Single- and repeat-dose toxicity of IDX14184, a nucleotide prodrug with antiviral activity for hepatitis C viral infection, in mice, rats, and monkeys

Impact of direct-acting antiviral treatment for hepatitis C on cardiovascular diseases and extrahepatic cancers

PURPOSE

The impact of direct-acting antivirals (DAAs) on extrahepatic complications in chronic hepatitis C (CHC) patients remains poorly described. We estimated the association of DAAs with cardiovascular events and extrahepatic cancers.

METHODS

The prospective ANRS CO22 HEPATHER cohort was enriched with individual data until December 2018 from the French Health Insurance Database (SNDS). CHC patients were enrolled between August 2012 and December 2015 in 32 French hepatology centers. A total of 8148 CHC adults were selected. Cardiovascular events (stroke, acute coronary syndrome, pulmonary embolism, heart failure, arrhythmias and conduction disorders [ACD], peripheral arterial disease [PAD]) and extrahepatic solid cancers were derived from the SNDS. Associations between DAAs and extrahepatic events were estimated using marginal structural models, with adjustments for clinical confounders.

RESULTS

Analyses of 12 905 person-years of no DAA exposure and 22 326 person-years following DAA exposure showed a decreased risk of PAD after DAA exposure (hazard ratio [HR], 0.54; 95% CI, 0.33-0.89), a beneficial effect of DAAs on overall cardiovascular outcomes in patients with advanced fibrosis (aHR, 0.58; 95% CI, 0.42-0.79), and an increased risk of ACD (hazard ratio [HR], 1.46; 95% CI, 1.04-2.04), predominant after the first year following DAA initiation. There was no association between DAAs and extrahepatic cancer risk (HR, 1.23; 95% CI, 0.50-3.03).

CONCLUSIONS

DAAs were not associated with extrahepatic cancer development or reduction. They were associated with a decreased risk of PAD and an increased risk of ACD, supporting long-term cardiac monitoring after DAA therapy.

Sofosbuvir-based hepatitis C therapies in patients with chronic and end-stage kidney disease

Sofosbuvir (SOF), a nucleotide inhibitor of the hepatitis C virus (HCV) polymerase, is a component of several all-oral HCV therapies. GS-331007, SOF's predominant metabolite, is renally eliminated and accumulates 5- to 20-fold in patients with advanced chronic kidney disease (CKD) or undergoing hemodialysis (HD), respectively. Preclinical data did not determine whether these exposures represented a risk for toxicity. Therefore subjects with advanced CKD were not included in registrational studies and SOF was not initially approved for use in advanced CKD. Nevertheless, after initial licensing, off-label use of SOF at full or reduced doses was reported in patients with kidney disease. Two clinical trials of SOF-containing therapies were conducted in patients with end-stage kidney disease, demonstrating safety and efficacy. These led to expanded US Food and Drug Administration approval in 2019 for the use of SOF-containing regimens in patients with advanced CKD, including dialysis dependence. Even so, given the availability of protease inhibitor-containing direct-acting antiviral regimens, there was a reluctance by some practitioners to use SOF-containing regimens in moderate to severe kidney disease. Here we review the existing data on SOF's pharmacokinetics, toxicology, efficacy and safety in patients with kidney disease. Data from both clinical trials and real-world practice settings indicate that in patients with moderate to severe kidney disease, full-dose SOF-based regimens have high rates of efficacy and acceptable safety and tolerability profiles, without increased risk for cardiac adverse events or clinically meaningful changes in kidney function. SOF-based regimens are safe and effective in patients who have moderate to severe kidney disease, including those undergoing HD.

Use of Human iPSC-CMs in Nonclinical Regulatory Studies for Cardiac Safety Assessment

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) provide a human-relevant platform for cardiac function assessment. Alternative assays using hiPSC-CMs are increasingly being employed for regulatory decision-making. A retrospective review revealed steady use of hiPSC-CM-based in vitro assays in nonclinical studies of drug-induced cardiotoxicity in regulatory submissions to the U.S. Food and Drug Administration (FDA). Most of the hiPSC-CMs data were obtained in exploratory studies and submitted as supportive evidence in concordance with other nonclinical data. Some of those studies were used to inform clinical trial design. This article provides an overview of the use of hiPSC-CMs in regulatory applications to FDA, with a focus on the integration of human-relevant in vitro data into proarrhythmic and non-proarrhythmic risk assessment. By identifying the regulatory submissions including hiPSC-CMs data, we explore their utility and discuss their limitations for predicting human cardiac safety in clinical trials. An important take-home message is that regulatory acceptance of hiPSC-CMs data is dependent on both the context of use and accurate data interpretation.

Global longitudinal strain as a predictor of short-term effect of oral antiviral regimens on myocardium in Egyptian patients with chronic viral hepatitis C

Background

Hepatitis C virus (HCV) infection has been noted with various cardiovascular (CV) diseases, and patients with detected HCV-RNA had higher CV mortality than uninfected individuals. The new direct-acting antiviral drugs (DAA) proved to be more effective with fewer side effects compared to interferon in eradicating HCV, but their effect on myocardium is still questionable. In order to get some answers for such question, two-dimensional speckle tracking echocardiography (2D-STE) was studied before and after treatment with different DAA regimens in HCV patients with either mildly impaired or normal basic left ventricular ejection fraction (LVEF).

Results

Global longitudinal strain (GLS) significantly worsened after finishing antiviral treatment in patients with basic impairment of LVEF (n = 100) and those with normal basic LVEF (n = 20) [p = 0.006 and 0.039, respectively]; also, segmental strain showed significant worsening of many segments. Such worsening was significantly more in those with basic impairment of LVEF compared to those with normal basic LVEF (p = 0.036). No significant difference was observed in GLS and segmental strain when classifying and comparing patients according to gender, presence of diabetes mellitus, hypertension, ischemic heart disease and established cardiac medications, or according to DAA regimen received.

Conclusion

DAA may have a cardiotoxic effect that could be early detected by 2D-STE, which was more significant in patients with pre-treatment impairment of LVEF.

The evolution of antiviral nucleoside analogues: A review for chemists and non-chemists. Part II: Complex modifications to the nucleoside scaffold

This is the second of two invited articles reviewing the development of nucleoside analogue antiviral drugs, written for a target audience of virologists and other non-chemists, as well as chemists who may not be familiar with the field. As with the first paper, rather than providing a chronological account, we have chosen to examine particular examples of structural modifications made to nucleoside analogues that have proven fruitful as various antiviral, anticancer, and other therapeutics. The first review covered the more common, and in most cases, single modifications to the sugar and base moieties of the nucleoside scaffold. This paper focuses on more recent developments, especially nucleoside analogues that contain more than one modification to the nucleoside scaffold. We hope that these two articles will provide an informative historical perspective of some of the successfully designed analogues, as well as many candidate compounds that encountered obstacles.

Antiviral Nucleotide Incorporation by Recombinant Human Mitochondrial RNA Polymerase Is Predictive of Increased In Vivo Mitochondrial Toxicity Risk

Nucleoside or nucleotide inhibitors are a highly successful class of antivirals due to selectivity, potency, broad coverage, and high barrier to resistance. Nucleosides are the backbone of combination treatments for HIV, hepatitis B virus, and, since the FDA approval of sofosbuvir in 2013, also for hepatitis C virus (HCV). However, many promising nucleotide inhibitors have advanced to clinical trials only to be terminated due to unexpected toxicity. Here we describe the in vitro pharmacology of compound 1, a monophosphate prodrug of a 2'-ethynyluridine developed for the treatment of HCV. Compound 1 inhibits multiple HCV genotypes in vitro (50% effective concentration [EC₅₀], 0.05 to 0.1 μM) with a selectivity index of >300 (50% cytotoxic concentration [CC₅₀], 30 μM in MT-4 cells). The active triphosphate metabolite of compound 1, compound 2, does not inhibit human α, β, or γ DNA polymerases but was a substrate for incorporation by the human mitochondrial RNA polymerase (POLRMT). In dog, the oral administration of compound 1 resulted in elevated serum liver enzymes and microscopic changes in the liver. Transmission electron microscopy showed significant mitochondrial swelling and lipid accumulation in hepatocytes. Gene expression analysis revealed dose-proportional gene signature changes linked to loss of hepatic function and increased mitochondrial dysfunction. The potential of in vivo toxicity through mitochondrial polymerase incorporation by nucleoside analogs has been previously shown. This study shows that even moderate levels of nucleotide analog incorporation by POLRMT increase the risk of in vivo mitochondrial dysfunction. Based on these results, further development of compound 1 as an anti-HCV compound was terminated.