Ombitasvir/Paritaprevir/Ritonavir Plus Dasabuvir: A Review in Chronic HCV Genotype 1 Infection

The role of the methoxy group in approved drugs

The methoxy substituent is prevalent in natural products and, consequently, is present in many natural product-derived drugs. It has also been installed in modern drug molecules with no remnant of natural product features because medicinal chemists have been taking advantage of the benefits that this small functional group can bestow on ligand-target binding, physicochemical properties, and ADME parameters. Herein, over 230 methoxy-containing small-molecule drugs, as well as several fluoromethoxy-containing drugs, are presented from the vantage point of the methoxy group. Biochemical mechanisms of action, medicinal chemistry SAR studies, and numerous X-ray cocrystal structures are analyzed to identify the precise role of the methoxy group for many of the drugs and drug classes. Although the methoxy substituent can be considered as the hybridization of a hydroxy and a methyl group, the combination of these functionalities often results in unique effects that can amount to more than the sum of the individual parts.

The Structure-property Relationships of Clinically Approved Protease Inhibitors

BACKGROUND

Proteases play important roles in the regulation of many physiological processes, and protease inhibitors have become one of the important drug classes. Especially because the development of protease inhibitors often starts from a substrate- based peptidomimetic strategy, many of the initial lead compounds suffer from pharmacokinetic liabilities.

OBJECTIVE

To reduce drug attrition rates, drug metabolism and pharmacokinetics studies are fully integrated into modern drug discovery research, and the structure-property relationship illustrates how the modification of the chemical structure influences the pharmacokinetic and toxicological properties of drug compounds. Understanding the structure- property relationships of clinically approved protease inhibitor drugs and their analogues could provide useful information on the lead-to-candidate optimization strategies.

METHODS

About 70 inhibitors against human or pathogenic viral proteases have been approved until the end of 2021. In this review, 17 inhibitors are chosen for the structure- property relationship analysis because detailed pharmacological and/or physicochemical data have been disclosed in the medicinal chemistry literature for these inhibitors and their close analogues.

RESULTS

The compiled data are analyzed primarily focusing on the pharmacokinetic or toxicological deficiencies found in lead compounds and the structural modification strategies used to generate candidate compounds.

CONCLUSION

The structure-property relationships hereby summarized how the overall druglike properties could be successfully improved by modifying the structure of protease inhibitors. These specific examples are expected to serve as useful references and guidance for developing new protease inhibitor drugs in the future.

Synthetic approaches and application of clinically approved small-molecule drugs to treat hepatitis

Hepatitis, a global public health concern, presents a significant burden on healthcare systems worldwide. Particularly, hepatitis B and C are viral infections that can lead to severe liver damage, cirrhosis, and even hepatocellular carcinoma (HCC). The urgency to combat these diseases has driven researchers to explore existing small-molecule drugs as potential therapeutics. This comprehensive review provides a systematic overview of synthetic routes to key antiviral agents used to manage hepatitis. Furthermore, it elucidates the mechanisms of action of these drugs, shedding light on their interference with viral replication and liver disease progression. The review also discusses the clinical applications of these drugs, including their use in combination therapies and various patient populations. By evaluating the synthetic pathways and clinical utility of these drugs, this review not only consolidates current knowledge but also highlights potential future directions for research and drug development in the fight against hepatitis, ultimately contributing to improved patient outcomes and reduced global disease burden.

A Synopsis of Hepatitis C Virus Treatments and Future Perspectives

Hepatitis C virus (HCV) infection is a worldwide public health problem. Chronic infection with HCV can lead to liver cirrhosis or cancer. Although some immune-competent individuals can clear the virus, others develop chronic HCV disease due to viral mutations or an impaired immune response. IFNs type I and III and the signal transduction induced by them are essential for a proper antiviral effect. Research on the viral cycle and immune escape mechanisms has formed the basis of therapeutic strategies to achieve a sustained virological response (SVR). The first therapies were based on IFNα; then, IFNα plus ribavirin (IFN-RBV); and then, pegylated-IFNα-RBV (PEGIFNα-RIV) to improve cytokine pharmacokinetics. However, the maximum SVR was 60%, and several significant side effects were observed, decreasing patients' treatment adherence. The development of direct-acting antivirals (DAAs) significantly enhanced the SVR (>90%), and the compounds were able to inhibit HCV replication without significant side effects, even in paediatric populations. The management of coinfected HBV-HCV and HCV-HIV patients has also improved based on DAA and PEG-IFNα-RBV (HBV-HCV). CD4 cells are crucial for an effective antiviral response. The IFNλ3, IL28B, TNF-α, IL-10, TLR-3, and TLR-9 gene polymorphisms are involved in viral clearance, therapeutic responses, and hepatic pathologies. Future research should focus on searching for strategies to circumvent resistance-associated substitution (RAS) to DAAs, develop new therapeutic schemes for different medical conditions, including organ transplant, and develop vaccines for long-lasting cellular and humoral responses with cross-protection against different HCV genotypes. The goal is to minimise the probability of HCV infection, HCV chronicity and hepatic carcinoma.

Direct acting anti-hepatitis C combinations as potential COVID-19 protease inhibitors

The coronavirus pandemic could be the most threatening outbreak in the twenty-first century. According to the latest records of world health organization, more than 130 millions have been infected by COVID-19, with more than 2.9 million reported deaths. Yet, there is no magic cure for treatment of COVID-19. The concept of drug repurposing has been introduced as a fast, life-saving approach for drug discovery. Drug repurposing infers investigating already approved drugs for new indications, using the available information about pathophysiology of diseases and pharmacodynamics of drugs. In a recent work, more than 3000 FDA approved drugs were tested using virtual screening as potential antiviral agents for COVID-19. In this work, the top ranked five hits from the previous docking results together with drugs of similar chemical feature and/or mechanistic destinations were further tested using AutoDock Vina. The results showed that anti-HCV combinations could be potential therapeutic regimens for COVID-19 infections.

Isoquinolines: Important Cores in Many Marketed and Clinical Drugs

BACKGROUND

Isoquinoline analogs are an important, structurally diverse class of compounds that are extensively used as pharmaceuticals. Derivatives containing the isoquinoline scaffold have become a focus of therapeutic research because of their wide range of biological characteristics. Examples of these drugs, many of which are in clinical application or at the pre-clinical stage, are used to treat a broad swathe of ailments, such as tumors, respiratory diseases, infections, nervous system diseases, cardiovascular and cerebrovascular diseases, endocrine and metabolic diseases.

METHODS

Data were collected from PubMed, Web of Science, and SciFinder, through searches of drug names.

RESULTS

At least 38 isoquinoline-based therapeutic drugs are in clinical application or clinical trials, and their chemical structure and pharmacokinetics are described in detail.

CONCLUSION

The isoquinoline ring is a privileged scaffold which is often preferred as a structural basis for drug design, and plays an important role in drug discovery. This review provides a guide for pharmacologists to find effective preclinical/clinical drugs and examines recent progress in the application of the isoquinoline scaffold.

Development and Validation of a New LC-MS/MS Analytical Method for Direct-Acting Antivirals and Its Application in End-Stage Renal Disease Patients

BACKGROUND AND OBJECTIVE

The effectiveness of direct-acting antivirals (DAAs) is not well established in end-stage renal disease (ESRD) patients. Assessment of the plasma concentrations may support understanding of their therapeutic outcomes in this population. The aim of this study is to develop a direct, yet matrix-effect tolerant, analytical method for determining DAAs in the plasma of ESRD patients while maintaining a moderate cost per sample and with an improved analyte extraction recovery.

METHODS

In this study, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the analysis of ombitasvir (OMB), paritaprevir (PRT) and ritonavir (RIT) in plasma. Sample preparation was performed using the liquid-liquid extraction (LLE) method. Isocratic separation was performed using a mixture of methanol and 10 mM ammonium acetate (79:21, v/v) followed by MS/MS detection. The method was validated and applied to determine DAAs in the plasma of ESRD patients (n = 7).

RESULTS

The developed method was linear (r²> 0.995), accurate (89.4 ± 7.8 to 108.3 ± 3.0) and precise (% CV 0.9-15.0) and showed improved recovery (> 80) over previously published ones in the range 5-250, 30-1,500, 20-1,000 ng/mL for OMB, PRT and RIT, respectively. Relative matrix effect was absent, and the method accurately determined the three DAAs in real-life samples (n = 7).

CONCLUSIONS

An efficient analytical method for the determination of DAAs is presented. The method overcomes the potential analytical response fluctuation in ESRD. The developed method show improved extraction recoveries and is suitable for routine application in developing economies where hepatitis C virus is most prevalent.

Effectiveness and safety of sofosbuvir/velpatasvir/voxilaprevir in patients with chronic hepatitis C previously treated with DAAs

BACKGROUND & AIMS

Around 5% of patients with chronic hepatitis C virus (HCV) infection treated with direct-acting antiviral (DAA) agents do not achieve sustained virological response (SVR). The currently approved retreatment regimen for prior DAA failure is a combination of sofosbuvir, velpatasvir, and voxilaprevir (SOF/VEL/VOX), although there is little data on its use in clinical practice. The aim of this study was to analyse the effectiveness and safety of SOF/VEL/VOX in the real-world setting.

METHODS

This was a prospective multicentre study assessing the efficacy of retreatment with SOF/VEL/VOX in patients who had experienced a prior DAA treatment failure. The primary endpoint was SVR 12 weeks after the completion of treatment (SVR12). Data on safety and tolerability were also recorded.

RESULTS

A total of 137 patients were included: 75% men, 35% with liver cirrhosis. Most were infected with HCV genotype (GT) 1 or 3. The most common prior DAA combinations were sofosbuvir plus an NS5A inhibitor or ombitasvir/paritaprevir/r+dasabuvir. A total of 136 (99%) patients achieved undetectable HCV RNA at the end of treatment. Overall SVR12 was 95% in the 135 patients reaching this point. SVR12 was lower in patients with cirrhosis (89%, p = 0.05) and those with GT3 infection (80%, p <0.001). Patients with GT3 infection and cirrhosis had the lowest SVR12 rate (69%). Of the patients who did not achieve SVR12, 1 was reinfected and 7 experienced treatment failure (6 GT3, 1 GT1a). The presence of resistance-associated substitutions did not impact SVR12. Adverse effects were mild and non-specific.

CONCLUSION

Real-world data show that SOF/VEL/VOX is an effective, safe rescue therapy for patients with prior DAA treatment failure despite the presence of resistance-associated substitutions. However, patients with liver cirrhosis infected by GT3 remain the most-difficult-to-treat group.

LAY SUMMARY

Treatment with sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) for 12 weeks is the current recommendation for the 5% of patients infected with HCV who do not achieve eradication of the virus under treatment with direct-acting antivirals. In a Spanish cohort of 137 patients who failed a previous combination of direct-acting antivirals, a cure rate of 95% was achieved with SOF/VEL/VOX. Genotypic characteristics of the virus (genotype 3) and the presence of cirrhosis were factors that decreased the rate of cure. Treatment with SOF/VEL/VOX is an effective and safe rescue therapy due to its high efficacy and very good safety profile.

Heart Transplantation in Systemic Sclerosis: New Impulses for Conventional Scleroderma Transplantation Regimen and Scleroderma Diagnostic Monitoring: 2 Case Reports

BACKGROUND

Although low (but increasing) rates of lung/lung-heart transplantations of scleroderma (systemic sclerosis [SSc]) patients have been reported, exclusive heart transplantation is a rare approach for treatment of heart failure due to SSc.

CASES

We report on 2 cases of SSc patients receiving a heart transplantation (HTx) due to severe and progressive right heart failure without pulmonary artery hypertension. One patient received a hepatitis C virus (HCV)-positive donor heart and recovered excellently from viral transmission after administration of a direct-acting antiviral (DAA) regimen. This is the first published case of an SSc patient who underwent HTx using an HCV-positive donor heart. The clinical course of both patients was monitored by different serum SSc biomarkers. Only xylosyltransferase activity proved to be a promising biomarker for disease stage determination and therapeutic monitoring, precisely reflecting fibrotic remodeling and successful organ recovery.

CONCLUSIONS

Successful implementation of the 2 cases described here demonstrates that HTx is a safe and effective therapeutic option for defined SSc sub-patient groups despite the progressive character of the underlying disease. In the future, xylosyltransferase activity might be conducive to simplify the identification of patients with low systemic involvement but a strong indication for single heart transplantation. Finally, we demonstrate that treatment of HCV viral transmission from HCV-positive donor to organ recipient using DAA gives us new opportunities to consider HCV-positive donor organs for HTx and might reveal new possibilities to ease the lack of donor organs.

Outcome and adverse events in patients with chronic hepatitis C treated with direct-acting antivirals: a clinical randomized study

OBJECTIVE

New potent direct-acting antiviral (DAA) regimens against hepatitis C virus have been approved in recent years. However, information about the rate of adverse events (AEs) across different DAA regimens is limited. We aimed to evaluate differences in AEs and treatment efficacy in patients with chronic hepatitis C (CHC), genotype (GT) 1 or 3, randomized to two different treatment arms, correspondingly.

PATIENTS AND METHODS

We randomly assigned 96 patients in a 1 : 1 ratio, to treatment for 12 weeks with either paritaprevir/ombitasvir/ritonavir/dasabuvir/ribavirin (RBV) or ledipasvir/sofosbuvir (SOF)/RBV if infected with GT1 (72 patients) or to daclatasvir/SOF/RBV for 12 weeks or SOF/RBV for 24 weeks, if infected with GT3 (24 patients). Data on AEs were collected throughout the entire study period.

RESULTS

A total of 70 (97%) patients with CHC with GT1 and 20 (83%) patients with GT3 achieved cure. The GT3 treatment arm was prematurely terminated, owing to change in national treatment guidelines. Thus, only AEs for GT1 patients are described. AEs occurred in 70 (97%) GT1 patients, and most common AEs were anemia (n=56/78%), fatigue (n=53/74%), and headache (n=33/46%). No difference was observed in relation to treatment group (P=1.0), anemia (P=1.0), or liver cirrhosis (P=0.53). In seven (11%) patients, AEs assessed by the investigator to be possibly related to the DAA regimen were still present 12 weeks after treatment.

CONCLUSIONS

We found no difference in AEs possibly related to the DAA regimen in patients with CHC, but surprisingly, AEs possibly related to the DAA regimen persisted in a significant number of patients after treatment. This finding can be of importance for clinicians in relation to patient information concerning AEs possibly related to DAA treatment.

The Safety and Antiviral Activity of BZF961 with or without Ritonavir in Patients Infected with Hepatitis C Virus: A Randomized, Multicenter Trial

PURPOSE

Infection with hepatitis C virus is the leading cause of infectious disease mortality in the United States. BZF961 is a novel small molecule inhibitor of the hepatitis C virus NS3-4A protease. Here we present the results of a randomized, double-blinded, placebo-controlled, multicentered study in treatment-naïve patients with chronic hepatitis C virus genotype-1 infection.

METHODS

Patients were enrolled sequentially in 2 parts and treated for 3days. BZF961 was administered as monotherapy (500mg BID for 3 days) or in combination with the cytochrome P450 3A4 inhibitor ritonavir to boost its exposure (BZF961 10, 20, or 50mg QD or BID).

FINDINGS

BZF961 was safe and well tolerated in the patients studied with no serious adverse events. There were no appreciable differences in adverse events among patients who received BZF961, BZF961 with ritonavir, or placebo. There was a significant, clinically meaningful reduction in viral load from baseline in patients treated either with BZF961 500mg every 12hours alone or BZF961 50mg every 12hours in combination with ritonavir. Activity against the hepatitis C virus of the lower-dose regimens was apparent but more modest. There were no relevant changes from baseline viral loads in placebo-treated patients.

IMPLICATIONS

Coadministration of ritonavir with BZF961 boosted BZF961 exposure (including C_min, which is the clinically relevant parameter associated with antiviral activity) in a therapeutic range with less variability compared with BZF961 alone. For strategic reasons, BZF961 is no longer under development.

Clopidogrel Increases Dasabuvir Exposure With or Without Ritonavir, and Ritonavir Inhibits the Bioactivation of Clopidogrel

Dasabuvir is mainly metabolized by cytochrome P450 (CYP) 2C8 and is predominantly used in a regimen containing ritonavir. Ritonavir and clopidogrel are inhibitors of CYP3A4 and CYP2C8, respectively. In a randomized, crossover study in 12 healthy subjects, we examined the impact of clinical doses of ritonavir (for 5 days), clopidogrel (for 3 days), and their combination on dasabuvir pharmacokinetics, and the effect of ritonavir on clopidogrel. Clopidogrel, but not ritonavir, increased the geometric mean AUC_0‐∞ of dasabuvir 4.7‐fold; range 2.0–10.1‐fold (P = 8·10⁻⁷), compared with placebo. Clopidogrel and ritonavir combination increased dasabuvir AUC_0‐∞ 3.9‐fold; range 2.1–7.9‐fold (P = 2·10⁻⁶), compared with ritonavir alone. Ritonavir decreased the AUC_0‐4h of clopidogrel active metabolite by 51% (P = 0.0001), and average platelet inhibition from 51% without ritonavir to 31% with ritonavir (P = 0.0007). In conclusion, clopidogrel markedly elevates dasabuvir concentrations, and patients receiving ritonavir are at risk for diminished clopidogrel response.

Effect of ombitasvir/paritaprevir/ritonavir + dasabuvir regimen on health-related quality of life for patients with hepatitis C

BACKGROUND & AIMS

This study analyses health-related quality of life data from 8 randomized clinical trials using ombitasvir/paritaprevir/ritonavir and dasabuvir ± ribavirin to investigate: (i) the impact of the treatment vs placebo during treatment on health-related quality of life; (ii) the sustainability of such treatment effect after 12-week treatment period; and (iii) if results from (i) and (ii) differ in subgenotypes 1a vs 1b.

METHODS

Six registration trials and 2 post-approval trials were pooled and analysed using longitudinal mixed models to estimate the effect of ombitasvir/paritaprevir/ritonavir and dasabuvir ± ribavirin on health-related quality of life outcomes adjusting for baseline scores, as well as patient demographics and clinical characteristics.

RESULTS

Patients treated with ribavirin-free ombitasvir/paritaprevir/ritonavir and dasabuvir regimen reported statistically significant increase in health-related quality of life outcomes as compared to placebo patients. While ombitasvir/paritaprevir/ritonavir and dasabuvir + ribavirin treatment saw statistically significant decline in health-related quality of life outcomes during treatment vs baseline and placebo, effect on health-related quality of life outcomes associated with ribavirin did not persist in the post-treatment period for ombitasvir/paritaprevir/ritonavir and dasabuvir patients followed for up to 52 weeks. The analysis also found Genotype 1b patients reported greater improvements in health-related quality of life as compared to genotype 1a patients.

CONCLUSIONS

During the active treatment period, small but statistically significant decrements in health-related quality of life outcomes were observed potentially driven by ribavirin, which were not sustained during the post-treatment follow-up period. Differences were observed by patient subgenotype, where health-related quality of life improvements were consistently higher for genotype 1b patients as compared to genotype 1a patients.

Hypericin inhibits hepatitis C virus replication via deacetylation and down-regulation of heme oxygenase-1

BACKGROUND

Hepatitis C virus (HCV) is a globally prevalent pathogen and a leading cause of death and morbidity. Traditional therapy with pegylated interferon-<alpha> and ribavirin has had only limited success, with some adverse effects. Direct-acting antivirals (DAAs) are effective in suppressing HCV replication, but are expensive.

PURPOSE

Hypericin has been reported to be a good antiviral agent for inhibiting HCV replication, however, little is known about its mechanisms of action. The aim of this study is to elucidate the mode of action of hypericin in Ava5 human hepatoma cell line (Huh7 derivative) harboring HCV subgenomic replicon RNA.

METHODS

To determine the non-structure protein 5A (NS5A) mRNA and NS3 protein expression levels, real-time PCR and Western blot analysis were performed, respectively. To investigate how hypericin inhibits HCV replication, 5-aza-2'-deoxycytidine (5-Aza-dC) and chidamide were used for determining histone modification. Furthermore, shRNA was applied to confirm the role of heme oxygenase (HO-1) in HCV repression.

RESULTS

Hypericin in experiment were tested and showed no cytotoxicity. Hypericin reduced HO-1 and NS5A in a time- and dose- dependent manner. Chidamide, but not 5-Aza-dc, restored hypericin-induced reduction in HCV NS3 expression and reversed HO-1 expression in Ava5 cells. LY294002 inhibited HCV replication via HO-1 down-regulation. Constitutive expressed p-AKT was not involved in hypericin-induced reduction in HCV replication. In addition, shHO-1 inhibited HCV replication.

CONCLUSION

In conclusion, hypericin inhibits HCV replication via down-regulation of HO-1 expression and deacetylation.

Real-world efficacy and safety of ombitasvir, paritaprevir/r+dasabuvir+ribavirin in genotype 1b patients with hepatitis C virus cirrhosis

BACKGROUND

Direct antiviral agents (DAA) showed very good results in terms of efficacy and safety in clinical trials, but real-life data are still needed in order to confirm this profile.

MATERIAL AND METHODS

In Romania, through a nationwide government-funded programme in 2015-2016, approx.5800 patients with virus C cirrhosis received fully reimbursed DAA therapy with OBV/PTV/r+DSV+RBV for 12 weeks. We analysed a national prospective cohort enrolling the first 2070 patients, all with genotype 1b. The only key inclusion criteria was advanced fibrosis (Metavir stage F4) confirmed by Fibromax testing (or liver biopsy/Fibroscan). Efficacy was assessed by the percentage of patients achieving SVR 12 weeks post-treatment (SVR12).

RESULTS

Forty patients stopped the treatment because of hepatic decompensation (1.9%), 21 stopped because of other adverse events and one was lost to follow-up. This cohort was 51% females, mean age 60 years (25÷82), 67% pretreated, 70% associated NASH, 67% with severe necro-inflammation (severity score 3-Fibromax), 37% with comorbidities, 10.4% with Child Pugh A6, 0.5% B7. The median MELD score was 8.09 (6 ÷ 22). SVR by intention-to-treat was reported in 1999/2070(96.6%), 55/2070 failed to respond. Liver decompensation was statistically associated in multivariate analysis with platelets< 10⁵ /mm³ (P = .03), increased total bilirubin (P < .001), prolonged INR (P = .02), and albumin<3.5 g/dL (P = .03).

CONCLUSIONS

OBV/PTV/r+DSV+RBV proved to be highly efficient in our population of cirrhotics with a 96.6% SVR. Serious adverse events related to therapy were reported in 61/2070(2.9%), most of them liver decompensation (1.9%), related to hepatic dysfunction, and lower platelet count.

Paritaprevir/ritonavir/ombitasvir plus dasabuvir in HIV/HCV-coinfected patients with genotype 1 in real-life practice

Background Data on the efficacy, safety, and concomitant use with other drugs of the combination ritonavir-boosted paritaprevir/ombitasvir plus dasabuvir (PrOD) in HIV/HCV-coinfected patients in real life are limited. The objectives of this study were to analyze these topics in HIV/HCV-coinfected subjects bearing HCV genotype 1 (GT1). Methods One hundred and eighty-two HIV/HCV-coinfected patients with GT1 (87 1a, 71 1b, 23 other) treated with PrOD, plus ribavirin (RBV) in 119 cases, in routine clinical practice were analyzed. The main variable of efficacy was sustained virological response (SVR) 12 weeks after completing therapy in an intention-to-treat (ITT) analysis and that of safety treatment discontinuation because of adverse effects. Factors associated with SVR were analyzed with a modified ITT (mITT) strategy. Results One hundred and seventy-two (94%) patients attained SVR, 3 (2%) experienced a relapse and two (1%) discontinued therapy due to adverse events. The rates of SVR in subjects with GT 1a and 1b by mITT were, respectively, 97% and 98%. Sixty-five (98%) out of 66 patients with cirrhosis and 107 (98%) out of 110 (p = 1) non-cirrhotics achieved SVR. Fifty-five (95%) patients on concomitant darunavir therapy developed SVR vs. 117 (99%) (p = 0.105) of those without DRV. RBV dose was reduced in 13 (11%) patients and permanently discontinued in 2 (2%), with no impact on SVR. Conclusions PrOD is highly effective and well tolerated in HIV/HCV-coinfected patients with GT1 in routine clinical practice. RBV is often required. However, RBV dose reduction or discontinuation is uncommonly needed and do not impair the SVR rate.

Sustained virological response to ombitasvir/paritaprevir/ritonavir and dasabuvir treatment for hepatitis C: Real-world data from a large healthcare provider

Treatment with ombitasvir/paritaprevir/ritonavir and dasabuvir, with or without ribavirin (OPrD ± RBV), was the first interferon-free direct-acting antiviral for hepatitis C virus (HCV) introduced to Israel's national basket of health services in February 2015. Patients with HCV genotype 1 (GT1) and advanced fibrosis (F3-F4) were eligible for treatment in 2015. This study aimed to characterize patients initiating OPrD ± RBV and assess sustained virological response (SVR). A retrospective cohort study was performed using the database of Maccabi Healthcare Services (MHS), a 2-million-member health plan in Israel. The study population included adults who initiated OPrD ± RBV through December 2015 per health basket criteria. A gap in medication fills (>14 days between a fill's run-out and the next fill) was used to estimate adherence. SVR was defined by the viral tests at least 12-week post-treatment. The study population consisted of 403 patients (56.3% male), with a mean age of 60.7 years (SD 11.0). Overall, 71.0% were naïve to prior HCV treatment, and 95.6% were treated with a 12-week regimen. A total of 348 patients (86.4%) completed the regimen in the usual time frame (highly adherent), whereas 8.2% completed with a gap, and 4.7% purchased less than the recommended dose. SVR rates overall and among highly adherent patients were 395/403 (98.0%; 95% CI 96.1-99.1) and 346/348 (99.4%; 95% CI 97.9-99.9), respectively. GT1b patients on 12-week regimens attained SVR rates of 194/196 (fibrosis F3) and 170/176 (cirrhosis). After a first year of provision of OPrD ± RBV with good adherence, high SVR rates were achieved in various patient subgroups and comorbidities.

Chemical genetics-based development of small molecules targeting hepatitis C virus

Hepatitis C virus (HCV) infection is a major worldwide problem that has emerged as one of the most significant diseases affecting humans. There are currently no vaccines or efficient therapies without side effects, despite today's advanced medical technology. Currently, the common therapy for most patients (i.e. genotype 1) is combination of HCV-specific direct-acting antivirals (DAAs). Up to 2011, the standard of care (SOC) was a combination of peg-IFNα with ribavirin (RBV). After approval of NS3/4A protease inhibitor, SOC was peg-IFNα and RBV with either the first-generation DAAs boceprevir or telaprevir. In the past several years, various novel small molecules have been discovered and some of them (i.e., HCV polymerase, protease, helicase and entry inhibitors) have undergone clinical trials. Between 2013 and 2016, the second-generation DAA drugs simeprevir, asunaprevir, daclatasvir, dasabuvir, sofosbuvir, and elbasvir were approved, as well as the combinational drugs Harvoni^®, Zepatier^®, Technivie^®, and Epclusa^®. A number of reviews have been recently published describing the structure-activity relationship (SAR) in the development of HCV inhibitors and outlining current therapeutic approaches to hepatitis C infection. Target identification involves studying a drug's mechanism of action (MOA), and a variety of target identification methods have been developed in the past few years. Chemical biology has emerged as a powerful tool for studying biological processes using small molecules. The use of chemical genetic methods is a valuable strategy for studying the molecular mechanisms of the viral lifecycle and screening for anti-viral agents. Two general screening approaches have been employed: forward and reverse chemical genetics. This review reveals information on the small molecules in HCV drug discovery by using chemical genetics for targeting the HCV protein and describes successful examples of targets identified with these methods.

Ombitasvir-Paritaprevir-Ritonavir-Dasabuvir (Viekira Pak)-Induced Lactic Acidosis

OBJECTIVE

To report a case series of three patients with hepatitis C virus infection who all presented with severe type B lactic acidosis shortly after starting treatment with ombitasvir-paritaprevir-ritonavir-dasabuvir.

DESIGN

Case series.

SETTING

ICU.

PATIENTS

Three patients, all who had HCV cirrhosis with mild hepatic impairment (Child-Pugh A) and had started taking ombitasvir-paritaprevir-ritonavir-dasabuvir within the preceding 2 weeks, presented with similar nonspecific symptoms of lethargy, fatigue, and nausea. All had elevated lactate levels at admission without evidence of hypovolemia, cardiogenic failure, or vasodilatory shock.

INTERVENTIONS

All patients were given appropriate supportive intensive care for what was initially suspected to be sepsis, including a minimum of 30 mL/kg of IV fluids, infectious workup including blood cultures, broad-spectrum antibiotics, and mechanical ventilatory support. The first patient received continuous veno-venous hemofiltration. The second patient received hemodialysis. The third patient was initially started on hemodialysis despite high norepinephrine requirements and ultimately transitioned to continuous veno-venous hemofiltration.

MEASUREMENTS AND MAIN RESULTS

The first patient died despite maximal intensive care. The second patient improved immediately upon starting hemodialysis and was extubated within 48 hours and discharged home. The third patient eventually became hypotensive and was treated with repeated sessions of renal replacement therapy. He ultimately was extubated and discharged home. The infectious workup was negative for all three patients, and antibiotics were discontinued after 2 days in the second and third patients.

CONCLUSIONS

Ombitasvir-paritaprevir-ritonavir-dasabuvir may cause type B lactic acidosis. Further study is warranted to identify risk factors and elucidate the mechanisms of excessive lactate production.

Ombitasvir/Paritaprevir/Ritonavir: A Review in Chronic HCV Genotype 4 Infection

A fixed-dose tablet comprising the NS5A inhibitor ombitasvir, the NS3/4A inhibitor paritaprevir and ritonavir (ombitasvir/paritaprevir/ritonavir) (Technivie(®), Viekirax(®)) is available for use, in combination with ribavirin, for the treatment of chronic hepatitis C virus (HCV) genotype 4 infection. High sustained virological response rates at 12 weeks post-treatment (SVR12) were achieved in treatment-naive or -experienced patients with chronic HCV genotype 4 infection, including patients without cirrhosis who received ombitasvir plus paritaprevir and ritonavir in combination with ribavirin for 12 weeks (SVR12 100 %) (PEARL-I trial), patients with compensated cirrhosis who received ombitasvir/paritaprevir/ritonavir plus ribavirin for 12 or 16 weeks (SVR12 97 and 98 %) (AGATE-I trial), or Egyptian patients without cirrhosis who received ombitasvir/paritaprevir/ritonavir plus ribavirin for 12 weeks (SVR12 94 %) or with compensated cirrhosis who received ombitasvir/paritaprevir/ritonavir plus ribavirin for 12 or 24 weeks (SVR12 97 and 93 %) (AGATE-II trial). Ombitasvir/paritaprevir/ritonavir was generally well tolerated in patients with chronic HCV genotype 4 infection without cirrhosis or with compensated cirrhosis in clinical trials. There have been postmarketing reports of hepatic decompensation and hepatic failure, which mainly occurred in patients with advanced cirrhosis who received regimens containing ombitasvir/paritaprevir/ritonavir. In conclusion, ombitasvir/paritaprevir/ritonavir is a valuable option for use in patients with chronic HCV genotype 4 infection without cirrhosis or with compensated cirrhosis.

Effectiveness and safety of ombitasvir, paritaprevir, ritonavir ± dasabuvir ± ribavirin: An early access programme for Spanish patients with genotype 1/4 chronic hepatitis C virus infection

Over the last 5 years, therapies for hepatitis C virus (HCV) infection have improved significantly, achieving sustained virologic response (SVR) rates of up to 100% in clinical trials in patients with HCV genotype 1. We investigated the effectiveness and safety of ombitasvir/paritaprevir/ritonavir±dasabuvir in an early access programme. This was a retrospective, multicentre, national study that included 291 treatment-naïve and treatment-experienced patients with genotype 1 or 4 HCV infection. Most patients (65.3%) were male, and the mean age was 57.5 years. The mean baseline viral load was 6.1 log, 69.8% had HCV 1b genotype, 72.9% had cirrhosis and 34.7% were treatment-naïve. SVR at 12 weeks posttreatment was 96.2%. Four patients had virological failure (1.4%), one leading to discontinuation. There were no statistical differences in virological response according to genotype or liver fibrosis. Thirty patients experienced serious adverse events (SAEs) (10.3%), leading to discontinuation in six cases. Hepatic decompensation was observed in five patients. Four patients died during treatment or follow-up, three of them directly related to liver failure. Multivariate analyses showed a decreased probability of achieving SVR associated with baseline albumin, bilirubin and Child-Pugh score B, and a greater probability of developing SAEs related to age and albumin. This combined therapy was highly effective in clinical practice with an acceptable safety profile and low rates of treatment discontinuation.

Antiviral response and resistance analysis of treatment-naïve HCV infected patients receiving multiple doses of the NS3 protease inhibitor GS-9256

The NS3 protease inhibitor (PI) GS-9256 has demonstrated antiviral activity in a monotherapy study and in combination with other DAAs for treatment of chronic hepatitis C virus (HCV) infection. The resistance profile of GS-9256 was investigated in a phase 1 monotherapy study of patients with HCV genotype (GT) 1 infection. No PI resistance associated substitutions (RASs) at positions 36, 155, 156, 168 and 170 were observed at baseline by population sequencing (15% cutoff) in the 54 patients enrolled in the study, however the PI RAS Q80K were detected in 41% of patients at baseline. In patients who received 75 mg of the investigational protease inhibitor (PI) GS-9256 BID, 300 mg of GS-9256 QD and 200 mg of GS-9256 BID for three days, NS3 RASs (A156V, R155K, D168G/E/N/V) were observed in 9/21, 3/7 and 8/8 post-treatment, respectively. Q80K was not selected in any patients post-treatment. The mean maximal viral load response was -3.0 ± 0.42 log₁₀ IU/mL HCV RNA in the 200 mg BID cohort. In more than 50% of the patients with RASs detected at Day 4, mutations were no longer detectable by population sequencing at Day 14. One patient had the R155K mutation persist to Week 24. Phenotypic analyses showed that substitutions at R155, A156 and D168 significantly reduced susceptibility to GS-9256. In conclusion, NS3 PI RASs were rapidly selected in the majority of patients receiving GS-9256 as monotherapy, despite undetectable levels at baseline. The R155, A156 and D168 substitutions identified in patients confer reduced susceptibility to GS-9256 and other PIs in vitro.

Network meta-analysis of first- and second-generation protease inhibitors for chronic hepatitis C genotype 1: efficacy based on RVR and SVR 24

PURPOSE

This study aimed to compare the efficacy among direct-acting antiviral agents (first and second-generation direct-acting antiviral agents (DAAs)) with placebo and with standard dual therapy (pegylated interferon + ribavirin (Peg-IFN + RBV)) in terms of rapid virologic response (RVR) and sustained virologic response (SVR) in chronic hepatitis C genotype 1 treatment.

METHODS

We performed a systematic review of randomized controlled trials (RCTs) in MEDLINE, International Pharmaceutical Abstracts, Cochrane Library, SCIELO, and Scopus and conducted a network meta-analysis to compare the efficacy of boceprevir (BOC), daclatasvir (DCV), grazoprevir, simeprevir (SMV) and telaprevir (TVR), in treatment-naive and treatment-experienced patients.

RESULTS

Sixteen studies encompassing 7171 patients were analysed. Associations between DAAs therapies (IFN-free regimens) could not be addressed since no common comparator was found in the RCTs among these associations and the other agents included in the present analysis. All agents were more efficacious than placebo or Peg-IFN + RBV in terms of RVR, while only BOC and SMV showed statistically significant superiority for the SVR outcome when compared to placebo or standard dual therapy. No significant differences between the DAAs were observed. The analysis prioritized treatment with DCV for both efficacy outcomes. Node-splitting analysis showed that our networks are robust (p > 0.05).

CONCLUSIONS

The superiority of DAAs over placebo or standard dual therapy with Peg-IFN + RBV was confirmed, indicating the greater efficacy of DCV. This study is the first network meta-analysis that included RVR as an outcome in the evaluation of these agents via indirect comparison. Further investigation should be carried out addressing safety and tolerability outcomes.

Characterization of NS5A polymorphisms and their impact on response rates in patients with HCV genotype 2 treated with daclatasvir-based regimens

OBJECTIVE

Daclatasvir (DCV) is a pan-genotypic non-structural protein 5A (NS5A) inhibitor that is approved for treatment of hepatitis C virus (HCV) genotype (GT)1 and GT3 in the USA and GT1, GT3 and GT4 in Europe. We set out to examine the impact of daclatasvir-based regimens on the sustained virologic response (SVR) in patients with GT2 infection with respect to GT2 subtype and NS5A polymorphisms at amino acid positions associated with daclatasvir resistance.

METHODS

Analyses were performed on 283 GT2 NS5A sequences from five daclatasvir regimen-based clinical trials (ClinicalTrials.gov: NCT-01257204, NCT-01359644, NCT-02032875, NCT-02032888 and NCT-01616524) and 143 NS5A sequences from the Los Alamos HCV database. Susceptibility analyses of substitutions at amino acid positions associated with daclatasvir resistance and patient-derived NS5A sequences were performed using an in vitro HCV replication assay.

RESULTS

Of 13 GT2 subtypes identified from 426 NS5A sequences, the most prevalent were GT2a (32%), GT2b (48%) and GT2c (10%). The most prevalent NS5A polymorphism was L31M (GT2a = 88%; GT2b = 59%; GT2c = 10%). Substitutions identified in 96% of GT2 NS5A sequences exhibited daclatasvir EC₅₀ values ranging from 0.005 to 20 nM when tested in vitro. A similar range in daclatasvir EC₅₀ values was observed for 16 diverse GT2 patient-derived NS5A sequences (EC₅₀ = 0.005-60 nM). Depending on the daclatasvir-based regimen studied (daclatasvir/interferon-based or daclatasvir/sofosbuvir-based), SVR rates ranged from 90% to 100% in GT2 patients with the most prevalent baseline NS5A-L31M polymorphism, compared with from 96% to 100% without this polymorphism.

CONCLUSIONS

High SVR rates were achieved in patients infected with GT2 treated with daclatasvir-based regimens irrespective of GT2 subtype or baseline NS5A polymorphisms.

2015 Philip S. Portoghese Medicinal Chemistry Lectureship. Curing Hepatitis C Virus Infection with Direct-Acting Antiviral Agents: The Arc of a Medicinal Chemistry Triumph

The development of direct-acting antiviral agents that can cure a chronic hepatitis C virus (HCV) infection after 8-12 weeks of daily, well-tolerated therapy has revolutionized the treatment of this insidious disease. In this article, three of Bristol-Myers Squibb's HCV programs are summarized, each of which produced a clinical candidate: the NS3 protease inhibitor asunaprevir (64), marketed as Sunvepra, the NS5A replication complex inhibitor daclatasvir (117), marketed as Daklinza, and the allosteric NS5B polymerase inhibitor beclabuvir (142), which is in late stage clinical studies. A clinical study with 64 and 117 established for the first time that a chronic HCV infection could be cured by treatment with direct-acting antiviral agents alone in the absence of interferon. The development of small molecule HCV therapeutics, designed by medicinal chemists, has been hailed as "the arc of a medical triumph" but may equally well be described as "the arc of a medicinal chemistry triumph".

Exploration of acetanilide derivatives of 1-(ω-phenoxyalkyl)uracils as novel inhibitors of Hepatitis C Virus replication

Hepatitis C Virus (HCV) is a major public health problem worldwide. While highly efficacious directly-acting antiviral agents have been developed in recent years, their high costs and relative inaccessibility make their use limited. Here, we describe new 1-(ω-phenoxyalkyl)uracils bearing acetanilide fragment in 3 position of pyrimidine ring as potential antiviral drugs against HCV. Using a combination of various biochemical assays and in vitro virus infection and replication models, we show that our compounds are able to significantly reduce viral genomic replication, independently of virus genotype, with their IC50 values in the nanomolar range. We also demonstrate that our compounds can block de novo RNA synthesis and that effect is dependent on a chemical structure of the compounds. A detailed structure-activity relationship revealed that the most active compounds were the N(3)-substituted uracil derivatives containing 6-(4-bromophenoxy)hexyl or 8-(4-bromophenoxy)octyl fragment at N(1) position.

Safety and efficacy of daclatasvir in the management of patients with chronic hepatitis C

Daclatasvir (Daklinza™), a new oral direct-acting antiviral, is an inhibitor of hepatitis C virus NS5A protein and has recently been approved in the United States, Europe and Japan in chronic hepatitis C. It shows potent pangenotypic activity and moderately high genetic barrier to resistance improving the sustained virological response (SVR) rates. In COMMAND phase 2 trials, daclatasvir demonstrated high SVR rates in HCV genotype 1-4 chronically infected patients treated with peginterferon-a (pegIFNα) plus ribavirin (RBV). Furthermore, it produced even higher response rates in all-oral combination with sofosbuvir, an interferon-free regimen, with or without ribavirin, in patients with advanced liver disease, HCV/HIV coinfection, liver transplantation in ALLY studies and other real-world studies. This narrative review provides information on the pharmacological properties, role, efficacy and safety of daclatasvir-containing regimens in chronic hepatitis C patients. Daclatasvir administered once-daily in combination with sofosbuvir is an effective 12-week treatment in adult patients with chronic hepatitis C and is generally safe and well tolerated.

Discovery of Novel Thiophene-Based, Thumb Pocket 2 Allosteric Inhibitors of the Hepatitis C NS5B Polymerase with Improved Potency and Physicochemical Profiles

The hepatitis C viral proteins NS3/4A protease, NS5B polymerase, and NS5A are clinically validated targets for direct-acting antiviral therapies. The NS5B polymerase may be inhibited directly through the action of nucleosides or nucleotide analogues or allosterically at a number of well-defined sites. Herein we describe the further development of a series of thiophene carboxylate allosteric inhibitors of NS5B polymerase that act at the thumb pocket 2 site. Lomibuvir (1) is an allosteric HCV NS5B inhibitor that has demonstrated excellent antiviral activity and potential clinical utility in combination with other direct acting antiviral agents. Efforts to further explore and develop this series led to compound 23, a compound with comparable potency and improved physicochemical properties.

Interferon-Free Treatments for Chronic Hepatitis C Genotype 1 Infection

Hepatitis C virus (HCV) infection affects as many as 185 million people globally, many of whom are chronically infected and progress over time to cirrhosis, decompensated liver disease, hepatocellular carcinoma, and eventually death without a liver transplant. In the United States, HCV genotype 1 constitutes about 75% of all infections. While interferon and ribavirin therapy was the cornerstone of treatment for many years, interferon-free treatments have become the standard of care with the emergence of new direct-acting agents, resulting in more effective treatment, shorter duration of therapy, better tolerability, lower pill burden, and ultimately better adherence. This review will summarize the evidence for the currently available combination therapies as well as emerging therapies in phase 3 trials for treatment of HCV genotype 1.

The Combination of Grazoprevir, a Hepatitis C Virus (HCV) NS3/4A Protease Inhibitor, and Elbasvir, an HCV NS5A Inhibitor, Demonstrates a High Genetic Barrier to Resistance in HCV Genotype 1a Replicons

The selection of resistance-associated variants (RAVs) against single agents administered to patients chronically infected with hepatitis C virus (HCV) necessitates that direct-acting antiviral agents (DAAs) targeting multiple viral proteins be developed to overcome failure resulting from emergence of resistance. The combination of grazoprevir (formerly MK-5172), an NS3/4A protease inhibitor, and elbasvir (formerly MK-8742), an NS5A inhibitor, was therefore studied in genotype 1a (GT1a) replicon cells. Both compounds were independently highly potent in GT1a wild-type replicon cells, with 90% effective concentration (EC90) values of 0.9 nM and 0.006 nM for grazoprevir and elbasvir, respectively. No cross-resistance was observed when clinically relevant NS5A and NS3 RAVs were profiled against grazoprevir and elbasvir, respectively. Kinetic analyses of HCV RNA reduction over 14 days showed that grazoprevir and elbasvir inhibited prototypic NS5A Y93H and NS3 R155K RAVs, respectively, with kinetics comparable to those for the wild-type GT1a replicon. In combination, grazoprevir and elbasvir interacted additively in GT1a replicon cells. Colony formation assays with a 10-fold multiple of the EC90 values of the grazoprevir-elbasvir inhibitor combination suppressed emergence of resistant colonies, compared to a 100-fold multiple for the independent agents. The selected resistant colonies with the combination harbored RAVs that required two or more nucleotide changes in the codons. Mutations in the cognate gene caused greater potency losses for elbasvir than for grazoprevir. Replicons bearing RAVs identified from resistant colonies showed reduced fitness for several cell lines and may contribute to the activity of the combination. These studies demonstrate that the combination of grazoprevir and elbasvir exerts a potent effect on HCV RNA replication and presents a high genetic barrier to resistance. The combination of grazoprevir and elbasvir is currently approved for chronic HCV infection.

Ombitasvir, paritaprevir, ritonavir, dasabuvir and ribavirin in cirrhosis after complete destruction of hepatocellular carcinoma

We observed a sustained viral response (SVR) of ombitasvir/paritaprevir/ritonavir, dasabuvir and ribavirin therapy, for 12 wk, in two cases with compensated liver cirrhosis and fully destroyed early hepatocellular carcinoma (HCC). Patients were infected with hepatitis C virus (HCV) genotype 1b and were previous null responders/relapsers to interferon-alpha/ribavirin (IFN/RBV). There was a rapid suppression of HCV RNA to undetectable levels within the first two treatment weeks. SVR was achieved even after marked reduction of the RBV dose. The treatment was well tolerated. Both subjects experienced worsening of liver disease during therapy, in different patterns: severe, transient, predominantly direct hyperbilirubinemia without cytolysis (case 1) or progressive increase of aminotransferases (grade 4) without severe hyperbilirubinemia (case 2). Adverse events spontaneously resolved. The patients remained in a good clinical condition without hepatic decompensation. There was no re-occurrence of HCC. This is the first report for treatment of HCV cirrhosis after complete HCC destruction.

Discovery of silyl proline containing HCV NS5A inhibitors with pan-genotype activity: SAR development

HCV NS5A inhibitors have shown impressive in vitro potency profiles in HCV replicon assays thus making them attractive components for inclusion in an all oral fixed dose combination treatment regimen. Herein we describe the research efforts that led to the discovery of silyl proline containing HCV NS5A inhibitors such as 7e and 8a with pan-genotype activity profile and acceptable pharmacokinetic properties.

Discovery of MK-8831, A Novel Spiro-Proline Macrocycle as a Pan-Genotypic HCV-NS3/4a Protease Inhibitor

We have been focused on identifying a structurally different next generation inhibitor to MK-5172 (our Ns3/4a protease inhibitor currently under regulatory review), which would achieve superior pangenotypic activity with acceptable safety and pharmacokinetic profile. These efforts have led to the discovery of a novel class of HCV NS3/4a protease inhibitors containing a unique spirocyclic-proline structural motif. The design strategy involved a molecular-modeling based approach, and the optimization efforts on the series to obtain pan-genotypic coverage with good exposures on oral dosing. One of the key elements in this effort was the spirocyclization of the P2 quinoline group, which rigidified and constrained the binding conformation to provide a novel core. A second focus of the team was also to improve the activity against genotype 3a and the key mutant variants of genotype 1b. The rational application of structural chemistry with molecular modeling guided the design and optimization of the structure-activity relationships have resulted in the identification of the clinical candidate MK-8831 with excellent pan-genotypic activity and safety profile.

Entry inhibitors: New advances in HCV treatment

Hepatitis C virus (HCV) infection affects approximately 3% of the world's population and causes chronic liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. Although current antiviral therapy comprising direct-acting antivirals (DAAs) can achieve a quite satisfying sustained virological response (SVR) rate, it is still limited by viral resistance, long treatment duration, combined adverse reactions, and high costs. Moreover, the currently marketed antivirals fail to prevent graft reinfections in HCV patients who receive liver transplantations, probably due to the cell-to-cell transmission of the virus, which is also one of the main reasons behind treatment failure. HCV entry is a highly orchestrated process involving initial attachment and binding, post-binding interactions with host cell factors, internalization, and fusion between the virion and the host cell membrane. Together, these processes provide multiple novel and promising targets for antiviral therapy. Most entry inhibitors target host cell components with high genetic barriers and eliminate viral infection from the very beginning of the viral life cycle. In future, the addition of entry inhibitors to a combination of treatment regimens might optimize and widen the prevention and treatment of HCV infection. This review summarizes the molecular mechanisms and prospects of the current preclinical and clinical development of antiviral agents targeting HCV entry.