The Effects of 2'-O-Methoxyethyl Containing Antisense Oligonucleotides on Platelets in Human Clinical Trials

Nucleic acids in modern molecular therapies: A realm of opportunities for strategic drug design

RNA vaccines have made evident to society what was already known by the scientific community: nucleic acids will be the "drugs of the future." By modifying the genome, interfering in transcription or translation, and by introducing new catalysts into the cell or by mimicking antibody effects, nucleic acids can generate therapeutic activities that are not accessible by any other therapeutic agents. There are, however, challenges that need to be solved in the next few years to make nucleic acids usable in a wide range of therapeutic scenarios. This review illustrates how simulation methods can help achieve this goal.

Frameworks for transformational breakthroughs in RNA-based medicines

RNA has sparked a revolution in modern medicine, with the potential to transform the way we treat diseases. Recent regulatory approvals, hundreds of new clinical trials, the emergence of CRISPR gene editing, and the effectiveness of mRNA vaccines in dramatic response to the COVID-19 pandemic have converged to create tremendous momentum and expectation. However, challenges with this relatively new class of drugs persist and require specialized knowledge and expertise to overcome. This Review explores shared strategies for developing RNA drug platforms, including layering technologies, addressing common biases and identifying gaps in understanding. It discusses the potential of RNA-based therapeutics to transform medicine, as well as the challenges associated with improving applicability, efficacy and safety profiles. Insights gained from RNA modalities such as antisense oligonucleotides (ASOs) and small interfering RNAs are used to identify important next steps for mRNA and gene editing technologies.

APOC3 siRNA and ASO therapy for dyslipidemia

PURPOSE OF REVIEW

The aim of this review is to present the clinical indications of apolipoprotein C-III (apoC3) inhibition in the therapeutic arsenal for the treatment of lipid disorders and associated risks and to compare the most advanced modalities of apoC3 inhibition currently available or in development, specifically APOC3 antisense oligonucleotides (ASO) and small interfering RNA (siRNA).

RECENT FINDINGS

ApoC3 inhibition significantly decreases triglyceride levels by mechanisms coupling both lipoprotein lipase (LPL) upregulation and LPL-independent mechanisms. The main apoC3 inhibitors in advanced clinical development are the GalNAc-ASO olezarsen and the GalNAc-siRNA plozasiran. Clinical studies conducted with volanesorsen, the olezarsen precursor, showed a favorable effect on hepatic steatosis (nonalcoholic fatty liver disease, NAFLD). Olezarsen does not appear to be associated with the main side effects attributed to volanesorsen including thrombocytopenia. Plozasiran is in advanced clinical development and requires subcutaneous injection every 3 months and present to-date an efficacy and safety profile comparable to that of the monthly ASO.

SUMMARY

Inhibition of apoC3 is effective across all the spectrum of hypertriglyceridemia, might have a favorable effect on hepatic steatosis (NAFLD) and the effect of apoC3 inhibition on cardiovascular risk is not limited to its effect on plasma triglycerides. APOC3 GalNAc-conjugated ASO and siRNA are both effective in decreasing plasma apoC3 and triglyceride levels.

Safety and Tolerability of GalNAc3-Conjugated Antisense Drugs Compared to the Same-Sequence 2'-O-Methoxyethyl-Modified Antisense Drugs: Results from an Integrated Assessment of Phase 1 Clinical Trial Data

The triantennary N-acetylgalactosamine (GalNAc3) cluster has demonstrated the utility of receptor-mediated uptake of ligand-conjugated antisense drugs targeting RNA expressed by hepatocytes. GalNAc3-conjugated 2'-O-methoxyethyl (2'MOE) modified antisense oligonucleotides (ASOs) have demonstrated a higher potency than the unconjugated form to support lower doses for an equivalent pharmacological effect. We utilized the Ionis integrated safety database to compare four GalNAc3-conjugated and four same-sequence unconjugated 2'MOE ASOs. This assessment evaluated data from eight randomized placebo-controlled dose-ranging phase 1 studies involving 195 healthy volunteers (79 GalNAc3 ASO, 24 placebo; 71 ASO, 21 placebo). No safety signals were identified by the incidence of abnormal threshold values in clinical laboratory tests for either ASO group. However, there was a significant increase in mean alanine transaminase levels compared with placebo in the upper dose range of the unconjugated 2'MOE ASO group. The mean percentage of subcutaneous injections leading to local cutaneous reaction was 30-fold lower in the GalNAc3-conjugated ASO group compared with the unconjugated ASO group (0.9% vs. 28.6%), with no incidence of flu-like reactions (0.0% vs. 0.7%). Three subjects (4.2%) in the unconjugated ASO group discontinued dosing. An improvement in the overall safety and tolerability profile of GalNAc3-conjugated 2'MOE ASOs is evident in this comparison of short-term clinical data in healthy volunteers.

Targeting the Liver with Nucleic Acid Therapeutics for the Treatment of Systemic Diseases of Liver Origin

Systemic diseases of liver origin (SDLO) are complex diseases in multiple organ systems, such as cardiovascular, musculoskeletal, endocrine, renal, respiratory, and sensory organ systems, caused by irregular liver metabolism and production of functional factors. Examples of such diseases discussed in this article include primary hyperoxaluria, familial hypercholesterolemia, acute hepatic porphyria, hereditary transthyretin amyloidosis, hemophilia, atherosclerotic cardiovascular diseases, α-1 antitrypsin deficiency-associated liver disease, and complement-mediated diseases. Nucleic acid therapeutics use nucleic acids and related compounds as therapeutic agents to alter gene expression for therapeutic purposes. The two most promising, fastest-growing classes of nucleic acid therapeutics are antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs). For each listed SDLO disease, this article discusses epidemiology, symptoms, genetic causes, current treatment options, and advantages and disadvantages of nucleic acid therapeutics by either ASO or siRNA drugs approved or under development. Furthermore, challenges and future perspectives on adverse drug reactions and toxicity of ASO and siRNA drugs for the treatment of SDLO diseases are also discussed. In summary, this review article will highlight the clinical advantages of nucleic acid therapeutics in targeting the liver for the treatment of SDLO diseases. SIGNIFICANCE STATEMENT: Systemic diseases of liver origin (SDLO) contain rare and common complex diseases caused by irregular functions of the liver. Nucleic acid therapeutics have shown promising clinical advantages to treat SDLO. This article aims to provide the most updated information on targeting the liver with antisense oligonucleotides and small interfering RNA drugs. The generated knowledge may stimulate further investigations in this growing field of new therapeutic entities for the treatment of SDLO, which currently have no or limited options for treatment.

Post-prandial analysis of fluctuations in the platelet count and platelet function in patients with the familial chylomicronemia syndrome

BACKGROUND

The familial chylomicronemia syndrome (FCS) is an ultra rare disease caused by lipoprotein lipase (LPL) deficiency associated with potentially lethal acute pancreatitis risk. Thrombocytopenia (platelet count < 150,000 × 10⁹/L) has been reported in patients with FCS, treated or not with volanesorsen, a second generation APOC3 anti-sense oligonucleotide. Chylomicrons are the lipoproteins delivering fat after a meal and FCS thus has a post-prandial origin. Platelet count and function have not been studied post-prandially in FCS.

OBJECTIVE

To evaluate post-prandial fluctuations in the platelet count (PLC) and functional defects of hemostasis in FCS.

METHODS

PLC, functional defects in hemostasis and hematologic variables were measured up-to 5 h after a meal in 6 homozygotes for FCS causing gene variants (HoLPL), 6 heterozygotes for LPL loss-of-function variants (HeLPL) and 7 normolipidemic controls.

RESULTS

Hourly post-prandial PLC was significantly lower in HoLPL than in controls (P < 0.009). Compared to the other groups, the PLC tended to decrease rapidly (in the first hour) post-meal in HoLPL (P = 0.03) and remained lower than baseline 5-h post-meal (P = 0.02) whereas it tended to slightly increase in normolipidemic controls (P = 0.02). Platelet function was not affected by the prandial status. In HoLPL, post-prandial fluctuations in the PLC positively correlated with the lymphocyte count (P = 0.005) and negatively with neutrophil/lymphocyte ratio (NLR).

CONCLUSION

The PLC decreases post-prandially in FCS (HoLPL), is not associated with changes in functional defects of hemostasis and correlates with the NLR, a marker of acute pancreatitis severity.

Targeting and delivery of microRNA-targeting antisense oligonucleotides in cardiovascular diseases

Discovered three decades ago, microRNAs (miRNAs) are now recognized as key players in the pathophysiology of multiple human diseases, including those affecting the cardiovascular system. As such, miRNAs have emerged as promising therapeutic targets for preventing the onset and/or progression of several cardiovascular diseases. Anti-miRNA antisense oligonucleotides or "antagomirs" precisely block the activity of specific miRNAs and are therefore a promising therapeutic strategy to repress pathological miRNAs. In this review, we describe advancements in antisense oligonucleotide chemistry that have significantly improved efficacy and safety. Moreover, we summarize recent approaches for the targeted delivery of antagomirs to cardiovascular tissues, highlighting major advantages as well as limitations of viral (i.e., adenovirus, adeno-associated virus, and lentivirus) and non-viral (i.e., liposomes, extracellular vesicles, and polymer nanoparticles) delivery systems. We discuss recent preclinical studies that use targeted antagomir delivery systems to treat three major cardiovascular diseases (atherosclerosis, myocardial infarction, and cardiac hypertrophy, including hypertrophy caused by hypertension), highlighting therapeutic results and discussing challenges that limit clinical applicability.

Complement C3d/C4d Deposition on Platelets Correlates with 2'-O-Methoxyethyl Antisense Oligonucleotide-Induced Thrombocytopenia in Monkeys

2'-O-Methoxyethyl antisense oligonucleotide (2'-MOE ASO)-induced severe thrombocytopenia (TCP) [platelet (PLT) count <50 K/μL] was observed in the Asian-sourced cynomolgus monkeys with low incidence (2%-4% at doses >5 mg/kg/week). The potential mechanisms for TCP were studied using the Mauritian-sourced cynomolgus monkeys, which were shown to be more susceptible to ASO-induced TCP, along with the Asian-sourced animals. ISIS 405879, a 2'-MOE ASO, induced severe TCP (PLT <50 K/μL) in seven of nine Mauritian-sourced monkeys but not in the Asian-sourced monkeys after 16 weeks of treatment at 40 mg/kg/week. Marked increases in PLT-bound C3d/C4d were detected in all thrombocytopenic Mauritian-sourced monkeys but not in the unaffected Mauritian- or Asian-sourced monkeys, suggesting increased PLT clearance due to complement deposition on the PLTs. However, this effect was independent of the ASO-mediated fluid-phase alternative complement activation. A correlation was also observed between serum antiglycoprotein (GP) IIb/IIIa immunoglobulin G (IgG) and PLT reduction. In addition, increases in total serum IgM, anti-PLT IgM, and anti-PLT factor 4 IgM levels were observed in monkeys from both sources but were more evident in the Mauritian-sourced monkeys. These data suggest an enhanced innate immune cell activation to ISIS 405879, leading to increased PLT destruction through complement fixation on the PLTs or PLT crossreacting polyclonal antibody production.

Platelet Activation by Antisense Oligonucleotides (ASOs) in the Göttingen Minipig, including an Evaluation of Glycoprotein VI (GPVI) and Platelet Factor 4 (PF4) Ontogeny

Antisense oligonucleotide (ASO) is a therapeutic modality that enables selective modulation of undruggable protein targets. However, dose- and sequence-dependent platelet count reductions have been reported in nonclinical studies and clinical trials. The adult Göttingen minipig is an acknowledged nonclinical model for ASO safety testing, and the juvenile Göttingen minipig has been recently proposed for the safety testing of pediatric medicines. This study assessed the effects of various ASO sequences and modifications on Göttingen minipig platelets using in vitro platelet activation and aggregometry assays. The underlying mechanism was investigated further to characterize this animal model for ASO safety testing. In addition, the protein abundance of glycoprotein VI (GPVI) and platelet factor 4 (PF4) was investigated in the adult and juvenile minipigs. Our data on direct platelet activation and aggregation by ASOs in adult minipigs are remarkably comparable to human data. Additionally, PS ASOs bind to platelet collagen receptor GPVI and directly activate minipig platelets in vitro, mirroring the findings in human blood samples. This further corroborates the use of the Göttingen minipig for ASO safety testing. Moreover, the differential abundance of GPVI and PF4 in minipigs provides insight into the influence of ontogeny in potential ASO-induced thrombocytopenia in pediatric patients.

Pharmacology and Clinical Development of Factor XI Inhibitors

Therapeutic anticoagulation is indicated for a variety of circumstances and conditions in several fields of medicine to prevent or treat venous and arterial thromboembolism. According to the different mechanisms of action, the available parenteral and oral anticoagulant drugs share the common principle of hampering or blocking key steps of the coagulation cascade, which unavoidably comes at the price of an increased propensity to bleed. Hemorrhagic complications affect patient prognosis both directly and indirectly (ie, by preventing the adoption of an effective antithrombotic strategy). Inhibition of factor XI (FXI) has emerged as a strategy with the potential to uncouple the pharmacological effect and the adverse events of anticoagulant therapy. This observation is based on the differential contribution of FXI to thrombus amplification, in which it plays a major role, and hemostasis, in which it plays an ancillary role in final clot consolidation. Several agents were developed to inhibit FXI at different stages (ie, suppressing biosynthesis, preventing zymogen activation, or impeding the biological action of the active form), including antisense oligonucleotides, monoclonal antibodies, small synthetic molecules, natural peptides, and aptamers. Phase 2 studies of different classes of FXI inhibitors in orthopedic surgery suggested that dose-dependent reductions in thrombotic complications are not paralleled by dose-dependent increases in bleeding compared with low-molecular-weight heparin. Likewise, the FXI inhibitor asundexian was associated with lower rates of bleeding compared with the activated factor X inhibitor apixaban in patients with atrial fibrillation, although no evidence of a therapeutic effect on stroke prevention is available so far. FXI inhibition could also be appealing for patients with other conditions, including end-stage renal disease, noncardioembolic stroke, or acute myocardial infarction, for which other phase 2 studies have been conducted. The balance between thromboprophylaxis and bleeding achieved by FXI inhibitors needs confirmation in large-scale phase 3 clinical trials powered for clinical end points. Several of such trials are ongoing or planned to define the role of FXI inhibitors in clinical practice and to clarify which FXI inhibitor may be most suited for each clinical indication. This article reviews the rationale, pharmacology, results of medium or small phase 2 studies, and future perspectives of drugs inhibiting FXI.

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

Background

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

Results

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

Conclusion

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

Antisense oligonucleotides to therapeutically target SARS-CoV-2 infection

Although the COVID-19 pandemic began over three years ago, the virus responsible for the disease, SARS-CoV-2, continues to infect people across the globe. As such, there remains a critical need for development of novel therapeutics against SARS-CoV-2. One technology that has remained relatively unexplored in COVID-19 is the use of antisense oligonucleotides (ASOs)-short single-stranded nucleic acids that bind to target RNA transcripts to modulate their expression. In this study, ASOs targeted against the SARS-CoV-2 genome and host entry factors, ACE2 and TMPRSS2, were designed and tested for their ability to inhibit cellular infection by SARS-CoV-2. Using our previously developed SARS-CoV-2 bioassay platform, we screened 180 total ASOs targeting various regions of the SARS-CoV-2 genome and validated several ASOs that potently blocked SARS-CoV-2 infection in vitro. Notably, select ASOs retained activity against both the WA1 and B.1.1.7 (commonly known as alpha) variants. Screening of ACE2 and TMPRSS2 ASOs showed that targeting of ACE2 also potently prevented infection by the WA1 and B.1.1.7 SARS-CoV-2 viruses in the tested cell lines. Combined with the demonstrated success of ASOs in other disease indications, these results support further research into the development of ASOs targeting SARS-CoV-2 and host entry factors as potential COVID-19 therapeutics.

Considerations in the Preclinical Assessment of the Safety of Antisense Oligonucleotides

The nucleic acid therapeutics field has made tremendous progress in the past decades. Continuous advances in chemistry and design have led to many successful clinical applications, eliciting even more interest from researchers including both academic groups and drug development companies. Many preclinical studies in the field focus on improving the delivery of antisense oligonucleotide drugs (ONDs) and/or assessing their efficacy in target tissues, often neglecting the evaluation of toxicity, at least in early phases of development. A series of consensus recommendations regarding regulatory considerations and expectations have been generated by the Oligonucleotide Safety Working Group and the Japanese Research Working Group for the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use S6 and Related Issues (WGS6) in several white papers. However, safety aspects should also be kept in sight in earlier phases while screening and designing OND to avoid subsequent failure in the development phase. Experts and members of the network "DARTER," a COST Action funded by the Cooperation in Science and Technology of the EU, have utilized their collective experience working with OND, as well as their insights into OND-mediated toxicities, to generate a series of consensus recommendations to assess OND toxicity in early stages of preclinical research. In the past few years, several publications have described predictive assays, which can be used to assess OND-mediated toxicity in vitro or ex vivo to filter out potential toxic candidates before moving to in vivo phases of preclinical development, that is, animal toxicity studies. These assays also have the potential to provide translational insight since they allow a safety evaluation in human in vitro systems. Yet, small preliminary in vivo studies should also be considered to complement this early assessment. In this study, we summarize the state of the art and provide guidelines and recommendations on the different tests available for these early stage preclinical assessments.

Clinical potential of inclisiran for patients with a high risk of atherosclerotic cardiovascular disease

Elevated low-density lipoprotein cholesterol (LDL-C) level is associated with an increased risk of atherosclerotic cardiovascular disease. Although high-intensity lipid-lowering therapies with statins and ezetimibe are highly effective for reducing LDL-C levels, over half of high-risk patients do not achieve guideline-recommended LDL-C goals. Thus, there is a significant gap between treatment guidelines and their implementation in daily clinical practice. The major causes are individual variability in the response to lipid-lowering therapies and variation in treatment adherence. Proprotein convertase subtilisin/kexin type 9 (PCSK9) monoclonal antibodies combined with statins provide marked and consistent reduction in LDL-C levels; however, poor adherence due to the need for subcutaneous injections every 2 or 4 weeks and high cost are major obstacles to their use in real-world clinical settings. Inclisiran, a recently approved novel small interfering ribonucleic acid (siRNA) molecule that inhibits PCSK9 synthesis, provides robust and long-term reduction in LDL-C levels with a low inter-individual variability in the LDL-C-lowering response. Moreover, its administration by biannual injection is expected to greatly improve treatment adherence. Clinical trials of this drug lasting for up to 4 years showed acceptable safety profiles, and ongoing studies accumulate evidence of its longer-term safety. This narrative review summarizes the available evidence on the efficacy and safety of inclisiran and analyzes its potential to overcome the gap between guideline recommendations and real-world clinical practice in current LDL-C-lowering therapies, with a focus on reduced LDL-C level variability and improved treatment adherence.

Integrated Assessment of Phase 2 Data on GalNAc3-Conjugated 2'-O-Methoxyethyl-Modified Antisense Oligonucleotides

Receptor-mediated delivery of an antisense oligonucleotide (ASO) using the ligand-conjugated antisense technology is establishing a new benchmark for antisense therapeutics. The triantennary N-acetylgalactosamine (GalNAc3) cluster is the first conjugated ligand to yield a marked increase in ASO potency for RNA targets expressed by hepatocytes, compared to the unconjugated form. In this study, we present an integrated safety assessment of data available from randomized, placebo-controlled, phase 2 studies for six GalNAc3-conjugated 2'-O-methoxyethyl (2'MOE)-modified ASOs. The total study population included 642 participants (130 placebo; 512 ASO) with up to 1 year of exposure. The primary measures were the incidence of signals from standardized laboratory tests and the mean test results over time. The GalNAc3-conjugated ASOs were well tolerated with no class effect identified across all doses tested compared to placebo. These results extend prior observations from phase 1 studies, now with treatment up to 1 year.

Single Oligonucleotide Capture of RNA And Temperature Elution Series ( SOCRATES ) for Identification of RNA-binding Proteins

The importance of studying the mechanistic aspects of long non-coding RNAs is being increasingly emphasized as more and more regulatory RNAs are being discovered. Non-coding RNA sequences directly associate with generic RNA-binding proteins as well as specific proteins, which cooperate in the downstream functions of the RNA and can also be dysregulated in various physiologic states and/or diseases. While current methods exist for identifying RNA-protein interactions, these methods require high quantities of input cells or use pooled capture reagents that may increase non-specific binding. We have developed a method to efficiently capture specific RNAs using less than one million input cells. One single oligonucleotide is used to pull down the target RNA of choice and oligonucleotide selection is driven by sequence accessibility. We perform thermal elution to specifically elute the target RNA and its associated proteins, which are identified by mass spectrometry. Ultimately, two target and control oligonucleotides are used to create an enrichment map of interacting proteins of interest. This protocol was validated in: eLife (2021), DOI: 10.7554/eLife.68263.

Nephrotoxicity of marketed antisense oligonucleotide drugs

The field of antisense oligonucleotide (ASO)-based therapies have been making strides in precision medicine due to their potent therapeutic application. Early successes in treating some genetic diseases are now attributed to an emerging class of antisense drugs. After two decades, the US Food and Drug Administration (FDA) has approved a considerable number of ASO drugs, primarily to treat rare diseases with optimal therapeutic outcomes. However, safety is one of the biggest challenges to the therapeutic utility of ASO drugs. Due to patients' and health care practitioners' urgent demands for medicines for untreatable conditions, many ASO drugs have been approved. However, a complete understanding of the mechanisms of adverse drug reactions (ADRs) and toxicities of ASOs still need to be resolved. The range of ADRs is unique to a specific drug, while few ADRs are common to a section of drugs as a whole. Nephrotoxicity is an important concern that needs to be addressed considering the clinical translation of any drug candidates ranging from small molecules to ASO-based drugs. This article encompasses what is known about the nephrotoxicity of ASO drugs, the potential mechanisms of action(s), and recommendations for future investigations on the safety of ASO drugs.

Silencing of Thrips palmi UHRF1BP1 and PFAS Using Antisense Oligos Induces Mortality and Reduces Tospovirus Titer in Its Vector

Thrips palmi (Thysanoptera: Thripidae) is an important pest of vegetables, legumes, and ornamentals. In addition, it transmits several plant viruses. T. palmi genes associated with innate immunity, endocytosis-related pathways, and cuticular development are highly enriched in response to Groundnut bud necrosis orthotospovirus (GBNV, genus Orthotospovirus, family Tospoviridae) infection. As the previous transcriptomic study suggested the involvement of T. palmi UHRF1BP1 and PFAS in GBNV infection, these two genes were targeted for silencing using antisense oligonucleotides (ASOs), and the effects on thrips’ fitness and virus acquisition were observed. Phosphorothioate modification of ASOs was carried out by replacing the nonbridging oxygen atom with a sulfur atom at the 3′ position to increase nuclease stability. The modified ASOs were delivered orally through an artificial diet. Exposure to ASOs reduced the target mRNA expression up to 2.70-fold optimally. Silencing of T. palmi UHRF1BP1 and PFAS induced 93.33% mortality that further increased up to 100% with an increase in exposure. Silencing of T. palmi UHRF1BP1 and PFAS also produced morphological deformities in the treated T. palmi. GBNV titer in T. palmi significantly declined post-exposure to ASOs. This is the first-ever report of silencing T. palmi UHRF1BP1 and PFAS using modified ASO to induce mortality and impair virus transmission in T. palmi. T. palmi UHRF1BP1 and PFAS would be novel genetic targets to manage thrips and restrict the spread of tospovirus.

Phase IIa, randomised, double-blind study of GSK3389404 in patients with chronic hepatitis B on stable nucleos(t)ide therapy

BACKGROUND & AIMS

Bepirovirsen, an antisense oligonucleotide targeting pregenomic and mRNA transcripts of HBV, has been conjugated to N-acetyl galactosamine (GSK3389404) to enhance hepatocyte delivery. This dose-finding study was the first to assess GSK3389404 for chronic HBV infection.

METHODS

This phase IIa, randomised, double-blind, placebo-controlled, 2-part study was conducted in 22 centres in Asia (NCT03020745). Pharmacokinetic findings from Part 1 informed Part 2 dosing. In Part 2, patients with chronic hepatitis B on nucleos(t)ide analogue therapy were randomised 11:2 to GSK3389404 (30, 60, 120 mg weekly or 120 mg bi-weekly) or placebo until Day 85. Coprimary endpoints included HBsAg response (≥1.5 log₁₀ IU/ml reduction from baseline) rate, safety and pharmacokinetics.

RESULTS

Parts 1 and 2 included 12 (9 GSK3389404, 3 placebo) and 66 patients (56 GSK3389404, 10 placebo), respectively. In Part 2, one patient each in the 60 mg weekly, 120 mg weekly and 120 mg bi-weekly arms achieved a HBsAg response. HBsAg reductions were dose-dependent (Day 85: mean 0.34 [60 mg weekly] to 0.75 log₁₀ IU/ml [120 mg weekly]) and occurred in hepatitis B e antigen-positive and -negative patients. No patient achieved HBsAg seroclearance. 43/56 (77%) GSK3389404- and 9/10 (90%) placebo-treated patients reported adverse events. No deaths were reported. Alanine aminotransferase flares (>2x upper limit of normal) occurred in 2 GSK3389404-treated patients (120 mg weekly, 120 mg bi-weekly); both were associated with decreased HBsAg, but neither was considered a responder. GSK3389404 plasma concentrations peaked 2-4 hours post dose; mean plasma half-life was 3-5 hours.

CONCLUSIONS

GSK3389404 showed an acceptable safety profile and target engagement, with dose-dependent reductions in HBsAg. However, no efficacious dosing regimen was identified.

CLINICAL TRIAL NUMBER

NCT03020745.

LAY SUMMARY

Hepatitis B virus (HBV) can result in chronic HBV infection, which may ultimately lead to chronic liver disease, primary liver cancer and death; HBV proteins may prevent the immune system from successfully controlling the virus. GSK3389404 is an investigational agent that targets HBV RNA, resulting in reduced viral protein production. This study assessed the safety of GSK3389404 and its ability to reduce the viral proteins in patients with chronic HBV infection. GSK3389404 showed dose-dependent reduction in hepatitis B surface antigen, with an acceptable safety profile. While no clear optimal dose was identified, the findings from this study may help in the development of improved treatment options for patients with chronic HBV infections.

The Effect of Nusinersen Therapy on Laboratory Parameters of Patients with Spinal Muscular Atrophy

INTRODUCTION

We evaluated the effect of nusinersen on clinical and laboratory parameters and presented its safety and effect on laboratory parameters.

METHODS

Two groups were formed from among patients with spinal muscular atrophy (SMA) followed up between September 2017 and June 2021: group 1, SMA type 1; group 2, SMA type 2 and 3. The laboratory parameters were evaluated in groups 1 and 2 between doses. Motor scale tests were performed on patients before each dose of nusinersen.

RESULTS

Twenty seven patients (group 1; n = 13, group 2; n = 14) were included. The mean age (±standard deviation) at the onset of symptoms was 3 ± 1.21 (range, 1.5-6) months in group 1 and 12 ± 4.27 (range, 8-24) months in group 2. No significant laboratory treatment-related abnormalities and adverse effects were observed. The cerebrospinal fluid protein levels and the frequency of conventional LP were higher in group 1. Serum creatinine (Cr) levels were higher in group 1 before the first dose and higher in group 2 before the fifth dose (p < 0.05). With treatment, the Cr levels of group 1 decreased and group 2 remained constant or increased. We observed that the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders and Hammersmith Functional Motor Scale-Expand scores increased as our patients received treatment (p < 0.05).

CONCLUSION

Our results support the safety and efficacy of nusinersen. However, changes in Cr levels according to the clinical type and treatment suggested that serum Cr could be a candidate marker for treatment follow-up.

Assessment of the Immunogenicity Potential for Oligonucleotide-Based Drugs

Therapeutic oligonucleotides (ONs) have characteristics of both small molecules and biologics. Although safety assessment of ONs largely follows guidelines established for small molecules, the unique characteristics of ONs often require incorporation of concepts from the safety assessment of biologics. The assessment of immunogenicity for ON therapeutics is one area where the approach is distinct from either established small molecule or biologic platforms. Information regarding immunogenicity of ONs is limited, but indicates that administration of ONs can result in antidrug antibody formation. In this study, we summarize the collective experience of the Oligonucleotide Safety Working Group in designing the immunogenicity assessment appropriate for this class of therapeutic, including advice on assay development, clinical monitoring, and evaluation of the impact of immunogenicity on exposure, efficacy, and safety of therapeutic ONs.

Establishing an environment in which rigorous scientific inquiry is practiced: a personal journey

For more than three decades, Ionis Pharmaceutics has pursued the challenging mission of creating a new platform for drug discovery. To overcome the numerous challenges faced required the integration of innovation across many scientific areas, despite many disappointments and failures. The approaches implemented to create and maintain a scientific environment to achieve the mission demanded the rigorous practice of science over three decades. The approaches taken are discussed in this perspective.

Effect of Vupanorsen on Non-High-Density Lipoprotein Cholesterol Levels in Statin-Treated Patients With Elevated Cholesterol: TRANSLATE-TIMI 70

Genetic loss-of-function variants in ANGPTL3 are associated with lower levels of plasma lipids. Vupanorsen is a hepatically targeted antisense oligonucleotide that inhibits Angiopoietin-like 3 (ANGPTL3) protein synthesis.

Antisense Oligonucleotide Induction of the hnRNPA1b Isoform Affects Pre-mRNA Splicing of SMN2 in SMA Type I Fibroblasts

Spinal muscular atrophy (SMA) is a severe, debilitating neuromuscular condition characterised by loss of motor neurons and progressive muscle wasting. SMA is caused by a loss of expression of SMN1 that encodes the survival motor neuron (SMN) protein necessary for the survival of motor neurons. Restoration of SMN expression through increased inclusion of SMN2 exon 7 is known to ameliorate symptoms in SMA patients. As a consequence, regulation of pre-mRNA splicing of SMN2 could provide a potential molecular therapy for SMA. In this study, we explored if splice switching antisense oligonucleotides could redirect the splicing repressor hnRNPA1 to the hnRNPA1b isoform and restore SMN expression in fibroblasts from a type I SMA patient. Antisense oligonucleotides (AOs) were designed to promote exon 7b retention in the mature mRNA and induce the hnRNPA1b isoform. RT-PCR and western blot analysis were used to assess and monitor the efficiency of different AO combinations. A combination of AOs targeting multiple silencing motifs in hnRNPA1 pre-mRNA led to robust hnRNPA1b induction, which, in turn, significantly increased expression of full-length SMN (FL-SMN) protein. A combination of PMOs targeting the same motifs also strongly induced hnRNPA1b isoform, but surprisingly SMN2 exon 5 skipping was detected, and the PMO cocktail did not lead to a significant increase in expression of FL-SMN protein. We further performed RNA sequencing to assess the genome-wide effects of hnRNPA1b induction. Some 3244 genes were differentially expressed between the hnRNPA1b-induced and untreated SMA fibroblasts, which are functionally enriched in cell cycle and chromosome segregation processes. RT-PCR analysis demonstrated that expression of the master regulator of these enrichment pathways, MYBL2 and FOXM1B, were reduced in response to PMO treatment. These findings suggested that induction of hnRNPA1b can promote SMN protein expression, but not at sufficient levels to be clinically relevant.

Preclinical Safety Assessment of Therapeutic Oligonucleotides

During the last decade, therapeutic oligonucleotide drugs (OND) have witnessed a tremendous development in chemistry and mechanistic understanding that have translated into successful clinical applications. Depending on the specific OND mechanism, chemistry, and design, the DMPK and toxicity properties can vary significantly between different OND classes and delivery approaches, the latter including lipid formulations or conjugation approaches to enhance productive OND uptake. At the same time, with the only difference between compounds being the nucleobase sequence, ONDs with same mechanism of action, chemistry, and design show relatively consistent behavior, allowing certain extrapolations between compounds within an OND class. This chapter provides a summary of the most common toxicities, the improved mechanistic understanding and the safety assessment activities performed for therapeutic oligonucleotides during the drug discovery and development process. Several of the considerations described for therapeutic applications should also be of value for the scientists mainly using oligonucleotides as research tools to explore various biological processes.

2'-O-(N-(Aminoethyl)carbamoyl)methyl Modification Allows for Lower Phosphorothioate Content in Splice-Switching Oligonucleotides with Retained Activity

2′-O-(N-(Aminoethyl)carbamoyl)methyl (2′-O-AECM)-modified oligonucleotides (ONs) and their mixmers with 2′-O-methyl oligonucleotides (2′-OMe ONs) with phosphodiester linkers as well as with partial and full phosphorothioate (PS) inclusion were synthesized and functionally evaluated as splice-switching oligonucleotides in several different reporter cell lines originating from different tissues. This was enabled by first preparing the AECM-modified A, C, G and U, which required a different strategy for each building block. The AECM modification has previously been shown to provide high resistance to enzymatic degradation, even without PS linkages. It is therefore particularly interesting and unprecedented that the 2′-O-AECM ONs are shown to have efficient splice-switching activity even without inclusion of PS linkages and found to be as effective as 2′-OMe PS ONs. Importantly, the PS linkages can be partially included, without any significant reduction in splice-switching efficacy. This suggests that AECM modification has the potential to be used in balancing the PS content of ONs. Furthermore, conjugation of 2′-O-AECM ONs to an endosomal escape peptide significantly increased splice-switching suggesting that this effect could possibly be due to an increase in uptake of ON to the site of action.

Meeting the needs of patients with ultrarare diseases

Patients with ultrarare diseases present unique challenges to the health care systems of developed economies that demand novel approaches, beginning with achieving a diagnosis and concluding with long-term treatment. The challenges derive from numbers. On the one hand, the rarity of the disease phenotypes means that the vast majority of ultrarare patients are never diagnosed, and for the fortunate few who are diagnosed, the journey to a genetic diagnosis is long and perilous. On the other hand, as more human genomes are sequenced, the number of these patients identified is growing logarithmically. Once patients are diagnosed, personalized medicines must be rapidly developed and delivered. Here I define the problems and propose a nonprofit model to meet the needs of some of these patients.

Phase 2 Study of the Factor XI Antisense Inhibitor IONIS-FXIRx in Patients With ESRD

Introduction

Patients with end-stage renal disease (ESRD) requiring hemodialysis (HD) have an increased risk of thrombotic events and bleeding. Antisense reduction of factor XI (FXI) with IONIS-FXI_Rx is a novel strategy that may safely reduce the risk of thrombotic events.

Methods

This multicenter study enrolled 49 patients receiving HD in 2 parts. First, 6 participants (pharmacokinetics [PK] cohort) received 1 open-label 300 mg dose of IONIS-FXI_Rx both before and after HD. Subsequently, 43 participants were treated in a double-blind, randomized design with 200 mg or 300 mg IONIS-FXI_Rx or placebo for 12 weeks. The PK, pharmacodynamics (PD), and adverse events of IONIS-FXI_Rx were evaluated (ClinicalTrials.gov: NCT02553889).

Results

The PK of IONIS-FXI_Rx was consistent with previous studies and similar whether injected before or after HD. No accumulation of IONIS-FXI_Rx was observed after repeat administration. By day 85, mean levels of FXI activity fell 56.0% in the 200 mg group, 70.7% in the 300 mg group, and 3.9% in the placebo group compared with baseline. FXI antigen levels paralleled FXI activity. Dose-dependent prolongation of activated partial thromboplastin time (aPTT) was observed, with no changes in international normalized ratio (INR). IONIS-FXI_Rx was not associated with drug-related serious adverse events. In the randomized phase of the study, major bleeding events occurred in 0 (0.0%; 200 mg), 1 (6.7%; 300 mg), and 1 (7.7%; placebo) patients and were not considered related to treatment.

Conclusion

IONIS-FXI_Rx reduced FXI activity in patients with ESRD receiving HD. Further studies are needed to determine the benefit-risk profile of FXI as a therapeutic target for patients who require HD.

Addressing the Needs of Patients with Ultra-Rare Mutations One Patient at a Time: The n-Lorem Approach

Thanks to the advent of genomic sequencing and numerous personalized medicine initiatives in various medical centers, it is now known that there are many patients who have heretofore never been diagnosed who have mutations that are unique to them and them only and others that may be members of an extremely rare mutation (<30 patients in the world). Although each mutation may be unique it is now estimated that there are millions of these unique or vanishingly small patient groups. Patients with diseases caused by ultra-rare mutations present challenges to the health care system that are as unique as their mutation. n-Lorem was founded to take advantage of the antisense technology that we created at Ionis to discover and develop personalized antisense oligonucleotides (ASOs) one patient at a time and provide those experimental ASO treatments for free for life. In our first 18 months of operation, we have demonstrated this goal is achievable and worked with the FDA to develop guidance for ASO treatment of patients with ultra-rare diseases. In this article, I define the problem, discuss the ASO solution, and our progress at n-Lorem to date. I then focus on important steps that we have taken to assure that these complex risk/benefit judgments are made with high quality and that each patient receives the highest quality ASO possible. I then describe the processes we have created to assure that the opportunity to learn from each patient and our aggregate experience are maximized and shared with all stakeholders.

Volanesorsen for treatment of familial chylomicronemia syndrome

INTRODUCTION

Familial chylomicronemia syndrome (FCS) is a rare subtype of severe hypertriglyceridemia that affects ~1 in 100, 000 to 1,000,000 individuals. The major risk to health is acute pancreatitis. FCS is defined by biallelic loss-of-function mutations in one of five canonical genes that encode proteins critical to lipolysis of large triglyceride-rich lipoprotein particles. Unlike the vast majority of patients with severe hypertriglyceridemia, FCS patients lack any lipolytic capacity and are thus resistant to standard medications.

AREAS COVERED

This review focuses on a mechanism that effectively reduces elevated triglyceride levels in FCS, namely interference of synthesis of apolipoprotein (apo) C-III. Volanesorsen is an antisense RNA drug administered subcutaneously that knocks down apo C-III, resulting in dramatic reductions in triglyceride levels both in FCS patients and in the wider population of subjects with severe hypertriglyceridemia.

EXPERT OPINION

Volanesorsen is a highly effective treatment to reduce elevated triglycerides in FCS patients, providing proof-of-concept of the validity of targeting apo C-III. However, off target effects of volanesorsen, including thrombocytopenia, may ultimately limit its use. Nonetheless, building on the knowledge derived from the volanesorsen experience, there is intensified interest in promising newer agents that also target apo C-III but have technical modifications that limit potential off target adverse effects.

Improvements in the Tolerability Profile of 2'-O-Methoxyethyl Chimeric Antisense Oligonucleotides in Parallel with Advances in Design, Screening, and Other Methods

The development process of antisense oligonucleotides (ASOs) as therapeutic agents in humans has advanced through the implementation of chemical compound modifications as well as increasingly sophisticated toxicological preclinical screening techniques. The Ionis Integrated Safety Database was utilized to determine if advances in ASO screening and clinical lead identification methods have improved the tolerability profiles of 2′-O-methoxyethyl (2′MOE)-modified ASOs as a class, relative to the first 2′MOE ASO approved for use in humans, mipomersen. Tolerability was assessed by the incidence and percentage of subcutaneous doses leading to adverse events at the injection site or flu-like reactions (FLRs), as well as by the incidence of dose discontinuations due to these events. In randomized placebo-controlled phase 1 and phase 2 trials, the incidence of each measure of tolerability was lower in the test group of 12 ASOs (713 ASO-treated subjects) compared with the reference, mipomersen (266 ASO-treated subjects); with the most marked reduction in the incidence of FLRs (0.6% vs. 9.4%). A similar reduction in the incidence of dose discontinuation due to FLRs was also observed (0.2% vs. 0.9%). When compared with mipomersen, 8 of 12 ASOs showed significant improvements in their respective mean percentage of doses leading to adverse events at the injection site, whereas 7 ASOs showed a significant improvement in mean percentage of doses leading to FLRs. These results support an overall improvement in the tolerability profile in 2′MOE ASOs that entered development after mipomersen, in parallel with advances in the drug discovery screening process as well as the gains in clinical experience during development of each ASO.

Current Status of Antisense Oligonucleotide-Based Therapy in Neuromuscular Disorders

Neuromuscular disorders include a wide range of diseases affecting the peripheral nervous system, which are primarily characterized by progressive muscle weakness and wasting. While there were no effective therapies until recently, several therapeutic approaches have advanced to clinical trials in the past few years. Among these, the antisense technology aiming at modifying RNA processing and function has remarkably progressed and a few antisense oligonucleotides (ASOs) have now been approved. Despite these recent clinical successes, several ASOs have also failed and clinical programs have been suspended, in most cases when the route of administration was systemic, highlighting the existing challenges notably with respect to effective ASO delivery. In this review we summarize the recent advances and current status of antisense based-therapies for neuromuscular disorders, using successful as well as unsuccessful examples to highlight the variability of outcomes depending on the target tissue and route of administration. We describe the different ASO-mediated therapeutic approaches, including splice-switching applications, steric-blocking strategies and targeted gene knock-down mediated by ribonuclease H recruitment. In this overview, we discuss the merits and challenges of the current ASO technology, and discuss the future of ASO development.

[RNA splicing modulation: Therapeutic progress and perspectives]

Advances in genetic and genomic research continue to increase our knowledge of hereditary diseases, and an increasing number of them are being attributed to aberrant splicing, thus representing ideal targets for RNA modulation therapies. New strategies to skip or re-include exons during the splicing process have emerged and are now widely evaluated in the clinic. Several drugs have recently been approved in particular for the treatment of Duchenne muscular dystrophy and spinal muscular atrophy. Among these molecules, antisense oligonucleotides, or ASOs, have gained increasing interest and have constantly been improved over the years through chemical modifications and design. However, their limited biodistribution following systemic administration still represents a major hurdle and the development of more potent alternative chemistries or new delivery systems has become a very active line of research in the past few years. In parallel, the use of small molecules with excellent biodistribution properties or of viral vectors to convey antisense sequences is also being investigated. In this review, we summarize the recent advances in splicing therapies through two examples of neuromuscular diseases and we discuss their main benefits and current limitations.

Targeted SMN Exon Skipping: A Useful Control to Assess In Vitro and In Vivo Splice-Switching Studies

The literature surrounding the use of antisense oligonucleotides continues to grow, with new disease and mechanistic applications constantly evolving. Furthermore, the discovery and advancement of novel chemistries continues to improve antisense delivery, stability and effectiveness. For each new application, a rational sequence design is recommended for each oligomer, as is chemistry and delivery optimization. To confirm oligomer delivery and antisense activity, a positive control AO sequence with well characterized target-specific effects is recommended. Here, we describe splice-switching antisense oligomer sequences targeting the ubiquitously expressed human and mouse SMN and Smn genes for use as control AOs for this purpose. We report two AO sequences that induce targeted skipping of SMN1/SMN2 exon 7 and two sequences targeting the Smn gene, that induce skipping of exon 5 and exon 7. These antisense sequences proved effective in inducing alternative splicing in both in vitro and in vivo models and are therefore broadly applicable as controls. Not surprisingly, we discovered a number of differences in efficiency of exon removal between the two species, further highlighting the differences in splice regulation between species.

Clinical review on triglycerides

Hypertriglyceridaemia is a common clinical problem. Epidemiologic and genetic studies have established that triglyceride-rich lipoproteins (TRL) and their remnants as important contributors to ASCVD while severe hypertriglyceridaemia raises risk of pancreatitis. While low-density lipoprotein is the primary treatment target for lipid lowering therapy, secondary targets that reflect the contribution of TRL such as apoB and non-HDL-C are recommended in the current guidelines. Reduction of severely elevated triglycerides is important to avert or reduce the risk of pancreatitis. Here we discuss interventions for hypertriglyceridaemia, including diet and lifestyle, established treatments such as fibrates and omega-3 fatty acid preparations and emerging therapies, including various biological agents.

Nusinersen treatment in adult patients with spinal muscular atrophy: a safety analysis of laboratory parameters

Background

Nusinersen is an intrathecally administered antisense oligonucleotide (ASO) that improves motor function in patients with spinal muscular atrophy (SMA). In addition to efficacy, the safety of a therapy is the decisive factor for the success of the treatment. For some ASOs, various organ toxicities have been described, such as thrombocytopenia, renal and liver impairment, or coagulation abnormalities. However, systematic data on laboratory parameters under treatment with nusinersen are mainly available from studies in infants and children. Therefore, our aim was to assess the safety of nusinersen therapy in adult SMA patients.

Methods

Laboratory data from 404 nusinersen injections performed in 50 adult patients with SMA type 2 and type 3 were retrospectively analyzed.

Results

The total observation period was 76.9 patient-years, and patients received up to 12 injections. Our data provides no new safety concerns. In cerebrospinal fluid (CSF), the mean white blood cell count and lactate remained stable over time. Total CSF protein increased by 2.9 mg/dL. No change in mean platelet count was observed under therapy. Only one patient showed sporadic mild thrombocytopenia. Coagulation parameters and inflammatory markers were stable. The mean creatinine level decreased by 0.09 mg/dL. Analysis of mean liver enzyme levels revealed no relevant changes during treatment.

Conclusion

Our data demonstrate a favorable safety profile of nusinersen therapy in adult SMA patients under longer-term “real-world” conditions. In particular, we found no evidence of clinically relevant platelet declines, coagulopathies, or renal or hepatic organ toxicities, which are common concerns with the use of ASOs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10569-8.

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.

Safety and efficacy of nusinersen in spinal muscular atrophy: The EMBRACE study

Introduction

The EMBRACE study (Clinical Trials No. NCT02462759) evaluated nusinersen in infants/children with infantile‐ or later‐onset spinal muscular atrophy (SMA) who were ineligible for the ENDEAR and CHERISH studies.

Methods

Participants were randomized to intrathecal nusinersen (12‐mg scaled equivalent dose; n = 14) or sham procedure (n = 7) in part 1 (~14 months) and subsequently received open‐label nusinersen for ~24 months in part 2 of the study.

Results

Part 1 was stopped early after the demonstration of motor function benefit with nusinersen in ENDEAR. There were no nusinersen‐related adverse events (AEs) and no study discontinuations due to nusinersen‐related AEs. The most common AEs included pyrexia, cough, pneumonia, and upper respiratory tract infections. Motor milestone responder rates were higher in those receiving nusinersen at last available assessment (93%) than in those receiving sham procedure in part 1 (29%) or transitioned from sham to nusinersen in part 2 (83%). This functional improvement was observed despite the small sample size and shortened part 1 trial duration that undermined the power of the study to demonstrate such treatment effects at a significant level.

Discussion

Nusinersen demonstrated a favorable long‐term benefit‐risk profile in this broad population of individuals with infantile‐ or later‐onset SMA.

Sequence-specific 2'-O-methoxyethyl antisense oligonucleotides activate human platelets through glycoprotein VI, triggering formation of platelet-leukocyte aggregates

Antisense oligonucleotides (ASO) are DNA-based, disease-modifying drugs. Clinical trials with 2'-O-methoxyethyl (2’MOE) ASO have shown dose- and sequence-specific lowering of platelet counts according to two phenotypes. Phenotype 1 is a moderate (but not clinically severe) drop in platelet count. Phenotype 2 is rare, severe thrombocytopenia. This article focuses on the underlying cause of the more common phenotype 1, investigating the effects of ASO on platelet production and platelet function. Five phosphorothioate ASO were studied: three 2’MOE sequences; 487660 (no effects on platelet count), 104838 (associated with phenotype 1), and 501861 (effects unknown) and two CpG sequences; 120704 and ODN 2395 (known to activate platelets). Human cord bloodderived megakaryocytes were treated with these ASO to study their effects on proplatelet production. Platelet activation (determined by surface P-selectin) and platelet-leukocyte aggregates were analyzed in ASO-treated blood from healthy human volunteers. None of the ASO inhibited proplatelet production by human megakaryocytes. All the ASO were shown to bind to the platelet receptor glycoprotein VI (KD ~0.2-1.5 μM). CpG ASO had the highest affinity to glycoprotein VI, the most potent platelet-activating effects and led to the greatest formation of platelet-leukocyte aggregates. 2’MOE ASO 487660 had no detectable platelet effects, while 2’MOE ASOs 104838 and 501861 triggered moderate platelet activation and SYKdependent formation of platelet-leukocyte aggregates. Donors with higher platelet glycoprotein VI levels had greater ASO-induced platelet activation. Sequence-dependent ASO-induced platelet activation and platelet-leukocyte aggregates may explain phenotype 1 (moderate drops in platelet count). Platelet glycoprotein VI levels could be useful as a screening tool to identify patients at higher risk of ASO-induced platelet side effects.

Pharmacokinetics and Proceedings in Clinical Application of Nucleic Acid Therapeutics

Oligonucleotide therapeutics are a novel promising class of drugs designed to specifically target either coding or non-coding RNA molecules to revolutionize treatment of various diseases. During preclinical development, investigations of the pharmacokinetic characteristics of these oligonucleotide-based drug candidates are essential. Oligonucleotides possess a long history of chemical modifications to enhance their stability and binding affinity, as well as reducing toxicity. Phosphorothioate backbone modifications of oligonucleotides were a hallmark of this development process that greatly enhanced plasma stability and protein binding of these agents. Modifications such as 2'-O-methylation further improved stability, while other modifications of the ribose, such as locked nucleic acid (LNA) modification, significantly increased binding affinity, potency, and tissue half-life. These attributes render oligonucleotide therapeutics able to regulate protein expression in both directions depending on the target RNA. Thus, a growing interest has emerged using these oligonucleotides in the treatment of neurodegenerative and cardiac disorders as well as cancer, since the deregulation of certain coding and non-coding RNAs plays a key role in the development of these diseases. Cutting edge research is being performed in the field of non-coding RNAs, identifying potential therapeutic targets, and developing novel oligonucleotide-based agents that outperform classical drugs. Some of these agents are either in clinical trials showing promising results or are already US Food and Drug Administration (FDA) approved, with more oligonucleotides being developed for therapeutic purposes. This is the advent of mechanism-based next-generation therapeutics for a wide range of diseases.

Effectiveness and safety of lomitapide in a patient with familial chylomicronemia syndrome

BACKGROUND

Familial chylomicronemia syndrome (FCS) is characterized by severe fasting hypertriglyceridemia, abdominal pain, and recurrent acute pancreatitis. Available triglyceride-lowering drugs are insufficient to avoid pancreatitis. Therefore, there is a significant unmet medical need for effective triglyceride-lowering drugs for patients with FCS.

CASE REPORT

We report the second case of a patient with FCS and recurrent pancreatitis treated with lomitapide. Lomitapide treatment resulted in a reduction of fasting TG levels from 2897 mg/dL (32.71 mmol/L) to an average of 954 mg/dL (10.77 mmol/L) on the 30 mg lomitapide equating to a 67% reduction from baseline. After 26 months of lomitapide treatment, histological activity score for hepatic fibrosis was stable although liver biopsy showed a marked increase of liver steatosis and mild perivenular and perisinusoidal fibrosis.

CONCLUSIONS

Lomitapide is effective in reducing triglycerides in FCS and preventing the recurrence of acute pancreatitis. A longer follow-up is necessary to evaluate long-term risk of progression toward severe stages of liver fibrosis. A prospective clinical trial may identify which subgroup of FCS patients would benefit from lomitapide treatment in the absence of significant liver adverse effects.

Antisense oligonucleotides and nucleic acids generate hypersensitive platelets

INTRODUCTION

Despite the great promise for therapies using antisense oligonucleotides (ASOs), their adverse effects, which include pro-inflammatory effects and thrombocytopenia, have limited their use. Previously, these effects have been linked to the phosphorothioate (PS) backbone necessary to prevent rapid ASO degradation in plasma. The main aim of this study was to assess the impact of the nucleic acid portion of an ASO-type drug on platelets and determine if it may contribute to thrombosis or thrombocytopenia.

METHODS

Platelets were isolated from healthy donors and men with advanced prostate cancer. Effects of antisense oligonucleotides (ASO), oligonucleotides, gDNA, and microRNA on platelet activation and aggregation were evaluated. A mouse model of lung thrombosis was used to confirm the effects of PS-modified oligonucleotides in vivo.

RESULTS

Platelet exposure to gDNA, miRNA, and oligonucleotides longer than 16-mer at a concentration above 8 mM resulted in the formation of hypersensitive platelets, characterized by an increased sensitivity to low-dose thrombin (0.1 nM) and increase in p-Selectin expression (6-8 fold greater than control; p < 0.001). The observed nucleic acid (NA) effects on platelets were toll-like receptor (TLR) -7 subfamily dependent. Injection of a p-Selectin inhibitor significantly (p = 0.02) reduced the formation of oligonucleotide-associated pulmonary microthrombosis in vivo.

CONCLUSION

Our results suggest that platelet exposure to nucleic acids independent of the presence of a PS modification leads to a generation of hypersensitive platelets and requires TLR-7 subfamily receptors. ASO studies conducted in cancer patients may benefit from testing the ASO effects on platelets ex vivo before initiation of patient treatment.

Opportunities and challenges for antisense oligonucleotide therapies

Antisense oligonucleotide (AON) therapies involve short strands of modified nucleotides that target RNA in a sequence-specific manner, inducing targeted protein knockdown or restoration. Currently, 10 AON therapies have been approved in the United States and Europe. Nucleotides are chemically modified to protect AONs from degradation, enhance bioavailability and increase RNA affinity. Whereas single stranded AONs can efficiently be delivered systemically, delivery of double stranded AONs requires capsulation in lipid nanoparticles or binding to a conjugate as the uptake enhancing backbone is hidden in this conformation. With improved chemistry, delivery vehicles and conjugates, doses can be lowered, thereby reducing the risk and occurrence of side effects. AONs can be used to knockdown or restore levels of protein. Knockdown can be achieved by single stranded or double stranded AONs binding the RNA transcript and activating RNaseH-mediated and RISC-mediated degradation respectively. Transcript binding by AONs can also prevent translation, hence reducing protein levels. For protein restoration, single stranded AONs are used to modulate pre-mRNA splicing and either include or skip an exon to restore protein production. Intervening at a genetic level, AONs provide therapeutic options for inherited metabolic diseases as well. This review provides an overview of the different AON approaches, with a focus on AONs developed for inborn errors of metabolism.

Antisense technology: A review

Antisense technology is beginning to deliver on the broad promise of the technology. Ten RNA-targeted drugs including eight single-strand antisense drugs (ASOs) and two double-strand ASOs (siRNAs) have now been approved for commercial use, and the ASOs in phase 2/3 trials are innovative, delivered by multiple routes of administration and focused on both rare and common diseases. In fact, two ASOs are used in cardiovascular outcome studies and several others in very large trials. Interest in the technology continues to grow, and the field has been subject to a significant number of reviews. In this review, we focus on the molecular events that result in the effects observed and use recent clinical results involving several different ASOs to exemplify specific molecular mechanisms and specific issues. We conclude with the prospective on the technology.

Apolipoprotein CIII and Angiopoietin-like Protein 8 are Elevated in Lipodystrophy and Decrease after Metreleptin

Context

Lipodystrophy syndromes cause hypertriglyceridemia that improves with leptin treatment using metreleptin. Mechanisms causing hypertriglyceridemia and improvements after metreleptin are incompletely understood.

Objective

Determine relationship of circulating lipoprotein lipase (LPL) modulators with hypertriglyceridemia in healthy controls and in patients with lipodystrophy before and after metreleptin.

Methods

Cross-sectional comparison of patients with lipodystrophy (generalized lipodystrophy n = 3; partial lipodystrophy n = 11) vs age/sex-matched healthy controls (n = 28), and longitudinal analyses in patients before and after 2 weeks and 6 months of metreleptin. The study was carried out at the National Institutes of Health, Bethesda, Maryland. Outcomes were LPL stimulators apolipoprotein (apo) C-II and apoA-V and inhibitors apoC-III and angiopoietin-like proteins (ANGPTLs) 3, 4, and 8; ex vivo activation of LPL by plasma.

Results

Patients with lipodystrophy were hypertriglyceridemic and had higher levels of all LPL stimulators and inhibitors vs controls except for ANGPTL4, with >300-fold higher ANGPTL8, 4-fold higher apoC-III, 3.5-fold higher apoC-II, 1.9-fold higher apoA-V, 1.6-fold higher ANGPTL3 (P < .05 for all). At baseline, all LPL modulators except ANGPLT4 positively correlated with triglycerides. Metreleptin decreased apoC-II and apoC-III after 2 weeks and 6 months, and decreased ANGPTL8 after 6 months (P < 0.05 for all). Plasma from patients with lipodystrophy caused higher ex vivo LPL activation vs hypertriglyceridemic control plasma (P < .0001), which did not change after metreleptin.

Conclusion

Elevations in LPL inhibitors apoC-III and ANGPTL8 may contribute to hypertriglyceridemia in lipodystrophy, and may mediate reductions in circulating and hepatic triglycerides after metreleptin. These therefore are strong candidates for therapies to lower triglycerides in these patients.

Outcomes of the European Federation of Pharmaceutical Industries and Associations Oligonucleotide Working Group Survey on Nonclinical Practices and Regulatory Expectations for Therapeutic Oligonucleotide Safety Assessment

The Oligonucleotide Working Group of the European Federation of Pharmaceutical Industries and Associations (EFPIA) conducted a survey of companies to understand the trends in nonclinical practices and regulatory expectations for oligonucleotide drug safety assessment. Twenty-two companies of different types, with varying oligonucleotide experience levels in the field, participated. The survey identified key regulatory challenges and areas of perceived health authority (HA) concern regarding nonclinical safety strategies for oligonucleotides, such as the choice of toxicology species, approaches to dose setting in toxicity studies, dose scaling from animals to humans, the implementation (and regulatory acceptability) of lean packages, and methods for dealing with impurities and human-specific off-targets. The perceived oligonucleotide experience of HAs and the relevance of guidance to oligonucleotide development were also assessed. The results showed a general lack of consensus on nonclinical safety assessment approaches being used for this growing class of medicines and highlight the need for continuing collaboration between sponsors and HAs to better define best practices.