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Therapeutic small interfering RNA (siRNA) requires sugar and backbone modifications to inhibit nuclease degradation. However, metabolic stabilization by phosphorothioate (PS), the only backbone chemistry used clinically, may be insufficient for targeting extrahepatic tissues. To improve oligonucleotide stabilization, we report the discovery, synthesis and characterization of extended nucleic acid (exNA) consisting of a methylene insertion between the 5'-C and 5'-OH of a nucleoside. exNA incorporation is compatible with common oligonucleotide synthetic protocols and the PS backbone, provides stabilization against 3' and 5' exonucleases and is tolerated at multiple oligonucleotide positions. A combined exNA-PS backbone enhances resistance to 3' exonuclease by ~32-fold over the conventional PS backbone and by >1,000-fold over the natural phosphodiester backbone, improving tissue exposure, tissue accumulation and efficacy in mice, both systemically and in the brain. The improved efficacy and durability imparted by exNA may enable therapeutic interventions in extrahepatic tissues, both with siRNA and with other oligonucleotides such as CRISPR guide RNA, antisense oligonucleotides, mRNA and tRNA.
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Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition, with 20% of familial and 2-3% of sporadic cases linked to mutations in the cytosolic superoxide dismutase (SOD1) gene. Mutant SOD1 protein is toxic to motor neurons, making SOD1 gene lowering a promising approach, supported by preclinical data and the 2023 FDA approval of the GapmeR ASO targeting SOD1, tofersen. Despite the approval of an ASO and the optimism it brings to the field, the pharmacodynamics and pharmacokinetics of therapeutic SOD1 modulation can be improved. Here, we developed a chemically stabilized divalent siRNA scaffold (di-siRNA) that effectively suppresses SOD1 expression in vitro and in vivo. With optimized chemical modification, it achieves remarkable CNS tissue permeation and SOD1 silencing in vivo. Administered intraventricularly, di-siRNASOD1 extended survival in SOD1-G93A ALS mice, surpassing survival previously seen in these mice by ASO modalities, slowed disease progression, and prevented ALS neuropathology. These properties offer an improved therapeutic strategy for SOD1-mediated ALS and may extend to other dominantly inherited neurological disorders.
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Glioblastoma multiforme is a universally lethal brain tumor that largely resists current surgical and drug interventions. Despite important advancements in understanding GBM biology, the invasiveness and heterogeneity of these tumors has made it challenging to develop effective therapies. Therapeutic oligonucleotides-antisense oligonucleotides and small-interfering RNAs-are chemically modified nucleic acids that can silence gene expression in the brain. However, activity of these oligonucleotides in brain tumors remains inadequately characterized. In this study, we developed a quantitative method to differentiate oligonucleotide-induced gene silencing in orthotopic GBM xenografts from gene silencing in normal brain tissue, and used this method to test the differential silencing activity of a chemically diverse panel of oligonucleotides. We show that oligonucleotides chemically optimized for pharmacological activity in normal brain tissue do not show consistent activity in GBM xenografts. We then survey multiple advanced oligonucleotide chemistries for their activity in GBM xenografts. Attaching lipid conjugates to oligonucleotides improves silencing in GBM cells across several different lipid classes. Highly hydrophobic lipid conjugates cholesterol and docosanoic acid enhance silencing but at the cost of higher neurotoxicity. Moderately hydrophobic, unsaturated fatty acid and amphiphilic lipid conjugates still improve activity without compromising safety. These oligonucleotide conjugates show promise for treating glioblastoma.
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Neoplasias Encefálicas , Glioblastoma , Oligonucleotídeos Antissenso , RNA Interferente Pequeno , Ensaios Antitumorais Modelo de Xenoenxerto , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/patologia , Animais , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/química , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/uso terapêutico , Humanos , Camundongos , Linhagem Celular Tumoral , Neoplasias Encefálicas/genética , Oligonucleotídeos Antissenso/química , Oligonucleotídeos Antissenso/uso terapêutico , Inativação Gênica , Camundongos NusRESUMO
INTRODUCTION: The most significant genetic risk factor for late-onset Alzheimer's disease (AD) is APOE4, with evidence for gain- and loss-of-function mechanisms. A clinical need remains for therapeutically relevant tools that potently modulate APOE expression. METHODS: We optimized small interfering RNAs (di-siRNA, GalNAc) to potently silence brain or liver Apoe and evaluated the impact of each pool of Apoe on pathology. RESULTS: In adult 5xFAD mice, siRNAs targeting CNS Apoe efficiently silenced Apoe expression and reduced amyloid burden without affecting systemic cholesterol, confirming that potent silencing of brain Apoe is sufficient to slow disease progression. Mechanistically, silencing Apoe reduced APOE-rich amyloid cores and activated immune system responses. DISCUSSION: These results establish siRNA-based modulation of Apoe as a viable therapeutic approach, highlight immune activation as a key pathway affected by Apoe modulation, and provide the technology to further evaluate the impact of APOE silencing on neurodegeneration.
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Doença de Alzheimer , Camundongos , Animais , Doença de Alzheimer/patologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Apolipoproteínas E/genética , Apolipoproteínas E/metabolismo , Apolipoproteína E4/genética , Amiloide/metabolismo , Encéfalo/patologia , Proteínas Amiloidogênicas/metabolismo , Peptídeos beta-Amiloides/metabolismo , Camundongos TransgênicosRESUMO
RNA interference (RNAi) is an endogenous process that can be harnessed using chemically modified small interfering RNAs (siRNAs) to potently modulate gene expression in many tissues. The route of administration and chemical architecture are the primary drivers of oligonucleotide tissue distribution, including siRNAs. Independently of the nature and type, oligonucleotides are eliminated from the body through clearance tissues, where their unintended accumulation may result in undesired gene modulation. Divalent siRNAs (di-siRNAs) administered into the CSF induce robust gene silencing throughout the central nervous system (CNS). Upon clearance from the CSF, they are mainly filtered by the kidneys and liver, with the most functionally significant accumulation occurring in the liver. siRNA- and miRNA-induced silencing can be blocked through substrate inhibition using single-stranded, stabilized oligonucleotides called antagomirs or anti-siRNAs. Using APOE as a model target, we show that undesired di-siRNA-induced silencing in the liver can be mitigated through administration of liver targeting GalNAc-conjugated anti-siRNAs, without impacting CNS activity. Blocking unwanted hepatic APOE silencing achieves fully CNS-selective silencing, essential for potential clinical translation. While we focus on CNS/liver selectivity, coadministration of differentially targeting siRNA and anti-siRNAs can be adapted as a strategy to achieve tissue selectivity in different organ combinations.
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Sistema Nervoso Central , Interferência de RNA , Animais , Humanos , Masculino , Camundongos , Acetilgalactosamina/química , Antagomirs/genética , Antagomirs/metabolismo , Apolipoproteínas E/genética , Sistema Nervoso Central/metabolismo , Inativação Gênica , Fígado/metabolismo , Camundongos Endogâmicos C57BL , MicroRNAs/genética , MicroRNAs/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismoAssuntos
Esclerose Lateral Amiotrófica , Oligonucleotídeos Antissenso , Humanos , Esclerose Lateral Amiotrófica/tratamento farmacológico , Esclerose Lateral Amiotrófica/genética , Mutação , Oligonucleotídeos Antissenso/uso terapêutico , Superóxido Dismutase-1/genética , Estados Unidos , United States Food and Drug Administration , Aprovação de Drogas , Determinação de Ponto FinalRESUMO
Metabolic stabilization of therapeutic oligonucleotides requires both sugar and backbone modifications, where phosphorothioate (PS) is the only backbone chemistry used in the clinic. Here, we describe the discovery, synthesis, and characterization of a novel biologically compatible backbone, extended nucleic acid (exNA). Upon exNA precursor scale up, exNA incorporation is fully compatible with common nucleic acid synthetic protocols. The novel backbone is orthogonal to PS and shows profound stabilization against 3'- and 5'-exonucleases. Using small interfering RNAs (siRNAs) as an example, we show exNA is tolerated at most nucleotide positions and profoundly improves in vivo efficacy. A combined exNA-PS backbone enhances siRNA resistance to serum 3'-exonuclease by ~ 32-fold over PS backbone and > 1000-fold over the natural phosphodiester backbone, thereby enhancing tissue exposure (~ 6-fold), tissues accumulation (4- to 20-fold), and potency both systemically and in brain. The improved potency and durability imparted by exNA opens more tissues and indications to oligonucleotide-driven therapeutic interventions.
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Huntington's disease (HD) is a severe neurodegenerative disorder caused by the expansion of the CAG trinucleotide repeat tract in the huntingtin gene. Inheritance of expanded CAG repeats is needed for HD manifestation, but further somatic expansion of the repeat tract in non-dividing cells, particularly striatal neurons, hastens disease onset. Called somatic repeat expansion, this process is mediated by the mismatch repair (MMR) pathway. Among MMR components identified as modifiers of HD onset, MutS homolog 3 (MSH3) has emerged as a potentially safe and effective target for therapeutic intervention. Here, we identify a fully chemically modified short interfering RNA (siRNA) that robustly silences Msh3 in vitro and in vivo. When synthesized in a di-valent scaffold, siRNA-mediated silencing of Msh3 effectively blocked CAG-repeat expansion in the striatum of two HD mouse models without affecting tumor-associated microsatellite instability or mRNA expression of other MMR genes. Our findings establish a promising treatment approach for patients with HD and other repeat expansion diseases.
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Doença de Huntington , Proteína 3 Homóloga a MutS , Expansão das Repetições de Trinucleotídeos , Animais , Camundongos , Corpo Estriado/metabolismo , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Doença de Huntington/genética , Doença de Huntington/terapia , Doença de Huntington/metabolismo , Neostriado/metabolismo , RNA de Cadeia Dupla , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Expansão das Repetições de Trinucleotídeos/genética , Proteína 3 Homóloga a MutS/genéticaRESUMO
The continuous evolution of SARS-CoV-2 variants complicates efforts to combat the ongoing pandemic, underscoring the need for a dynamic platform for the rapid development of pan-viral variant therapeutics. Oligonucleotide therapeutics are enhancing the treatment of numerous diseases with unprecedented potency, duration of effect, and safety. Through the systematic screening of hundreds of oligonucleotide sequences, we identified fully chemically stabilized siRNAs and ASOs that target regions of the SARS-CoV-2 genome conserved in all variants of concern, including delta and omicron. We successively evaluated candidates in cellular reporter assays, followed by viral inhibition in cell culture, with eventual testing of leads for in vivo antiviral activity in the lung. Previous attempts to deliver therapeutic oligonucleotides to the lung have met with only modest success. Here, we report the development of a platform for identifying and generating potent, chemically modified multimeric siRNAs bioavailable in the lung after local intranasal and intratracheal delivery. The optimized divalent siRNAs showed robust antiviral activity in human cells and mouse models of SARS-CoV-2 infection and represent a new paradigm for antiviral therapeutic development for current and future pandemics.
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COVID-19 , Humanos , Animais , Camundongos , RNA Interferente Pequeno/genética , COVID-19/terapia , SARS-CoV-2/genética , Antivirais/farmacologia , Antivirais/uso terapêutico , Oligonucleotídeos , PulmãoRESUMO
Mutant messenger RNA (mRNA) and protein contribute to the clinical manifestation of many repeat-associated neurological disorders, with the presence of nuclear RNA clusters being a common pathological feature. Yet, investigations into Huntington's disease-caused by a CAG repeat expansion in exon 1 of the huntingtin (HTT) gene-have primarily focused on toxic protein gain-of-function as the primary disease-causing feature. To date, mutant HTT mRNA has not been identified as an in vivo hallmark of Huntington's disease. Here, we report that, in two Huntington's disease mouse models (YAC128 and BACHD-97Q-ΔN17), mutant HTT mRNA is retained in the nucleus. Widespread formation of large mRNA clusters (â¼0.6-5â µm3) occurred in 50-75% of striatal and cortical neurons. Cluster formation was independent of age and driven by expanded repeats. Clusters associate with chromosomal transcriptional sites and quantitatively co-localize with the aberrantly processed N-terminal exon 1-intron 1 mRNA isoform, HTT1a. HTT1a mRNA clusters are observed in a subset of neurons from human Huntington's disease post-mortem brain and are likely caused by somatic expansion of repeats. In YAC128 mice, clusters, but not individual HTT mRNA, are resistant to antisense oligonucleotide treatment. Our findings identify mutant HTT/HTT1a mRNA clustering as an early, robust molecular signature of Huntington's disease, providing in vivo evidence that Huntington's disease is a repeat expansion disease with mRNA involvement.
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Effective systemic delivery of small interfering RNAs (siRNAs) to tissues other than liver remains a challenge. siRNAs are small (â¼15 kDa) and therefore rapidly cleared by the kidneys, resulting in limited blood residence times and tissue exposure. Current strategies to improve the unfavorable pharmacokinetic (PK) properties of siRNAs rely on enhancing binding to serum proteins through extensive phosphorothioate modifications or by conjugation of targeting ligands. Here, we describe an alternative strategy for enhancing blood and tissue PK based on dynamic modulation of the overall size of the siRNA. We engineered a high-affinity universal oligonucleotide anchor conjugated to a high-molecular-weight moiety, which binds to the 3' end of the guide strand of an asymmetric siRNA. Data showed a strong correlation between the size of the PK-modifying anchor and clearance kinetics. Large 40-kDa PK-modifying anchors reduced renal clearance by â¼23-fold and improved tissue exposure area under the curve (AUC) by â¼26-fold, resulting in increased extrahepatic tissue retention (â¼3- to 5-fold). Furthermore, PK-modifying oligonucleotide anchors allowed for straightforward and versatile modulation of blood residence times and biodistribution of a panel of chemically distinct ligands. The effects were more pronounced for conjugates with low lipophilicity (e.g., N-Acetylgalactosamine [GalNAc]), where significant improvement in uptake by hepatocytes and dose-dependent silencing in the liver was observed.
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Interventional Oncology (IO) is a subspecialty field of Interventional Radiology bridging between diagnostic radiology and the clinical oncology team, addressing the diagnosis and treatment of cancer. There have been many exciting advancements in the field of IO in recent years; far too many to cover in a single paper. To give each topic sufficient attention, we have limited the scope of this review article to four topics which we feel have the potential to drastically change how cancer is treated managed in the immediate future.
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BACKGROUND: Apoptosis contributes to the severity of ischemia-reperfusion injury (IRI), limiting the use of extended criteria donors in liver transplantation (LT). Machine perfusion has been proposed as a platform to administer specific therapies to improve graft function. Alternatively, the inhibition of genes associated with apoptosis during machine perfusion could alleviate IRI post-LT. The aim of the study was to investigate whether inhibition of an apoptosis-associated gene (FAS) using a small interfering RNA (siRNA) approach could alleviate IRI in a rat LT model. METHODS: In 2 different experimental protocols, FASsiRNA (500 µg) was administered to rat donors 2 h before organ procurement, followed by 22 h of static cold storage, (SCS) or was added to the perfusate during 1 h of ex situ hypothermic oxygenated perfusion (HOPE) to livers previously preserved for 4 h in SCS. RESULTS: Transaminase levels were significantly lower in the SCS-FASsiRNA group at 24 h post-LT. Proinflammatory cytokines (interleukin-2, C-X-C motif chemokine 10, tumor necrosis factor alpha, and interferon gamma) were significantly decreased in the SCS-FASsiRNA group, whereas the interleukin-10 anti-inflammatory cytokine was significantly increased in the HOPE-FASsiRNA group. Liver absorption of FASsiRNA after HOPE session was demonstrated by confocal microscopy; however, no statistically significant differences on the apoptotic index, necrosis levels, and FAS protein transcription between treated and untreated groups were observed. CONCLUSIONS: FAS inhibition through siRNA therapy decreases the severity of IRI after LT in a SCS protocol; however the association of siRNA therapy with a HOPE perfusion model is very challenging. Future studies using better designed siRNA compounds and appropriate doses are required to prove the siRNA therapy effectiveness during liver HOPE liver perfusion.
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Transplante de Fígado , Traumatismo por Reperfusão , Obtenção de Tecidos e Órgãos , Animais , Humanos , Fígado/patologia , Transplante de Fígado/efeitos adversos , Transplante de Fígado/métodos , Preservação de Órgãos/métodos , Perfusão/métodos , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Ratos , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/prevenção & controleRESUMO
siRNAs comprise a class of drugs that can be programmed to silence any target gene. Chemical engineering efforts resulted in development of divalent siRNAs (di-siRNAs), which support robust and long-term efficacy in rodent and nonhuman primate brains upon direct cerebrospinal fluid (CSF) administration. Oligonucleotide distribution in the CNS is nonuniform, limiting clinical applications. The contribution of CSF infusion placement and dosing regimen on relative accumulation, specifically in the context of large animals, is not well characterized. To our knowledge, we report the first systemic, comparative study investigating the effects of 3 routes of administration - intrastriatal (i.s.), i.c.v., and intrathecal catheter to the cisterna magna (ITC) - and 2 dosing regimens - single and repetitive via an implanted reservoir device - on di-siRNA distribution and accumulation in the CNS of Dorset sheep. CSF injections (i.c.v. and ITC) resulted in similar distribution and accumulation across brain regions. Repeated dosing increased homogeneity, with greater relative deep brain accumulation. Conversely, i.s. administration supported region-specific delivery. These results suggest that dosing regimen, not CSF infusion placement, may equalize siRNA accumulation and efficacy throughout the brain. These findings inform the planning and execution of preclinical and clinical studies using siRNA therapeutics in the CNS.
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Terapia Genética/métodos , RNA Interferente Pequeno/administração & dosagem , Animais , Vias de Administração de Medicamentos , OvinosRESUMO
This case study describes the process of selecting the most appropriate state-wide hospital system to manage COVID-19 cases in a setting of low community transmission of COVID-19 infection. A rapid review of the literature was conducted of the advantages and disadvantages of having designated COVID hospitals. This led to three different options being presented for discussion. Following consultation, the option chosen was for all hospital facilities to remain prepared to care for COVID-19 patients where they present rather than having specified designated hospitals because this was considered the most practical option currently.
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Infecções por Coronavirus/terapia , Transmissão de Doença Infecciosa/estatística & dados numéricos , Hospitais Comunitários/organização & administração , Pandemias/prevenção & controle , Pneumonia Viral/terapia , Austrália , Betacoronavirus/patogenicidade , COVID-19 , Humanos , SARS-CoV-2 , Austrália OcidentalRESUMO
RNA interference (RNAi) is a potent mechanism that silences mRNA and protein expression in all cells and tissue types. RNAi is known to exert many of its functional effects in the cytoplasm, and thus, the cellular localization of target mRNA may impact observed potency. Here, we demonstrate that cell identity has a profound impact on accessibility of apolipoprotein E (ApoE) mRNA to RNAi. We show that, whereas both neuronal and glial cell lines express detectable ApoE mRNA, in neuronal cells, ApoE mRNA is not targetable by RNAi. Screening of a panel of thirty-five chemically modified small interfering RNAs (siRNAs) did not produce a single hit in a neuronal cell line, whereas up to fifteen compounds showed strong efficacy in glial cells. Further investigation of the cellular localization of ApoE mRNA demonstrates that ApoE mRNA is partially spliced and preferentially localized to the nucleus (â¼80%) in neuronal cells, whereas more than 90% of ApoE mRNA is cytoplasmic in glial cells. Such an inconsistency in intracellular localization and splicing might provide an explanation for functional differences in RNAi compounds. Thus, cellular origin might have an impact on accessibility of mRNA to RNAi and should be taken into account during the screening process.
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Sustained silencing of gene expression throughout the brain using small interfering RNAs (siRNAs) has not been achieved. Here we describe an siRNA architecture, divalent siRNA (di-siRNA), that supports potent, sustained gene silencing in the central nervous system (CNS) of mice and nonhuman primates following a single injection into the cerebrospinal fluid. Di-siRNAs are composed of two fully chemically modified, phosphorothioate-containing siRNAs connected by a linker. In mice, di-siRNAs induced the potent silencing of huntingtin, the causative gene in Huntington's disease, reducing messenger RNA and protein throughout the brain. Silencing persisted for at least 6 months, with the degree of gene silencing correlating to levels of guide strand tissue accumulation. In cynomolgus macaques, a bolus injection of di-siRNA showed substantial distribution and robust silencing throughout the brain and spinal cord without detectable toxicity and with minimal off-target effects. This siRNA design may enable RNA interference-based gene silencing in the CNS for the treatment of neurological disorders.
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Sistema Nervoso Central/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Proteína Huntingtina/metabolismo , RNA Interferente Pequeno/administração & dosagem , RNA Interferente Pequeno/química , Animais , Proteína Huntingtina/genética , Camundongos , Mutação , RNA Mensageiro , RNA Interferente Pequeno/metabolismoRESUMO
Huntington's disease (HD) is a monogenic neurodegenerative disorder representing an ideal candidate for gene silencing with oligonucleotide therapeutics (i.e., antisense oligonucleotides [ASOs] and small interfering RNAs [siRNAs]). Using an ultra-sensitive branched fluorescence in situ hybridization (FISH) method, we show that â¼50% of wild-type HTT mRNA localizes to the nucleus and that its nuclear localization is observed only in neuronal cells. In mouse brain sections, we detect Htt mRNA predominantly in neurons, with a wide range of Htt foci observed per cell. We further show that siRNAs and ASOs efficiently eliminate cytoplasmic HTT mRNA and HTT protein, but only ASOs induce a partial but significant reduction of nuclear HTT mRNA. We speculate that, like other mRNAs, HTT mRNA subcellular localization might play a role in important neuronal regulatory mechanisms.
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Doença de Huntington/metabolismo , Neurônios/citologia , Neurônios/metabolismo , RNA Mensageiro/metabolismo , Animais , Núcleo Celular/metabolismo , Células Cultivadas , Feminino , Inativação Gênica , Células HeLa , Humanos , Hibridização in Situ Fluorescente , Camundongos , Oligonucleotídeos Antissenso/genética , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/fisiologia , Expansão das Repetições de Trinucleotídeos/genéticaRESUMO
BACKGROUND: Despite a decade of substantial investments in programs to improve access to primary care for Aboriginal mothers and infants, more than 50% of Western Australian Aboriginal babies are still not receiving primary and preventative care in the early months of life. Western Australian hospitals now input birth data into the Western Australian electronic clinical management system within 48 hours of birth. However, difficulties have arisen in ensuring that the appropriate primary care providers receive birth notification and clinical information by the time babies are discharged from the hospital. No consistent process exists to ensure that choices about primary care are discussed with Aboriginal families. METHODS/DESIGN: We will undertake a population-based, stepped wedge, cluster randomized controlled trial of an enhanced model of early infant primary care. The intervention is targeted support and care coordination for Aboriginal families with new babies starting as soon as possible during the antenatal period or after birth. Dedicated health professionals and research staff will consult with families about the families' healthcare needs, provide information about healthcare in the first 3 months of life, offer assistance with birth and Medicare forms, consult with families about their choice for primary care provider, offer to notify the chosen primary care provider about the baby's health needs, and offer assistance with healthcare coordination at the time of discharge from the hospital. We will evaluate this model of care using a rigorous stepped wedge approach. Our primary outcome measure is a reduced hospitalization rate in infants younger than 3 months of age. Secondary outcome measures include completed Aboriginal and Torres Strait Islander child health screening assessments, immunization coverage, and satisfaction of the families about early infant primary care. We will also assess the cost effectiveness of the model of care. DISCUSSION: This study will be conducted over a 4-year period in partnership with birthing hospitals and primary care providers including Western Australian Aboriginal Community Controlled Health Services and the new Primary Health Networks. The results of our trial will be used to develop improved primary care models and to improve health outcomes for all Aboriginal infants. These are vital steps toward more equitable health service delivery for the Aboriginal and Torres Strait Islander children in Australia. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry Registration number: ACTRN12615000976583 Date registered: 17 September 2015.