myeloid cells (like dendritic cells, macrophages or neutrophils).5 Binding of carbohydrates to CLRs typically triggers a cascade of pro-inflammatory or anti-inflammatory responses, depending on the receptor.6 This makes CLRs an attractive target for therapeutic strategies. By carefully designing ligands specific to a particular CLR, it is possible to selectively target a particular immune cell subtype and achieve the desired immunological outcomes. [7–9]
| Receptor | Ligand | Cell type |
| DC-SIGN | High mannose oligosaccharide | Dendritic cells |
| Mannose receptor | High mannose oligosaccharide | Macrophages, immature DCs |
| Langerin | Mannose | Langerhans cells |
| Dectin-1 | Beta-glucans | Myeloid cells |
| Siglecs | Sialic-acid derivates | Myeloid cells |
| DCIR | Asialo-biantennary N-glycan | Myeloid cells |
| ASPGR | Galactose, GalNAc | Hepatocytes |
| Galectins | Galactose-containing glycans | Immune cells |
| Selectins | Fucosylated and sialylated tetrasaccharides sialyl Lewisx , sialyl Lewisa | Endothelial cells, platelets, leukocytes |
Moving further – Glycomimetics
Despite large structural variety of glycans as targeting motifs, carbohydrate ligands have some limitations and drawbacks. Carbohydrate binding sites are often hydrophilic and solvent-exposed, and ligand binding often relies on the multivalency of low affinity bindings, which may not be suitable for the targeting of small molecules. To overcome this challenge, the ligands can be modified or substituted by a chemical analogue to increase the affinity towards the receptor by several folds compared to the natural counterpart. The term “glycomimetics” refers to molecules that replicate the structure and function of carbohydrates but display improved pharmacological properties.15 Employing the basics of medicinal chemistry, these modified glycans can also be designed to improve bioavailability, increase cell permeation or increase resistance to enzymatic degradation.
Benefits of Glycans as targeting molecules
- Natural Ligands for Many Receptors
- Many cell-surface receptors (lectins, selectins, siglecs, galectins, etc.) naturally recognize specific glycan motifs.
- This makes glycans biologically relevant targeting agents with high specificity for certain receptors (e.g., mannose for mannose receptors on macrophages, sialic acids for siglecs).
- Smaller Size vs. Antibodies
- Glycans are much smaller than antibodies (~100–150 kDa).
- Better tissue penetration, lower risk of steric hindrance, and potentially improved biodistribution.
- Reduced Immunogenicity
- Antibodies (especially non-human or engineered ones) can trigger immune responses.
- Glycans, being natural components of biology, often show reduced immunogenicity when used appropriately.
- Ease of Chemical Modification
- Glycans can be chemically synthesized, modified, or attached to nanocarriers with high precision. Additionally, glycan conjugation minimally impacts the overall stability of nanoparticles, unlike antibody conjugation, where the larger molecular size often compromises stability.
- Antibody engineering is more complex and costly.
- Cost and Stability
- Glycan synthesis (especially short oligosaccharides or mimetics) can be cheaper and more stable than antibody production, which requires complex biological systems.
- Glycans are generally more stable under harsh conditions than proteins.
- Exploiting Multivalency
- Glycan–lectin interactions are typically weak (millimolar affinity for monovalent interactions). However, multivalent presentation (glycoclusters, glycopolymers) drastically increases binding strength (“cluster glycoside effect”).
- This allows for tunable targeting specificity and avidity.
- Unique Access to Certain Biological Pathways
- Some receptors are only efficiently engaged by glycans (e.g., selectin-mediated cell adhesion in inflammation, asialoglycoprotein receptor in the liver). Antibodies, since do not necessarily interact with the binding pocket, cannot mimic these natural interactions as effectively.
Asparia Glycomic’s Services
Design your targeted delivery strategy
Designing the optimal active targeting strategy remains a significant challenge. At Asparia Glycomics, we are dedicated to helping you achieve your research objectives with precision and expertise. Whether you are working with a known chemical entity or designing a novel glycoderivative, our team of highly skilled scientists, with over 20 years of proven experience, will guide you at every step. We adhere to the highest industry standards, ensuring that the final product exceeds expectations for both quality and performance.
Our Custom Glycan Synthesis Service offers full flexibility to design molecules adapted to your research requirements. We can introduce various linkers and functional groups, such as –NH₂, –N₃, -DBCO, or others of your choice, to match the conjugation strategy you intend to use. In addition, we provide bioconjugation services that include direct coupling of glycans to carrier proteins, peptides, (bio)polymers, or other biomolecules, supporting applications in vaccine development and diagnostic assays. These options facilitate improved glycan presentation, stronger binding interactions, and efficient integration into experimental workflows.
Asparia Glycomics provide unparalleled opportunities to design and tailor molecules to your exact specifications. We are experts in both chemical and enzymatic synthesis, and we can also extract specific glycans from natural sources. All glycans produced are thoroughly characterized using state-of-the-art analytical techniques, ensuring the highest level of confidence in structure and purity.
If you have a target in mind but are uncertain about the specificity of its glycan ligand, our Custom Glycan Array Technology provides a powerful solution. By screening a wide range of well-defined glycan structures, we can pinpoint precise binding interactions and uncover novel recognition motifs. This approach not only helps validate your target but also accelerates the discovery of the most effective glycan ligands for your application—whether in therapeutic development, vaccine design, or diagnostic innovation.
Applications
The translation of glycobiology into therapeutic strategies is now progressing from conceptual demonstrations to tangible clinical applications. Glycans and glycomimetics provide unique opportunities to selectively engage immune cell receptors, modulate signaling pathways, and enable precise drug delivery. Their versatility spans diverse modalities, from liver-directed nucleic acid therapeutics and cancer immunotherapies to vaccine adjuvants and engineered cell therapies. In this section, we highlight some key applications that illustrate how rational glycan design, multivalent presentation, and conjugation strategies are being harnessed to overcome biological barriers and unlock novel therapeutic avenues.
Hepatic delivery
The most successful example of glycan-based has not been employed for immune targeting, but for hepatic delivery instead.16 N-acetylgalactosamine (GalNAc) has emerged as a highly effective ligand for targeted delivery of therapeutics to hepatocytes via the asialoglycoprotein receptor (ASGPR), a C-type lectin receptor abundantly and selectively expressed on the surface of liver parenchymal cells. The ASGPR recognizes terminal GalNAc residues with high affinity, enabling receptor-mediated endocytosis of GalNAc-conjugated molecules. This property has been extensively exploited in the development of nucleic acid–based therapies, particularly small interfering RNAs (siRNAs) and antisense oligonucleotides (ASOs). The natural ligand is galactose and GalNAc, however, triantennary GalNAc conjugates demonstrate optimal binding and internalization, facilitating efficient uptake into hepatocytes while minimizing distribution to extrahepatic tissues. This specificity not only enhances therapeutic potency but also improves safety by reducing systemic exposure. Clinical translation of GalNAc-based platforms has led to multiple approved siRNA therapies for liver-associated genetic and metabolic disorders, underscoring the robustness of this delivery strategy.
Immune cell targeting & modulation
Traditional targeting strategies such as antibodies are highly effective at recognizing and binding to their targets. However, in the case of immune receptors, where ligand binding induces conformational changes and initiates downstream signaling cascades, antibodies often fall short, as they primarily block or stabilize interactions rather than trigger signaling. This limitation provides the rationale for employing glycans as targeting agents.
By carefully selecting the target receptor, the immune response can be tuned toward either pro-inflammatory or anti-inflammatory outcomes. In cancer therapy, the goal is to elicit pro-inflammatory responses that enhance anti-tumor immune response. For example, antigens coupled with mannose or GalNAc increase the uptake of the conjugate by dendritic cells while promoting a stronger immune response.11,12,17 On the other hand, in autoimmune diseases the preferred strategy is to induce anti-inflammatory pathways to restore immune tolerance. For example, Siglec-targeted therapies could help reduce inflammation by regulating the activity of immune cells involved in the inflammatory process.4,13
Vaccine development
mRNA vaccines are typically formulated using lipid nanoparticles (LNPs), which consist of multiple lipids in defined ratios. However, current LNPs generally lack the ability for targeted delivery. Efficient nanocarriers capable of directing mRNA vaccines specifically to antigen-presenting cells (APCs) remain an unmet need. Targeted delivery to immune cells could enhance the immunological response while potentially lowering the required dose and minimizing adverse side effects. Furthermore, by engaging immune receptors, the nanocarrier itself could function not only as a delivery vehicle but also as an adjuvant, further boosting vaccine efficacy. One promising approach involves mannosylated LNPs, which show increased binding and uptake by dendritic cells compared to unmodified LNPs, making them attractive candidates for boosting mRNA vaccine potency.11,12
Sweet CARs
The discovery and application of chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of hematologic cancers; however, it fails short to treat solid cancers due to the scarcity of tumor-specific antigens. Glycosylation in cancer is heavily altered
compared to healthy tissues, offering an opportunity as tumor-specific antigens. Targeting glycoproteins with CARs (“sweet CARs”) is attractive because CAR recognition does not rely on major histocompatibility complex presentation, enabling direct engagement of surface glycoepitopes.18
A central challenge is the production of anti-glycan single-chain variable fragments (scFvs) with high specificity and affinity, given the subtle structural diversity and context dependence of glycans on different protein backbones and sites. Glycosylation is a non-templated, post-translational modification that produces extensive microheterogeneity, complicating immunogen design and binder selection. Access to well-defined synthetic glycans and glycoconjugates can mitigate these issues by supplying structurally precise, highly pure antigens for immunization and screening, thereby improving the likelihood of generating antibodies with the desired epitope specificity and advancing the development of glycan-targeted CAR constructs. This strategy is also being applied to the development of anti-glycan antibodies for use in designing glycan-targeted antibody–drug conjugates (ADCs).19
Conclusions
Glycan-based targeting represents a versatile and continuously growing approach to both deliver therapeutics and actively modulate immune responses. The field has clear, clinically validated proof-points (most notably GalNAc–ASGPR mediated liver delivery), and expanding their targets towards lectin families (CLRs, Siglecs, and other carbohydrate binding proteins) opening multiple therapeutic avenues across oncology, vaccinology, autoimmunity and infectious disease. However, important scientific and translational challenges remain, principally raising from the complex synthesis and obtaining of these molecules, the need to transform weak monovalent glycan interactions into therapeutically useful binding through glycomimetic chemistry, and the identification of viable therapeutical targets.
Asparia Glycomics, with its long track record of successful partnerships, is strategically positioned to accelerate your research from concept to clinic. The company’s combined capabilities in chemical and enzymatic synthesis and comprehensive structural characterization directly address the major technical bottlenecks identified above. By offering end-to-end services, from feasibility and synthetic route development to scale-up and advanced bioconjugation, Asparia support you research process by reducing risk and helping you focus on your research.
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