Search Results (26)

Since the discovery of RNA interference (RNAi), small interfering RNA (siRNA) has emerged as a transformative therapeutic modality, shifting the paradigm from permanent genomic modification to the flexible interception of genetic information. Despite the delivery gap caused by biological barriers, innovations in chemical stabilization and delivery platforms have propelled siRNA from niche applications to the mainstream management of chronic conditions. This review provides a comprehensive analysis of the distinct mechanistic advantages of siRNA over antisense oligonucleotides, with particular emphasis on its catalytic turnover via the RISC and high target specificity. We further evaluate the critical transition from first-generation lipid nanoparticles to ligand-conjugated systems, specifically trivalent N-acetylgalactosamine (GalNAc). Through an examination of the clinical success of Inclisiran and the recent approval of Plozasiran, we discuss how these advances have improved patient compliance and extended dosing intervals. Furthermore, this article explores the emerging frontier of extra-hepatic delivery and the expansion toward metabolic and oncological targets. Ultimately, this review highlights the potential of siRNA to become a programmable standard of care for a broad spectrum of previously intractable diseases. Full article

Background: RNA therapeutics represent a rapidly advancing field with significant potential for treating viral infections and cancer. This review examines the current landscape of RNA-based strategies, including siRNA, miRNA mimics, and antisense oligonucleotides. For viral infections, the focus is on hepatitis B (HBV) and C (HCV), HIV, and SARS-CoV-2. Approaches include targeting viral transcripts directly (e.g., siRNAs against HBV surface antigen) or host factors critical for viral replication (e.g., anti-miR-122 miravirsen for HCV). The successful development of mRNA vaccines for COVID-19 is highlighted as a major breakthrough, demonstrating the feasibility of rapid RNA vaccine deployment. The manuscript reviews several RNA therapeutics in oncology that have reached clinical trials. These include TargomiR (a miR-16 mimic for mesothelioma), cobomarsen (an anti-miR-155 for lymphomas), and MRX34 (a miR-34a mimic for various solid tumours). The review also covers emerging candidates like an miR-221 inhibitor and various strategies for breast cancer, such as targeting Bcl-2, KRAS, and specific miRNAs. A critical challenge across both fields is developing efficient and safe delivery systems, including lipid nanoparticles, GalNAc conjugates, and bacterial minicells. Despite promising preclinical results, clinical translation has been hampered by issues like insufficient delivery efficiency to human tumours, toxicity, and the complex, interconnected regulatory networks of miRNAs, which can lead to unpredictable off-target effects. Conclusions: While RNA therapeutics hold immense promise, overcoming delivery barriers and enhancing understanding of RNA regulatory networks are essential for future success. Full article

In 2025, the FDA approved 46 novel drugs, including four TIDEs (one peptide, three oligonucleotides, and one antibody drug conjugate containing peptide as a payload). The three approved oligonucleotide therapeutics—fitusiran, donidalorsen, and plozasiran—bring the total number of approved oligonucleotide drugs to 24 across 16 clinical indications since 1998. Fitusiran and donidalorsen are the first oligonucleotide therapies approved for antithrombin deficiency and hereditary angioedema, respectively, while plozasiran represents the second approved therapy for familial chylomicronemia syndrome. All three agents employ GalNAc-mediated hepatocyte targeting, highlighting the continued importance of liver-directed delivery platforms in oligonucleotide drug development and underscoring the growing clinical maturity of this therapeutic class. Peptide-based therapeutics continue to emerge as pioneering treatments for longstanding diseases. In 2025, elamipretide further expanded this paradigm by becoming the first disease-specific treatment approved for Barth syndrome. This review provides an overview of TIDES approved in 2025, with emphasis on their chemical structures, medical targets, modes of action, routes of administration, and associated adverse effects. Full article

The development and application of therapeutic oligonucleotides, such as siRNA, miRNA, ASOs and aptamers, is a rapidly growing field in biomedicine. These molecules are undergoing extensive preclinical and clinical testing, and the market for synthetic RNA drugs is expanding. However, several challenges remain, including targeted delivery and high costs associated with development, screening and production. One significant advance has been the creation of GalNAc-conjugates, which selectively target ASGPR and deliver oligonucleotides to hepatocytes. Although these conjugates have shown promising results, their widespread use is limited by the lack of effective synthesis methods. Thus, the development of new methods for the synthesis of ligand-oligonucleotide conjugates is an important task to which this study is devoted. In this study, we created a library of siRNA conjugates with the GalNAc L-96 ligand to suppress the expression of the PCSK9 gene associated with elevated LDL and an increased risk of developing cardiovascular diseases. The selection of the most effective siRNA molecules was carried out using an algorithm previously developed by our research group, which considers thermodynamic stability, predicted specificity and effectiveness. To experimentally confirm the effectiveness of conjugates, an in vitro model based on the cultivation of hepatocyte cells was developed. Optimization of the conjugate synthesis process has significantly reduced the cost of manufacturing technology, which creates the potential for efficient scaling of synthesis for transfer and application in the pharmaceutical industry. The results of the study showed that the development of the siRNA sequence optimized in silico resulted in a significant increase in the inhibitory effect of the GalNAc-siRNA conjugate compared to a compound similar to a commercial drug. Full article

In 2025, the U.S. Food and Drug Administration (FDA) approved 44 new drugs, reflecting a slight decrease compared to previous years but maintaining the overall trends in pharmaceutical innovation. Biologics accounted for 25% of approvals, including nine monoclonal antibodies (mAbs), two antibody–drug conjugates (ADCs), and one fusion protein, with cancer remaining the primary therapeutic focus. TIDES, comprising three oligonucleotides and one peptide, continued to consolidate their presence in the market, with the three oligonucleotides featuring N-acetylgalactosamine (GalNAc) for liver-targeted delivery. Small molecules dominate the remainder, with a high prevalence of N-aromatic moieties and fluorine atoms present in most of the molecules. Peptide manufacturing and sustainability concerns, including PFAS usage, remain key challenges. Despite these advances, the high cost of innovative therapies limits access, particularly in low- and middle-income countries. This report provides a structural and chemical analysis of the newly approved drugs, highlighting trends in molecular design, therapeutic areas, and technological innovations shaping modern drug discovery. Full article

RNA-based drugs hold significant potential, offering promising new treatments for a wide range of diseases, especially those with a genetic basis. By leveraging RNA interference (RNAi) and other RNA-mediated mechanisms, these therapies can precisely modulate gene expression and address the root causes of genetic defects. RNA-based drugs hold significant potential for treating a range of diseases. However, the transition of these therapies from laboratory research to clinical applications has encountered hurdles. This review explores the composition and outcomes of clinical trials for various modified short RNA drugs. We detail their mechanisms of action, delivery systems—with a focus on lipid nanoparticles and N-acetylgalactosamine (GalNAc) conjugates—and clinical efficacy in treating conditions such as transthyretin (TTR) amyloidosis. Our analysis reveals that while several RNAi-based drugs have achieved clinical approval, a critical unmet need remains: advanced delivery systems capable of precisely targeting diverse tissues, particularly outside the liver. We also underscore the importance of rigorous target validation utilising sophisticated bioinformatics tools and in vitro/in vivo assays to minimise off-target effects and ensure robust therapeutic efficacy. This review proposes a novel framework for optimising RNA drug development, emphasising the crucial interplay between delivery strategies, target specificity, and understanding disease-specific target biology. Full article

Introduction/aim: N-acetylgalactoseamine-conjugated small interfering RNAs (GalNAc-siRNAs) are an emerging class of drugs possessing an extensive clinical potential because of their high target specificity to the asialoglycoprotein receptor (ASGPR) in hepatocytes. Overall, GalNAc-sRNAs are well-tolerated across species but differences in pharmacokinetic (PK) and pharmacodynamic (PD) properties have been observed. Furthermore, despite GalNAc-siRNA’s high liver specificity, distribution into off-target organs does occur. Through whole-body physiologically based pharmacokinetic (PBPK) modeling, this study seeks to mechanistically address species differences, establish clinical PK-PD relationships, and characterize off-target organ accumulation, ultimately expediting the preclinical-to-clinical translation of GalNAc-sRNAs in drug development. Materials/Methods: For model development, validation, and establishment of species’ translations, three in-house GalNAc-siRNAs with PK data from different biospecimens, as well as downstream effects on mRNA and target proteins in mouse, monkey, and human, were leveraged. A WB-PBPK-PD legacy model, developed as an extension to the generic model for large molecules in the platform Open Systems Pharmacology Suite, was further validated and applied to address the specific aims of this study. Results: The model successfully quantified the PK-PD relationships across species and characterized accumulation in off-target organs. The model further sheds light on species-specific differences, such as liver permeability, subcutaneous absorption rate, as well as PD-related mechanisms. Moreover, the model confirmed previously established compound-specific pharmacokinetic differences and similarities. Conclusions: This PBPK-PD can serve as a framework for future investigations of novel GalNAc-siRNAs across species. Full article

Lipoprotein (a) [Lp(a)] has been recognized as an independent, inherited, causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis, thus representing a major target of residual CV risk. Currently, no drug has been officially approved for lowering Lp(a) levels, and in clinical practice, Lp(a) is mainly used to (re)define CV risk, particularly in individuals at borderline CV risk and people with a family history of premature coronary heart disease, according to various guidelines. Specific Lp(a)-targeted antisense oligonucleotides (ASOs) and small interfering RNA (siRNA) agents have been developed to produce substantial Lp(a) reductions via the inhibition of apo(a) synthesis in the liver. These drugs are conjugated to N-acetylgalactosamine (GalNAc) to ensure their binding to asialoglycoproteins, which are specifically expressed on the surface of the hepatocytes. Such drugs include pelacarsen (an injectable ASO) and olpasiran, zerlasiran, and lepodisiran (injectable siRNA agents). Muvalaplin represents another therapeutic option to lower Lp(a) levels, since it is an oral selective small molecule inhibitor of Lp(a) formation, thus potentially exerting certain advantages in terms of its clinical use. The present narrative review summarizes the available clinical data on the efficacy and safety of these investigational Lp(a)-lowering therapies, as reported in phase 1 and 2 trials. The effects of these drugs on other [aside from Lp(a)] lipid parameters are also discussed. The phase 3 CV trial outcomes are ongoing for some of these agents (i.e., pelacarsen, olpasiran, and lepodisiran) and are briefly mentioned. Overall, there is an urgent need for evidence-based guidelines on Lp(a) reduction in daily clinical practice, following the results of the phase 3 CV trials, as well as for establishing the ideal Lp(a) quantification method (i.e., using an apo(a) isoform-independent assay with appropriate calibrators, reporting the Lp(a) level in molar units). Full article

Small interfering RNA (siRNA) has been deemed a promising therapeutic method for treating diverse diseases. siRNA-based therapeutics provide a distinct mechanism of action by selectively targeting and silencing disease-causing genes at the post-transcriptional level. This paper provides an overview of the present state of siRNA-based therapeutics, highlighting their potential in different therapeutic areas. The first section of this review introduces the basic principles of siRNA technology, including its mechanism of action and delivery methods. Subsequently, we discuss the impediments associated with siRNA delivery and manufacturing development and the strategies for overcoming these obstacles. The clinical advancement of siRNA therapeutics in various disease areas, including cancer, genetic disorders, viral infections, and inflammatory diseases, is summarized. Lastly, we summarize the successes, failures, and lessons learned from the development of siRNAs. With advancements in delivery systems and improvements in target selection, the field of medicine can be revolutionized, and siRNA therapeutics can offer new treatment options for patients. Full article

Background/Objectives: N-acetyl-galactosamine small interfering RNAs (GalNAc-siRNA) are an emerging class of drugs due to their durable knockdown of disease-related proteins. Direct conjugation of GalNAc onto the siRNA enables targeted uptake into hepatocytes via GalNAc recognition of the Asialoglycoprotein Receptor (ASGPR). With a transient plasma exposure combined with a prolonged liver half-life, GalNAc-siRNA exhibits distinct disposition characteristics. We aimed to develop a generic GalNAc-siRNAs whole-body physiologically based pharmacokinetic–pharmacodynamic (WB-PBPK-PD) model for describing the pharmacokinetic–pharmacodynamic (PK-PD) relationship and overall tissue distribution in the open-source platform Open Systems Pharmacology Suite. Methods: Model development was performed using published studies in mice leveraging the PK-Sim^® standard implementation for large molecules with added implementations of ASGPR-mediated liver disposition and downstream target effects. Adequate model performance was achieved across study measurements and included studies adopting a combination of global and compound-specific parameters. Results: The analysis identified significant compound dependencies, e.g., endosomal stability, with direct consequences for the pharmacological effect. Additionally, knowledge gaps in mechanistic understanding related to extravasation and overall tissue distribution were identified during model development. The presented study provides a generic WB-PBPK-PD model for the investigation of GalNAc-siRNAs implemented in a standardized open-source platform. Full article

N-Acetylgalactosamine (GalNAc) is an efficient and multifunctional delivery tool in the development and synthesis of chemically modified oligonucleotide therapeutics (conjugates). Such therapeutics demonstrate improved potency in vivo due to the selective and efficient delivery to hepatocytes in the liver via receptor-mediated endocytosis, which is what drives the high interest in this molecule. The ways to synthesize such structures are relatively new and have not been optimized in terms of the yields and stages both in lab and large-scale synthesis. Another significant criterion, especially in large-scale synthesis, is to match ecological norms and perform the synthesis in accordance with the Green Chemistry approach, i.e., to control and minimize the amounts of reagents and resources consumed and the waste generated. Here, we provide a robust and resource effective pot-economy method for the synthesis of triantennary GalNAc and GalNAc phosphoramidite/CPG optimized for laboratory scales. Full article

Hyperuricemia, i.e., increased plasma uric acid concentration, is a common problem in clinical practice, leading to gout or nephrolithiasis, and is associated with other disorders, such as metabolic syndrome, cardiovascular disease, and chronic renal disease. Xanthine oxidoreductase (XOR) is a critical rate-limiting enzyme involved in uric acid synthesis and a promising target for hyperuricemia therapy. However, XOR inhibitors currently face clinical problems such as a short half-life and side effects. Here, we found that specifically targeting liver Xor with GalNAc-siRNAs had a good therapeutic effect on hyperuricemia. First, siRNAs were designed to target various sites in the homologous region between Homo sapiens and Mus musculus Xor mRNA and were screened in primary mouse hepatocytes. Then, the siRNAs were modified to increase their stability in vivo and conjugated with GalNAc for liver-specific delivery. The effects of GalNAc-siRNAs were evaluated in three hyperuricemia mouse models, including potassium oxonate and hypoxanthine administration in WT and humanized XDH mice and Uox knockout mice. Febuxostat, a specific XOR inhibitor used for hyperuricemia treatment, was used as a positive control. Targeting liver Xor with GalNAc-siRNAs by subcutaneous administration reduced plasma uric acid levels, uric acid accumulation in the kidney, renal inflammation, and fibrosis, thereby alleviating kidney damage in hyperuricemia mouse models without hepatoxicity. The results demonstrated that targeting liver Xor with GalNAc-siRNAs was a promising strategy for hyperuricemia therapy. Full article

For the first time, a novel dithiomaleimides (DTM) based tetra-antennary GalNAc conjugate was developed, which enable both efficient siRNA delivery and good traceability, without incorporating extra fluorophores. This conjugate can be readily constructed by three click-type reactions, that is, amidations, thiol-dibromomaleimide addition and copper catalyzed azide–alkyne cycloaddition (CuAAC). And it also has comparable siRNA delivery efficiency, with a GalNAc L96 standard to mTTR target. Additionally, due to the internal DTMs, a highly fluorescent emission was observed, which benefited delivery tracking and reduced the cost and side effects of the extra addition of hydrophobic dye molecules. In all, the simple incorporation of DTMs to the GalNAc conjugate structure has potential in gene therapy and tracking applications. Full article

Over the past two decades, it was discovered that introducing synthetic small interfering RNAs (siRNAs) into the cytoplasm facilitates effective gene-targeted silencing. This compromises gene expression and regulation by repressing transcription or stimulating sequence-specific RNA degradation. Substantial investments in developing RNA therapeutics for disease prevention and treatment have been made. We discuss the application to proprotein convertase subtilisin/kexin type 9 (PCSK9), which binds to and degrades the low-density lipoprotein cholesterol (LDL-C) receptor, interrupting the process of LDL-C uptake into hepatocytes. PCSK9 loss-of-function modifications show significant clinical importance by causing dominant hypocholesterolemia and lessening the risk of cardiovascular disease (CVD). Monoclonal antibodies and small interfering RNA (siRNA) drugs targeting PCSK9 are a significant new option for managing lipid disorders and improving CVD outcomes. In general, monoclonal antibodies are restricted to binding with cell surface receptors or circulating proteins. Similarly, overcoming the intracellular and extracellular defenses that prevent exogenous RNA from entering cells must be achieved for the clinical application of siRNAs. N-acetylgalactosamine (GalNAc) conjugates are a simple solution to the siRNA delivery problem that is especially suitable for treating a broad spectrum of diseases involving liver-expressed genes. Inclisiran is a GalNAc-conjugated siRNA molecule that inhibits the translation of PCSK9. The administration is only required every 3 to 6 months, which is a significant improvement over monoclonal antibodies for PCSK9. This review provides an overview of siRNA therapeutics with a focus on detailed profiles of inclisiran, mainly its delivery strategies. We discuss the mechanisms of action, its status in clinical trials, and its prospects. Full article

Covalently closed dumbbell-shaped DNA delivery vectors comprising the double-stranded gene(s) of interest and single-stranded hairpin loops on both ends represent a safe, stable and efficacious alternative to viral and other non-viral DNA-based vector systems. As opposed to plasmids and DNA minicircles, dumbbells can be conjugated via the loops with helper functions for targeted delivery or imaging. Here, we investigated the non-covalent linkage of tri-antennary N-acetylgalactosamine (GalNAc3) or a homodimer of a CD137/4-1BB-binding aptamer (aptCD137-2) to extended dumbbell vector loops via complementary oligonucleotides for targeted delivery into hepatocytes or nasopharyngeal cancer cells. Enlarging the dumbbell loop size from 4 to 71 nucleotides for conjugation did not impair gene expression. GalNAc3 and aptCD137-2 residues were successfully attached to the extended dumbbell loop via complementary oligonucleotides. DNA and RNA oligonucleotide-based dumbbell-GalNAc3 conjugates were taken up from the cell culture medium by hepatoblastoma-derived human tissue culture cells (HepG2) with comparable efficiency. RNA oligonucleotide-linked conjugates triggered slightly higher levels of gene expression, presumably due to the RNaseH-mediated linker cleavage, the release of the dumbbell from the GalNAc3 residue and more efficient nuclear targeting of the unconjugated dumbbell DNA. The RNaseH-triggered RNA linker cleavage was confirmed in vitro. Finally, we featured dumbbell vectors expressing liver cancer cell-specific RNA trans-splicing-based suicide RNAs with GalNAc3 residues. Dumbbells conjugated with two GalNAc3 residues triggered significant levels of cell death when added to the cell culture medium. Dumbbell vector conjugates can be explored for targeted delivery and gene therapeutic applications. Full article