GalNAc-ASO Delivery Service
Overview
The clinical success of oligonucleotide therapeutics hinges on the ability to deliver genetic payloads to specific tissues with high efficiency and minimal systemic toxicity. CD BioGlyco provides an industry-leading GalNAc-ASO delivery service, leveraging the highly efficient asialoglycoprotein receptor (ASGPR) pathway. By chemically conjugating a trivalent GalNAc cluster to ASOs, we enable nearly exclusive delivery to hepatocytes. This approach overcomes the traditional challenges of "naked" oligonucleotides, such as rapid renal clearance and poor cellular uptake. Our platform transforms potent sequences into liver-targeted therapies, offering a 10- to 60-fold increase in potency and enabling convenient subcutaneous administration for a broad spectrum of hepatic and metabolic disorders.
Core Technologies
Our GalNAc-ASO platform integrates several proprietary and gold-standard chemical engineering strategies:
- Trivalent GalNAc Clusters
We utilize a triantennary ligand configuration optimized for the trimeric structure of the ASGPR. This design achieves nanomolar binding affinity, capitalizing on the ~500,000 receptors present on each hepatocyte to ensure rapid and robust internalization.
- Second-Generation ASO Chemistries
To maximize intracellular stability and RNase H1 recruitment, we employ advanced modifications including 2′-O-methoxyethyl (2′-MOE), 2′-fluoro (2′-F), and constrained ethyl (cEt) sugars. These are coupled with a phosphorothioate (PS) backbone to enhance plasma protein binding and nuclease resistance.
- Gapmer Design Optimization
Our team specializes in "Gapmer" architectures, a central 8–10 nucleotide DNA core flanked by modified "wings." This design triggers the endogenous RNase H1 enzyme to degrade target mRNA specifically while maintaining the structural integrity of the ASO.
- Receptor-Mediated Endocytosis & Recycling
Our conjugates are engineered to dissociate from the ASGPR in the acidic environment of the endosome. This allows the receptor to recycle back to the cell surface in approximately 15 minutes, maintaining a continuous "conveyor belt" of therapeutic delivery.
Precision in Targeting. Power in Silence.
The GalNAc-ASO delivery service is designed to support the entire development continuum, from initial screening to pilot manufacturing. We provide custom synthesis across various scales, from low-milligram amounts for primary in vitro assays to multi-gram quantities for non-human primate (NHP) studies and toxicology. Our platform supports a wide array of oligonucleotide modalities, including standard gapmers, steric-blocking ASOs for splicing modulation, and exon-skipping oligos.
Beyond synthesis, our service scope includes comprehensive analytical characterization and biological validation. We provide ASGPR-binding affinity assays, in vitro knockdown efficiency testing in primary hepatocyte cultures, and metabolic stability profiling in liver S9 fractions. Our technical team also assists in the development of custom linkers and spacer technologies, allowing for the fine-tuning of the release kinetics of the ASO payload within the hepatocyte. Whether you are targeting rare metabolic enzymes or viral transcripts, CD BioGlyco delivers a complete, high-purity package tailored to your specific therapeutic goals.
Workflow
Bioinformatic Target Profiling
We employ sophisticated bioinformatic algorithms and proprietary sequence-design software to systematically screen and select optimal ASO sequences. Our analysis prioritizes candidate sequences with high hybridization affinity and specificity for the target mRNA region, while rigorously evaluating and minimizing potential off-target interactions across the transcriptome. The design is further optimized for specific "gapmer" architectures, ensuring efficient recruitment of RNase to mediate targeted mRNA degradation and achieve potent gene silencing.
Chemical Modification Engineering
Our team of expert chemists designs a tailored chemical modification pattern for your ASO, selecting from established modifications such as 2'-Methoxyethyl (2'-MOE) ribose and phosphorothioate (PS) backbone linkages. This strategic engineering is based on your specific requirements for pharmacokinetic profile, tissue distribution, and duration of action. The chosen pattern is calibrated to confer maximum resistance to nucleases, enhance binding affinity, and ensure stability in both the endo-lysosomal and cytoplasmic compartments, thereby maximizing therapeutic efficacy.
Automated Solid-Phase Synthesis
The designed ASO sequence is produced with high precision and efficiency using state-of-the-art, automated solid-phase synthesizers. This high-throughput platform ensures excellent stepwise coupling efficiency, resulting in a high-yield synthesis of the full-length oligonucleotide. During synthesis, specific functional handles, such as primary amino (e.g., 5'-amino-modifier C6) or thiol groups, are site-specifically incorporated into the backbone, providing the essential chemical moiety for the subsequent, directed conjugation of the targeting ligand.
GalNAc Cluster Conjugation
The trivalent GalNAc targeting ligand, optimized for high-affinity binding to the hepatocyte-specific asialoglycoprotein receptor (ASGPR), is conjugated to the ASO. This is achieved through a stable (non-cleavable) or bio-cleavable (e.g., disulfide or carbamate) linker chemistry. We strategically evaluate and offer both 5'-end and 3'-end conjugation strategies; the optimal site is selected based on the specific ASO sequence architecture, the chosen modification pattern, and the desired intracellular metabolic pathway to ensure optimal bioactivity and receptor-mediated internalization.
Multi-Step Purification & Quality Control
Each synthesis batch undergoes rigorous, multi-step purification to achieve therapeutic-grade material. We employ a sequential chromatographic process, typically beginning with ion-exchange (IEX) HPLC to remove truncated failure sequences, followed by reverse-phase (RP) HPLC to eliminate excess salts, ligands, and organic impurities. The final product is validated through a comprehensive suite of analytical tests: LC-MS for exact mass confirmation and identity, analytical size-exclusion chromatography (SEC) to confirm monomeric purity and assess aggregation, and sensitive endotoxin testing to ensure the conjugate is suitable for in vivo preclinical studies.
Publication Data
Journal: Nucleic Acids Research
DOI: 10.1093/nar/gku531
IF: 13.1
Published: 2014
Results: This study introduces a novel class of constrained ethyl (cEt) bicyclic nucleic acid modifications for ASOs, demonstrating their superior properties over existing chemistries like locked nucleic acid (LNA) and 2′-O-methoxyethyl (MOE). The authors systematically designed and synthesized cEt-modified ASOs, incorporating them into gapmer configurations targeting apolipoprotein B (ApoB) and other transcripts. Key findings revealed that cEt modifications significantly enhance binding affinity to complementary RNA while maintaining robust RNase H1 activity. Compared to LNA, cEt-modified ASOs exhibited markedly reduced hepatotoxicity in mice and improved therapeutic index. The modifications also conferred exceptional resistance to nuclease degradation and extended the duration of target suppression in vivo. Furthermore, the study established optimal positioning strategies for cEt residues within the gapmer design to maximize potency and safety. This work establishes cEt chemistry as a highly promising advancement for next-generation ASO therapeutics, offering enhanced efficacy and reduced toxicity profiles.
Applications
Acute Hepatic Porphyrias
By silencing the ALAS1 gene in the liver, our GalNAc-ASO service helps manage the neurotoxic attacks associated with heme biosynthesis defects.
Primary Hyperoxaluria
Our conjugates target the HAO1 gene in hepatocytes to reduce glyoxylate production, lowering oxalate levels and preventing progressive renal damage and stone formation.
Dyslipidemia and Triglyceride Control
We enable the silencing of ANGPTL3 and APOC3, key regulators of lipid metabolism, to research severe hypertriglyceridemia and reduce the risk of pancreatitis.
Complement-Mediated Disorders
Our service facilitates the liver-specific silencing of complement factors like C3 and C5, providing a localized therapeutic research approach for systemic inflammatory conditions.
Advantages
Optimized ASGPR Recycling
Our conjugates take advantage of the rapid recycling rate of the ASGPR, which can internalize millions of molecules per hour, ensuring that the therapeutic threshold is reached quickly.
Enhanced Safety Profile
Targeting the liver specifically minimizes the accumulation of ASOs in other organs like the kidneys and spleen. Published data indicate a 30-fold reduction in injection site reactions and systemic inflammation markers.
Predictable Pharmacokinetics
The small, well-defined molecular structure of the conjugate allows for consistent PK/PD profiles across different animal models, simplifying the transition from rodent studies to clinical trials.
Resistance to Nucleases
By incorporating 2'-MOE and phosphorothioate modifications, our GalNAc-ASO conjugates are highly resistant to exo- and endonucleases, ensuring the genetic payload remains active within the intracellular environment.
Frequently Asked Questions
Customer Review
The team at CD BioGlyco provided invaluable advice on the 2'-MOE modification pattern. Their expertise in liver-targeted delivery is evident in the robust silencing data we generated in our HBV models.
— By Dr. S.V., Principal Scientist
Switching to GalNAc-ASO from CD BioGlyco allowed us to use subcutaneous dosing in our chronic hypercholesterolemia studies. The animal welfare benefits and ease of administration were significant.
— By Senior Researcher, Cardiovascular Sciences
CD BioGlyco delivered high-purity gram-scale batches with a comprehensive analytical package. Their turnaround time for custom trivalent conjugation is the best in the industry.
— By Dr. J.P., Head of Oligonucleotide Research
Associated Services
High-purity mRNA encoding GFP, Luciferase, or LacZ for validating liver delivery efficiency and kinetics.
Stabilized mRNA encoding Cas9 or other nucleases for precise, liver-directed genomic modifications.
Optimized mRNA for the long-term restoration of missing hepatic enzymes in metabolic disorders.
Specialized mRNA for the induction of site-specific recombination in Cre-lox liver models.
CD BioGlyco is dedicated to providing the most advanced liver-targeting solutions to the global biotechnology community. Our GalNAc-ASO delivery service represents the pinnacle of oligonucleotide engineering, combining high-affinity trivalent ligands with state-of-the-art chemical modifications. Whether you are developing a first-in-class therapy for a rare metabolic disease or a blockbuster treatment for cardiovascular health, our team is ready to provide the precision and purity your project demands. Contact us for more information and to discuss your project.
Reference
- Prakash, T.P.; et al. Targeted delivery of antisense oligonucleotides to hepatocytes using triantennary N-acetyl galactosamine improves potency 10-fold in mice. Nucleic Acids Research. 2014, 42(13): 8796-8807. (Open Access)