Inhibition of Rous sarcoma viral RNA translation by a specific oligodeoxyribonucleotide

Practical Guidance for the Use of Patisiran in the Management of Polyneuropathy in Hereditary Transthyretin-Mediated Amyloidosis

Variant transthyretin amyloidosis (ATTRv) is an autosomal dominant inherited genetic disorder that affects 5000-10,000 people worldwide. It is caused by mutations in the transthyretin (TTR) gene and results in amyloid deposition in a variety of organs due to abnormal accumulation of TTR protein fibrils. Although this is a multisystem disorder, the heart and peripheral nerves are the preferentially affected organs. Over 150 TTR gene mutations have been associated with this disease and the clinical phenotype can vary significantly. Severe forms of the disorder can be fatal. Fortunately, the oligonucleotide-based therapy era has resulted in the development of several novel treatment options. Patisiran is a small interfering RNA (siRNA) encapsulated in a lipid nanoparticle that targets both mutant and wild-type TTR and results in significant reductions of the TTR protein in the serum and in tissue deposits. Patisiran has been approved for treatment of adults with polyneuropathy due to hereditary TTR-mediated amyloidosis in both the United States (US) and European Union (EU). In this review, we will discuss the development of patisiran, the clinical trials that lead to treatment approval, and provide guideline parameters for use in clinical practice.  .

RNA-based medicine: from molecular mechanisms to therapy

RNA-based therapeutics have the potential to revolutionize the treatment and prevention of human diseases. While early research faced setbacks, it established the basis for breakthroughs in RNA-based drug design that culminated in the extraordinarily fast development of mRNA vaccines to combat the COVID-19 pandemic. We have now reached a pivotal moment where RNA medicines are poised to make a broad impact in the clinic. In this review, we present an overview of different RNA-based strategies to generate novel therapeutics, including antisense and RNAi-based mechanisms, mRNA-based approaches, and CRISPR-Cas-mediated genome editing. Using three rare genetic diseases as examples, we highlight the opportunities, but also the challenges to wide-ranging applications of this class of drugs.

Basic notions about gene therapy from the nucleic acid perspective and applications in a pediatric disease: Duchenne muscular dystrophy

Gene therapy involves the introduction of genetic material into cells as a therapeutic molecule to cure a disease. Through the transfer of specific nucleic acid to the target tissue, gene expression can be downregulated, augmented, or corrected thanks to the nucleic acid sequence as a support of gene expression. This is achieved through molecular interactions according to the sequence arrangement or the secondary structure of the molecules or through their catalytic properties. Over the past two decades, the rapid advances of knowledge and technologies in gene therapy have led to the development of different strategies and to the extension of its use to numerous indications, including certain cancers. Major success has been achieved in clinical trials and the field of gene therapy is booming. Several gene therapy products are now on the market in Europe, the United States, and China. In this review, we cover the basic principles of gene therapy and the characteristics of the main vectors used to transfer genetic material into the cell. As an example of applications, we address the various strategies applied to a rare pediatric muscle disease: Duchenne muscular dystrophy. © 2023 Published by Elsevier Masson SAS on behalf of French Society of Pediatrics.

LinearCoFold and LinearCoPartition: linear-time algorithms for secondary structure prediction of interacting RNA molecules

Many RNAs function through RNA-RNA interactions. Fast and reliable RNA structure prediction with consideration of RNA-RNA interaction is useful, however, existing tools are either too simplistic or too slow. To address this issue, we present LinearCoFold, which approximates the complete minimum free energy structure of two strands in linear time, and LinearCoPartition, which approximates the cofolding partition function and base pairing probabilities in linear time. LinearCoFold and LinearCoPartition are orders of magnitude faster than RNAcofold. For example, on a sequence pair with combined length of 26,190 nt, LinearCoFold is 86.8× faster than RNAcofold MFE mode, and LinearCoPartition is 642.3× faster than RNAcofold partition function mode. Surprisingly, LinearCoFold and LinearCoPartition's predictions have higher PPV and sensitivity of intermolecular base pairs. Furthermore, we apply LinearCoFold to predict the RNA-RNA interaction between SARS-CoV-2 genomic RNA (gRNA) and human U4 small nuclear RNA (snRNA), which has been experimentally studied, and observe that LinearCoFold's prediction correlates better with the wet lab results than RNAcofold's.

Enhancing Antisense Oligonucleotide-Based Therapeutic Delivery with DG9, a Versatile Cell-Penetrating Peptide

Antisense oligonucleotide-based (ASO) therapeutics have emerged as a promising strategy for the treatment of human disorders. Charge-neutral PMOs have promising biological and pharmacological properties for antisense applications. Despite their great potential, the efficient delivery of these therapeutic agents to target cells remains a major obstacle to their widespread use. Cellular uptake of naked PMO is poor. Cell-penetrating peptides (CPPs) appear as a possibility to increase the cellular uptake and intracellular delivery of oligonucleotide-based drugs. Among these, the DG9 peptide has been identified as a versatile CPP with remarkable potential for enhancing the delivery of ASO-based therapeutics due to its unique structural features. Notably, in the context of phosphorodiamidate morpholino oligomers (PMOs), DG9 has shown promise in enhancing delivery while maintaining a favorable toxicity profile. A few studies have highlighted the potential of DG9-conjugated PMOs in DMD (Duchenne Muscular Dystrophy) and SMA (Spinal Muscular Atrophy), displaying significant exon skipping/inclusion and functional improvements in animal models. The article provides an overview of a detailed understanding of the challenges that ASOs face prior to reaching their targets and continued advances in methods to improve their delivery to target sites and cellular uptake, focusing on DG9, which aims to harness ASOs' full potential in precision medicine.

Furan-based (photo)oxidation reactions and their application in nucleic acid and protein targeting

Oligonucleotides (ODNs) find applications as diagnostic and therapeutic tools due to their unique ability to interact, thanks to Watson-Crick base pairing, with a specific DNA or RNA target strand. Although most of the tools available today rely on mere hydrogen bond formation, chemical modifications to enable covalent interstrand-crosslinking (ICL) have been reported, and are gaining a place under the spotlight as they potentially offer a series of advantages over the state of the art, including a higher potency and selectivity. This methodological paper focuses on the use of a pro-reactive furan moiety and its subsequent oxidation for applications in ODN targeting. The design of effective capture and targeting probes to ensure high ICL yields is discussed and the mechanisms underlying the (photo)chemical oxidation of furan are explained. Furthermore, examples of furan-containing DNAs designed for different applications, including DNA-DNA or DNA-RNA ICL and DNA-peptide/protein targeting, are provided. The paper highlights the advantages of using different oxidative chemical triggers, such as N-bromosuccinimide or singlet oxygen, to offer additional selectivity control over the ICL reaction.

C5-Propynyl modified 2'-fluoroarabinonucleic acids form stable duplexes with RNA that are RNase H competent

The clinical success of the antisense approach for the treatment of genetic disorders is indisputably the result of chemical modifications along the oligonucleotide (ON) scaffold, which impart desirable properties including high RNA affinity, nuclease stability and improved drug delivery. While effective, many modifications are not capable of eliciting an RNase H response limiting their application in antisense systems. To contribute to the structural design and inventory of nucleoside analogues with favorable antisense properties, herein we describe the synthesis of C5-propynyl-2'-fluoroarabinonucleic acids (FANAP). Incorporation of individual and multiple uridine (FaraUP) and cytidine (FaraCP) inserts into ONs revealed, both stabilized duplexes formed with RNA. In contrast, these modifications demonstrated a negligible (FaraUP) or reduced (FaraCP) effect on DNA binding. Moreover, modified ONs containing these analogues supported E. coli RNase H cleavage of RNA with an altered cleavage pattern observed relative to controls. Moreover, a 2'-O-methoxyethyl (2'-O-MOE) gapmer with a FANAP core was able to elicit RNA cleavage at an increased rate compared to C5-propynyl-arabinonucleic acids (ANAP). Enzymatic hydrolysis of these gapmers was assessed with nuclease S1 digestion and revealed greater stability of ANAP compared to FANAP. These results suggest C5-propynyl ANA/FANA modifications demonstrate promising potential for the design of therapeutic ONs.

Volumetric absorptive microsampling coupled with hybridization LC-MS/MS for quantitation of antisense oligonucleotides

Background: Volumetric absorptive microsampling has emerged as a less invasive alternative to venous sampling for small-molecule pharmacokinetic studies, but its application to novel therapeutics such as antisense oligonucleotides (ASOs) is not well-established. Results: A workflow was developed using Mitra microsampling coupled with hybridization LC-MS/MS for accurate determination of fomivirsen, a 21-mer ASO, in human blood. Quantitative recovery was achieved regardless of blood hematocrit level or microsample age by implementing impact-assisted extraction. A thorough method evaluation confirmed sensitivity, linearity, precision/accuracy, matrix effect, metabolite interference and four months of microsample stability. Conclusion: The combined impact-assisted extraction and hybridization LC-MS/MS workflow demonstrated the successful quantitation of fomivirsen, establishing the validity and applicability of the approach for ASO drug candidates.

Antisense Therapy for Infectious Diseases

Infectious diseases, particularly Tuberculosis (TB) caused by Mycobacterium tuberculosis, pose a significant global health challenge, with 1.6 million reported deaths in 2021, making it the most fatal disease caused by a single infectious agent. The rise of drug-resistant infectious diseases adds to the urgency of finding effective and safe intervention therapies. Antisense therapy uses antisense oligonucleotides (ASOs) that are short, chemically modified, single-stranded deoxyribonucleotide molecules complementary to their mRNA target. Due to their designed target specificity and inhibition of a disease-causing gene at the mRNA level, antisense therapy has gained interest as a potential therapeutic approach. This type of therapy is currently utilized in numerous diseases, such as cancer and genetic disorders. Currently, there are limited but steadily increasing studies available that report on the use of ASOs as treatment for infectious diseases. This review explores the sustainability of FDA-approved and preclinically tested ASOs as a treatment for infectious diseases and the adaptability of ASOs for chemical modifications resulting in reduced side effects with improved drug delivery; thus, highlighting the potential therapeutic uses of ASOs for treating infectious diseases.

Convergent synthesis of phosphorodiamidate morpholino oligonucleotides (PMOs) by the H-phosphonate approach

Phosphorodiamidate morpholino oligonucleotides (PMOs) are a promising type of antisense oligonucleotides, but their challenging synthesis makes them difficult to access. This research presents an efficient synthetic approach for PMOs using the H-phosphonate approach. The use of phosphonium-type condensing reagents significantly reduced coupling times compared with the current synthetic approach. Furthermore, phosphonium-type condensing reagents facilitated the fragment condensation of PMO, synthesizing up to 8-mer containing all four nucleobases with remarkable coupling efficacy. This is the first report on the convergent synthesis of PMOs. This approach would facilitate the large-scale synthesis of PMOs and accelerate their popularity and accessibility as a next-generation therapy.

Alternative splicing in neurodegenerative disease and the promise of RNA therapies

Alternative splicing generates a myriad of RNA products and protein isoforms of different functions from a single gene. Dysregulated alternative splicing has emerged as a new mechanism broadly implicated in the pathogenesis of neurodegenerative diseases such as Alzheimer disease, amyotrophic lateral sclerosis, frontotemporal dementia, Parkinson disease and repeat expansion diseases. Understanding the mechanisms and functional outcomes of abnormal splicing in neurological disorders is vital in developing effective therapies to treat mis-splicing pathology. In this Review, we discuss emerging research and evidence of the roles of alternative splicing defects in major neurodegenerative diseases and summarize the latest advances in RNA-based therapeutic strategies to target these disorders.

Development of nucleic acid medicines based on chemical technology

Oligonucleotide-based therapeutics have attracted attention as an emerging modality that includes the modulation of genes and their binding proteins related to diseases, allowing us to take action on previously undruggable targets. Since the late 2010s, the number of oligonucleotide medicines approved for clinical uses has dramatically increased. Various chemistry-based technologies have been developed to improve the therapeutic properties of oligonucleotides, such as chemical modification, conjugation, and nanoparticle formation, which can increase nuclease resistance, enhance affinity and selectivity to target sites, suppress off-target effects, and improve pharmacokinetic properties. Similar strategies employing modified nucleobases and lipid nanoparticles have been used for developing coronavirus disease 2019 mRNA vaccines. In this review, we provide an overview of the development of chemistry-based technologies aimed at using nucleic acids for developing therapeutics over the past several decades, with a specific emphasis on the structural design and functionality of chemical modification strategies.

The multifaceted roles of mass spectrometric analysis in nucleic acids drug discovery and development

The deceptively simple concepts of mass determination and fragment analysis are the basis for the application of mass spectrometry (MS) to a boundless range of analytes, including fundamental components and polymeric forms of nucleic acids (NAs). This platform affords the intrinsic ability to observe first-hand the effects of NA-active drugs on the chemical structure, composition, and conformation of their targets, which might affect their ability to interact with cognate NAs, proteins, and other biomolecules present in a natural environment. The possibility of interfacing with high-performance separation techniques represents a multiplying factor that extends these capabilities to cover complex sample mixtures obtained from organisms that were exposed to NA-active drugs. This report provides a brief overview of these capabilities in the context of the analysis of the products of NA-drug activity and NA therapeutics. The selected examples offer proof-of-principle of the applicability of this platform to all phases of the journey undertaken by any successful NA drug from laboratory to bedside, and provide the rationale for its rapid expansion outside traditional laboratory settings in support to ever growing manufacturing operations.

Ensemble-Learning and Feature Selection Techniques for Enhanced Antisense Oligonucleotide Efficacy Prediction in Exon Skipping

Antisense oligonucleotide (ASO)-mediated exon skipping has become a valuable tool for investigating gene function and developing gene therapy. Machine-learning-based computational methods, such as eSkip-Finder, have been developed to predict the efficacy of ASOs via exon skipping. However, these methods are computationally demanding, and the accuracy of predictions remains suboptimal. In this study, we propose a new approach to reduce the computational burden and improve the prediction performance by using feature selection within machine-learning algorithms and ensemble-learning techniques. We evaluated our approach using a dataset of experimentally validated exon-skipping events, dividing it into training and testing sets. Our results demonstrate that using a three-way-voting approach with random forest, gradient boosting, and XGBoost can significantly reduce the computation time to under ten seconds while improving prediction performance, as measured by R² for both 2'-O-methyl nucleotides (2OMe) and phosphorodiamidate morpholino oligomers (PMOs). Additionally, the feature importance ranking derived from our approach is in good agreement with previously published results. Our findings suggest that our approach has the potential to enhance the accuracy and efficiency of predicting ASO efficacy via exon skipping. It could also facilitate the development of novel therapeutic strategies. This study could contribute to the ongoing efforts to improve ASO design and optimize gene therapy approaches.

Multidimensional futuristic approaches to address the pandemics beyond COVID-19

Globally, the impact of the coronavirus disease 2019 (COVID-19) pandemic has been enormous and unrelenting with ∼6.9 million deaths and ∼765 million infections. This review mainly focuses on the recent advances and potentially novel molecular tools for viral diagnostics and therapeutics with far-reaching implications in managing the future pandemics. In addition to briefly highlighting the existing and recent methods of viral diagnostics, we propose a couple of potentially novel non-PCR-based methods for rapid, cost-effective, and single-step detection of nucleic acids of viruses using RNA mimics of green fluorescent protein (GFP) and nuclease-based approaches. We also highlight key innovations in miniaturized Lab-on-Chip (LoC) devices, which in combination with cyber-physical systems, could serve as ideal futuristic platforms for viral diagnosis and disease management. We also discuss underexplored and underutilized antiviral strategies, including ribozyme-mediated RNA-cleaving tools for targeting viral RNA, and recent advances in plant-based platforms for rapid, low-cost, and large-scale production and oral delivery of antiviral agents/vaccines. Lastly, we propose repurposing of the existing vaccines for newer applications with a major emphasis on Bacillus Calmette-Guérin (BCG)-based vaccine engineering.

Investigation of Sequence-Penetration Relationships of Antisense Oligonucleotides

A major limitation for the development of more effective oligonucleotide therapeutics has been a lack of understanding of their penetration into the cytosol. While prior work has shown how backbone modifications affect cytosolic penetration, it is unclear how cytosolic penetration is affected by other features including base composition, base sequence, length, and degree of secondary structure. We have applied the chloroalkane penetration assay, which exclusively reports on material that reaches the cytosol, to investigate the effects of these characteristics on the cytosolic uptake of druglike oligonucleotides. We found that base composition and base sequence had moderate effects, while length did not correlate directly with the degree of cytosolic penetration. Investigating further, we found that the degree of secondary structure had the largest and most predictable correlations with cytosolic penetration. These methods and observations add a layer of design for maximizing the efficacy of new oligonucleotide therapeutics.

Small interfering RNA-based nanotherapeutics for treating skin-related diseases

INTRODUCTION

RNA interference (RNAi) has demonstrated great potential in treating skin-related diseases, as small interfering RNA (siRNA) can efficiently silence specific genes. The design of skin delivery systems for siRNA is important to protect the nucleic acid while facilitating both skin targeting and cellular ingestion. Entrapment of siRNA into nanocarriers can accomplish these aims, contributing to improved targeting, controlled release, and increased transfection.

AREAS COVERED

The siRNA-based nanotherapeutics for treating skin disorders are summarized. First, the mechanisms of RNAi are presented, followed by the introduction of challenges for skin therapy. Then, the different nanoparticle types used for siRNA skin delivery are described. Subsequently, we introduce the mechanisms of how nanoparticles enhance siRNA skin penetration. Finally, the current investigations associated with nanoparticulate siRNA application in skin disease management are reviewed.

EXPERT OPINION

The potential application of nanotherapeutic RNAi allows for a novel skin application strategy. Further clinical studies are required to confirm the findings in the cell-based or animal experiments. The capability of large-scale production and reproducibility of nanoparticle products are also critical for translation to commercialization. siRNA delivery by nanocarriers should be optimized to attain cutaneous targeting without the risk of toxicity.

Extracellular Vesicles for Therapeutic Nucleic Acid Delivery: Loading Strategies and Challenges

Extracellular vesicles (EVs) are membrane vesicles released into the extracellular milieu by cells of various origins. They contain different biological cargoes, protecting them from degradation by environmental factors. There is an opinion that EVs have a number of advantages over synthetic carriers, creating new opportunities for drug delivery. In this review, we discuss the ability of EVs to function as carriers for therapeutic nucleic acids (tNAs), challenges associated with the use of such carriers in vivo, and various strategies for tNA loading into EVs.

Future directions for medicinal chemistry in the field of oligonucleotide therapeutics

In the last decade, the field of oligonucleotide therapeutics has matured, with the regulatory approval of several single-stranded and double-stranded RNA drugs. In this Perspective, I discuss enabling developments and likely future directions in the field from the perspective of oligonucleotide chemistry.

Designer, Programmable DNA-peptide hybrid materials with emergent properties to probe and modulate biological systems

The chemistry of DNA endows it with certain functional properties that facilitate the generation of self-assembled nanostructures, offering precise control over their geometry and morphology, that can be exploited for advanced biological applications. Despite the structural promise of these materials, their applications are limited owing to lack of functional capability to interact favourably with biological systems, which has been achieved by functional proteins or peptides. Herein, we outline a strategy for functionalizing DNA structures with short-peptides, leading to the formation of DNA-peptide hybrid materials. This proposition offers the opportunity to leverage the unique advantages of each of these bio-molecules, that have far reaching emergent properties in terms of better cellular interactions and uptake, better stability in biological media, an acceptable and programmable immune response and high bioactive molecule loading capacities. We discuss the synthetic strategies for the formation of these materials, namely, solid-phase functionalization and solution-coupling functionalization. We then proceed to highlight selected biological applications of these materials in the domains of cell instruction & molecular recognition, gene delivery, drug delivery and bone & tissue regeneration. We conclude with discussions shedding light on the challenges that these materials pose and offer our insights on future directions of peptide-DNA research for targeted biomedical applications.

Inotersen to Treat Polyneuropathy Associated with Hereditary Transthyretin (hATTR) Amyloidosis

Background

Amyloidosis is a group of diseases with the common pathophysiology of protein misfolding and aberrant deposition in tissue. There are both acquired and hereditary forms of this disease, and this review focuses on the latter hereditary transthyretin-mediated (hATTR). hATTR affects about 50,000 individuals globally and mostly appears as one of three syndromes - cardiac, polyneuropathy, and oculoleptomeningeal. Polyneuropathy is the most common form, and there is usually some overlap in individual patients.

Results

Recently, novel therapeutic options emerged in the form of groundbreaking drugs, Patisiran and Inotersen, small interfering RNA molecules that target TTR and reduce the production of this protein. By targeting TTR mRNA transcripts, Inotersen decreases protein translation and production, reducing the deposition of misfolded proteins. It was shown to be both effective and safe for use and specifically formulated to concentrate in the liver - where protein production takes place.

Conclusion

hATTR is a rare, progressive, and debilitating disease. Its most common presentation is that of polyneuropathy, and it carries a very poor prognosis and a natural history conveying a median survival of < 12 years. Novel therapeutic options are groundbreaking by providing disease-modifying specific, targeted therapies against TTR production and deposition. The use of RNA interference (RNAi) opens the door to the treatment of hereditary diseases by targeting them at the genetic level.

RNA Therapeutics for Improving CAR T-cell Safety and Efficacy

Autologous chimeric antigen receptor (CAR) T cells have recently emerged as potent tools in the fight against cancer, with promising therapeutic efficacy against hematological malignancies. However, several limitations hamper their widespread clinical use, including availability of target antigen, severe toxic effects, primary and secondary resistance, heterogeneous quality of autologous T cells, variable persistence, and low activity against solid tumors. Development of allogeneic off-the-shelf CAR T cells could help address some of these limitations but is impeded by alloimmunity with either rejection and limited expansion of allo-CAR T cells or CAR T cells versus host reactions. RNA therapeutics, such as small interfering RNAs, microRNAs, and antisense oligonucleotides, are able to silence transcripts in a sequence-specific and proliferation-sensitive way, which may offer a way to overcome some of the challenges facing CAR T-cell development and clinical utility. Here, we review how different RNA therapeutics or a combination of RNA therapeutics and genetic engineering could be harnessed to improve the safety and efficacy of autologous and allogeneic CAR T-cell therapy.

Circular RNAs in and out of Cells: Therapeutic Usages of Circular RNAs

RNAs are versatile molecules that are primarily involved in gene regulation and can thus be widely used to advance the fields of therapeutics and diagnostics. In particular, circular RNAs which are highly stable, have emerged as strong candidates for use on next-generation therapeutic platforms. Endogenous circular RNAs control gene regulatory networks by interacting with other biomolecules or through translation into polypeptides. Circular RNAs exhibit cell-type specific expression patterns, which can be altered in tissues and body fluids depending on pathophysiological conditions. Circular RNAs that are aberrantly expressed in diseases can function as biomarkers or therapeutic targets. Moreover, exogenous circular RNAs synthesized in vitro can be introduced into cells as therapeutic molecules to modulate gene expression networks in vivo. Depending on the purpose, synthetic circular RNA sequences can either be identical to endogenous circular RNA sequences or artificially designed. In this review, we introduce the life cycle and known functions of intracellular circular RNAs. The current stage of endogenous circular RNAs as biomarkers and therapeutic targets is also described. Finally, approaches and considerations that are important for applying the available knowledge on endogenous circular RNAs to design exogenous circular RNAs for therapeutic purposes are presented.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

mRNA COVID-19 Vaccines-Facts and Hypotheses on Fragmentation and Encapsulation

BACKGROUND

The adventure of the mRNA vaccine began thirty years ago in the context of influenza. This consisted in encapsulating the mRNA coding for a viral protein in a lipid particle. We show how the mRNA encoding S protein has been modified for that purpose in the context of the anti-SARS-CoV-2 vaccination.

RESULTS

by using data coming from genetic and epidemiologic databases, we show the theoretical possibility of fragmentation of this mRNA into small RNA sequences capable of inhibiting important bio-syntheses such as the production of beta-globin.

DISCUSSION

we discuss two aspects related to mRNA vaccine: (i) the plausibility of mRNA fragmentation, and (ii) the role of liposomal nanoparticles (LNPs) used in the vaccine and their impact on mRNA biodistribution.

CONCLUSION

we insist on the need to develop lipid nanoparticles allowing personalized administration of vaccines and avoiding adverse effects due to mRNA fragmentation and inefficient biodistribution. Hence, we recommend (i) adapting the mRNA of vaccines to the least mutated virus proteins and (ii) personalizing its administration to the categories of chronic patients at risk most likely to suffer from adverse effects.

Antisense oligonucleotide is a promising intervention for liver diseases

As the body's critical metabolic organ, the liver plays an essential role in maintaining proper body homeostasis. However, as people's living standards have improved and the number of unhealthy lifestyles has increased, the liver has become overburdened. These have made liver disease one of the leading causes of death worldwide. Under the influence of adverse factors, liver disease progresses from simple steatosis to hepatitis, to liver fibrosis, and finally to cirrhosis and cancer, followed by increased mortality. Until now, there has been a lack of accepted effective treatments for liver disease. Based on current research, antisense oligonucleotide (ASO), as an alternative intervention for liver diseases, is expected to be an effective treatment due to its high efficiency, low toxicity, low dosage, strong specificity, and additional positive characteristics. In this review, we will first introduce the design, modification, delivery, and the mechanisms of ASO, and then summarize the application of ASO in liver disease treatment, including in non-alcoholic fatty liver disease (NAFLD), hepatitis, liver fibrosis, and liver cancer. Finally, we discuss challenges and perspectives on the transfer of ASO drugs into clinical use. This review provides a current and comprehensive understanding of the integrative and systematic functions of ASO for its use in liver disease.

Nano drug delivery systems for antisense oligonucleotides (ASO) therapeutics

Cancer, infectious diseases, and metabolic and hereditary genetic disorders are a global health burden affecting millions of people, with contemporary treatments offering limited relief. Antisense technology treats diseases by targeting their causal agents using its ability to alter or inhibit endogenous or malfunctioning genes. Nine antisense oligonucleotide (ASO) drugs that represent four different chemical classes have been approved for the treatment of rare diseases, including nusinersen, the first new oligonucleotide-based drug. Advances in medicinal chemistry, understanding the molecular pathways, and the availability of vast genetic data have resulted in enormous improvements in the therapeutic performance of ASO drugs; however, their susceptibility to degradation in the circulation, rapid renal clearance, and immunostimulatory adverse effects greatly limit their clinical applications. An increasing number of ASO-based therapeutics is being tested in clinical trials. Improvements to the delivery of ASO drugs could potentially change the therapeutic landscape for many conditions in the near future. This review describes the technological advances and developments in drug delivery systems pertaining to ASO therapeutics.

Early-Stage Identification and Avoidance of Antisense Oligonucleotides Causing Species-Specific Inflammatory Responses in Human Volunteer Peripheral Blood Mononuclear Cells

A human peripheral blood mononuclear cell (PBMC)-based assay was developed to identify antisense oligonucleotide (ASO) with the potential to activate a cellular innate immune response outside of an acceptable level. The development of this assay was initiated when ISIS 353512 targeting the messenger ribonucleic acid for human C-reactive protein (CRP) was tested in a phase I clinical trial, in which healthy human volunteers unexpectedly experienced increases in interleukin-6 (IL-6) and CRP. This level of immune stimulation was not anticipated following rodent and nonhuman primate safety studies in which no evidence of exaggerated proinflammatory effects were observed. The IL-6 increase induced by ISIS 353512 was caused by activation of B cells. The IL-6 induction was inhibited by chloroquine pretreatment of PBMCs and the nature of ASOs suggested that the response is mediated by a Toll-like receptor (TLR), in all likelihood TLR9. While assessing the inter PBMC donor variability, two classes of human PBMC responders to ISIS 353512 were identified (discriminator and nondiscriminators). The discriminator donor PBMCs were shown to produce low level of IL-6 after 24 h in culture, in the absence of ASO treatment. The PBMC assay using discriminator donors was shown to be reproducible, allowing to assess reliably the immune potential of ASOs by comparison to known benchmark ASO controls that were previously shown to be either safe or inflammatory in clinical trials. Clinical Trial registration numbers: NCT00048321 NCT00330330 NCT00519727.

Small non-coding RNA therapeutics for cardiovascular disease

Novel bio-therapeutic agents that harness the properties of small, non-coding nucleic acids hold great promise for clinical applications. These include antisense oligonucleotides that inhibit messenger RNAs, microRNAs (miRNAs), or long non-coding RNAs; positive effectors of the miRNA pathway (short interfering RNAs and miRNA mimics); or small RNAs that target proteins (i.e. aptamers). These new therapies also offer exciting opportunities for cardiovascular diseases and promise to move the field towards more precise approaches based on disease mechanisms. There have been substantial advances in developing chemical modifications to improve the in vivo pharmacological properties of antisense oligonucleotides and reduce their immunogenicity. Carrier methods (e.g. RNA conjugates, polymers, and lipoplexes) that enhance cellular uptake of RNA therapeutics and stability against degradation by intracellular nucleases are also transforming the field. A number of small non-coding RNA therapies for cardiovascular indications are now approved. Moreover, there is a large pipeline of therapies in clinical development and an even larger list of putative therapies emerging from pre-clinical studies. Progress in this area is reviewed herein along with the hurdles that need to be overcome to allow a broader clinical translation.

Nucleic Acids as Novel Therapeutic Modalities to Address Multiple Sclerosis Onset and Progression

The issue of treating Multiple Sclerosis (MS) begins with disease-modifying treatments (DMTs) which may cause lymphopenia, dyspnea, and many other adverse effects. Consequently, further identification and evaluation of alternative treatments are crucial to monitoring their long-term outcomes and hopefully, moving toward personalized approaches that can be translated into clinical treatments. In this article, we focused on the novel therapeutic modalities that alter the interaction between the cellular constituents contributing to MS onset and progression. Furthermore, the studies that have been performed to evaluate and optimize drugs' efficacy, and particularly, to show their limitations and strengths are also presented. The preclinical trials of novel approaches for multiple sclerosis treatment provide promising prospects to cure the disease with pinpoint precision. Considering the fact that not a single treatment could be effective enough to cover all aspects of MS treatment, additional researches and therapies need to be developed in the future. Since the pathophysiology of MS resembles a jigsaw puzzle, researchers need to put a host of pieces together to create a promising window towards MS treatment. Thus, a combination therapy encompassing all these modules is highly likely to succeed in dealing with the disease. The use of different therapeutic approaches to re-induce self-tolerance in autoreactive cells contributing to MS pathogenesis is presented. A Combination therapy using these tools may help to deal with the clinical disabilities and symptoms of the disease in the future.

Gold Nanoparticle-Mediated Gene Therapy

Gold nanoparticles (AuNPs) have gained increasing attention as novel drug-delivery nanostructures for the treatment of cancers, infections, inflammations, and other diseases and disorders. They are versatile in design, synthesis, modification, and functionalization. This has many advantages in terms of gene editing and gene silencing, and their application in genetic illnesses. The development of several techniques such as CRISPR/Cas9, TALEN, and ZFNs has raised hopes for the treatment of genetic abnormalities, although more focused experimentation is still needed. AuNPs, however, have been much more effective in trending research on this subject. In this review, we highlight recently well-developed advancements that are relevant to cutting-edge gene therapies, namely gene editing and gene silencing in diseases caused by a single gene in humans by taking an edge of the unique properties of the AuNPs, which will be an important outlook for future research.

Gene regulatory and gene editing tools and their applications for retinal diseases and neuroprotection: From proof-of-concept to clinical trial

Gene editing and gene regulatory fields are continuously developing new and safer tools that move beyond the initial CRISPR/Cas9 technology. As more advanced applications are emerging, it becomes crucial to understand and establish more complex gene regulatory and editing tools for efficient gene therapy applications. Ophthalmology is one of the leading fields in gene therapy applications with more than 90 clinical trials and numerous proof-of-concept studies. The majority of clinical trials are gene replacement therapies that are ideal for monogenic diseases. Despite Luxturna's clinical success, there are still several limitations to gene replacement therapies including the size of the target gene, the choice of the promoter as well as the pathogenic alleles. Therefore, further attempts to employ novel gene regulatory and gene editing applications are crucial to targeting retinal diseases that have not been possible with the existing approaches. CRISPR-Cas9 technology opened up the door for corrective gene therapies with its gene editing properties. Advancements in CRISPR-Cas9-associated tools including base modifiers and prime editing already improved the efficiency and safety profile of base editing approaches. While base editing is a highly promising effort, gene regulatory approaches that do not interfere with genomic changes are also becoming available as safer alternatives. Antisense oligonucleotides are one of the most commonly used approaches for correcting splicing defects or eliminating mutant mRNA. More complex gene regulatory methodologies like artificial transcription factors are also another developing field that allows targeting haploinsufficiency conditions, functionally equivalent genes, and multiplex gene regulation. In this review, we summarized the novel gene editing and gene regulatory technologies and highlighted recent translational progress, potential applications, and limitations with a focus on retinal diseases.

Oligonucleotide-based therapies for cystic fibrosis

In the clinically successful era of CFTR modulators and Theratyping, 10-20% of individuals with cystic fibrosis (CF) may develop disease due to CFTR mutations that remain undruggable. These individuals produce low levels of CFTR mRNA and/or not enough protein to be rescued with modulator drugs. Alternative therapeutic approaches to correct the CFTR defect at the mRNA level using nucleic acid technologies are currently feasible; e.g., oligonucleotides platforms, which are being rapidly developed to correct genetic disorders. Drug-like properties, great specificity, and predictable off-target effects by design make oligonucleotides a valuable approach with fewer clinical and ethical challenges than genomic editing strategies. Together with personalized and precision medicine approaches, oligonucleotides are ideal therapeutics to target CF-causing mutations that affect only a few individuals resilient to modulator therapies.

Noncoding RNAs in liver physiology and metabolic diseases

The liver holds central roles in detoxification, energy metabolism and whole-body homeostasis but can develop malignant phenotypes when being chronically overwhelmed with fatty acids and glucose. The global rise of metabolic-associated fatty liver disease (MAFLD) is already affecting a quarter of the global population. Pharmaceutical treatment options against different stages of MAFLD do not yet exist and several clinical trials against hepatic transcription factors and other proteins have failed. However, emerging roles of noncoding RNAs, including long (lncRNA) and short noncoding RNAs (sRNA), in various cellular processes pose exciting new avenues for treatment interventions. Actions of noncoding RNAs mostly rely on interactions with proteins, whereby the noncoding RNA fine-tunes protein function in a process termed riboregulation. The developmental stage-, disease stage- and cell type-specific nature of noncoding RNAs harbors enormous potential to precisely target certain cellular pathways in a spatio-temporally defined manner. Proteins interacting with RNAs can be categorized into canonical or non-canonical RNA binding proteins (RBPs) depending on the existence of classical RNA binding domains. Both, RNA- and RBP-centric methods have generated new knowledge of the RNA-RBP interface and added an additional regulatory layer. In this review, we summarize recent advances of how of RBP-lncRNA interactions and various sRNAs shape cellular physiology and the development of liver diseases such as MAFLD and hepatocellular carcinoma.

Therapeutic Strategies in Huntington’s Disease: From Genetic Defect to Gene Therapy

Despite the identification of an expanded CAG repeat on exon 1 of the huntingtin gene located on chromosome 1 as the genetic defect causing Huntington’s disease almost 30 years ago, currently approved therapies provide only limited symptomatic relief and do not influence the age of onset or disease progression rate. Research has identified various intricate pathogenic cascades which lead to neuronal degeneration, but therapies interfering with these mechanisms have been marked by many failures and remain to be validated. Exciting new opportunities are opened by the emerging techniques which target the mutant protein DNA and RNA, allowing for “gene editing”. Although some issues relating to “off-target” effects or immune-mediated side effects need to be solved, these strategies, combined with stem cell therapies and more traditional approaches targeting specific pathogenic cascades, such as excitotoxicity and bioavailability of neurotrophic factors, could lead to significant improvement of the outcomes of treated Huntington’s disease patients.

Beyond GalNAc! Drug delivery systems comprising complex oligosaccharides for targeted use of nucleic acid therapeutics

Nucleic Acid Therapeutics (NATs) are establishing a leading role for the management and treatment of genetic diseases following FDA approval of nusinersen, patisiran, and givosiran in the last 5 years, the breakthrough of milasen, with more approvals undoubtedly on the way. Givosiran takes advantage of the known interaction between the hepatocyte specific asialoglycoprotein receptor (ASGPR) and N-acetyl galactosamine (GalNAc) ligands to deliver a therapeutic effect, underscoring the value of targeting moieties. In this review, we explore the history of GalNAc as a ligand, and the paradigm it has set for the delivery of NATs through precise targeting to the liver, overcoming common hindrances faced with this type of therapy. We describe various complex oligosaccharides (OSs) and ask what others could be used to target receptors for NAT delivery and the opportunities awaiting exploration of this chemical space.

Precision Anti-Cancer Medicines by Oligonucleotide Therapeutics in Clinical Research Targeting Undruggable Proteins and Non-Coding RNAs

Cancer incidence and mortality continue to increase, while the conventional chemotherapeutic drugs confer limited efficacy and relevant toxic side effects. Novel strategies are urgently needed for more effective and safe therapeutics in oncology. However, a large number of proteins are considered undruggable by conventional drugs, such as the small molecules. Moreover, the mRNA itself retains oncological functions, and its targeting offers the double advantage of blocking the tumorigenic activities of the mRNA and the translation into protein. Finally, a large family of non-coding RNAs (ncRNAs) has recently emerged that are also dysregulated in cancer, but they could not be targeted by drugs directed against the proteins. In this context, this review describes how the oligonucleotide therapeutics targeting RNA or DNA sequences, are emerging as a new class of drugs, able to tackle the limitations described above. Numerous clinical trials are evaluating oligonucleotides for tumor treatment, and in the next few years some of them are expected to reach the market. We describe the oligonucleotide therapeutics targeting undruggable proteins (focusing on the most relevant, such as those originating from the MYC and RAS gene families), and for ncRNAs, in particular on those that are under clinical trial evaluation in oncology. We highlight the challenges and solutions for the clinical success of oligonucleotide therapeutics, with particular emphasis on the peculiar challenges that render it arduous to treat tumors, such as heterogeneity and the high mutation rate. In the review are presented these and other advantages offered by the oligonucleotide as an emerging class of biotherapeutics for a new era of precision anti-cancer medicine.

Antisense Oligonucleotides and Small Interfering RNA for the Treatment of Dyslipidemias

The burden of atherosclerotic disease worldwide necessitates implementing the treatment of its risk factors. Among them, hypercholesterolemia has a central role. In addition to conventional small organic compounds and the recently introduced monoclonal antibodies, new technologies are arising such as the antisense oligonucleotides and small interfering RNAs (siRNAs) that operate upstream, blocking the mRNA translation of the proteins specifically involved in lipid metabolism. In this review, we briefly explain the mechanisms of action of these molecules and discuss the difficulties related to their in vivo use as therapeutical agents. We go over the oligonucleotides tested in clinical trials that could potentially revolutionize the care of patients by acting on proteins involved in the lipoprotein metabolism and regulation, namely: angiopoietin-like protein 3 (ANGPTL3); lipoprotein a (Lp(a)); apolipoprotein B (Apo B); apolipoprotein C III (Apo C-III); and proprotein convertase subtilisin–kexin type 9 (PCSK9). Finally, the differences between ASOs and siRNAs, their future possible clinical applications, and the role of Inclisiran, a siRNA direct against PCSK9 to reduce LDL-C, were reviewed in detail.

Antisense oligonucleotide: A promising therapeutic option to beat COVID-19

The COVID-19 crisis and the development of the first approved mRNA vaccine have highlighted the power of RNA-based therapeutic strategies for the development of new medicines. Aside from RNA-vaccines, antisense oligonucleotides (ASOs) represent a new and very promising class of RNA-targeted therapy. Few drugs have already received approval from the Food and Drug Administration. Here, we underscored why and how ASOs hold the potential to change the therapeutic landscape to beat SARS-CoV-2 viral infections. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions.

Arabinonucleic acids containing C5-propynyl modifications form stable hybrid duplexes with RNA that are efficiently degraded by E. coli RNase H

The promise of the antisense approach to treat a variety of diseases with oligonucleotides and solutions to challenges that have been encountered in their development is attributable to chemical modification of the nucleic acid scaffold. Herein, we describe preliminary data regarding the synthesis of a novel C5-propynyl-β-d-arabinouridine (araU^P) phosphoramidite and its incorporation into oligonucleotides. Substitution of araU^P in dT₁₈ results in minor stabilization of duplexes formed with RNA when modifications are placed consecutively and a uniformly modified araU^P 18-mer increases stability by 34 °C relative to DNA. The modified oligomer exhibits improved nuclease and serum stability when compared to DNA and duplexes formed between RNA and araU^P oligonucleotides are substrates for E. coli RNase H. These preliminary results merit further investigation into C5-propynyl modified arabino nucleic acids for potential therapeutic gene silencing applications.

Absorption, Distribution, Metabolism, and Excretion of US Food and Drug Administration-Approved Antisense Oligonucleotide Drugs

Absorption, distribution, metabolism, and excretion (ADME) are the key biologic processes for determination of a drug's pharmacokinetic parameters, which have direct impacts on efficacy and adverse drug reactions (ADRs). The chemical structures, dosage forms, and sites and routes of administration are the principal determinants of ADME profiles and consequent impacts on their efficacy and ADRs. Newly developed large molecule biologic antisense oligonucleotide (ASO) drugs have completely unique ADME that is not fully defined. ASO-based drugs are single-stranded synthetic antisense nucleic acids with diverse modes of drug actions from induction of mRNA degradation, exon skipping and restoration, and interactions with proteins. ASO drugs have a great potential to treat certain human diseases that have remained untreatable with small molecule-based drugs. The ADME of ASO drugs contributes to their unique set of ADRs and toxicity. In this review, to better understand their ADME, the 10 US Food and Drug Administration (FDA)-approved ASO drugs were selected: fomivirsen, pegaptanib, mipomersen, nusinersen, inotersen, defibrotide, eteplirsen, golodirsen, viltolarsen, and casimersen. A meta-analysis was conducted on their formulation, dosage, sites of administration, local and systematic distribution, metabolism, degradation, and excretion. Membrane permeabilization through endocytosis and nucleolytic degradation by endonucleases and exonucleases are major ADME features of the ASO drugs that differ from small-molecule drugs. The information summarized here provides comprehensive ADME characteristics of FDA-approved ASO drugs, leading to a better understanding of their therapeutic efficacy and their potential ADRs and toxicity. Numerous knowledge gaps, particularly on cellular uptake and subcellular trafficking and distribution, are identified, and future perspectives and directions are discussed. SIGNIFICANCE STATEMENT: Through a systematic analysis of the existing information of absorption, distribution, metabolism, and excretion (ADME) parameters for 10 US Food and Drug Administration (FDA)-approved antisense oligonucleotide (ASO) drugs, this review provides an overall view of the unique ADME characteristics of ASO drugs, which are distinct from small chemical drug ADME. This knowledge is useful for discovery and development of new ASO drugs as well as clinical use of current FDA-approved ASO drugs.

Adverse Drug Reactions and Toxicity of the Food and Drug Administration-Approved Antisense Oligonucleotide Drugs

The market for large molecule biologic drugs has grown rapidly, including antisense oligonucleotide (ASO) drugs. ASO drugs work as single-stranded synthetic oligonucleotides that reduce production or alter functions of disease-causing proteins through various mechanisms, such as mRNA degradation, exon skipping, and ASO-protein interactions. Since the first ASO drug, fomivirsen, was approved in 1998, the U.S. Food and Drug Administration (FDA) has approved 10 ASO drugs to date. Although ASO drugs are efficacious in treating some diseases that are untargetable by small-molecule chemical drugs, concerns on adverse drug reactions (ADRs) and toxicity cannot be ignored. Illustrative of this, mipomersen was recently taken off the market due to its hepatotoxicity risk. This paper reviews ADRs and toxicity from FDA drug labeling, preclinical studies, clinical trials, and postmarketing real-world studies on the 10 FDA-approved ASO drugs, including fomivirsen and pegaptanib, mipomersen, nusinersen, inotersen, defibrotide, eteplirsen, golodirsen, viltolarsen, and casimersen. Unique and common ADRs and toxicity for each ASO drug are summarized here. The risk of developing hepatotoxicity, kidney toxicity, and hypersensitivity reactions co-exists for multiple ASO drugs. Special precautions need to be in place when certain ASO drugs are administrated. Further discussion is extended on studying the mechanisms of ADRs and toxicity of these drugs, evaluating the existing physiologic and pathologic states of patients, optimizing the dose and route of administration, and formulating personalized treatment plans to improve the clinical utility of FDA-approved ASO drugs and discovery and development of new ASO drugs with reduced ADRs. SIGNIFICANCE STATEMENT: The current review provides a comprehensive analysis of unique and common ADRs and the toxicity of FDA-approved ASO drugs. The information can help better manage the risk of severe hepatotoxicity, kidney toxicity, and hypersensitivity reactions in the usage of currently approved ASO drugs and the discovery and development of new and safer ASO drugs.

Validation and application of hybridization liquid chromatography-tandem mass spectrometry methods for quantitative bioanalysis of antisense oligonucleotides

Background: Antisense oligonucleotide (ASO), an emerging modality in drug research and development, demands accurate and sensitive bioanalysis to understand its pharmacokinetic and pharmacodynamic properties. Results: By combining the advantages of both ligand binding and liquid chromatography-mass spectrometry/tandem mass (LC-MS/MS), hybridization LC-MS/MS methods were successfully developed and validated/qualified in a good lab practice (GLP) environment for the quantitation of an ASO drug candidate in monkey serum, cerebrospinal fluid (CSF) and tissues in the range of 0.5-500 ng/ml. Special treatment of CSF samples was employed to mitigate nonspecific binding, improve long-term storage stability and enable the usage of artificial CSF as a more accessible surrogate matrix. The method was also qualified and applied to ASO quantitation in various monkey tissue samples using a cocktail tissue homogenate as a surrogate matrix. Conclusion: This work was the first reported GLP validation and application of ASO bioanalysis using the hybridization LC-MS/MS platform.

Implication of microRNA as a potential biomarker of myocarditis

Myocarditis was previously attributed to an epidemic viral infection. Additional harmful reagents, in addition to viruses, play a role in its etiology. Coronavirus disease 2019 (COVID-19) vaccine-induced myocarditis has recently been described, drawing attention to vaccine-induced myocarditis in children and adolescents. Its pathology is based on a series of complex immune responses, including initial innate immune responses in response to viral entry, adaptive immune responses leading to the development of antigen-specific antibodies, and autoimmune responses to cellular injury caused by cardiomyocyte rupture that releases antigens. Chronic inflammation and fibrosis in the myocardium eventually result in cardiac failure. Recent advancements in molecular biology have remarkably increased our understanding of myocarditis. In particular, microRNAs (miRNAs) are a hot topic in terms of the role of new biomarkers and the pathophysiology of myocarditis. Myocarditis has been linked with microRNA-221/222 (miR-221/222), miR-155, miR-10a*, and miR-590. Despite the lack of clinical trials of miRNA intervention in myocarditis yet, multiple clinical trials of miRNAs in other cardiac diseases have been aggressively conducted to help pave the way for future research, which is bolstered by the success of recently U.S. Food and Drug Administration-approved small-RNA medications. This review presents basic information and recent research that focuses on myocarditis and related miRNAs as a potential novel biomarker and the therapeutics.

MicroRNAs as Regulators of Phagocytosis

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression and thus act as important regulators of cellular phenotype and function. As their expression may be dysregulated in numerous diseases, they are of interest as biomarkers. What is more, attempts of modulation of some microRNAs for therapeutic reasons have been undertaken. In this review, we discuss the current knowledge regarding the influence of microRNAs on phagocytosis, which may be exerted on different levels, such as through macrophages polarization, phagosome maturation, reactive oxygen species production and cytokines synthesis. This phenomenon plays an important role in numerous pathological conditions.

Splicing Modulation as a Promising Therapeutic Strategy for Lysosomal Storage Disorders: The Mucopolysaccharidoses Example

Over recent decades, the many functions of RNA have become more evident. This molecule has been recognized not only as a carrier of genetic information, but also as a specific and essential regulator of gene expression. Different RNA species have been identified and novel and exciting roles have been unveiled. Quite remarkably, this explosion of novel RNA classes has increased the possibility for new therapeutic strategies that tap into RNA biology. Most of these drugs use nucleic acid analogues and take advantage of complementary base pairing to either mimic or antagonize the function of RNAs. Among the most successful RNA-based drugs are those that act at the pre-mRNA level to modulate or correct aberrant splicing patterns, which are caused by specific pathogenic variants. This approach is particularly tempting for monogenic disorders with associated splicing defects, especially when they are highly frequent among affected patients worldwide or within a specific population. With more than 600 mutations that cause disease affecting the pre-mRNA splicing process, we consider lysosomal storage diseases (LSDs) to be perfect candidates for this type of approach. Here, we introduce the overall rationale and general mechanisms of splicing modulation approaches and highlight the currently marketed formulations, which have been developed for non-lysosomal genetic disorders. We also extensively reviewed the existing preclinical studies on the potential of this sort of therapeutic strategy to recover aberrant splicing and increase enzyme activity in our diseases of interest: the LSDs. Special attention was paid to a particular subgroup of LSDs: the mucopolysaccharidoses (MPSs). By doing this, we hoped to unveil the unique therapeutic potential of the use of this sort of approach for LSDs as a whole.

RNA Therapeutics: the Next Generation of Drugs for Cardiovascular Diseases

Purpose of Review

RNA therapeutics are a new and rapidly expanding class of drugs to prevent or treat a wide spectrum of diseases. We discuss the defining characteristics of the diverse family of molecules under the RNA therapeutics umbrella.

Recent Findings

RNA therapeutics are designed to regulate gene expression in a transient manner. For example, depending upon the strategy employed, RNA therapies offer the versatility to replace, supplement, correct, suppress, or eliminate the expression of a targeted gene. RNA therapies include antisense nucleotides, microRNAs and small interfering RNAs, RNA aptamers, and messenger RNAs. Further, we discuss the mechanism(s) by which different RNA therapies either reduce or increase the expression of their targets.

Summary

We review the RNA therapeutics approved (and those in trials) to treat cardiovascular indications. RNA-based therapeutics are a new, rapidly growing class of drugs that will offer new alternatives for an increasing array of cardiovascular conditions.

Impacts and mechanisms of alternative mRNA splicing in cancer metabolism, immune response, and therapeutics

Alternative pre-mRNA splicing (AS) provides the potential to produce diversity at RNA and protein levels. Disruptions in the regulation of pre-mRNA splicing can lead to diseases. With the development of transcriptome and genome sequencing technology, increasing diseases have been identified to be associated with abnormal splicing of mRNAs. In tumors, abnormal alternative splicing frequently plays critical roles in cancer pathogenesis and may be considered as new biomarkers and therapeutic targets for cancer intervention. Metabolic abnormalities and immune disorders are important hallmarks of cancer. AS produces multiple different isoforms and diversifies protein expression, which is utilized by the immune and metabolic reprogramming systems to expand gene functions. The abnormal splicing events contributed to tumor progression, partially due to effects on immune response and metabolic reprogramming. Herein, we reviewed the vital role of alternative splicing in regulating cancer metabolism and immune response. We discussed how alternative splicing regulates metabolic reprogramming of cancer cells and antitumor immune response, and the possible strategies to targeting alternative splicing pathways or splicing-regulated metabolic pathway in the context of anticancer immunotherapy. Further, we highlighted the challenges and discuss the perspectives for RNA-based strategies for the treatment of cancer with abnormally alternative splicing isoforms.

Current Advances in RNA Therapeutics for Human Diseases

Following the discovery of nucleic acids by Friedrich Miescher in 1868, DNA and RNA were recognized as the genetic code containing the necessary information for proper cell functioning. In the years following these discoveries, vast knowledge of the seemingly endless roles of RNA have become better understood. Additionally, many new types of RNAs were discovered that seemed to have no coding properties (non-coding RNAs), such as microRNAs (miRNAs). The discovery of these new RNAs created a new avenue for treating various human diseases. However, RNA is relatively unstable and is degraded fairly rapidly once administered; this has led to the development of novel delivery mechanisms, such as nanoparticles to increase stability as well as to prevent off-target effects of these molecules. Current advances in RNA-based therapies have substantial promise in treating and preventing many human diseases and disorders through fixing the pathology instead of merely treating the symptomology similarly to traditional therapeutics. Although many RNA therapeutics have made it to clinical trials, only a few have been FDA approved thus far. Additionally, the results of clinical trials for RNA therapeutics have been ambivalent to date, with some studies demonstrating potent efficacy, whereas others have limited effectiveness and/or toxicity. Momentum is building in the clinic for RNA therapeutics; future clinical care of human diseases will likely comprise promising RNA therapeutics. This review focuses on the current advances of RNA therapeutics and addresses current challenges with their development.