Factor XI inhibition in hemodialysis patients: the safer anticoagulation?

Chronic hemodialysis patients exhibit an excessive cardiovascular risk and a marked increase in both thromboembolism and bleeding episodes. Factor XI inhibition may provide anticoagulation, with a low risk of bleeding, and several factor XI inhibitors, including fesomersen, an antisense oligonucleotide, are under development. Recently, a phase 2 study of fesomersen showed a good safety profile in chronic hemodialysis patients and suggested that clotting rates of the arteriovenous fistula and the dialysis circuit are lower.

Efficacy and Safety of Donidalorsen for Hereditary Angioedema.

BACKGROUND: Hereditary angioedema is a rare disorder characterized by episodic, potentially life-threatening swelling caused by kallikrein-kinin dysregulation. Long-term prophylaxis can stabilize this system. Donidalorsen, an antisense oligonucleotide, specifically reduces prekallikrein expression. METHODS: In this phase 3, double-blind, randomized trial, we assigned patients with hereditary angioedema to receive donidalorsen (80 mg subcutaneously) or placebo once every 4 or 8 weeks. The primary end point was the time-normalized number of investigator-confirmed hereditary angioedema attacks per 4 weeks (attack rate) from week 1 to week 25. RESULTS: A total of 90 patients received donidalorsen every 4 weeks (45 patients), donidalorsen every 8 weeks (23 patients), or placebo (22 patients). The least-squares mean time-normalized attack rate was 0.44 (95% CI, 0.27 to 0.73) in the 4-week group, 1.02 (95% CI, 0.65 to 1.59) in the 8-week group, and 2.26 (95% CI, 1.66 to 3.09) in the placebo group. The mean attack rate from week 1 to week 25 was 81% lower (95% CI, 65 to 89) in the 4-week group than in the placebo group (P<0.001) and 55% lower (95% CI, 22 to 74) in the 8-week group than in the placebo group (P = 0.004); the median reduction in the attack rate from baseline was 90% in the 4-week group, 83% in the 8-week group, and 16% in the placebo group. The mean attack rate during weeks 5 to 25 was 87% lower (95% CI, 72 to 94) in the 4-week group than in the placebo group (P<0.001) and 60% lower (95% CI, 25 to 79) in the 8-week group than in the placebo group. Donidalorsen administered every 4 weeks resulted in an improvement in the least-squares mean total score for the change at week 25 on the Angioedema Quality-of-Life Questionnaire (scores range from 0 to 100, with a score of 100 indicating the worst possible quality of life) that was 18.6 points (95% CI, 9.5 to 27.7) better than that with placebo (P<0.001). The most common adverse events were erythema at the injection site, headache, and nasopharyngitis; 98% of adverse events were mild or moderate in severity. CONCLUSIONS: Donidalorsen treatment reduced the hereditary angioedema attack rate, a finding that supports potential prophylactic use for hereditary angioedema. (Funded by Ionis Pharmaceuticals; OASIS-HAE ClinicalTrials.gov number, NCT05139810.).

Olezarsen for Hypertriglyceridemia in Patients at High Cardiovascular Risk.

BACKGROUND: Reducing the levels of triglycerides and triglyceride-rich lipoproteins remains an unmet clinical need. Olezarsen is an antisense oligonucleotide targeting messenger RNA for apolipoprotein C-III (APOC3), a genetically validated target for triglyceride lowering. METHODS: In this phase 2b, randomized, controlled trial, we assigned adults either with moderate hypertriglyceridemia (triglyceride level, 150 to 499 mg per deciliter) and elevated cardiovascular risk or with severe hypertriglyceridemia (triglyceride level, ≥500 mg per deciliter) in a 1:1 ratio to either a 50-mg or 80-mg cohort. Patients were then assigned in a 3:1 ratio to receive monthly subcutaneous olezarsen or matching placebo within each cohort. The primary outcome was the percent change in the triglyceride level from baseline to 6 months, reported as the difference between each olezarsen group and placebo. Key secondary outcomes were changes in levels of APOC3, apolipoprotein B, non-high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol. RESULTS: A total of 154 patients underwent randomization at 24 sites in North America. The median age of the patients was 62 years, and the median triglyceride level was 241.5 mg per deciliter. The 50-mg and 80-mg doses of olezarsen reduced triglyceride levels by 49.3 percentage points and 53.1 percentage points, respectively, as compared with placebo (P<0.001 for both comparisons). As compared with placebo, each dose of olezarsen also significantly reduced the levels of APOC3, apolipoprotein B, and non-HDL cholesterol, with no significant change in the LDL cholesterol level. The risks of adverse events and serious adverse events were similar in the three groups. Clinically meaningful hepatic, renal, or platelet abnormalities were uncommon, with similar risks in the three groups. CONCLUSIONS: In patients with predominantly moderate hypertriglyceridemia at elevated cardiovascular risk, olezarsen significantly reduced levels of triglycerides, apolipoprotein B, and non-HDL cholesterol, with no major safety concerns identified. (Funded by Ionis Pharmaceuticals; Bridge-TIMI 73a ClinicalTrials.gov number, NCT05355402.).

The safety and toxicity profile of SPL84, an inhaled antisense oligonucleotide for treatment of cystic fibrosis patients with the 3849 +10kb C->T mutation, supports a Phase 1/2 clinical study.

INTRODUCTION: SPL84 is an inhaled antisense oligonucleotide (ASO) in development for the treatment of cystic fibrosis (CF) patients carrying the 3849 + 10kb C->T (3849) mutation. To support the initiation of the first clinical study, a full battery of safety and toxicology studies were performed. RESEARCH DESIGN AND METHODS: SPL84 was administered by inhalation to mice and monkeys to determine the no observed adverse effect level (NOAEL) and establish sufficient safety margins for the starting clinical dose. RESULTS: There were no preclinical safety findings with SPL84; no related clinical signs, nor any effect on body weight, food consumption, or clinical pathology. The microscopic changes in the lungs were regarded as non-adverse and reflected a normal clearance process for inhaled compounds. Systemic exposure in both species was low. The NOAEL for mice and monkeys was the highest administered dose in both species, resulting in safety margins ~ 40X the proposed starting clinical dose. CONCLUSION: These successful results supported the initiation of a phase 1/2 clinical study of SPL84 (ongoing), assessing the safety, tolerability, and pharmacokinetics of a single ascending dose in healthy subjects to be followed by assessment of safety, tolerability, pharmacokinetics, and preliminary efficacy of multiple ascending doses in CF patients carrying the 3849 mutation.

Bepirovirsen (GSK3228836) in chronic hepatitis B infection: an evaluation of phase II progress.

INTRODUCTION: Chronic hepatitis B infection is a major global health issue associated with significant liver-related morbidity and mortality. While existing treatments can suppress the virus effectively, they are incapable of inducing functional cure, as defined by hepatitis B surface antigen (HBsAg) seroclearance. Currently, numerous novel compounds are being developed, including bepirovirsen, an antisense oligonucleotide (ASO). AREAS COVERED: This review summarizes the mechanism of action, pharmacokinetics, clinical efficacy and safety data collected from phase I and II studies of bepirovirsen. The data were extracted from publications relevant to the pivotal trials of bepirovirsen, in either full manuscript or conference abstracts. EXPERTOPINION: Bepirovirsen, a 20-mer ASO, has already entered phase III clinical evaluation using the optimal dosing regimen of 300 mg subcutaneous injection weekly for 24 weeks in nucleoside analogue-treated HBeAg-negative non-cirrhotic patients with low (<3000 IU/mL) baseline HBsAg. The durability and long-term clinical outcomes among Bepirovirsen responders will need to be evaluated. The stop-to-cure approach in those reaching HBsAg < 100 IU/mL should also be explored. In the long run, Bepirovirsen has the potential to facilitate viral hepatitis elimination.

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.

Eplontersen for Hereditary Transthyretin Amyloidosis With Polyneuropathy.

Importance: Transthyretin gene silencing is an emerging treatment strategy for hereditary transthyretin (ATTRv) amyloidosis. Objective: To evaluate eplontersen, an investigational ligand-conjugated antisense oligonucleotide, in ATTRv polyneuropathy. Design, Setting, and Participants: NEURO-TTRansform was an open-label, single-group, phase 3 trial conducted at 40 sites across 15 countries (December 2019-April 2023) in 168 adults with Coutinho stage 1 or 2 ATTRv polyneuropathy, Neuropathy Impairment Score 10-130, and a documented TTR variant. Patients treated with placebo from NEURO-TTR (NCT01737398; March 2013-November 2017), an inotersen trial with similar eligibility criteria and end points, served as a historical placebo ("placebo") group. Interventions: Subcutaneous eplontersen (45 mg every 4 weeks; n = 144); a small reference group received subcutaneous inotersen (300 mg weekly; n = 24); subcutaneous placebo weekly (in NEURO-TTR; n = 60). Main Outcomes and Measures: Primary efficacy end points at week 65/66 were changes from baseline in serum transthyretin concentration, modified Neuropathy Impairment Score +7 (mNIS+7) composite score (scoring range, -22.3 to 346.3; higher scores indicate poorer function), and Norfolk Quality of Life Questionnaire-Diabetic Neuropathy (Norfolk QoL-DN) total score (scoring range, -4 to 136; higher scores indicate poorer quality of life). Analyses of efficacy end points were based on a mixed-effects model with repeated measures adjusted by propensity score weights. Results: Among 144 eplontersen-treated patients (mean age, 53.0 years; 69% male), 136 (94.4%) completed week-66 follow-up; among 60 placebo patients (mean age, 59.5 years; 68% male), 52 (86.7%) completed week-66 follow-up. At week 65, adjusted mean percentage reduction in serum transthyretin was -81.7% with eplontersen and -11.2% with placebo (difference, -70.4% [95% CI, -75.2% to -65.7%]; P < .001). Adjusted mean change from baseline to week 66 was lower (better) with eplontersen vs placebo for mNIS+7 composite score (0.3 vs 25.1; difference, -24.8 [95% CI, -31.0 to -18.6; P < .001) and for Norfolk QoL-DN (-5.5 vs 14.2; difference, -19.7 [95% CI, -25.6 to -13.8]; P < .001). Adverse events by week 66 that led to study drug discontinuation occurred in 6 patients (4%) in the eplontersen group vs 2 (3%) in the placebo group. Through week 66, there were 2 deaths in the eplontersen group consistent with known disease-related sequelae (cardiac arrhythmia; intracerebral hemorrhage); there were no deaths in the placebo group. Conclusions and Relevance: In patients with ATTRv polyneuropathy, the eplontersen treatment group demonstrated changes consistent with significantly lowered serum transthyretin concentration, less neuropathy impairment, and better quality of life compared with a historical placebo. Trial Registration: ClinicalTrials.gov Identifier: NCT04136184; EU Clinical Trials Register: EudraCT 2019-001698-10.

Systemic administration of the antisense oligonucleotide NS-089/NCNP-02 for skipping of exon 44 in patients with Duchenne muscular dystrophy: Study protocol for a phase I/II clinical trial.

AIM: The purpose of this study is to evaluate the safety and pharmacokinetics of the novel morpholino oligomer NS-089/NCNP-02 which can induce exon 44 skipping, in patients with DMD. Additionally, we aimed to identify markers predictive of therapeutic efficacy and determine the optimal dosing for future studies. METHODS: This is an open-label, dose-escalation, two-center phase I/II trial in ambulant patients with DMD, presence of an out-of-frame deletion, and a mutation amenable to exon 44 skipping. Part 1 is a stepwise dose-finding stage (4 weeks) during which NS-089/NCNP-02 will be administered intravenously at four dose levels once weekly (1.62, 10, 40, and 80 mg/kg); Part 2 is a 24-week evaluation period based on the dosages determined during Part 1. The primary (safety) endpoints are the results of physical examinations, vital signs, 12-lead electrocardiogram and echocardiography tests, and adverse event reporting. Secondary endpoints include expression of dystrophin protein, motor function assessment, exon 44 skipping efficiency, plasma and urinary NS-089/NCNP-02 concentrations, and changes in blood creatine kinase levels. DISCUSSION: Exon-skipping therapy using ASOs shows promise in selected patients, and this first-in-human study is expected to provide critical information for subsequent clinical development of NS-089/NCNP-02.

Potential Novel RNA-Targeting Agents for Effective Lipoprotein(a) Lowering: A Systematic Assessment of the Evidence From Completed and Ongoing Developmental Clinical Trials.

ABSTRACT: An increase in blood lipoprotein (a) [Lp(a)] levels, mostly genetically determined, has been identified as an independent risk factor of atherosclerotic cardiovascular disease. No drug has yet been approved that markedly lowers Lp(a) and thereby reduces residual cardiovascular risk. The aim of this article was to critically review the evidence from clinical development studies to date on the efficacy and safety of new RNA-based therapeutics for targeted lowering of Lp(a). PubMed/MEDLINE, Scopus, Web of Science, and ClinicalTrials.gov were searched without any language or date restriction up to November 5, 2022, and a total of 12 publications and 22 trial records were included. Several drugs were found that are currently in various stages of clinical development, such as the antisense oligonucleotide pelacarsen and the small interfering RNA molecule olpasiran and drugs coded as SLN360 and LY3819469. Among them, pelacarsen has progressed the most, currently reaching phase 3. All these drugs have so far shown satisfactory pharmacokinetic properties, consistently high and stable, dose-dependent efficacy in lowering Lp(a) even by more than 90%, with an acceptable safety profile in subjects with highly elevated Lp(a). In addition, reports of early clinical trials with pelacarsen imply a promising suppressive effect on key mechanisms of atherogenesis. Future research should focus on confirming these beneficial clinical effects in patients with lower average Lp(a) levels and clearly demonstrating the association between lowering Lp(a) and reducing adverse cardiovascular outcomes.

Correlations between preclinical BJAB assay ranking of antisense drugs and clinical trial adverse events.

This analysis sought to assess the clinical predictivity of an in vitro assay which utilized the human B-lymphoma BJAB cell line, for identification of antisense oligonucleotides (ASOs) with the potential to elicit innate immune activation in humans. Adverse events (AEs) from clinical trial data were analyzed based on prior clinical knowledge and network analysis of the clinical data to identify correlations with the BJAB assay. Clinically evaluated ASOs were ranked by the BJAB assay's mean log-fold increase in TNF expression levels. Flu-like reactions (FLRs) and injection site reactions (ISRs), were chosen as AEs of interest, along with those Medical Dictionary for Regulatory Activities preferred terms identified using AE network analysis. Fifteen different 2'-O-methoxyethyl (2'MOE) modified ASOs were ranked by the incidence of each AE group in the integrated safety data from 35 clinical trials. ISRs are considered to be local to the injection site, whereas FLRs are reflected by systemic constitutional symptoms. The correlations identified in this analysis of integrated clinical data provide evidence that the ASO sequences selected by the BJAB assay have a lower likelihood of causing systemic inflammatory AEs associated with FLRs, but not ISRs.

Efficacy and Safety of Bepirovirsen in Chronic Hepatitis B Infection.

BACKGROUND: Bepirovirsen is an antisense oligonucleotide that targets all hepatitis B virus (HBV) messenger RNAs and acts to decrease levels of viral proteins. METHODS: We conducted a phase 2b, randomized, investigator-unblinded trial involving participants with chronic HBV infection who were receiving or not receiving nucleoside or nucleotide analogue (NA) therapy. Participants were randomly assigned (in a 3:3:3:1 ratio) to receive weekly subcutaneous injections of bepirovirsen at a dose of 300 mg for 24 weeks (group 1), bepirovirsen at a dose of 300 mg for 12 weeks then 150 mg for 12 weeks (group 2), bepirovirsen at a dose of 300 mg for 12 weeks then placebo for 12 weeks (group 3), or placebo for 12 weeks then bepirovirsen at a dose of 300 mg for 12 weeks (group 4). Groups 1, 2, and 3 received loading doses of bepirovirsen. The composite primary outcome was a hepatitis B surface antigen (HBsAg) level below the limit of detection and an HBV DNA level below the limit of quantification maintained for 24 weeks after the planned end of bepirovirsen treatment, without newly initiated antiviral medication. RESULTS: The intention-to-treat population comprised 457 participants (227 receiving NA therapy and 230 not receiving NA therapy). Among those receiving NA therapy, a primary-outcome event occurred in 6 participants (9%; 95% credible interval, 0 to 31) in group 1, in 6 (9%; 95% credible interval, 0 to 43) in group 2, in 2 (3%; 95% credible interval, 0 to 16) in group 3, and 0 (0%; post hoc credible interval, 0 to 8) in group 4. Among participants not receiving NA therapy, a primary-outcome event occurred in 7 participants (10%; 95% credible interval, 0 to 38), 4 (6%; 95% credible interval, 0 to 25), 1 (1%; post hoc credible interval, 0 to 6), and 0 (0%; post hoc credible interval, 0 to 8), respectively. During weeks 1 through 12, adverse events, including injection-site reactions, pyrexia, fatigue, and increased alanine aminotransferase levels, were more common with bepirovirsen (groups 1, 2, and 3) than with placebo (group 4). CONCLUSIONS: In this phase 2b trial, bepirovirsen at a dose of 300 mg per week for 24 weeks resulted in sustained HBsAg and HBV DNA loss in 9 to 10% of participants with chronic HBV infection. Larger and longer trials are required to assess the efficacy and safety of bepirovirsen. (Funded by GSK; B-Clear ClinicalTrials.gov number, NCT04449029.).

Safety, tolerability, pharmacokinetics and preliminary antitumour activity of an antisense oligonucleotide targeting STAT3 (danvatirsen) as monotherapy and in combination with durvalumab in Japanese patients with advanced solid malignancies: a phase 1 study.

OBJECTIVES: We assessed the safety, tolerability, pharmacokinetics, preliminary antitumour activity and pharmacodynamics of danvatirsen, an antisense oligonucleotide targeting signal transducer and activator of transcription 3 (STAT3), monotherapy and danvatirsen plus durvalumab, an antiprogrammed cell death ligand 1 monoclonal antibody, in patients with advanced solid malignancies. DESIGN: Phase 1, open-label study with two cohorts. SETTING: Two centres in Japan. PARTICIPANTS: Japanese individuals aged ≥20 years, with histologically confirmed solid malignancies, except for hepatocellular carcinoma, refractory to standard therapy. INTERVENTIONS: In cohort 1, patients received danvatirsen monotherapy; in cohort 2, patients received danvatirsen plus durvalumab combination therapy. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary endpoint was safety and tolerability based on adverse events (AEs). Secondary endpoints were pharmacokinetics, immunogenicity, antitumour activity and pharmacodynamics. RESULTS: Eleven patients were assigned to treatment and included in the analysis. Danvatirsen dose reductions were only required in cohort 2 for hepatic function abnormal (alanine aminotransferase (ALT)/ aspartate aminotransferase (AST)/gamma-glutamyl transferase (γGT) increased), neutrophil count decreased and platelet count decreased. One patient experienced grade 3 ALT/AST increased and new appearance of eosinophilia as a dose-limiting toxicity. AEs were reported in 90.9% (10/11) patients. Commonly reported AEs causally related to the danvatirsen were platelet count decreased (60% (3/5)) and ALT/AST/γGT increased (50% (3/6)) in cohorts 1 and 2, respectively; none was causally related to durvalumab. One serious AE occurred in cohort 1 (pancreatitis; unrelated to study treatment). One case of ALT/AST/γGT increased occurred in cohort 2, leading to discontinuation. No AEs led to death. Danvatirsen did not accumulate in plasma after multiple dosing. In cohort 2, three patients had disease control at 12 weeks and one had unconfirmed partial response. STAT3 expression tended to decrease regardless of monotherapy or combination therapy. CONCLUSIONS: Danvatirsen was well tolerated by Japanese patients with advanced solid tumours as monotherapy and combined with durvalumab. No new safety signals arose. TRIAL REGISTRATION NUMBER: NCT03394144; ClinicalTrials.gov.

RNA-targeted therapeutics in cardiovascular disease: the time is now.

Ribonucleic acid (RNA)-targeted therapeutics, including antisense oligonucleotide technologies as well as small interfering RNAs (siRNAs), represent a new class of medications that may overcome several of the disadvantages of small molecule drugs or monoclonal antibodies. Specifically, upstream targeting at the messenger RNA (mRNA) level renders any disease-related protein a potential target, even those pathways previously deemed 'undruggable'. Additional advantages include the comparably simple and cost-effective way of manufacturing and the long dosing intervals. A few agents are already approved and a wide array of cardiovascular drugs is in development, aimed at hypercholesterolaemia, hypertension, myocardial storage diseases, and the coagulation system. Here, we provide an update on the current status of RNA-targeted therapeutics in the cardiovascular arena.

AZD8233 antisense oligonucleotide targeting PCSK9 does not prolong QT interval.

AIMS: AZD8233 is a proprotein convertase subtilisin/kexin type 9 (PCSK9) antisense oligonucleotide under development for treatment of hypercholesterolaemia. A prespecified concentration-QT analysis was performed based on data from a single ascending dose study that was prospectively designed to act as a TQT study substitute. METHODS: Subcutaneous single doses ranging from 4 to 120 mg were evaluated in 73 adult healthy male subjects. Time-matched 12-lead digital ECG and plasma concentrations (n = 15) were measured at baseline and up to 48 hours after dose in each subject. The analysis was performed using a linear mixed effect model, where change from baseline QTc (ΔQTc) was a dependent variable and time-matched AZD8233 concentration was an independent variable. RESULTS: The high clinical exposure scenario was defined as 1.7-fold the expected Cmax following an assumed therapeutic dose of 60 mg, which corresponds to AZD8233 plasma concentration of 1.39 µg/mL. Estimated placebo-corrected and baseline-adjusted QTcF interval (ΔΔQTcF) at this concentration was -2.2 ms (90% CI: -4.11, -0.28). Furthermore, the upper 90% ΔΔQTcF confidence interval was estimated to be below 10 ms at all observed concentrations. CONCLUSION: As the effect on ΔΔQTcF is below the threshold for regulatory concern (10 ms), it can be concluded that AZD8233 does not induce QTcF prolongation at the high clinical exposure scenario.

Safety and efficacy of therapies for chylomicronemia.

INTRODUCTION: Primary chylomicronemia is characterized by pathological accumulation of chylomicrons in the plasma causing severe hypertriglyceridemia, typically >10 mmol/L (>875 mg/dL). Patients with the ultra-rare familial chylomicronemia syndrome (FCS) subtype completely lack lipolytic capacity and respond minimally to traditional triglyceride-lowering therapies. The mainstay of treatment is a low-fat diet, which is difficult to follow and compromises quality of life. New therapies are being developed primarily to prevent episodes of life-threatening acute pancreatitis. AREAS COVERED: Antagonists of apolipoprotein (apo) C-III, such as the antisense oligonucleotide (ASO) volanesorsen, significantly reduce triglyceride levels in chylomicronemia. However, approval of and access to volanesorsen are restricted since a substantial proportion of treated FCS patients developed thrombocytopenia. Newer apo C-III antagonists, namely, the ASO olezarsen (formerly AKCEA-APOCIII-LRx) and short interfering RNA (siRNA) ARO-APOC3, appear to show efficacy with less risk of thrombocytopenia. Potential utility of antagonists of angiopoietin-like protein 3 (ANGPTL3) such as evinacumab and the siRNA ARO-ANG3 in subtypes of chylomicronemia remains to be defined. EXPERT OPINION: Emerging pharmacologic therapies for chylomicronemia show promise, particularly apo C-III antagonists. However, these treatments are still investigational. Further study of their efficacy and safety in patients with both rare FCS and more common multifactorial chylomicronemia is needed.

Intravitreal antisense oligonucleotide sepofarsen in Leber congenital amaurosis type 10: a phase 1b/2 trial.

CEP290-associated Leber congenital amaurosis type 10 (LCA10) is a retinal disease resulting in childhood blindness. Sepofarsen is an RNA antisense oligonucleotide targeting the c.2991+1655A>G variant in the CEP290 gene to treat LCA10. In this open-label, phase 1b/2 ( NCT03140969 ), 12-month, multicenter, multiple-dose, dose-escalation trial, six adult patients and five pediatric patients received ≤4 doses of intravitreal sepofarsen into the worse-seeing eye. The primary objective was to evaluate sepofarsen safety and tolerability via the frequency and severity of ocular adverse events (AEs); secondary objectives were to evaluate pharmacokinetics and efficacy via changes in functional outcomes. Six patients received sepofarsen 160 µg/80 µg, and five patients received sepofarsen 320 µg/160 µg. Ten of 11 (90.9%) patients developed ocular AEs in the treated eye (5/6 with 160 µg/80 µg; 5/5 with 320 µg/160 µg) versus one of 11 (9.1%) in the untreated eye; most were mild in severity and dose dependent. Eight patients developed cataracts, of which six (75.0%) were categorized as serious (2/3 with 160 µg/80 µg; 4/5 with 320 µg/160 µg), as lens replacement was required. As the 160-µg/80-µg group showed a better benefit-risk profile, higher doses were discontinued or not initiated. Statistically significant improvements in visual acuity and retinal sensitivity were reported (post hoc analysis). The manageable safety profile and improvements reported in this trial support the continuation of sepofarsen development.

Inhibition of Prekallikrein for Hereditary Angioedema.

BACKGROUND: Hereditary angioedema is characterized by recurrent and unpredictable swellings that are disabling and potentially fatal. Selective inhibition of plasma prekallikrein production by antisense oligonucleotide treatment (donidalorsen) may reduce the frequency of attacks and the burden of disease. METHODS: In this phase 2 trial, we randomly assigned, in a 2:1 ratio, patients with hereditary angioedema with C1 inhibitor deficiency to receive four subcutaneous doses of either donidalorsen (80 mg) or placebo, with one dose administered every 4 weeks. The primary end point was the time-normalized number of investigator-confirmed angioedema attacks per month (attack rate) between week 1 (baseline) and week 17. Secondary end points included quality of life, as measured with the Angioedema Quality of Life Questionnaire (scores range from 0 to 100, with higher scores indicating worse quality of life), and safety. RESULTS: A total of 20 patients were enrolled, of whom 14 were randomly assigned to receive donidalorsen and 6 to receive placebo. The mean monthly rate of investigator-confirmed angioedema attacks was 0.23 (95% confidence interval [CI], 0.08 to 0.39) among patients receiving donidalorsen and 2.21 (95% CI, 0.58 to 3.85) among patients receiving placebo (mean difference, -90%; 95% CI, -96 to -76; P<0.001). The mean change from baseline to week 17 in the Angioedema Quality of Life Questionnaire score was -26.8 points in the donidalorsen group and -6.2 points in the placebo group (mean difference, -20.7 points; 95% CI, -32.7 to -8.7). The incidence of mild-to-moderate adverse events was 71% among patients receiving donidalorsen and 83% among those receiving placebo. CONCLUSIONS: Among patients with hereditary angioedema, donidalorsen treatment resulted in a significantly lower rate of angioedema attacks than placebo in this small, phase 2 trial. (Funded by Ionis Pharmaceuticals; ISIS 721744-CS2 ClinicalTrials.gov number, NCT04030598.).

Adverse Drug Reactions and Toxicity of the Food and Drug Administration-Approved Antisense Oligonucleotide Drugs.

The market for large molecule biologic drugs has grown rapidly, including antisense oligonucleotide (ASO) drugs. ASO drugs work as single-stranded synthetic oligonucleotides that reduce production or alter functions of disease-causing proteins through various mechanisms, such as mRNA degradation, exon skipping, and ASO-protein interactions. Since the first ASO drug, fomivirsen, was approved in 1998, the U.S. Food and Drug Administration (FDA) has approved 10 ASO drugs to date. Although ASO drugs are efficacious in treating some diseases that are untargetable by small-molecule chemical drugs, concerns on adverse drug reactions (ADRs) and toxicity cannot be ignored. Illustrative of this, mipomersen was recently taken off the market due to its hepatotoxicity risk. This paper reviews ADRs and toxicity from FDA drug labeling, preclinical studies, clinical trials, and postmarketing real-world studies on the 10 FDA-approved ASO drugs, including fomivirsen and pegaptanib, mipomersen, nusinersen, inotersen, defibrotide, eteplirsen, golodirsen, viltolarsen, and casimersen. Unique and common ADRs and toxicity for each ASO drug are summarized here. The risk of developing hepatotoxicity, kidney toxicity, and hypersensitivity reactions co-exists for multiple ASO drugs. Special precautions need to be in place when certain ASO drugs are administrated. Further discussion is extended on studying the mechanisms of ADRs and toxicity of these drugs, evaluating the existing physiologic and pathologic states of patients, optimizing the dose and route of administration, and formulating personalized treatment plans to improve the clinical utility of FDA-approved ASO drugs and discovery and development of new ASO drugs with reduced ADRs. SIGNIFICANCE STATEMENT: The current review provides a comprehensive analysis of unique and common ADRs and the toxicity of FDA-approved ASO drugs. The information can help better manage the risk of severe hepatotoxicity, kidney toxicity, and hypersensitivity reactions in the usage of currently approved ASO drugs and the discovery and development of new and safer ASO drugs.

Palmitic acid conjugation enhances potency of tricyclo-DNA splice switching oligonucleotides.

Tricyclo-DNA (tcDNA) is a conformationally constrained oligonucleotide analog that has demonstrated great therapeutic potential as antisense oligonucleotide (ASO) for several diseases. Like most ASOs in clinical development, tcDNA were modified with phosphorothioate (PS) backbone for therapeutic purposes in order to improve their biodistribution by enhancing association with plasma and cell protein. Despite the advantageous protein binding properties, systemic delivery of PS-ASO remains limited and PS modifications can result in dose limiting toxicities in the clinic. Improving extra-hepatic delivery of ASO is highly desirable for the treatment of a variety of diseases including neuromuscular disorders such as Duchenne muscular dystrophy. We hypothesized that conjugation of palmitic acid to tcDNA could facilitate the delivery of the ASO from the bloodstream to the interstitium of the muscle tissues. We demonstrate here that palmitic acid conjugation enhances the potency of tcDNA-ASO in skeletal and cardiac muscles, leading to functional improvement in dystrophic mice with significantly reduced dose of administered ASO. Interestingly, palmitic acid-conjugated tcDNA with a full phosphodiester backbone proved effective with a particularly encouraging safety profile, offering new perspectives for the clinical development of PS-free tcDNA-ASO for neuromuscular diseases.

Safety, tolerability and antiviral activity of the antisense oligonucleotide bepirovirsen in patients with chronic hepatitis B: a phase 2 randomized controlled trial.

Chronic infection with hepatitis B virus (HBV) leads to an increased risk of death from cirrhosis and hepatocellular carcinoma. Functional cure rates are low with current treatment options (nucleos(t)ide analogs (NAs) and pegylated interferons). Bepirovirsen is an antisense oligonucleotide targeting all HBV messenger RNAs; in cell culture and animal models, bepirovirsen leads to reductions in HBV-derived RNAs, HBV DNA and viral proteins. This phase 2 double-blinded, randomized, placebo-controlled trial is the first evaluation of the safety and activity of an antisense oligonucleotide targeting HBV RNA in both treatment-naïve and virally suppressed individuals with chronic HBV infection. The primary objective was to assess the safety and tolerability of bepirovirsen in individuals with chronic hepatitis B (CHB) (NCT02981602). The secondary objective was to assess antiviral activity, including the change from baseline to day 29 in serum hepatitis B surface antigen (HBsAg) concentration. Participants with CHB infection ≥6 months and serum HBsAg ≥50 IU ml-1 were enrolled from seven centers across Hong Kong and the Republic of Korea and randomized (3:1 within each dose cohort) to receive bepirovirsen or placebo via subcutaneous injection twice weekly during weeks 1 and 2 (days 1, 4, 8 and 11) and once weekly during weeks 3 and 4 (days 15 and 22). Participants were then followed for 26 weeks. Twenty-four participants were treatment-naïve and seven were receiving stable NA therapy. Treatment-emergent adverse events were mostly mild/moderate (most commonly injection site reactions). Eleven (61.1%) and three (50.0%) treatment-naïve participants experienced one or more treatment-emergent adverse event in the bepirovirsen and placebo groups, respectively. In participants receiving NA therapy, the corresponding numbers were three (60.0%) and one (50.0%). Transient, self-resolving alanine aminotransferase flares (≥2× upper limit of normal) were observed in eight treatment-naïve participants and three participants on stable NA regimens in the bepirovirsen treatment arms. HBsAg reductions were observed and were significant versus placebo for treatment-naïve participants receiving bepirovirsen 300 mg (P = 0.001), but not for the bepirovirsen 150 mg group (P = 0.245) or participants receiving stable NA therapy (P = 0.762). Two participants in each of the 300 mg dose groups achieved HBsAg levels below the lower limit of quantitation by day 29 (n = 3) or day 36 (n = 1). Bepirovirsen had a favorable safety profile. These preliminary observations warrant further investigation of the safety and activity of bepirovirsen in a larger CHB patient population.