Inhibition of Rous sarcoma viral RNA translation by a specific oligodeoxyribonucleotide

Multi-Omics and miRNA Interaction Joint Analysis Highlight New Insights Into Anthocyanin Biosynthesis in Peanuts (Arachis hypogaea L.)

Peanut (Arachis hypogaea L.) is one of the most important economic and oil crops in the world. At present, peanut varieties with rich anthocyanin in testa are rare in the market, but the selection and breeding of varieties with the related traits has always attracted the attention of breeders. In this study, two peanut varieties with the pink and purple testa, G110 (G) and Z18-40 (Z) were used to conduct interaction joint analysis of multi-omics and miRNA-target gene. The anthocyanin content of Z18-40 was 7.49-8.62-folds higher than G110 on 30 DAF (days after flowering) and 45 DAF via Ultraviolet-visible Spectrophotometer (UV-5800, Shanghai, China). And then, a total of 14 candidate genes related with the anthocyanin biosynthesis were identified for correlation in different comparison groups (R ² ≥ 0.80), among of a novel gene Ah21440 related with hydroxycinnamoyl transferase (HCT) biosynthesis was identified. In addition, Cyanidin 3-O-glucoside (Kuromanin, pmb0550) was the only common differentially accumulated metabolite (DAM) identified using multi-omics joint analysis in G1_vs_G2, Z1_vs_Z2, G1_vs_Z1, and G2_vs_Z2, respectively. Correlation analysis of miRNA-target genes and DEGs in the transcriptome shows that, AhmiR2950, AhmiR398, AhmiR50, and AhmiR51 regulated to HCT and chalcone biosynthesis related candidate genes (Ah21440, AhCHS, AhCHI). Lastly, all of 14 candidate genes and 4 differentially expressed miRNAs were validated using quantitative real-time PCR (qRT-PCR), which trends were consistent with that of the former transcriptome data. The results provide important reference for in-depth research on the anthocyanin metabolism mechanism in peanut testa.

Innovative approaches for treatment of osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone tumor, which usually occurs in children and adolescents. It is generally a high-grade malignancy presenting with extreme metastases to the lungs or other bones. The etiology of the disease is multifaceted and still remains obscure. A combination of surgery and chemotherapy has played a major role in the treatment of OS over the past three decades, and consequently, the overall survival rates for the disease have remained unchanged. Therefore, there is an urgent need to employ new comprehensive analyses and technologies to develop significantly more informative classification systems, with the aim of developing more effective and less toxic therapies for OS patients. This review discusses the existing knowledge of OS therapy and potential methods to develop novel therapeutic agents for the disease.

Oligonucleotide Therapeutics: From Discovery and Development to Patentability

Following the first proof of concept of using small nucleic acids to modulate gene expression, a long period of maturation led, at the end of the last century, to the first marketing authorization of an oligonucleotide-based therapy. Since then, 12 more compounds have hit the market and many more are in late clinical development. Many companies were founded to exploit their therapeutic potential and Big Pharma was quickly convinced that oligonucleotides could represent credible alternatives to protein-targeting products. Many technologies have been developed to improve oligonucleotide pharmacokinetics and pharmacodynamics. Initially targeting rare diseases and niche markets, oligonucleotides are now able to benefit large patient populations. However, there is still room for oligonucleotide improvement and further breakthroughs are likely to emerge in the coming years. In this review we provide an overview of therapeutic oligonucleotides. We present in particular the different types of oligonucleotides and their modes of action, the tissues they target and the routes by which they are administered to patients, and the therapeutic areas in which they are used. In addition, we present the different ways of patenting oligonucleotides. We finally discuss future challenges and opportunities for this drug-discovery platform.

Targeting TGF-ß in the Central Nervous System: Assessment of Cynomolgus Monkey—Toxicity and Pharmacokinetics for an LNA-Antisense Oligonucleotide

Increasingly antisense oligonucleotides (ASOs) are developed for potential treatment of CNS disorders, and due to the inability to cross the blood brain barrier, they require direct administration into the cerebrospinal fluid (CSF). In this regard, intrathecal (i.th.) administration in cynomolgus monkeys (Macaca fascicularis) is a well-established approach for preclinical safety studies. Here, we present an innovative preclinical approach that is intended to support rapid entry into clinical development with ASOs targeting the CNS. The preclinical approach comprises one non-GLP study in 26 non-human primates, followed by a pivotal GLP repeated dose toxicity study in the same species. No pivotal rodent studies were conducted, and regulatory guidance to initiate this study was met by in vitro work. The non-GLP study consists of three separate phases: Phase A determines toxicity after i.th. administrations with five escalating dose levels in a single male and female animal, respectively. Dosing is conducted on days 1, 8, 15, 22, and 29 and the experiment is terminated 36 days after start of the study. The second phase (Phase B) investigates pharmacokinetics over a 2- or 4-week period at two dose levels following single administrations in eight (8) animals (4 females, 4 males). Finally, a third phase (Phase C) investigates toxicity and pharmacokinetics after repeated (9×) dosing over a 13-week period at two dose levels in sixteen (8 females, 8 males) animals. In each phase, clinical observations and physical/neurological parameters are investigated directly pre-dose, 4 h and 24 h post-dose, respectively. In all phases, CSF and blood samples are taken pre-dose and after each dosing, for determination of test article concentration, biomarkers of tolerability and biomarkers of pharmacology. In all phases, tissue samples from the liver, kidney, spinal cord, and brain are collected for determination of NVP-13 tissue concentrations. The above concept has successfully supported first-in-human clinical trials. The entire non-GLP program is completed within less than six months and requires fewer animals in comparison to the conduct of three independent studies.

Safe and Effective Cynomolgus Monkey GLP-Tox Study with Repetitive Intrathecal Application of a TGFBR2 Targeting LNA-Gapmer Antisense Oligonucleotide as Treatment Candidate for Neurodegenerative Disorders

The capability of the adult central nervous system to self-repair/regenerate was demonstrated repeatedly throughout the last decades but remains in debate. Reduced neurogenic niche activity paralleled by a profound neuronal loss represents fundamental hallmarks in the disease course of neurodegenerative disorders. We and others have demonstrated the endogenous TGFβ system to represent a potential pathogenic participant in disease progression, of amyotrophic lateral sclerosis (ALS) in particular, by generating and promoting a disequilibrium of neurodegenerative and neuroregenerative processes. The novel human/primate specific LNA Gapmer Antisense Oligonucleotide "NVP-13", targeting TGFBR2, effectively reduced its expression and lowered TGFβ signal transduction in vitro and in vivo, paralleled by boosting neurogenic niche activity in human neuronal progenitor cells and nonhuman primate central nervous system. Here, we investigated NVP-13 in vivo pharmacology, safety, and tolerability following repeated intrathecal injections in nonhuman primate cynomolgus monkeys for 13 weeks in a GLP-toxicology study approach. NVP-13 was administered intrathecally with 1, 2, or 4 mg NVP-13/animal within 3 months on days 1, 15, 29, 43, 57, 71, and 85 in the initial 13 weeks. We were able to demonstrate an excellent local and systemic tolerability, and no adverse events in physiological, hematological, clinical chemistry, and microscopic findings in female and male Cynomolgus Monkeys. Under the conditions of this study, the no observed adverse effect level (NOAEL) is at least 4 mg/animal NVP-13.

Small Drugs, Huge Impact: The Extraordinary Impact of Antisense Oligonucleotides in Research and Drug Development

Antisense oligonucleotides (ASOs) are an increasingly represented class of drugs. These small sequences of nucleotides are designed to precisely target other oligonucleotides, usually RNA species, and are modified to protect them from degradation by nucleases. Their specificity is due to their sequence, so it is possible to target any RNA sequence that is already known. These molecules are very versatile and adaptable given that their sequence and chemistry can be custom manufactured. Based on the chemistry being used, their activity may significantly change and their effects on cell function and phenotypes can differ dramatically. While some will cause the target RNA to decay, others will only bind to the target and act as a steric blocker. Their incredible versatility is the key to manipulating several aspects of nucleic acid function as well as their process, and alter the transcriptome profile of a specific cell type or tissue. For example, they can be used to modify splicing or mask specific sites on a target. The entire design rather than just the sequence is essential to ensuring the specificity of the ASO to its target. Thus, it is vitally important to ensure that the complete process of drug design and testing is taken into account. ASOs' adaptability is a considerable advantage, and over the past decades has allowed multiple new drugs to be approved. This, in turn, has had a significant and positive impact on patient lives. Given current challenges presented by the COVID-19 pandemic, it is necessary to find new therapeutic strategies that would complement the vaccination efforts being used across the globe. ASOs may be a very powerful tool that can be used to target the virus RNA and provide a therapeutic paradigm. The proof of the efficacy of ASOs as an anti-viral agent is long-standing, yet no molecule currently has FDA approval. The emergence and widespread use of RNA vaccines during this health crisis might provide an ideal opportunity to develop the first anti-viral ASOs on the market. In this review, we describe the story of ASOs, the different characteristics of their chemistry, and how their characteristics translate into research and as a clinical tool.

Insights into nucleic acid-based self-assembling nanocarriers for targeted drug delivery and controlled drug release

Over the past few decades, rapid advances of nucleic acid nanotechnology always drive the development of nanoassemblies with programmable design, powerful functionality, excellent biocompatibility and outstanding biosafety. Nowadays, nucleic acid-based self-assembling nanocarriers (NASNs) play an increasingly greater role in the research and development in biomedical studies, particularly in drug delivery, release and targeting. In this review, NASNs are systematically summarized the strategies cooperated with their broad applications in drug delivery. We first discuss the self-assembling methods of nanocarriers comprised of DNA, RNA and composite materials, and summarize various categories of targeting media, including aptamers, small molecule ligands and proteins. Furthermore, drug release strategies by smart-responding multiple kinds of stimuli are explained, and various applications of NASNs in drug delivery are discussed, including protein drugs, nucleic acid drugs, small molecule drugs and nanodrugs. Lastly, we propose limitations and potential of NASNs in the future development, and expect that NASNs enable facilitate the development of new-generation drug vectors to assist in solving the growing demands on disease diagnosis and therapy or other biomedicine-related applications in the real world.

Quantification of Antisense Oligonucleotides by Splint Ligation and Quantitative Polymerase Chain Reaction

Reliable detection and quantification of antisense oligonucleotides (ASOs) in experimental and clinical specimens are essential to understand the biological function of novel oligonucleotide-based therapeutics. In this study, we describe a method to detect and quantify ASOs in biological samples, whereby the ASO acts as a splint to direct the ligation of complementary probes and quantitative real-time PCR was used to monitor ligation products. Low levels of 2′-O-methoxyethyl (2′-O-MOE) gapmer ASO in serum, liver, kidney, lung, heart, muscle, and brain tissues can be detected over a 6-log linear range for detection using this method. This method allows quantification of various types of chemically modified ASOs, including phosphorothioate linkage, 2′-O-methyl, 2′-O-MOE, and locked nucleic acid, as well as siRNAs. This method does not require probe modifications, and can be performed using standard laboratory equipment; making it a fast, sensitive, and reliable technique that can be widely applied. This detection method may find potential applications in detection of therapeutic oligonucleotides in biological samples.

Antisense oligonucleotides targeting the SMN2 promoter region enhance SMN2 expression in spinal muscular atrophy cell lines and mouse model

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease caused by homozygous deletions or mutations in survival motor neuron gene 1 (SMN1). Currently, the primary therapeutic strategy for SMA is to increase the level of SMN via correcting SMN2 splicing (nusinersen and risdiplam). However, some patients with SMA do not respond to such treatments, thereby warranting a need to develop new therapeutic strategies. We have previously reported that SMN2 expression is epigenetically regulated by DNA methylation levels of the SMN2 promoter region. In the present study, we determined that methyl-CpG-binding protein 2 (MeCP2) may bind to this critical promoter region (nt-167 to 43). Antisense oligonucleotides (ASO-P1 and ASO-P2) were designed to target the key methylation sites in the SMN2 promoter region, which enhanced the overall transcription and functional protein expression levels in the SMA cell lines. These results were similar to those observed in nusinersen-treated SMA cells. Moreover, a combined treatment of ASO-P1 and ASO-NUS in SMA cell lines further increases fl-SMN2 transcript and SMN protein levels. The delivery of ASO-P1 to the central nervous system of severe SMA mice corrected the molecular, pathological, and functional phenotypes of this disease and increased survival rates. Our findings suggest that the key methylation regions in the SMN2 promoter region may be a novel therapeutic target for SMA.

Long non-coding RNAs as possible therapeutic targets in protozoa, and in Schistosoma and other helminths

Long non-coding RNAs (lncRNAs) emerged in the past 20 years due to massive amounts of scientific data regarding transcriptomic analyses. They have been implicated in a plethora of cellular processes in higher eukaryotes. However, little is known about lncRNA possible involvement in parasitic diseases, with most studies only detecting their presence in parasites of human medical importance. Here, we review the progress on lncRNA studies and their functions in protozoans and helminths. In addition, we show an example of knockdown of one lncRNA in Schistosoma mansoni, SmLINC156349, which led to in vitro parasite adhesion, motility, and pairing impairment, with a 20% decrease in parasite viability and 33% reduction in female oviposition. Other observed phenotypes were a decrease in the proliferation rate of both male and female worms and their gonads, and reduced female lipid and vitelline droplets that are markers for well-developed vitellaria. Impairment of female worms' vitellaria in SmLINC156349-silenced worms led to egg development deficiency. All those results demonstrate the great potential of the tools and methods to characterize lncRNAs as potential new therapeutic targets. Further, we discuss the challenges and limitations of current methods for studying lncRNAs in parasites and possible solutions to overcome them, and we highlight the future directions of this exciting field.

MicroRNA-Related Strategies to Improve Cardiac Function in Heart Failure

Heart failure (HF) describes a group of manifestations caused by the failure of heart function as a pump that supports blood flow through the body. MicroRNAs (miRNAs), as one type of non-coding RNA molecule, have crucial roles in the etiology of HF. Accordingly, miRNAs related to HF may represent potential novel therapeutic targets. In this review, we first discuss the different roles of miRNAs in the development and diseases of the heart. We then outline commonly used miRNA chemical modifications and delivery systems. Further, we summarize the opportunities and challenges for HF-related miRNA therapeutics targets, and discuss the first clinical trial of an antisense drug (CDR132L) in patients with HF. Finally, we outline current and future challenges and potential new directions for miRNA-based therapeutics for HF.

Tritium labeling of antisense oligonucleotides via different conjugation agents

A novel approach to tritium-labeled antisense oligonucleotides (ASO) was established by conjugating N-succinimidyl propionate, as well as maleimide-derivatives, to the 3′-end of ASOs targeting metastasis-associated lung adenocarcinoma transcript 1 (Malat1) containing amino- or sulfhydryl-linkers. In vitro stability and Malat1 RNA reduction studies demonstrated that N-ethylmaleimide (NEM) could be used as a stable tag while maintaining the desired target interaction. The corresponding radioactive label conjugation using [3H]-NEM resulted in tritium-labeled ASOs with a high molar specific activity of up to 17 Ci/mmol. Single-dose in vivo studies in mice were carried out to compare [3H]-ASOs with their unlabeled counterpart ASOs, with and without conjugation to N-acetylgalactosamine (GalNAc), for tissue and plasma concentrations time profiles. Despite the structural modification of the labeled ASOs, in vitro target interaction and in vivo pharmacokinetic behaviors were similar to that of the unlabeled ASOs. In conclusion, this new method provides a powerful technique for fast and safe access to tritium-labeled oligonucleotides, e.g., for pharmacokinetic, mass balance, or autoradiography studies.

Graphical abstract

Systematic Combination of Oligonucleotides and Synthetic Polymers for Advanced Therapeutic Applications

The potential of oligonucleotides is exceptional in therapeutics because of their high safety, potency, and specificity compared to conventional therapeutic agents. However, many obstacles, such as low in vivo stability and poor cellular uptake, have hampered their clinical success. Use of polymeric carriers can be an effective approach for overcoming the biological barriers and thereby maximizing the therapeutic efficacy of the oligonucleotides due to the availability of highly tunable synthesis and functional modification of various polymers. As loaded in the polymeric carriers, the therapeutic oligonucleotides, such as antisense oligonucleotides, small interfering RNAs, microRNAs, and even messenger RNAs, become nuclease-resistant by bypassing renal filtration and can be efficiently internalized into disease cells. In this review, we introduced a variety of systematic combinations between the therapeutic oligonucleotides and the synthetic polymers, including the uses of highly functionalized polymers responding to a wide range of endogenous and exogenous stimuli for spatiotemporal control of oligonucleotide release. We also presented intriguing characteristics of oligonucleotides suitable for targeted therapy and immunotherapy, which can be fully supported by versatile polymeric carriers.

Ribonuclease recruitment using a small molecule reduced c9ALS/FTD r(G4C2) repeat expansion in vitro and in vivo ALS models

[Figure: see text].

Therapeutic application of sequence-specific binding molecules for novel genome editing tools

Genome editing has been expected to widely increase the available treatment options for various diseases and permit pharmaceutical interventions in previously untreatable conditions. The availability of genome editing tools was dramatically increased by the development of the CRISPR-Cas9 system. However, a number of issues limit the use of the CRISPR-Cas9 system and other gene-editing tools in the clinical treatment of diseases. This review summarized the history and types of genome editing tools and limitations of their use. In addition, the study addressed several next-generation technologies aiming to overcome the limitations of current gene therapy protocols in an effort to accelerate the clinical development of potential treatment options. This review has provided an extensive foundation of the current state of genome editing technology and its clinical development. This review also indicate that the study additionally highlighted the need for multidisciplinary approaches to overcome current bottlenecks in the development of genome editing.

Antisense oligonucleotides: absorption, distribution, metabolism, and excretion

INTRODUCTION

Antisense oligonucleotides (ASOs) have emerged as a promising novel drug modality that aims to address unmet medical needs. A record of six ASO drugs have been approved since 2016, and more candidates are in clinical development. ASOs are the most advanced class within the RNA-based therapeutics field.

AREAS COVERED

This review highlights the two major backbones that are currently used to build the most advanced ASO platforms - the phosphorodiamidate morpholino oligomers (PMOs) and the phosphorothioates (PSs). The absorption, distribution, metabolism, and excretion (ADME) properties of the PMO and PS platforms are discussed in detail.

EXPERT OPINION

Understanding the ADME properties of existing ASOs can foster further improvement of this cutting-edge therapy, thereby enabling researchers to safely develop ASO drugs and enhancing their ability to innovate.

ABBREVIATIONS

2'-MOE, 2'-O-methoxyethyl; 2'PS, 2 modified PS; ADME, absorption, distribution, metabolism, and excretion; ASO, antisense oligonucleotide; AUC, area under the curve; BNA, bridged nucleic acid; CPP, cell-penetrating peptide; CMV, cytomegalovirus; CNS, central nervous system; CYP, cytochrome P; DDI, drug-drug interaction; DMD, Duchenne muscular dystrophy; FDA, Food and Drug Administration; GalNAc3, triantennary N-acetyl galactosamine; IT, intrathecal; IV, intravenous; LNA, locked nucleic acid; mRNA, messenger RNA; NA, not applicable; PBPK, physiologically based pharmacokinetics; PD, pharmacodynamic; PK, pharmacokinetic; PMO, phosphorodiamidate morpholino oligomer; PMOplus, PMOs with positionally specific positive molecular charges; PPMO, peptide-conjugated PMO; PS, phosphorothioate; SC, subcutaneous; siRNA, small-interfering RNA; SMA, spinal muscular atrophy.

Polyglutamine Ataxias: Our Current Molecular Understanding and What the Future Holds for Antisense Therapies

Polyglutamine (polyQ) ataxias are a heterogenous group of neurological disorders all caused by an expanded CAG trinucleotide repeat located in the coding region of each unique causative gene. To date, polyQ ataxias encompass six disorders: spinocerebellar ataxia types 1, 2, 3, 6, 7, and 17 and account for a larger group of disorders simply known as polyglutamine disorders, which also includes Huntington's disease. These diseases are typically characterised by progressive ataxia, speech and swallowing difficulties, lack of coordination and gait, and are unfortunately fatal in nature, with the exception of SCA6. All the polyQ spinocerebellar ataxias have a hallmark feature of neuronal aggregations and share many common pathogenic mechanisms, such as mitochondrial dysfunction, impaired proteasomal function, and autophagy impairment. Currently, therapeutic options are limited, with no available treatments that slow or halt disease progression. Here, we discuss the common molecular and clinical presentations of polyQ spinocerebellar ataxias. We will also discuss the promising antisense oligonucleotide therapeutics being developed as treatments for these devastating diseases. With recent advancements and therapeutic approvals of various antisense therapies, it is envisioned that some of the studies reviewed may progress into clinical trials and beyond.

Nucleic Acid Drugs-Current Status, Issues, and Expectations for Exosomes

Simple Summary

Nucleic acid drugs provide novel therapeutic modalities with characteristics that differ from those of small molecules and antibodies. In this review, I focus on the various mechanisms through which nucleic acid drugs act on, the status of their clinical development, and discuss several hurdles that need to be surmounted. In addition, by listing examples of how the progress in exosome biology can lead to the solution of problems in nucleic acid drug therapy, I hope that many more nucleic acid drugs including anticancer drugs will be developed in the future.

Abstract

Nucleic acid drugs are being developed as novel therapeutic modalities. They have great potential to treat human diseases such as cancers, viral infections, and genetic disorders due to unique characteristics that make it possible to approach undruggable targets using classical small molecule or protein/antibody-based biologics. In this review, I describe the advantages, classification, and clinical status of nucleic acid therapeutics. To date, more than 10 products have been launched, and many products have been tested in clinics. To promote the use of nucleic acid therapeutics such as antibodies, several hurdles need to be surmounted. The most important issue is the delivery of nucleic acids and several other challenges have been reported. Recent advanced delivery platforms are lipid nanoparticles and ligand conjugation approaches. With the progress of exosome biology, exosomes are expected to contribute to the solution of various problems associated with nucleic acid drugs.

Delivery of Oligonucleotide Therapeutics: Chemical Modifications, Lipid Nanoparticles, and Extracellular Vesicles

Oligonucleotides (ONs) comprise a rapidly growing class of therapeutics. In recent years, the list of FDA-approved ON therapies has rapidly expanded. ONs are small (15-30 bp) nucleotide-based therapeutics which are capable of targeting DNA and RNA as well as other biomolecules. ONs can be subdivided into several classes based on their chemical modifications and on the mechanisms of their target interactions. Historically, the largest hindrance to the widespread usage of ON therapeutics has been their inability to effectively internalize into cells and escape from endosomes to reach their molecular targets in the cytosol or nucleus. While cell uptake has been improved, "endosomal escape" remains a significant problem. There are a range of approaches to overcome this, and in this review, we focus on three: altering the chemical structure of the ONs, formulating synthetic, lipid-based nanoparticles to encapsulate the ONs, or biologically loading the ONs into extracellular vesicles. This review provides a background to the design and mode of action of existing FDA-approved ONs. It presents the most common ON classifications and chemical modifications from a fundamental scientific perspective and provides a roadmap of the cellular uptake pathways by which ONs are trafficked. Finally, this review delves into each of the above-mentioned approaches to ON delivery, highlighting the scientific principles behind each and covering recent advances.

Muscle Regeneration and RNA: New Perspectives for Ancient Molecules

The ability of the ribonucleic acid (RNA) to self-replicate, combined with a unique cocktail of chemical properties, suggested the existence of an RNA world at the origin of life. Nowadays, this hypothesis is supported by innovative high-throughput and biochemical approaches, which definitively revealed the essential contribution of RNA-mediated mechanisms to the regulation of fundamental processes of life. With the recent development of SARS-CoV-2 mRNA-based vaccines, the potential of RNA as a therapeutic tool has received public attention. Due to its intrinsic single-stranded nature and the ease with which it is synthesized in vitro, RNA indeed represents the most suitable tool for the development of drugs encompassing every type of human pathology. The maximum effectiveness and biochemical versatility is achieved in the guise of non-coding RNAs (ncRNAs), which are emerging as multifaceted regulators of tissue specification and homeostasis. Here, we report examples of coding and ncRNAs involved in muscle regeneration and discuss their potential as therapeutic tools. Small ncRNAs, such as miRNA and siRNA, have been successfully applied in the treatment of several diseases. The use of longer molecules, such as lncRNA and circRNA, is less advanced. However, based on the peculiar properties discussed below, they represent an innovative pool of RNA biomarkers and possible targets of clinical value.

Two Antibody-Guided Lactic-co-Glycolic Acid-Polyethylenimine (LGA-PEI) Nanoparticle Delivery Systems for Therapeutic Nucleic Acids

We previously reported a new polymer, lactic-co-glycolic acid-polyethylenimine (LGA-PEI), as an improved nanoparticle (NP) delivery for therapeutic nucleic acids (TNAs). Here, we further developed two antibody (Ab)-conjugated LGA-PEI NP technologies for active-targeting delivery of TNAs. LGA-PEI was covalently conjugated with a single-chain variable fragment antibody (scFv) against mesothelin (MSLN), a biomarker for pancreatic cancer (PC), or a special Ab fragment crystallizable region-binding peptide (FcBP), which binds to any full Ab (IgG). TNAs used in the current study included tumor suppressor microRNA mimics (miR-198 and miR-520h) and non-coding RNA X-inactive specific transcript (XIST) fragments; green fluorescence protein gene (GFP plasmid DNA) was also used as an example of plasmid DNA. MSLN scFv-LGA-PEI NPs with TNAs significantly improved their binding and internalization in PC cells with high expression of MSLN in vitro and in vivo. Anti-epidermal growth factor receptor (EGFR) monoclonal Ab (Cetuximab) binding to FcBP-LGA-PEI showed active-targeting delivery of TNAs to EGFR-expressing PC cells.

Structure-based design of antisense oligonucleotides that inhibit SARS-CoV-2 replication

Antisense oligonucleotides (ASOs) are an emerging class of drugs that target RNAs. Current ASO designs strictly follow the rule of Watson-Crick base pairing along target sequences. However, RNAs often fold into structures that interfere with ASO hybridization. Here we developed a structure-based ASO design method and applied it to target severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our method makes sure that ASO binding is compatible with target structures in three-dimensional (3D) space by employing structural design templates. These 3D-ASOs recognize the shapes and hydrogen bonding patterns of targets via tertiary interactions, achieving enhanced affinity and specificity. We designed 3D-ASOs that bind to the frameshift stimulation element and transcription regulatory sequence of SARS-CoV-2 and identified lead ASOs that strongly inhibit viral replication in human cells. We further optimized the lead sequences and characterized structure-activity relationship. The 3D-ASO technology helps fight coronavirus disease-2019 and is broadly applicable to ASO drug development.

Deliver the promise: RNAs as a new class of molecular entities for therapy and vaccination

The concepts of developing RNAs as new molecular entities for therapies have arisen again and again since the discoveries of antisense RNAs, direct RNA-protein interactions, functional noncoding RNAs, and RNA-directed gene editing. The feasibility was demonstrated with the development and utilization of synthetic RNA agents to selectively control target gene expression, modulate protein functions or alter the genome to manage diseases. Rather, RNAs are labile to degradation and cannot cross cell membrane barriers, making it hard to develop RNA medications. With the development of viable RNA technologies, such as chemistry and pharmaceutics, eight antisense oligonucleotides (ASOs) (fomivirsen, mipomersen, eteplirsen, nusinersen, inotersen, golodirsen, viltolarsen and casimersen), one aptamer (pegaptanib), and three small interfering RNAs (siRNAs) (patisiran, givosiran and lumasiran) have been approved by the United States Food and Drug Administration (FDA) for therapies, and two mRNA vaccines (BNT162b2 and mRNA-1273) under Emergency Use Authorization for the prevention of COVID-19. Therefore, RNAs have become a great addition to small molecules, proteins/antibodies, and cell-based modalities to improve the public health. In this article, we first summarize the general characteristics of therapeutic RNA agents, including chemistry, common delivery strategies, mechanisms of actions, and safety. By overviewing individual RNA medications and vaccines approved by the FDA and some agents under development, we illustrate the unique compositions and pharmacological actions of RNA products. A new era of RNA research and development will likely lead to commercialization of more RNA agents for medical use, expanding the range of therapeutic targets and increasing the diversity of molecular modalities.

Pharmacological treatment of migraine: Drug classes, mechanisms of action, clinical trials and new treatments

Migraine is the sixth most prevalent disease globally, a major cause of disability, and it imposes an enormous personal and socioeconomic burden. Migraine treatment is often limited by insufficient therapy response, leading to the need for individually adjusted treatment approaches. In this review, we analyse historical and current pharmaceutical development approaches in acute and chronic migraine based on a comprehensive and systematic analysis of Food and Drug Administration (FDA)-approved drugs and those under investigation. The development of migraine therapeutics has significantly intensified during the last 3 years, as shown by our analysis of the trends of drug development between 1970 and 2020. The spectrum of drug targets has expanded considerably, which has been accompanied by an increase in the number of specialised clinical trials. This review highlights the mechanistic implications of FDA-approved and currently investigated drugs and discusses current and future therapeutic options based on identified drug classes of interest.

Aptamers: Cutting edge of cancer therapies

The development of an aptamer-based therapeutic has rapidly progressed following the first two reports in the 1990s, underscoring the advantages of aptamer drugs associated with their unique binding properties. In 2004, the US Food and Drug Administration (FDA) approved the first therapeutic aptamer for the treatment of neovascular age-related macular degeneration, Macugen developed by NeXstar. Since then, eleven aptamers have successfully entered clinical trials for various therapeutic indications. Despite some of the pre-clinical and clinical successes of aptamers as therapeutics, no aptamer has been approved by the FDA for the treatment of cancer. This review highlights the most recent and cutting-edge approaches in the development of aptamers for the treatment of cancer types most refractory to conventional therapies. Herein, we will review (1) the development of aptamers to enhance anti-cancer immunity and as delivery tools for inducing the expression of immunogenic neoantigens; (2) the development of the most promising therapeutic aptamers designed to target the hard-to-treat cancers such as brain tumors; and (3) the development of "carrier" aptamers able to target and penetrate tumors and metastasis, delivering RNA therapeutics to the cytosol and nucleus.

Nanoscale synapse organization and dysfunction in neurodevelopmental disorders

Neurodevelopmental disorders such as those linked to intellectual disabilities or autism spectrum disorder are thought to originate in part from genetic defects in synaptic proteins. Single gene mutations linked to synapse dysfunction can broadly be separated in three categories: disorders of transcriptional regulation, disorders of synaptic signaling and disorders of synaptic scaffolding and structures. The recent developments in super-resolution imaging technologies and their application to synapses have unraveled a complex nanoscale organization of synaptic components. On the one hand, part of receptors, adhesion proteins, ion channels, scaffold elements and the pre-synaptic release machinery are partitioned in subsynaptic nanodomains, and the respective organization of these nanodomains has tremendous impact on synaptic function. For example, pre-synaptic neurotransmitter release sites are partly aligned with nanometer precision to postsynaptic receptor clusters. On the other hand, a large fraction of synaptic components is extremely dynamic and constantly exchanges between synaptic domains and extrasynaptic or intracellular compartments. It is largely the combination of the exquisitely precise nanoscale synaptic organization of synaptic components and their high dynamic that allows the rapid and profound regulation of synaptic function during synaptic plasticity processes that underlie adaptability of brain function, learning and memory. It is very tempting to speculate that genetic defects that lead to neurodevelopmental disorders and target synaptic scaffolds and structures mediate their deleterious impact on brain function through perturbing synapse nanoscale dynamic organization. We discuss here how applying super-resolution imaging methods in models of neurodevelopmental disorders could help in addressing this question.

Small nucleic acids and the path to the clinic for anti-CRISPR

CRISPR-based therapeutics have entered clinical trials but no methods to inhibit Cas enzymes have been demonstrated in a clinical setting. The ability to inhibit CRISPR-based gene editing or gene targeting drugs should be considered a critical step in establishing safety standards for many CRISPR-Cas therapeutics. Inhibitors can act as a failsafe or as an adjuvant to reduce off-target effects in patients. In this review we discuss the need for clinical inhibition of CRISPR-Cas systems and three existing inhibitor technologies: anti-CRISPR (Acr) proteins, small molecule Cas inhibitors, and small nucleic acid-based CRISPR inhibitors, CRISPR SNuBs. Due to their unique properties and the recent successes of other nucleic acid-based therapeutics, CRISPR SNuBs appear poised for clinical application in the near-term.

RNA-Based Therapies for Neurodegenerative Diseases

Most neurodegenerative disorders afflict the ageing population and are often incurable. Therefore, therapeutic development is a major focus in biomedical research. We highlight a new class of drugs, RNA molecules, to control gene expression and decrease neurotoxicity. Their efficacy is shown in pre-clinical studies, clinical trials and in cases of approved patient treatment. As the number of RNA-based strategies increases, so does the promise of targeting more disease-associated genes through a variety of different mechanisms.

An Investigation into the Potential of Targeting Escherichia coli rne mRNA with Locked Nucleic Acid (LNA) Gapmers as an Antibacterial Strategy

The increase in antibacterial resistance is a serious challenge for both the health and defence sectors and there is a need for both novel antibacterial targets and antibacterial strategies. RNA degradation and ribonucleases, such as the essential endoribonuclease RNase E, encoded by the rne gene, are emerging as potential antibacterial targets while antisense oligonucleotides may provide alternative antibacterial strategies. As rne mRNA has not been previously targeted using an antisense approach, we decided to explore using antisense oligonucleotides to target the translation initiation region of the Escherichia coli rne mRNA. Antisense oligonucleotides were rationally designed and were synthesised as locked nucleic acid (LNA) gapmers to enable inhibition of rne mRNA translation through two mechanisms. Either LNA gapmer binding could sterically block translation and/or LNA gapmer binding could facilitate RNase H-mediated cleavage of the rne mRNA. This may prove to be an advantage over the majority of previous antibacterial antisense oligonucleotide approaches which used oligonucleotide chemistries that restrict the mode-of-action of the antisense oligonucleotide to steric blocking of translation. Using an electrophoretic mobility shift assay, we demonstrate that the LNA gapmers bind to the translation initiation region of E. coli rne mRNA. We then use a cell-free transcription translation reporter assay to show that this binding is capable of inhibiting translation. Finally, in an in vitro RNase H cleavage assay, the LNA gapmers facilitate RNase H-mediated mRNA cleavage. Although the challenges of antisense oligonucleotide delivery remain to be addressed, overall, this work lays the foundations for the development of a novel antibacterial strategy targeting rne mRNA with antisense oligonucleotides.

Antisense technology: an overview and prospectus

Antisense technology is now beginning to deliver on its promise to treat diseases by targeting RNA. Nine single-stranded antisense oligonucleotide (ASO) drugs representing four chemical classes, two mechanisms of action and four routes of administration have been approved for commercial use, including the first RNA-targeted drug to be a major commercial success, nusinersen. Although all the approved drugs are for use in patients with rare diseases, many of the ASOs in late- and middle-stage clinical development are intended to treat patients with very common diseases. ASOs in development are showing substantial improvements in potency and performance based on advances in medicinal chemistry, understanding of molecular mechanisms and targeted delivery. Moreover, the ASOs in development include additional mechanisms of action and routes of administration such as aerosol and oral formulations. Here, we describe the key technological advances that have enabled this progress and discuss recent clinical trials that illustrate the impact of these advances on the performance of ASOs in a wide range of therapeutic applications. We also consider strategic issues such as target selection and provide perspectives on the future of the field.

The current landscape of nucleic acid therapeutics

The increasing number of approved nucleic acid therapeutics demonstrates the potential to treat diseases by targeting their genetic blueprints in vivo. Conventional treatments generally induce therapeutic effects that are transient because they target proteins rather than underlying causes. In contrast, nucleic acid therapeutics can achieve long-lasting or even curative effects via gene inhibition, addition, replacement or editing. Their clinical translation, however, depends on delivery technologies that improve stability, facilitate internalization and increase target affinity. Here, we review four platform technologies that have enabled the clinical translation of nucleic acid therapeutics: antisense oligonucleotides, ligand-modified small interfering RNA conjugates, lipid nanoparticles and adeno-associated virus vectors. For each platform, we discuss the current state-of-the-art clinical approaches, explain the rationale behind its development, highlight technological aspects that facilitated clinical translation and provide an example of a clinically relevant genetic drug. In addition, we discuss how these technologies enable the development of cutting-edge genetic drugs, such as tissue-specific nucleic acid bioconjugates, messenger RNA and gene-editing therapeutics.

Fluorescent base analogues in gapmers enable stealth labeling of antisense oligonucleotide therapeutics

To expand the antisense oligonucleotide (ASO) fluorescence labeling toolbox beyond covalent conjugation of external dyes (e.g. ATTO-, Alexa Fluor-, or cyanine dyes), we herein explore fluorescent base analogues (FBAs) as a novel approach to endow fluorescent properties to ASOs. Both cytosine and adenine analogues (tC, tC^O, 2CNqA, and pA) were incorporated into a 16mer ASO sequence with a 3-10-3 cEt-DNA-cEt (cEt = constrained ethyl) gapmer design. In addition to a comprehensive photophysical characterization, we assess the label-induced effects on the gapmers' RNA affinities, RNA-hybridized secondary structures, and knockdown efficiencies. Importantly, we find practically no perturbing effects for gapmers with single FBA incorporations in the biologically critical gap region and, except for pA, the FBAs do not affect the knockdown efficiencies. Incorporating two cytosine FBAs in the gap is equally well tolerated, while two adenine analogues give rise to slightly reduced knockdown efficiencies and what could be perturbed secondary structures. We furthermore show that the FBAs can be used to visualize gapmers inside live cells using fluorescence microscopy and flow cytometry, enabling comparative assessment of their uptake. This altogether shows that FBAs are functional ASO probes that provide a minimally perturbing in-sequence labeling option for this highly relevant drug modality.

LncRNAs as Therapeutic Targets for Autophagy-involved Cardiovascular Diseases: A Review of Molecular Mechanism and T herapy Strategy

BACKGROUND

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. The concept of precision medicine in CVD therapy today requires the incorporation of individual genetic and environmental variability to achieve personalized disease prevention and tailored treatment. Autophagy, an evolutionarily conserved intracellular degradation process, has been demonstrated to be essential in the pathogenesis of various CVDs. Nonetheless, there have been no effective treatments for autophagy- involved CVDs. Long noncoding RNAs (lncRNAs) are noncoding RNA sequences that play versatile roles in autophagy regulation, but much needs to be explored about the relationship between lncRNAs and autophagy-involved CVDs.

SUMMARY

Increasing evidence has shown that lncRNAs contribute considerably to modulate autophagy in the context of CVDs. In this review, we first summarize the current knowledge of the role lncRNAs play in cardiovascular autophagy and autophagy-involved CVDs. Then, recent developments of antisense oligonucleotides (ASOs) designed to target lncRNAs to specifically modulate autophagy in diseased hearts and vessels are discussed, focusing primarily on structure-activity relationships of distinct chemical modifications and relevant clinical trials.

PERSPECTIVE

ASOs are promising in cardiovascular drug innovation. We hope that future studies of lncRNA-based therapies would overcome existing technical limitations and help people who suffer from autophagy-involved CVDs.

Peptides and Antibiotic Therapy: Advances in Design and Delivery

Antibiotic resistance (AMR) is an increasing public health crisis worldwide. This threatens our ability to adequately care for patients with infections due to multi-drug-resistant (MDR) pathogens. As such, there is an urgent need to develop new classes of antimicrobials that are not based on currently utilized antibiotic scaffolds. One promising avenue of antimicrobial research that deserves renewed examination involves the use of peptides. Although antimicrobial peptides (AMPs) have been studied for a number of years, innovations in peptide design and their applications are increasingly making this approach a viable alternative to traditional small-molecule antibiotics. This review will provide updates on two ways in which peptides are being explored as antibiotics. The first topic will focus on novel types of peptides and conjugation methods that are being exploited to act as antibiotics themselves. These direct-acting modified peptides could serve as potentially useful drugs while mitigating many of the known liabilities of AMPs. The second topic relates to the use of peptides as delivery vehicles for other active compounds with antimicrobial activity. Cell-penetrating peptides (CPPs) are peptides designed to carry compounds across cell membranes and are a promising method for delivering a variety of antimicrobial compounds. When conjugated to other compounds, CPPs have been shown to be effective at increasing the uptake of both small- and large-molecular-weight compounds. This includes conjugation to antisense molecules and traditional antibiotics, resulting in increased effectiveness of these antimicrobials. One particular approach utilizes CPPs conjugated to phosphorodiamidate morpholino oligomers (PMOs). PMOs are designed to target particular pathogens in a gene-specific way. They target mRNA and block protein translation. Peptide-conjugated PMOs (PPMOs) allow for efficient delivery into the Gram-negative cytoplasm, and recent updates to their in vitro and in vivo activity are reviewed. This includes recent data to suggest that PPMOs maintain activity in the setting of multi-drug-resistant (MDR) strains, an important finding as it relates to the further development of this therapeutic approach. Other topics include the ability to have activity in the biofilm setting, a finding that likely relates to the peptide portion of the conjugate. Finally, what is known and anticipated related to the development of resistance to these peptides will be discussed.

From Antisense RNA to RNA Modification: Therapeutic Potential of RNA-Based Technologies

Therapeutic oligonucleotides interact with a target RNA via Watson-Crick complementarity, affecting RNA-processing reactions such as mRNA degradation, pre-mRNA splicing, or mRNA translation. Since they were proposed decades ago, several have been approved for clinical use to correct genetic mutations. Three types of mechanisms of action (MoA) have emerged: RNase H-dependent degradation of mRNA directed by short chimeric antisense oligonucleotides (gapmers), correction of splicing defects via splice-modulation oligonucleotides, and interference of gene expression via short interfering RNAs (siRNAs). These antisense-based mechanisms can tackle several genetic disorders in a gene-specific manner, primarily by gene downregulation (gapmers and siRNAs) or splicing defects correction (exon-skipping oligos). Still, the challenge remains for the repair at the single-nucleotide level. The emerging field of epitranscriptomics and RNA modifications shows the enormous possibilities for recoding the transcriptome and repairing genetic mutations with high specificity while harnessing endogenously expressed RNA processing machinery. Some of these techniques have been proposed as alternatives to CRISPR-based technologies, where the exogenous gene-editing machinery needs to be delivered and expressed in the human cells to generate permanent (DNA) changes with unknown consequences. Here, we review the current FDA-approved antisense MoA (emphasizing some enabling technologies that contributed to their success) and three novel modalities based on post-transcriptional RNA modifications with therapeutic potential, including ADAR (Adenosine deaminases acting on RNA)-mediated RNA editing, targeted pseudouridylation, and 2′-O-methylation.

34S-SIL of PCSK9-Active Oligonucleotide as Tools for Accurate Quantification by Mass Spectrometry

Stable isotope labeling (SIL) of active pharmaceutical ingredients (API) is a well-established technique for the accurate quantification of small-molecule drugs. As the scope of active ingredients is expanding into areas of larger molecules, such as oligonucleotides (ONs), the development of new quantification techniques is critical. Herein, we describe the analysis of a ³⁴S-SIL anti-PCSK9 gapmer-type antisense ON. A new method for the quantification of this API in complex biological matrices was developed and applied to mouse, dog, and monkey tissue homogenates, which gave improved accuracy and reproducibility compared with the use of auxiliary ONs as internal standard.

The Evolution of Antisense Oligonucleotide Chemistry-A Personal Journey

Over the last four decades, tremendous progress has been made in use of synthetic oligonucleotides as therapeutics. This has been possible largely by introducing chemical modifications to provide drug like properties to oligonucleotides. In this article I have summarized twists and turns on use of chemical modifications and their road to success and highlight areas of future directions.

RNA therapeutics for cardiovascular disease

PURPOSE OF REVIEW

The development of mRNA vaccines against coronavirus disease 2019 has brought worldwide attention to the transformative potential of RNA-based therapeutics. The latter is essentially biological software that can be rapidly designed and generated, with an extensive catalog of applications. This review aims to highlight the mechanisms of action by which RNA-based drugs can affect specific gene targets and how RNA drugs can be employed to treat cardiovascular disease, with the focus on the therapeutics being evaluated in clinical trials. The recent advances in nanotechnology aiding the translation of such therapies into the clinic are also discussed.

RECENT FINDINGS

There is a growing body of studies demonstrating utility of RNA for targeting previously 'undruggable' pathways involved in development and progression of cardiovascular disease. Some challenges in RNA delivery have been overcome thanks to nanotechnology. There are several RNA-based drugs to treat hypercholesterolemia and myocardial infarction which are currently in clinical trials.

SUMMARY

RNA therapeutics is a rapidly emerging field of biotherapeutics based upon a powerful and versatile platform with a nearly unlimited capacity to address unmet clinical needs. These therapeutics are destined to change the standard of care for many diseases, including cardiovascular disease.

Beyond ribose and phosphate: Selected nucleic acid modifications for structure-function investigations and therapeutic applications

Over the past 25 years, the acceleration of achievements in the development of oligonucleotide-based therapeutics has resulted in numerous new drugs making it to the market for the treatment of various diseases. Oligonucleotides with alterations to their scaffold, prepared with modified nucleosides and solid-phase synthesis, have yielded molecules with interesting biophysical properties that bind to their targets and are tolerated by the cellular machinery to elicit a therapeutic outcome. Structural techniques, such as crystallography, have provided insights to rationalize numerous properties including binding affinity, nuclease stability, and trends observed in the gene silencing. In this review, we discuss the chemistry, biophysical, and structural properties of a number of chemically modified oligonucleotides that have been explored for gene silencing.

The Challenges and Strategies of Antisense Oligonucleotide Drug Delivery

Antisense oligonucleotides (ASOs) are used to selectively inhibit the translation of disease-associated genes via Ribonuclease H (RNaseH)-mediated cleavage or steric hindrance. They are being developed as a novel and promising class of drugs targeting a wide range of diseases. Despite the great potential and numerous ASO drugs in preclinical research and clinical trials, there are many limitations to this technology. In this review we will focus on the challenges of ASO delivery and the strategies adopted to improve their stability in the bloodstream, delivery to target sites, and cellular uptake. Focusing on liposomal delivery, we will specifically describe liposome-incorporated growth factor receptor-bound protein-2 (Grb2) antisense oligodeoxynucleotide BP1001. BP1001 is unique because it is uncharged and is essentially non-toxic, as demonstrated in preclinical and clinical studies. Additionally, its enhanced biodistribution makes it an attractive therapeutic modality for hematologic malignancies as well as solid tumors. A detailed understanding of the obstacles that ASOs face prior to reaching their targets and continued advances in methods to overcome them will allow us to harness ASOs’ full potential in precision medicine.

U7 snRNA: A tool for gene therapy

Most U-rich small nuclear ribonucleoproteins (snRNPs) are complexes that mediate the splicing of pre-mRNAs. U7 snRNP is an exception in that it is not involved in splicing but is a key factor in the unique 3' end processing of replication-dependent histone mRNAs. However, by introducing controlled changes in the U7 snRNA histone binding sequence and in the Sm motif, it can be used as an effective tool for gene therapy. The modified U7 snRNP (U7 Sm OPT) is thus not involved in the processing of replication-dependent histone pre-mRNA but targets splicing by inducing efficient skipping or inclusion of selected exons. U7 Sm OPT is of therapeutic importance in diseases that are an outcome of splicing defects, such as myotonic dystrophy, Duchenne muscular dystrophy, amyotrophic lateral sclerosis, β-thalassemia, HIV-1 infection and spinal muscular atrophy. The benefits of using U7 Sm OPT for gene therapy are its compact size, ability to accumulate in the nucleus without causing any toxic effects in the cells, and no immunoreactivity. The risk of transgene misregulation by using U7 Sm OPT is also low because it is involved in correcting the expression of an endogenous gene controlled by its own regulatory elements. Altogether, using U7 Sm OPT as a tool in gene therapy can ensure lifelong treatment, whereas an oligonucleotide or other drug/compound would require repeated administration. It would thus be strategic to harness these unique properties of U7 snRNP and deploy it as a tool in gene therapy.

Site-Selective Artificial Ribonucleases: Renaissance of Oligonucleotide Conjugates for Irreversible Cleavage of RNA Sequences

RNA-targeting therapeutics require highly efficient sequence-specific devices capable of RNA irreversible degradation in vivo. The most developed methods of sequence-specific RNA cleavage, such as siRNA or antisense oligonucleotides (ASO), are currently based on recruitment of either intracellular multi-protein complexes or enzymes, leaving alternative approaches (e.g., ribozymes and DNAzymes) far behind. Recently, site-selective artificial ribonucleases combining the oligonucleotide recognition motifs (or their structural analogues) and catalytically active groups in a single molecular scaffold have been proven to be a great competitor to siRNA and ASO. Using the most efficient catalytic groups, utilising both metal ion-dependent (Cu(II)-2,9-dimethylphenanthroline) and metal ion-free (Tris(2-aminobenzimidazole)) on the one hand and PNA as an RNA recognising oligonucleotide on the other, allowed site-selective artificial RNases to be created with half-lives of 0.5-1 h. Artificial RNases based on the catalytic peptide [(ArgLeu)₂Gly]₂ were able to take progress a step further by demonstrating an ability to cleave miRNA-21 in tumour cells and provide a significant reduction of tumour growth in mice.

The Limitless Future of RNA Therapeutics

Recent advances in the generation, purification and cellular delivery of RNA have enabled development of RNA-based therapeutics for a broad array of applications. RNA therapeutics comprise a rapidly expanding category of drugs that will change the standard of care for many diseases and actualize personalized medicine. These drugs are cost effective, relatively simple to manufacture, and can target previously undruggable pathways. It is a disruptive therapeutic technology, as small biotech startups, as well as academic groups, can rapidly develop new and personalized RNA constructs. In this review we discuss general concepts of different classes of RNA-based therapeutics, including antisense oligonucleotides, aptamers, small interfering RNAs, microRNAs, and messenger RNA. Furthermore, we provide an overview of the RNA-based therapies that are currently being evaluated in clinical trials or have already received regulatory approval. The challenges and advantages associated with use of RNA-based drugs are also discussed along with various approaches for RNA delivery. In addition, we introduce a new concept of hospital-based RNA therapeutics and share our experience with establishing such a platform at Houston Methodist Hospital.

Development of Antisense Oligonucleotide Gapmers for the Treatment of Huntington's Disease

The field of neuromuscular and neurodegenerative diseases has been revolutionized by the advent of genetics and molecular biology to evaluate the pathogenicity, thereby providing considerable insight to develop suitable therapies. With the successful translation of antisense oligonucleotides (AOs) from in vitro into animal models and clinical practice, modifications are being continuously made to the AOs to improve the pharmacokinetics and pharmacodynamics. In order to activate RNase H-mediated cleavage of the target mRNA, as well as to increase the binding affinity and specificity, gapmer AOs are designed to have a phosphorothioate (PS) backbone flanked with the modified AOs on both sides. Antisense-mediated knockdown of mutated huntingtin is a promising therapeutic approach for Huntington's disease (HD), a devastating disorder affecting the motor and cognitive abilities. This chapter focuses on the modified gapmer AOs for the treatment of HD.