Enhancing siRNA efficacy in vivo with extended nucleic acid backbones.

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.

Quantifying the activity profile of ASO and siRNA conjugates in glioblastoma xenograft tumors in vivo.

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.

Silencing Apoe with divalent-siRNAs improves amyloid burden and activates immune response pathways in Alzheimer's disease.

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.

A combinatorial approach for achieving CNS-selective RNAi.

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.

Extended Nucleic Acid (exNA): A Novel, Biologically Compatible Backbone that Significantly Enhances Oligonucleotide Efficacy in vivo.

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.

Di-valent siRNA-mediated silencing of MSH3 blocks somatic repeat expansion in mouse models of Huntington's disease.

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.

Divalent siRNAs are bioavailable in the lung and efficiently block SARS-CoV-2 infection.

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.

Mutant huntingtin messenger RNA forms neuronal nuclear clusters in rodent and human brains.

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 () gene-have primarily focused on toxic protein gain-of-function as the primary disease-causing feature. To date, mutant mRNA has not been identified as an hallmark of Huntington's disease.

PK-modifying anchors significantly alter clearance kinetics, tissue distribution, and efficacy of therapeutics siRNAs.

Effective systemic delivery of small interfering RNAs (siRNAs) to tissues other than liver remains a challenge. siRNAs are small (∼15 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.

Interventional oncology update.

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.

Delivering siRNA Compounds During HOPE to Modulate Organ Function: A Proof-of-concept Study in a Rat Liver Transplant Model.

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.

Comparative route of administration studies using therapeutic siRNAs show widespread gene modulation in Dorset sheep.

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.

Should Australian states and territories have designated COVID hospitals in low community transmission? Case study for Western Australia.

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.

Cell Type Impacts Accessibility of mRNA to Silencing by RNA Interference.

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.

A divalent siRNA chemical scaffold for potent and sustained modulation of gene expression throughout the central nervous system.

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.

Nuclear Localization of Huntingtin mRNA Is Specific to Cells of Neuronal Origin.

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]).

Improving access to primary care for Aboriginal babies in Western Australia: study protocol for a randomized controlled trial.

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.

Impact of Ipsilateral Blood Draws, Injections, Blood Pressure Measurements, and Air Travel on the Risk of Lymphedema for Patients Treated for Breast Cancer.

Purpose: The goal of this study was to investigate the association between blood draws, injections, blood pressure readings, trauma, cellulitis in the at-risk arm, and air travel and increases in arm volume in a cohort of patients treated for breast cancer and screened for lymphedema.

Patients And Methods: Between 2005 and 2014, patients undergoing treatment of breast cancer at our institution were screened prospectively for lymphedema. Bilateral arm volume measurements were performed preoperatively and postoperatively using a Perometer.

A Novel Parent Questionnaire for the Detection of Seizures in Children.

Background: We developed a seizure questionnaire that could be administered by a trained research assistant in a two-step process, approximating the clinical diagnostic process of a pediatric epileptologist. This questionnaire was designed to study seizure prevalence in a research population of 10-year-old children at risk for epilepsy.

Methods: English-speaking parents of children 6 months to 12 years old were recruited from the pediatric neurology clinics at Boston Medical Center and interviewed using a computerized questionnaire.

Establishing and sustaining a prospective screening program for breast cancer-related lymphedema at the massachusetts general hospital: lessons learned.

There has been an increasing call to prospectively screen patients with breast cancer for the development of breast cancer-related lymphedema (BCRL) following their breast cancer treatment. While the components of a prospective screening program have been published, some centers struggle with how to initiate, establish, and sustain a screening program of their own. The intent of this manuscript is to share our experience and struggles in establishing a prospective surveillance program within the infrastructure of our institution.

Impact of adjuvant taxane-based chemotherapy on development of breast cancer-related lymphedema: results from a large prospective cohort.

Taxane-based chemotherapy for the treatment of breast cancer is associated with fluid retention in the extremities; however, its association with development of breast cancer-related lymphedema is unclear. We sought to determine if adjuvant taxane-based chemotherapy increased risk of lymphedema or mild swelling of the upper extremity. 1121 patients with unilateral breast cancer were prospectively screened for lymphedema with perometer measurements.

The impact of breast cancer-related lymphedema on the ability to perform upper extremity activities of daily living.

We sought to assess the association of breast cancer-related lymphedema (BCRL) with the ability to perform upper extremity activities of daily living (ADL) in our patient population. 324 breast cancer patients who had received treatment for unilateral breast cancer at our institution between 2005 and 2014 were prospectively screened for lymphedema. Bilateral arm measurements were performed pre-operatively and during post-operative follow-up using a Perometer.