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BioDrugs : Clinical Immunotherapeutics,... Sep 2022The highly specific induction of RNA interference-mediated gene knockdown, based on the direct application of small interfering RNAs (siRNAs), opens novel avenues... (Review)
Review
The highly specific induction of RNA interference-mediated gene knockdown, based on the direct application of small interfering RNAs (siRNAs), opens novel avenues towards innovative therapies. Two decades after the discovery of the RNA interference mechanism, the first siRNA drugs received approval for clinical use by the US Food and Drug Administration and the European Medicines Agency between 2018 and 2022. These are mainly based on an siRNA conjugation with a targeting moiety for liver hepatocytes, N-acetylgalactosamine, and cover the treatment of acute hepatic porphyria, transthyretin-mediated amyloidosis, hypercholesterolemia, and primary hyperoxaluria type 1. Still, the development of siRNA therapeutics faces several challenges and issues, including the definition of optimal siRNAs in terms of target, sequence, and chemical modifications, siRNA delivery to its intended site of action, and the absence of unspecific off-target effects. Further siRNA drugs are in clinical studies, based on different delivery systems and covering a wide range of different pathologies including metabolic diseases, hematology, infectious diseases, oncology, ocular diseases, and others. This article reviews the knowledge on siRNA design and chemical modification, as well as issues related to siRNA delivery that may be addressed using different delivery systems. Details on the mode of action and clinical status of the various siRNA therapeutics are provided, before giving an outlook on issues regarding the future of siRNA drugs and on their potential as one emerging standard modality in pharmacotherapy. Notably, this may also cover otherwise un-druggable diseases, the definition of non-coding RNAs as targets, and novel concepts of personalized and combination treatment regimens.
Topics: Acetylgalactosamine; Humans; Prealbumin; RNA Interference; RNA, Small Interfering
PubMed: 35997897
DOI: 10.1007/s40259-022-00549-3 -
Signal Transduction and Targeted Therapy Jun 2020RNA interference (RNAi) is an ancient biological mechanism used to defend against external invasion. It theoretically can silence any disease-related genes in a... (Review)
Review
RNA interference (RNAi) is an ancient biological mechanism used to defend against external invasion. It theoretically can silence any disease-related genes in a sequence-specific manner, making small interfering RNA (siRNA) a promising therapeutic modality. After a two-decade journey from its discovery, two approvals of siRNA therapeutics, ONPATTRO (patisiran) and GIVLAARI™ (givosiran), have been achieved by Alnylam Pharmaceuticals. Reviewing the long-term pharmaceutical history of human beings, siRNA therapy currently has set up an extraordinary milestone, as it has already changed and will continue to change the treatment and management of human diseases. It can be administered quarterly, even twice-yearly, to achieve therapeutic effects, which is not the case for small molecules and antibodies. The drug development process was extremely hard, aiming to surmount complex obstacles, such as how to efficiently and safely deliver siRNAs to desired tissues and cells and how to enhance the performance of siRNAs with respect to their activity, stability, specificity and potential off-target effects. In this review, the evolution of siRNA chemical modifications and their biomedical performance are comprehensively reviewed. All clinically explored and commercialized siRNA delivery platforms, including the GalNAc (N-acetylgalactosamine)-siRNA conjugate, and their fundamental design principles are thoroughly discussed. The latest progress in siRNA therapeutic development is also summarized. This review provides a comprehensive view and roadmap for general readers working in the field.
Topics: Acetylgalactosamine; Genetic Diseases, Inborn; Genetic Therapy; Humans; Pyrrolidines; RNA Interference; RNA, Double-Stranded; RNA, Small Interfering
PubMed: 32561705
DOI: 10.1038/s41392-020-0207-x -
Nature Chemical Biology Sep 2021Selective protein degradation platforms have afforded new development opportunities for therapeutics and tools for biological inquiry. The first lysosome-targeting...
Selective protein degradation platforms have afforded new development opportunities for therapeutics and tools for biological inquiry. The first lysosome-targeting chimeras (LYTACs) targeted extracellular and membrane proteins for degradation by bridging a target protein to the cation-independent mannose-6-phosphate receptor (CI-M6PR). Here, we developed LYTACs that engage the asialoglycoprotein receptor (ASGPR), a liver-specific lysosome-targeting receptor, to degrade extracellular proteins in a cell-type-specific manner. We conjugated binders to a triantenerrary N-acetylgalactosamine (tri-GalNAc) motif that engages ASGPR to drive the downregulation of proteins. Degradation of epidermal growth factor receptor (EGFR) by GalNAc-LYTAC attenuated EGFR signaling compared to inhibition with an antibody. Furthermore, we demonstrated that a LYTAC consisting of a 3.4-kDa peptide binder linked to a tri-GalNAc ligand degrades integrins and reduces cancer cell proliferation. Degradation with a single tri-GalNAc ligand prompted site-specific conjugation on antibody scaffolds, which improved the pharmacokinetic profile of GalNAc-LYTACs in vivo. GalNAc-LYTACs thus represent an avenue for cell-type-restricted protein degradation.
Topics: Acetylgalactosamine; Asialoglycoprotein Receptor; Humans; Lysosomes; Tumor Cells, Cultured
PubMed: 33767387
DOI: 10.1038/s41589-021-00770-1 -
Nucleic Acids Research Dec 2020One hallmark of trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNAs is the remarkable durability of silencing that can persist for months in preclinical species...
One hallmark of trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNAs is the remarkable durability of silencing that can persist for months in preclinical species and humans. Here, we investigated the underlying biology supporting this extended duration of pharmacological activity. We found that siRNA accumulation and stability in acidic intracellular compartments is critical for long-term activity. We show that functional siRNA can be liberated from these compartments and loaded into newly generated Argonaute 2 protein complexes weeks after dosing, enabling continuous RNAi activity over time. Identical siRNAs delivered in lipid nanoparticles or as GalNAc conjugates were dose-adjusted to achieve similar knockdown, but only GalNAc-siRNAs supported an extended duration of activity, illustrating the importance of receptor-mediated siRNA trafficking in the process. Taken together, we provide several lines of evidence that acidic intracellular compartments serve as a long-term depot for GalNAc-siRNA conjugates and are the major contributor to the extended duration of activity observed in vivo.
Topics: Acetylgalactosamine; Animals; Argonaute Proteins; Asialoglycoprotein Receptor; Biological Transport; Drug Carriers; Drug Stability; Female; Gene Silencing; Glycoconjugates; Hepatocytes; Humans; Hydrogen-Ion Concentration; Liver; Mice; Mice, Inbred C57BL; Nanoparticles; Prealbumin; RNA, Small Interfering; Time Factors
PubMed: 32808038
DOI: 10.1093/nar/gkaa670 -
Delivery of Oligonucleotides to the Liver with GalNAc: From Research to Registered Therapeutic Drug.Molecular Therapy : the Journal of the... Aug 2020Targeted delivery of oligonucleotides to liver hepatocytes using N-acetylgalactosamine (GalNAc) conjugates that bind to the asialoglycoprotein receptor has become a... (Review)
Review
Targeted delivery of oligonucleotides to liver hepatocytes using N-acetylgalactosamine (GalNAc) conjugates that bind to the asialoglycoprotein receptor has become a breakthrough approach in the therapeutic oligonucleotide field. This technology has led to the approval of givosiran for the treatment of acute hepatic porphyria, and there are another seven conjugates in registrational review or phase 3 trials and at least another 21 conjugates at earlier stages of clinical development. This review highlights some of the recent chemical and preclinical advances in this space, leading to a large number of clinical candidates against a diverse range of targets in liver hepatocytes. The review focuses on the use of this delivery system for small interfering RNAs (siRNAs) and antisense molecules that cause downregulation of target mRNA and protein. A number of other approaches such as anti-microRNAs and small activating RNAs are starting to exploit the technology, broadening the potential of this approach for therapeutic oligonucleotide intervention.
Topics: Acetylgalactosamine; Animals; Drug Carriers; Drug Delivery Systems; Drug Development; Drug Evaluation, Preclinical; Gene Transfer Techniques; Genetic Therapy; Hepatocytes; Humans; Liver; Oligonucleotides; RNA, Messenger; RNA, Small Interfering; Research; Translational Research, Biomedical
PubMed: 32592692
DOI: 10.1016/j.ymthe.2020.06.015 -
Kidney International Nov 2015Recent years have brought notable progress in the field of IgA nephropathy. Here, we highlight important new directions and latest developments, including successful... (Review)
Review
Recent years have brought notable progress in the field of IgA nephropathy. Here, we highlight important new directions and latest developments, including successful discovery of several genetic susceptibility loci, formulation of the multihit pathogenesis model, introduction of the Oxford pathology scoring system, and formalization of the Kidney Disease Improving Global Outcomes (KDIGO) consensus treatment guidelines. We focus on the latest genetic findings that confirm a strong contribution of inherited factors and explain some of the geoethnic disparities in disease susceptibility. Most IgA nephropathy susceptibility loci discovered to date encode genes involved in the maintenance of the intestinal epithelial barrier and response to mucosal pathogens. The concerted pattern of interpopulation allelic differentiation across all genetic loci parallels the disease prevalence and correlates with variation in local pathogens, suggesting that multilocus adaptation might have shaped the present-day landscape of IgA nephropathy. Importantly, the 'Intestinal Immune Network for IgA Production' emerged as one of the new targets for potential therapeutic intervention. We place these findings in the context of the multihit pathogenesis model and existing knowledge of IgA immunobiology. Lastly, we provide our perspective on the existing treatment options, discuss areas of clinical uncertainty, and outline ongoing clinical trials and translational studies.
Topics: Acetylgalactosamine; Complement System Proteins; Glomerulonephritis, IGA; Glycosylation; Humans; Immunoglobulin A; Prognosis
PubMed: 26376134
DOI: 10.1038/ki.2015.252 -
Nature Jun 2022The composition of the intestinal microbiome varies considerably between individuals and is correlated with health. Understanding the extent to which, and how, host...
The composition of the intestinal microbiome varies considerably between individuals and is correlated with health. Understanding the extent to which, and how, host genetics contributes to this variation is essential yet has proved to be difficult, as few associations have been replicated, particularly in humans. Here we study the effect of host genotype on the composition of the intestinal microbiota in a large mosaic pig population. We show that, under conditions of exacerbated genetic diversity and environmental uniformity, microbiota composition and the abundance of specific taxa are heritable. We map a quantitative trait locus affecting the abundance of Erysipelotrichaceae species and show that it is caused by a 2.3 kb deletion in the gene encoding N-acetyl-galactosaminyl-transferase that underpins the ABO blood group in humans. We show that this deletion is a ≥3.5-million-year-old trans-species polymorphism under balancing selection. We demonstrate that it decreases the concentrations of N-acetyl-galactosamine in the gut, and thereby reduces the abundance of Erysipelotrichaceae that can import and catabolize N-acetyl-galactosamine. Our results provide very strong evidence for an effect of the host genotype on the abundance of specific bacteria in the intestine combined with insights into the molecular mechanisms that underpin this association. Our data pave the way towards identifying the same effect in rural human populations.
Topics: ABO Blood-Group System; Acetylgalactosamine; Animals; Bacteria; Gastrointestinal Microbiome; Genotype; N-Acetylgalactosaminyltransferases; Quantitative Trait Loci; Swine
PubMed: 35477154
DOI: 10.1038/s41586-022-04769-z -
Nature Communications Feb 2018Small interfering RNAs (siRNAs) conjugated to a trivalent N-acetylgalactosamine (GalNAc) ligand are being evaluated in investigational clinical studies for a variety of...
Small interfering RNAs (siRNAs) conjugated to a trivalent N-acetylgalactosamine (GalNAc) ligand are being evaluated in investigational clinical studies for a variety of indications. The typical development candidate selection process includes evaluation of the most active compounds for toxicity in rats at pharmacologically exaggerated doses. The subset of GalNAc-siRNAs that show rat hepatotoxicity is not advanced to clinical development. Potential mechanisms of hepatotoxicity can be associated with the intracellular accumulation of oligonucleotides and their metabolites, RNA interference (RNAi)-mediated hybridization-based off-target effects, and/or perturbation of endogenous RNAi pathways. Here we show that rodent hepatotoxicity observed at supratherapeutic exposures can be largely attributed to RNAi-mediated off-target effects, but not chemical modifications or the perturbation of RNAi pathways. Furthermore, these off-target effects can be mitigated by modulating seed-pairing using a thermally destabilizing chemical modification, which significantly improves the safety profile of a GalNAc-siRNA in rat and may minimize the occurrence of hepatotoxic siRNAs across species.
Topics: Acetylgalactosamine; Animals; Liver; Male; RNA Interference; RNA, Small Interfering; Rats; Rats, Sprague-Dawley
PubMed: 29459660
DOI: 10.1038/s41467-018-02989-4 -
Journal of the American Chemical Society Mar 2019The first bacterial α2-6-sialyltransferase cloned from Photobacterium damselae (Pd2,6ST) has been widely applied for the synthesis of various α2-6-linked sialosides....
The first bacterial α2-6-sialyltransferase cloned from Photobacterium damselae (Pd2,6ST) has been widely applied for the synthesis of various α2-6-linked sialosides. However, the extreme substrate flexibility of Pd2,6ST makes it unsuitable for site-specific α2-6-sialylation of complex substrates containing multiple galactose and/or N-acetylgalactosamine units. To tackle this problem, a general redox-controlled site-specific sialylation strategy using Pd2,6ST is described. This approach features site-specific enzymatic oxidation of galactose units to mask the unwanted sialylation sites and precisely controlling the site-specific α2-6-sialylation at intact galactose or N-acetylgalactosamine units.
Topics: Acetylgalactosamine; Binding Sites; Galactose; N-Acetylneuraminic Acid; Oxidation-Reduction; Sialyltransferases; Substrate Specificity
PubMed: 30843692
DOI: 10.1021/jacs.9b00044 -
Molecular Therapy : the Journal of the... Mar 2018Significant progress has been made in the advancement of RNAi therapeutics by combining a synthetic triantennary N-acetylgalactosamine ligand targeting the...
Significant progress has been made in the advancement of RNAi therapeutics by combining a synthetic triantennary N-acetylgalactosamine ligand targeting the asialoglycoprotein receptor with chemically modified small interfering RNA (siRNA) designs, including the recently described Enhanced Stabilization Chemistry. This strategy has demonstrated robust RNAi-mediated gene silencing in liver after subcutaneous administration across species, including human. Here we demonstrate that substantial efficacy improvements can be achieved through further refinement of siRNA chemistry, optimizing the positioning of 2'-deoxy-2'-fluoro and 2'-O-methyl ribosugar modifications across both strands of the double-stranded siRNA duplex to enhance stability without compromising intrinsic RNAi activity. To achieve this, we employed an iterative screening approach across multiple siRNAs to arrive at advanced designs with low 2'-deoxy-2'-fluoro content that yield significantly improved potency and duration in preclinical species, including non-human primate. Liver exposure data indicate that the improvement in potency is predominantly due to increased metabolic stability of the siRNA conjugates.
Topics: Acetylgalactosamine; Animals; Argonaute Proteins; Gene Expression Regulation; Gene Silencing; Hepatocytes; Liver; Male; Mice; Mice, Transgenic; RNA Interference; RNA, Messenger; RNA, Small Interfering
PubMed: 29456020
DOI: 10.1016/j.ymthe.2017.12.021