Safety evaluation of 2'-deoxy-2'-fluoro nucleotides in GalNAc-siRNA conjugates.

For oligonucleotide therapeutics, chemical modifications of the sugar-phosphate backbone are frequently used to confer drug-like properties. Because 2'-deoxy-2'-fluoro (2'-F) nucleotides are not known to occur naturally, their safety profile was assessed when used in revusiran and ALN-TTRSC02, two short interfering RNAs (siRNAs), of the same sequence but different chemical modification pattern and metabolic stability, conjugated to an N-acetylgalactosamine (GalNAc) ligand for targeted delivery to hepatocytes. Exposure to 2'-F-monomer metabolites was low and transient in rats and humans. In vitro, 2'-F-nucleoside 5'-triphosphates were neither inhibitors nor preferred substrates for human polymerases, and no obligate or non-obligate chain termination was observed. Modest effects on cell viability and mitochondrial DNA were observed in vitro in a subset of cell types at high concentrations of 2'-F-nucleosides, typically not attained in vivo. No apparent functional impact on mitochondria and no significant accumulation of 2'-F-monomers were observed after weekly administration of two GalNAc-siRNA conjugates in rats for ∼2 years. Taken together, the results support the conclusion that 2'-F nucleotides can be safely applied for the design of metabolically stabilized therapeutic GalNAc-siRNAs with favorable potency and prolonged duration of activity allowing for low dose and infrequent dosing.

Incidental Ultrastructural Findings in the Sural Nerve and Dorsal Root Ganglion of Aged Control Sprague Dawley Rats in a Nonclinical Carcinogenicity Study.

Xenobiotic-induced peripheral nerve damage is a growing concern. Identifying relative risks that a new drug may cause peripheral nerve injury over long periods of administration is gathering importance in the evaluation of animal models. Separating out age-related changes in peripheral nerves of rats caused by compression injury from drug-induced effects has been difficult. Biopsy of the sural nerve is utilized in humans for investigations of peripheral neuropathy, because it is largely removed from the effects of nerve compression. This study used transmission electron microscopy to identify incidental findings in the sural nerves and dorsal root ganglia of aged control rats over time. The goal was to establish a baseline understanding of the range of possible changes that could be noted in controls compared to rats treated with any new investigative drug. In this evaluation, most sural nerve fibers from aged control rats had few ultrastructural abnormalities of pathologic significance. However, glycogenosomes, polyglucosan bodies, swollen mitochondria, autolysosomes, split myelin, Schwann cell processes, and endoneural macrophages with phagocytosed debris (considered an indication of ongoing degenerative changes) were occasionally noted.

Measuring Adverse Childhood Experiences: Comparing Individual, Composite, Score-based and Latent Profile-based Scoring Schemas Among Gay, Bisexual, and Other Men Who Have Sex with Men.

Adverse childhood experiences (ACEs; e.g., neglect, sexual abuse) among gay, bisexual, and other men who have sex with men (GBM) may not occur in isolation, but may be connected and occur in clusters. Most studies have measured ACEs individually, hierarchically, additively, or in a binary fashion (presence or absence of ACEs), rather than treating them as connected and clustered. This study examined these competing approaches of scoring ACEs and their relative power at predicting health outcomes. We examined abuse (sexual, physical, and emotional) and neglect (physical and emotional) experiences among a non-random sample of 470 Toronto GBM using the Childhood Trauma Questionnaire Short Form subscales. We compared five scoring schemas: (1) five individual scores for each form of maltreatment; (2) a composite score summing all of the maltreatment scores; (3) a hierarchical regression model with sexual abuse entered first then followed by physical abuse, emotional abuse, physical neglect, and emotional neglect; (4) a severity-based categorization; and (5) a latent profile-based categorization. Experiences of abuse and neglect were not uncommon (22-33%) and some participants experienced multiple forms of abuse and neglect (r = .33-.65, df = 464-467; p < .001; shared variance, r2 = 11-43%). Results show the dose-response effects of ACEs and highlight the importance of examining ACEs in clusters rather than individually. Latent profile analysis identified GBM who experienced multiple and frequent ACEs, and also identified the types of ACEs they experienced: crucial information that was obscured in score-based or severity-based approaches.

The Nonclinical Safety Profile of GalNAc-conjugated RNAi Therapeutics in Subacute Studies.

Short interfering RNAs (siRNAs) and antisense oligonucleotides (ASOs) are the most clinically advanced oligonucleotide-based platforms. A number of N-acetylgalactosamine (GalNAc)-conjugated siRNAs (GalNAc-siRNAs), also referred to as RNA interference (RNAi) therapeutics, are currently in various stages of development, though none is yet approved. While the safety of ASOs has been the subject of extensive review, the nonclinical safety profiles of GalNAc-siRNAs have not been reported. With the exception of sequence differences that confer target RNA specificity, GalNAc-siRNAs are largely chemically uniform, containing limited number of phosphorothioate linkages, and 2'-O-methyl and 2'-deoxy-2'-fluoro ribose modifications. Here, we present the outcomes of short-term (3-5 week) rat and monkey weekly repeat-dose toxicology studies of six Enhanced Stabilization Chemistry GalNAc-siRNAs currently in clinical development. In nonclinical studies at supratherapeutic doses, these molecules share similar safety signals, with histologic findings in the organ of pharmacodynamic effect (liver), the organ of elimination (kidney), and the reticuloendothelial system (lymph nodes). The majority of these changes are nonadverse, partially to completely reversible, correlate well with pharmacokinetic parameters and tissue distribution, and often reflect drug accumulation. Furthermore, all GalNAc-siRNAs tested to date have been negative in genotoxicity and safety pharmacology studies.

Are media literacy interventions effective at changing attitudes and intentions towards risky health behaviors in adolescents? A meta-analytic review.

Youth are inundated with media products promoting risky health behaviors (RHBs), including substance use and risky sexual activity. Media literacy interventions emphasize critical media consumption to decrease RHBs. However, it is unclear whether they positively influence attitudes and behavioral intentions towards RHBs. We conducted meta-analyses of 15 studies (N = 5000) testing intervention effectiveness on media literacy skills and 20 studies (N = 9177) testing effectiveness on attitudes and intentions towards RHBs. We found positive effects on media literacy skills (Hedge's g = .417, [95% CI, .29-.54]) and attitudes and intentions (Hedge's g = .100 [95% CI, .01-.19]). Intervention medium and target behavior moderated intervention success on attitudes and intentions, but no moderators emerged for media literacy skills. These interventions produce positive effects on media literacy skills and positive but smaller effects on attitudes and behavioral intentions, depending on medium and target behaviour. Implications for adolescent health initiatives are discussed.

Effect of an RNA interference drug on the synthesis of proprotein convertase subtilisin/kexin type 9 (PCSK9) and the concentration of serum LDL cholesterol in healthy volunteers: a randomised, single-blind, placebo-controlled, phase 1 trial.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to LDL receptors, leading to their degradation. Genetics studies have shown that loss-of-function mutations in PCSK9 result in reduced plasma LDL cholesterol and decreased risk of coronary heart disease. We aimed to investigate the safety and efficacy of ALN-PCS, a small interfering RNA that inhibits PCSK9 synthesis, in healthy volunteers with raised cholesterol who were not on lipid-lowering treatment. METHODS: We did a randomised, single-blind, placebo-controlled, phase 1 dose-escalation study in healthy adult volunteers with serum LDL cholesterol of 3·00 mmol/L or higher. Participants were randomly assigned in a 3:1 ratio by computer algorithm to receive one dose of intravenous ALN-PCS (with doses ranging from 0·015 to 0·400 mg/kg) or placebo. The primary endpoint was safety and tolerability of ALN-PCS. Secondary endpoints were the pharmacokinetic characteristics of ALN-PCS and its pharmacodynamic effects on PCSK9 and LDL cholesterol. Study participants were masked to treatment assignment. Analysis was per protocol and we used ANCOVA to analyse pharmacodynamic endpoint data. This trial is registered with ClinicalTrials.gov, number NCT01437059. FINDINGS: Of 32 participants, 24 were randomly allocated to receive a single dose of ALN-PCS (0·015 mg/kg [n=3], 0·045 mg/kg [n=3], 0·090 mg/kg [n=3], 0·150 mg/kg [n=3], 0·250 mg/kg [n=6], or 0·400 mg/kg [n=6]) and eight to placebo. The proportions of patients affected by treatment-emergent adverse events were similar in the ALN-PCS and placebo groups (19 [79%] vs seven [88%]). ALN-PCS was rapidly distributed, with peak concentration and area under the curve (0 to last measurement) increasing in a roughly dose-proportional way across the dose range tested. In the group given 0·400 mg/kg of ALN-PCS, treatment resulted in a mean 70% reduction in circulating PCSK9 plasma protein (p<0·0001) and a mean 40% reduction in LDL cholesterol from baseline relative to placebo (p<0·0001). INTERPRETATION: Our results suggest that inhibition of PCSK9 synthesis by RNA interference (RNAi) provides a potentially safe mechanism to reduce LDL cholesterol concentration in healthy individuals with raised cholesterol. These results support the further assessment of ALN-PCS in patients with hypercholesterolaemia, including those being treated with statins. This study is the first to show an RNAi drug being used to affect a clinically validated endpoint (ie, LDL cholesterol) in human beings. FUNDING: Alnylam Pharmaceuticals.

Expanding RNAi therapeutics to extrahepatic tissues with lipophilic conjugates.

Therapeutics based on short interfering RNAs (siRNAs) delivered to hepatocytes have been approved, but new delivery solutions are needed to target additional organs. Here we show that conjugation of 2'-O-hexadecyl (C16) to siRNAs enables safe, potent and durable silencing in the central nervous system (CNS), eye and lung in rodents and non-human primates with broad cell type specificity. We show that intrathecally or intracerebroventricularly delivered C16-siRNAs were active across CNS regions and cell types, with sustained RNA interference (RNAi) activity for at least 3 months. Similarly, intravitreal administration to the eye or intranasal administration to the lung resulted in a potent and durable knockdown. The preclinical efficacy of an siRNA targeting the amyloid precursor protein was evaluated through intracerebroventricular dosing in a mouse model of Alzheimer's disease, resulting in amelioration of physiological and behavioral deficits. Altogether, C16 conjugation of siRNAs has the potential for safe therapeutic silencing of target genes outside the liver with infrequent dosing.

Sexual abuse disclosure among incarcerated female adolescents and young adults.

BACKGROUND: Childhood sexual abuse (CSA) is over-represented among incarcerated girls and women. In order to inform effective methods of response, they represent a critical group for better understanding disclosure processes. OBJECTIVE: The purpose of the current study was to assess the CSA and CSA disclosure experiences of incarcerated female adolescents and young adults. PARTICIPANTS AND SETTING: Participants were 94 serious female offenders, ages 15-24 (M = 18.72, SD = 1.94), incarcerated in a secure juvenile facility. METHOD: In one-on-one interviews, participants answered questions about abuse characteristics, whether they had previously disclosed, to whom they had disclosed and after how long, and reasons for prior disclosure or nondisclosure. RESULTS: Over half of the sample (51.8%,n = 44) reported experiencing CSA. Most individuals who reported a CSA history had previously disclosed (79.5%, n = 35), with approximately equal proportions claiming to disclose within one week (40%) and after a year or years (45.8%). However, 20.5% (n = 9) claimed that our study interview was their first disclosure. Several reasons for their disclosure patterns were endorsed: Most commonly feelings of shame or embarrassment prevented disclosure (56%) and no longer wanting to keep the abuse a secret motivated disclosure (44%). CONCLUSIONS: Although many incarcerated girls and women share a history of CSA, our results indicate that the abuse and disclosure experiences of incarcerated females are diverse. Understanding their disclosure patterns can inform mental health services, rehabilitation, and professional interviewing strategies that may facilitate disclosure (e.g., forensic interviews, facility intake interviews).

Nonclinical Safety Profile of Revusiran, a 1st-Generation GalNAc-siRNA Conjugate for Treatment of Hereditary Transthyretin-Mediated Amyloidosis.

Revusiran is a 1st-generation short interfering RNA targeting transthyretin conjugated to an N-acetylgalactosamine ligand to facilitate delivery to hepatocytes via uptake by the asialoglycoprotein receptors. Revusiran, in development for the treatment of hereditary transthyretin-mediated amyloidosis, was discontinued after an imbalance in deaths in the "ENDEAVOUR" phase 3 clinical trial. Nonclinical safety assessments included safety pharmacology, acute and repeat-dose toxicity, genotoxicity, and carcinogenicity. There were no effects on cardiovascular or respiratory function in monkeys after single doses of up to 100 mg/kg. No neurological effects were noted in monkeys in repeat-dose studies up to 300 mg/kg. Revusiran was well tolerated in repeat-dose mouse (weekly doses) and rat and monkey (five daily doses followed by weekly doses) toxicity studies. The no observed adverse effect level (NOAEL) in rats was 30 mg/kg based on reversible microscopic changes in liver that were accompanied by correlating elevations in clinical chemistry at higher doses. Dose-limiting toxicity was absent in monkeys, and the NOAEL was 200 mg/kg. There was no evidence of genotoxicity in vitro or in vivo at limit doses or carcinogenicity in a 2-year study in rats at doses up to 100 mg/kg. Overall, these results demonstrate that revusiran had a favorable nonclinical safety profile.

Onset Time and Durability of Huntingtin Suppression in Rhesus Putamen After Direct Infusion of Antihuntingtin siRNA.

One possible treatment for Huntington's disease involves direct infusion of a small, interfering RNA (siRNA) designed to reduce huntingtin expression into brain tissue from a chronically implanted programmable pump. Here, we studied the suppression of huntingtin mRNA achievable with short infusion times, and investigated how long suppression may persist after infusion ceases. Rhesus monkeys received 3 days of infusion of Magnevist into the putamen to confirm catheter patency and fluid distribution. After a 1-week washout period, monkeys received radiolabeled siRNA targeting huntingtin. After 1 or 3 days of siRNA delivery, monkeys were either terminated, or their pumps were shut off and they were terminated 10 or 24 days later. Results indicate that the onset of huntingtin mRNA suppression in the rhesus putamen occurs rapidly, achieving a plateau throughout the putamen within 4 days. Conversely, loss of huntingtin suppression progresses slowly, persisting an estimated 27-39 days in the putamen and surrounding white matter. These findings indicate the rapid onset and durability of siRNA-mediated target gene suppression observed in other organs also occurs in the brain, and support the use of episodic delivery of siRNA into the brain for treatment of Huntington's disease and possibly other neurodegenerative diseases.

Epigenetics and the environment.

DNA methylation and histone modification promote changes in chromatin structure that may affect gene expression in a heritable manner without directly altering the genome. As such, these phenomena are considered to be epigenetic in nature and are believed to contribute to the normal processes of human development but also to aberrant disease states such as cancer. Epigenetic processes probably contribute mechanistically to toxicant-induced changes in gene expression and cancer. Nickel is a potent human carcinogen that has been shown to alter DNA methylation patterns and affect histone acetylation status. Both of these changes are associated with the proximity of the affected regions to heterochromatin. The two processes probably occur in concert in mammalian cells. However, in yeast cells, DNA methylation is absent, and nickel is capable of regulating gene expression through changes in acetylation of the lysine residues in the N terminal tail of histone H4. Arsenic is another important environmental carcinogen, and it is methylated during its metabolism. Hence, it has been proposed that arsenic metabolism may deplete intracellular methyl group stores and thereby lead to changes in DNA methylation that may be involved in carcinogenesis. However, the data concerning DNA methylation changes following arsenic exposure are equivocal, leading researchers to propose that DNA hypo- and hypermethylation are both important in the development of arsenic-induced cancers. Heightened awareness by toxicologists of the importance of epigenetics in normal human development and in carcinogenesis should lead to the identification of other toxicants that manifest their effects, at least in part, via epigenetic mechanisms.

Reviews Preclinical Safety and Immune-Modulating Effects of Therapeutic Monoclonal Antibodies to Interleukin-6 and Tumor Necrosis Factor-alpha in Cynomolgus Macaques.

Inhibitors of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) have been shown to be efficacious in a number of autoimmune diseases. In this study, the safety of long-term administration of anti-TNF-alpha and anti-IL-6 monoclonal antibodies (mAbs) was evaluated in cynomolgus macaques. Effects on the immune system were evaluated by analysis of lymphocyte subsets and histopathology of lymphoid tissues. To evaluate the functioning of the immune system, the ability of mAb-treated monkeys to mount a humoral immune response (IgG and IgM) to keyhole limpet hemocyanin (KLH) was evaluated. Treatment with the anti-TNF-alpha mAb produced no histopathological changes in any of the lymphoid tissues examined. There was a small (< 2-fold) elevation in circulating T-and B-lymphocytes during anti-TNF-alpha mAb treatment that was not considered to be toxicologically significant. The antibody response to KLH was unaffected by anti-TNF-alpha mAb treatment. Treatment with anti-IL-6 mAb resulted in a decrease in the size of germinal centers in the spleens of a minority of the animals and a modest but significant decrease in the IgG antibody response to KLH. Weekly intravenous treatment with the anti-IL-6 mAb and twice-weekly subcutaneous treatment with the anti-TNF-alpha mAb for up to 6 months was not associated with any signs of toxicity, and no animal developed an infection throughout the study period. This study demonstrates that the anti-IL-6 and anti-TNF-alpha mAbs produce specific modulating effects on the immune system without rendering the animals immune compromised.

The role of oxidative stress in nickel and chromate genotoxicity.

Some general principles regarding oxidative stress and molecular responses to toxic metals are presented in this manuscript. The remainder of the manuscript, however, will focus on the role of oxidative stress in particulate nickel-induced genetic damage and mutations. The phagocytosis of particulate nickel compounds and the dissolution of the particles inside the cell and the resulting oxidative stress produced in the nucleus is a key component of the nickel carcinogenic mechanism. The crosslinking of amino acids to DNA by nickel that does not involve direct participation of nickel in a ternary complex but nickel-induced oxidative stress will be discussed as well. The selective ability of particulate nickel compounds to silence the expression of genes located near heterochromatin and the effect of vitamin E on the genotoxicity and mutations induced by particulate and soluble nickel compounds will also be discussed. Particulate nickel compounds have been shown to produce more oxidative stress than water-soluble nickel compounds. In addition to nickel, the role of oxidative stress in chromate-induced genotoxicity will also be discussed with particular attention directed to the effects of vitamin E on mutations and chromosomal aberrations inducedby chromate.