Ombitasvir/paritaprevir/ritonavir and dasabuvir tablets for hepatitis C virus genotype 1 infection

Paritaprevir as a pan-antiviral against different flaviviruses

Introduction

The flavivirus infections caused by the Zika virus (ZIKV), Dengue virus (DENV), and West Nile virus (WNV) cause mild to serious pathological conditions, such as fever, joint pain, shock, internal bleeding, organ failure, nausea, breathlessness, brain tissue damage, neurodegenerative diseases, and deaths. As currently no efficient vaccine or drug is available to prevent or treat these diseases in humans, it is essential to identify potential drug-like molecules to treat these diseases. For these reasons, several known anti-viral drugs are repurposed against the proteases of ZIKV, WNV, and DENV to inhibit their activities.

Methods

The GOLD 5.0 molecular docking program was used to dock 20 HIV and HCV drugs against the ZIKV protease. Based on docking scores, 5 drugs were found to bind to the ZIKV protease with high affinities. Subsequently, the AMBER ff14SB force field was employed to simulate these drug-bound complexes of ZIKV protease. The MM/PBSA free energy method was utilized to compute the binding free energies of these complexes. Consequently, the two best ZIKV protease inhibitors were repurposed against the proteases of DENV and WNV.

Results and Discussion

It is found that out of the 5 drugs, Ritonavir and Paritaprevir bind to the NS2B-NS3 protease of the ZIKV strongly with the Gibbs binding free energies (∆Gbind) of -17.44±3.18 kcal/mol and -14.25±3.11 kcal/mol respectively. Remarkably, Ritonavir binds to the ZIKV Protease about 12 kcal/mol more strongly compared to its binding to the HIV protease. It is further found that Paritaprevir binds to DENV and WNV proteases as strongly as it binds to the ZIKV protease. Hence it is proposed that Paritaprevir may act as a potent pan-antiviral against the Zika, West Nile, and Dengue viral diseases.

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.

Progress, evolving therapeutic/diagnostic approaches, and challenges in the management of hepatitis C virus infections

Hepatitis C virus (HCV) infections are emerging as one of the foremost challenges in healthcare owing to its chronicity and the virus's quasispecies nature. Worldwide, over 170 million people are chronically infected with HCV, with an annual mortality of over 500,000 people across the world. The emerging pathophysiological evidence links HCV infections to a risk of developing liver diseases such as cirrhosis and hepatocellular carcinoma. Despite the great strides that have been made towards understanding the pathophysiology of disease progression, the tailored treatments of HCV infection remain to be established. The present review provides an update of the literature pertaining to evolving therapeutic approaches and prophylactic measures for the effective management of HCV infections. An extensive discussion of established and experimental immune prophylactic measures also sheds light on current developments in the design of vaccination strategies against HCV infection. We have also attempted to address the application of nanotechnology in formulating effective therapeutic interventions against HCV. Pointing out the limitations of the existing diagnostic methods and therapeutic approaches against HCV might inspire the design and development of novel, efficient, reliable, and cost-effective diagnostic technologies as well as novel therapeutic and immune prophylactic interventions for the effective management of HCV.

The “Invisible Enemy” SARS-CoV-2: Viral Spread and Drug Treatment

Nowadays, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has become the main subject of the scientific medical world and all World Organizations, causing millions of deaths worldwide. In this review, we have highlighted the context of the Coronavirus disease 2019 (COVID-19) pandemic, how the virus spreads, the symptoms and complications that may occur, and, especially, the drug treatment of viral infection, with emphasis on monoclonal antibodies. While well-known strains such as Alpha, Beta, Gamma, and, especially, Delta have shown an accelerated transmission among the population, the new Omicron variant (discovered on 24 November 2021) indicates more significant infectiousness and the poor efficacy of monoclonal antibody therapy due to mutations on the spike protein receptor-binding domain. With these discoveries, the experiments began, the first being in silico and in vitro, but these are not enough, and in vivo experiments are needed to see exactly the cause of neutralization of the action of these drugs. Following the documentation of the latest medical and scientific research, it has been concluded that there are many chemical molecules that have the potential to treat SARS-CoV-2 infection, but more detailed clinical trials are needed for their use in therapy. In addition, it is important to consider the structure of the viral strain in the administration of treatment.

Analysis of Factors Associated with Hiccups Using the FAERS Database

In this study, we used the large number of cases in the FDA adverse-event reporting system (FAERS) database to investigate risk factors for drug-induced hiccups and to explore the relationship between hiccups and gender. From 11,810,863 adverse drug reactions reported between the first quarter of 2004 and the first quarter of 2020, we extracted only those in which side effects occurred between the beginning and end of drug administration. Our sample included 1454 adverse reactions for hiccups, with 1159 involving males and 257 involving females (the gender in 38 reports was unknown). We performed univariate analyses of the presence or absence of hiccups for each drug and performed multivariate analysis by adding patient information. The multivariate analysis showed nicotine products to be key suspect drugs for both men and women. For males, the risk factors for hiccups included older age, lower body weight, nicotine, and 14 other drugs. For females, only nicotine and three other drugs were extracted as independent risk factors. Using FAERS, we were thus able to extract new suspect drugs for drug-induced hiccups. Furthermore, this is the first report of a gender-specific analysis of risk factors for hiccups that provides novel insights into drug-induced hiccups, and it suggests that the mechanism responsible is strongly related to gender. Thus, this study can contribute to elucidating the mechanism underlying this phenomenon.

HIV Protease Inhibitor Ritonavir Impairs Endothelial Function Via Reduction in Adipose Mass and Endothelial Leptin Receptor-Dependent Increases in NADPH Oxidase 1 (Nox1), C-C Chemokine Receptor Type 5 (CCR5), and Inflammation

Background Cardiovascular disease is currently the leading cause of death in patients with human immunodeficiency virus on combination antiretroviral therapy. Although the use of the protease inhibitor ritonavir has been associated with increased prevalence of cardiovascular disease, the underlying mechanisms remain ill-defined. Herein, we tested the hypothesis that ritonavir-mediated lipoatrophy causes endothelial dysfunction via reducing endothelial leptin signaling. Methods and Results Long-term (4 weeks) but not short-term (3 days) treatment with ritonavir reduced body weight, fat mass, and leptin levels and induced endothelial dysfunction in mice. Moreover, ritonavir increased vascular NADPH oxidase 1, aortic H₂O₂ levels as well as interleukin-1β, GATA3 (GATA binding protein 3), the macrophage marker (F4/80), and C-C chemokine receptor type 5 (CCR5) expression. Reactive oxygen species scavenging with tempol restored endothelial function, and both NADPH oxidase 1 and CCR5 deletion in mice protected from ritonavir-mediated endothelial dysfunction and vascular inflammation. Remarkably, leptin infusion markedly improved endothelial function and significantly reduced vascular NADPH oxidase 1, interleukin-1β, GATA3, F4/80, and CCR5 levels in ritonavir-treated animals. Selective deficiency in endothelial leptin receptor abolished the protective effects of leptin infusion on endothelial function. Conversely, selective increases in endothelial leptin signaling with protein tyrosine phosphatase deletion blunted ritonavir-induced endothelial dysfunction. Conclusions All together, these data indicate that ritonavir-associated endothelial dysfunction is a direct consequence of a reduction in adiposity and leptin secretion, which decreases endothelial leptin signaling and leads to a NADPH oxidase 1-induced, CCR5-mediated reduction in NO bioavailability. These latter data also introduce leptin deficiency as an additional contributor to cardiovascular disease and leptin as a negative regulator of CCR5 expression, which may provide beneficial avenues for limiting human immunodeficiency virus infection.

Incidence and predictors for abnormal liver function during direct-acting antiviral agents in chronic hepatitis C patients

Abrupt alanine aminotransferase (ALT) elevation during direct-acting antiviral agents (DAA) treatment is an uncommon but noticeable adverse event in chronic hepatitis C (CHC) patients, which may lead to early termination of treatment. This study aims to investigate the incidence, outcome and predictors of the on-treatment ALT elevation during DAA therapy.CHC patients treated with DAA regimen in Chang Gung Memorial Hospital, Linkou branch during March 2015 to March 2019 were recruited. Prospective scheduled ALT assessment at baseline, 2nd, 4th, 8th, and 12th/24th weeks were recorded. Pretherapy host and viral factors were compared between patients with and without on-treatment ALT elevation. Multivariate logistic regression was used for independent factors for on-treatment ALT elevation.A total of 1563 CHC patients treated with grazoprevir/elbasvir, glecaprevir/pibrentasvir and sofosbuvir-based regimen were analyzed. On-treatment ALT elevation occurred in 10.9% patients while those treated with glecaprevir/pibrentasvir had the least possibility (5.4%). Only 1.4% patients had ≥grade 3 ALT elevation events. The presence of such events had no impact on sustained virological response 12 rates. Hepatitis B virus coinfection (aOR: 3.599, P < 0.001) and higher pretherapy ALT (1-5x, ≥5x upper limit of normal: aOR: 2.632, P = 0.024, aOR: 4.702, P = .011, respectively) were significant predictors for ALT elevation.On-treatment ALT elevation occurred in one-tenth CHC patients treated with preferred DAAs but had no impact on sustained virological response rate.

Overview of hepatitis C infection, molecular biology, and new treatment

The World Health Organization estimates that 71 million people worldwide have chronic hepatitis C viral infection. A major challenge is overall lack of public awareness of hepatitis C, particularly among infected people of their infection status. Chronic hepatitis C infection is associated with advanced liver disease, is the main cause of hepatocellular carcinoma and causes many extra-hepatic manifestations. The existence of seven viral genotypes complicates targeting of treatment. Recent years have seen the approval of many direct acting antivirals targeted at hepatitis C virus non-structural proteins. These have revolutionized therapy as they allow achievement of extremely high sustained virologic responses. Of great significance is the development of pan-genotypic drug combinations, including the NS3/4A-NS5A inhibitor combinations sofosbuvir-velpatasvir and glecaprevir-pibrentasvir. However, resistance-associated mutations can result in failure of these treatments in a small number of patients. This, combined with the high costs of treatment, highlights the importance of continued research into effective anti-hepatitis C therapies, for example aimed at viral entry. Recent developments include identification of the potential of low-cost anti-histamines for repurposing as inhibitors of hepatitis C viral entry. In this review we focus on molecular biology of hepatitis C virus, and the new developments in hepatitis C treatment.

Hepatitis C virus leaves an epigenetic signature post cure of infection by direct-acting antivirals

The increasing worldwide prevalence of Hepatocellular carcinoma (HCC), characterized by resistance to conventional chemotherapy, poor prognosis and eventually mortality, place it as a prime target for new modes of prevention and treatment. Hepatitis C Virus (HCV) is the predominant risk factor for HCC in the US and Europe. Multiple epidemiological studies showed that sustained virological responses (SVR) following treatment with the powerful direct acting antivirals (DAAs), which have replaced interferon-based regimes, do not eliminate tumor development. We aimed to identify an HCV-specific pathogenic mechanism that persists post SVR following DAAs treatment. We demonstrate that HCV infection induces genome-wide epigenetic changes by performing chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) for histone post-translational modifications that are epigenetic markers for active and repressed chromatin. The changes in histone modifications correlate with reprogramed host gene expression and alter signaling pathways known to be associated with HCV life cycle and HCC. These epigenetic alterations require the presence of HCV RNA or/and expression of the viral proteins in the cells. Importantly, the epigenetic changes induced following infection persist as an "epigenetic signature" after virus eradication by DAAs treatment, as detected using in vitro HCV infection models. These observations led to the identification of an 8 gene signature that is associated with HCC development and demonstrate persistent epigenetic alterations in HCV infected and post SVR liver biopsy samples. The epigenetic signature was reverted in vitro by drugs that inhibit epigenetic modifying enzyme and by the EGFR inhibitor, Erlotinib. This epigenetic "scarring" of the genome, persisting following HCV eradication, suggest a novel mechanism for the persistent pathogenesis of HCV after its eradication by DAAs. Our study offers new avenues for prevention of the persistent oncogenic effects of chronic hepatitis infections using specific drugs to revert the epigenetic changes to the genome.

Tamoxifen-induced hepatotoxicity caused by drug interaction with direct-acting antiviral agents for hepatitis C

A 68-year-old man develops acute hepatocellular injury during treatment with direct-acting antiviral agents (DAA) for hepatitis C. Medical history reveals the intake of tamoxifen as adjuvant treatment for breast cancer, currently in remission. After stopping tamoxifen, despite the continuation of the anti-HCV agents, a complete resolution of liver injury occurs. This interesting case illustrates tamoxifen hepatotoxicity induced by CYP3A4 interaction with direct anti-HCV agents. It stresses the importance of checking for interactions before starting treatment for hepatitis C.

Pharmacokinetic Enhancers (Boosters)-Escort for Drugs against Degrading Enzymes and Beyond

Pharmacokinetic enhancers (boosters) are compounds used in combination with a primary therapeutic agent (drug) and are not used for their direct effects on the disease but because they enhance or restore the activity of the primary agent. Hence, in certain cases, they represent an indispensable escort for enzyme-labile drugs. Pharmacokinetic enhancers can exert their activity on different ways. In the most common case, they inhibit enzymes such as human cytochrome P450 enzymes in the liver or other organs and, thereby, block or reduce undesired metabolism and inactivation of the primary drug. In this review, an overview will be given on the therapeutically most important classes of pharmacokinetic enhancers like β-lactamase inhibitors, inhibitors of CYP (cytochrome P450) enzymes in HIV therapy and hepatitis C, boosters for fluoropyrimidine-type anticancer agents, compounds utilized for enabling therapy of Parkinson's disease with levodopa, and others. Inhibitors of efflux pumps in both pathogenic bacteria and tumor cells will be addresses shortly.

[Myocardial injury associated with chronic hepatitis C: Clinical types and pathogenetic components]

Heart injury is one of the extrahepatic manifestations of chronic hepatitis C (CHC). The paper gives Russian and foreign authors' data on a relationship between CHC and myocardial injury. It discusses different pathogenetic components (the direct effect of the virus, immunological components), through which hepatitis C virus can induce myocarditis and cardiomyopathies in patients with CHC.

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.

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.

Genetic Analysis of Serum-Derived Defective Hepatitis C Virus Genomes Revealed Novel Viral cis Elements for Virus Replication and Assembly

Defective viral genomes (DVGs) of hepatitis C virus (HCV) exist, but their biological significances have not been thoroughly investigated. Here, we analyzed HCV DVGs circulating in patient sera that possess deletions in the structural protein-encoding region. About 30% of 41 HCV clinical isolates possess DVGs that originated from the full-length genome in the same patients. No correlation between DVGs, viremia, and alanine aminotransferase (ALT) levels was found. Sequencing analysis of DVGs revealed the existence of deletion hot spots, with upstream sites in E1 and downstream sites in E2 and NS2. Interestingly, the coding sequences for the core protein and the C-terminal protease domain of NS2 were always intact in DVGs despite the fact that both proteins are dispensable for HCV genome replication. Mechanistic studies showed that transmembrane segment 3 (TMS3) of NS2, located immediately upstream of its protease domain, was required for the cleavage of NS2-NS3 and the replication of DVGs. Moreover, we identified a highly conserved secondary structure (SL750) within the core domain 2-coding region that is critical for HCV genome packaging. In summary, our analysis of serum-derived HCV DVGs revealed novel viral cis elements that play important roles in virus replication and assembly.IMPORTANCE HCV DVGs have been identified in vivo and in vitro, but their biogenesis and physiological significances remain elusive. In addition, a conventional packaging signal has not yet been identified on the HCV RNA genome, and mechanisms underlying the specificity in the encapsidation of the HCV genome into infectious particles remain to be uncovered. Here, we identified new viral cis elements critical for the HCV life cycle by determining genetic constraints that define the boundary of serum-derived HCV DVGs. We found that transmembrane segment 3 of NS2, located immediately upstream of its protease domain, was required for the cleavage of NS2-NS3 and the replication of DVGs. We identified a highly conserved secondary structure (SL750) within the core-coding region that is critical for HCV genome packaging. In summary, our analysis of serum-derived HCV DVGs revealed previously unexpected novel cis elements critical for HCV replication and morphogenesis.

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.

Safety and Efficacy of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir with or without Ribavirin for Treatment of Hepatitis C Virus Genotype 1: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Interferon-free regimens are rapidly evolving for patients with chronic hepatitis C virus (HCV) infection. We performed this meta-analysis to investigate the safety and efficacy of a combination regimen (ombitasvir [OBV]/paritaprevir [PTV]/ritonavir [r] ± dasabuvir [DSV]) for the treatment of patients with HCV genotype 1 infection.

METHODS

A computerized literature search for relevant clinical trials was conducted during May 2017. Data on sustained virological response (SVR), virological relapse, and safety outcomes were extracted and calculated as pooled proportion (PP) or risk ratio (RR) with their 95% confidence interval (CI), using StatsDirect and RevMan software.

RESULTS

The final analysis included 13 studies for HCV genotype 1 (3115 patients). The pooled effect estimate showed that 12-week treatment of genotype 1 patients with the OBV/PTV/r regimen achieved a high SVR rate (PP = 94%, 95% CI 92-96) that increased to (PP = 97%, 95% CI 96-98) upon the addition of DSV. These results were consistent when independent subgroup analyses were conducted based on viral subgenotypes, the presence of cirrhosis, or former treatment failure. Adding ribavirin (RBV) to this regimen was not associated with increased SVR rates (risk ratio = 1, 95% CI 0.98-1.02), while it increased the risk of serious adverse events (p = 0.02), insomnia (p = 0.001), and pruritus (p < 0.001).

CONCLUSION

The current meta-analysis showed a high efficacy for the OBV/PTV/r regimen in the treatment of HCV genotype 1 (with DSV) infection, regardless of the presence of cirrhosis or former treatment failure. Adding RBV to this regimen slightly decreased the relapse rate. Future studies with larger sample sizes are required to investigate the efficacy of this regimen in other HCV genotypes and to establish the evidence about the effect of adding RBV to OBV/PTV/r + DSV.

Mechanism of in-vitro inhibition of UGT1A1 by paritaprevir

OBJECTIVES

The direct-acting protease inhibitor paritaprevir is a new pharmaco-logic option available for treatment of chronic hepatitis C (HCV). Paritaprevir is reported to inhibit human UGT 1A1, but the mechanism of inhibition and its possible clinical consequences are not established. Our objective was to evaluate the in-vitro metabolic interaction between paritaprevir and the oral contraceptive steroid ethinyl estradiol (EE), a UGT 1A1 substrate.

METHODS

Enzyme kinetic parameters were determined using human liver microsomes for the biotransformation of EE to its glucuronide metabolites, and the potency and mechanism of inhibition by paritaprevir. Probenecid was used as a reference inhibitor for purposes of assay validation.

KEY FINDINGS

The underlying pattern of EE kinetics was complex, with evidence of substrate inhibition. The in-vitro inhibition constant (K_i ) value for paritaprevir vs EE on average was 20 μm and was consistent with a competitive inhibition mechanism. The ratio of in-vivo maximum plasma concentration of paritaprevir to in-vitro K_i was <0.1.

CONCLUSIONS

Paritaprevir is an in-vitro inhibitor of UGT 1A1. However, the in-vitro K_i value relative to maximum clinical plasma concentrations is below the threshold to trigger a recommendation for pharmacokinetic drug interaction studies.

Effectiveness of dasabuvir/ombitasvir/paritaprevir/ritonavir for hepatitis C virus in clinical practice: A population-based observational study

BACKGROUND

Direct acting antivirals for hepatitis C virus have shown dramatic results in clinical trials. However, their effectiveness has yet to be demonstrated within observational cohorts which lack exclusion criteria found in randomized control trials.

AIM

To determine the effectiveness of dasabuvir/ombitasvir/paritaprevir/ritonavir in achieving sustained virological response.

METHODS

Retrospective observational cohort study of all Clalit Health Services members with hepatitis C virus genotype 1 who were dispensed dasabuvir/ombitasvir/paritaprevir/ritonavir from January 1, 2015 to-November 31, 2015.

RESULTS

There were 564 participants during the study period. The average age was 61.9 years, 52.0% were male, and 61.5% were born Eastern/Central Europe or Central Asia. The prevalence of diabetes was 31.7% and 70.3% were overweight/obese. Cirrhosis was present in 41.0% of participants, of whom 52.8% had stage 4 fibrosis. Of the cohort, 416 (74.8%) had follow-up viral load testing at 10 or more weeks after the end of treatment. We report a sustained virological response of 98.8% among those tested.

CONCLUSIONS

Treatment with dasabuvir/ombitasvir/paritaprevir/ritonavir demonstrated a near universal effectiveness in achieving a sustained virological response among HCV patients in a large cohort.

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.

Interferon-free regimens in patients with hepatitis C infection and renal dysfunction or kidney transplantation

Treatment of patients with chronic kidney disease (CKD) and chronic hepatitis C (CHC) differs from that used in the general CHC population mostly when glomerular filtration rate (GFR) is below 30 mL/min, as sofosbuvir, the backbone of several current regimens, is officially contraindicated. Given that ribavirin free regimens are preferable in CKD, elbasvir/grazoprevir is offered in CHC patients with genotype 1 or 4 and ombitasvir/paritaprevir and dasabuvir in genotype 1b for 12 wk. Although regimens containing peginterferon with or without ribavirin are officially recommended for patients with CKD and genotype 2, 3, 5, 6, such regimens are rarely used because of their low efficacy and the poor safety and tolerance profile. In this setting, especially in the presence of advanced liver disease, sofosbuvir-based regimens are often used, despite sofosbuvir contraindication. It seems to have good overall safety with only 6% or 3.4% of CKD patients to discontinue therapy or develop serious adverse events without drug discontinuation. In addition, sustained virological response (SVR) rates with sofosbuvir based regimens in CKD patients appear to be comparable with SVR rates in patients with normal renal function. Treatment recommendations for kidney transplant recipients are the same with those for patients with CHC, taking into consideration potential drug-drug interactions and baseline GFR before treatment initiation. This review summarizes recent data on the current management of CHC in CKD patients highlighting their strengths and weaknesses and determining their usefulness in clinical practice.

N-Heterocyclic Carbene Capture by Cytochrome P450 3A4

Cytochrome P450 3A4 (CYP3A4) is the dominant P450 enzyme involved in human drug metabolism, and its inhibition may result in adverse interactions or, conversely, favorably reduce the systemic elimination rates of poorly bioavailable drugs. Herein we describe a spectroscopic investigation of the interaction of CYP3A4 with N-methylritonavir, an analog of ritonavir, widely used as a pharmacoenhancer. In contrast to ritonavir, the binding affinity of N-methylritonavir for CYP3A4 is pH-dependent. At pH <7.4, the spectra are definitively type I, whereas at pH ≥7.4 the spectra have split Soret bands, including a red-shifted component characteristic of a P450-carbene complex. Variable-pH UV-visible spectroscopy binding studies with molecular fragments narrows the source of this pH dependence to its N-methylthiazolium fragment. The C2 proton of this group is acidic, and variable-pH resonance Raman spectroscopy tentatively assigns it a pKa of 7.4. Hence, this fragment of N-methylritonavir is expected to be readily deprotonated under physiologic conditions to yield a thiazol-2-ylidene, which is an N-heterocyclic carbene that has high-affinity for and is presumed to be subsequently captured by the heme iron. This mechanism is supported by time-dependent density functional theory with an active site model that accurately reproduces distinguishing features of the experimental UV-visible spectra of N-methylritonavir bound to CYP3A4. Finally, density functional theory calculations support that this novel interaction is as strong as the tightest-binding azaheterocycles found in P450 inhibitors and could offer new avenues for inhibitor development.

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.

Review article: safety and tolerability of direct-acting anti-viral agents in the new era of hepatitis C therapy

BACKGROUND

Direct-acting anti-virals (DAAs) licensed to treat chronic HCV infection have revolutionised treatment algorithms by drastically mitigating side effects while enhancing efficacy relative to interferon-based therapy.

AIM

To review adverse events (AEs) uniquely associated with DAA therapy across a broad spectrum of patient populations.

METHODS

Searches of PubMed and FDA surveillance studies were undertaken to complete an exhaustive review. Search terms included 'DAAs', 'safety', and 'tolerability'.

RESULTS

While DAAs are remarkably well tolerated, they are accompanied by unique AEs. Simeprevir, an NS3/4A protease inhibitor, has been known, albeit infrequently, to cause mild hyperbilirubinemia and photosensitivity reactions; and paritaprevir boosted with ritonavir causes bilirubin and ALT elevations. Asunaprevir, another protease inhibitor, infrequently causes elevated transaminase levels. NS5A and NS5B inhibitors are well tolerated, although sofosbuvir is contraindicated in patients with severe renal impairment. Ribavirin co-administered in certain treatment regimens has been associated with cough, rash and haemolytic anaemia.

CONCLUSIONS

With the impending reality of a more tolerable interferon-sparing regimen, the future of DAA therapy offers shorter treatment duration, simplified disease management, and a patient-centred regimen. With advantages come drawbacks, including development of resistance to therapy and accessibility to this expensive treatment. DAA therapy continues to advance at a brisk pace with a promising trend for higher tolerability, even in difficult-to-treat subgroups such as those with cirrhosis, nonresponders to prior therapy, and transplant recipients. Subgroup-specific contraindications and safety-related limitations are active areas of research. Concerted research efforts and continuing advances lend hope to the goal of rendering HCV a routinely curable disease.

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.

Cutaneous Eruption due to Telaprevir

Hepatitis C virus (HCV) chronically infects 0.5-3% of the world population. A large group of patients develop cirrhosis and its complications. Since 2011, telaprevir and boceprevir are used, improving the disease evolution. One of the main side effects of these drugs is skin eruption. We report a 53-year-old patient with cirrhosis due to HCV who started the classic treatment associated with telaprevir. In the ninth week, he presented a severe rash that required the interruption of this drug. We emphasize the importance of early recognition and appropriate management of adverse skin reaction.

A Journey around the Medicinal Chemistry of Hepatitis C Virus Inhibitors Targeting NS4B: From Target to Preclinical Drug Candidates

Hepatitis C virus (HCV) infection is a global health burden with an estimated 130-170 million chronically infected individuals and is the cause of serious liver diseases such as cirrhosis and hepatocellular carcinoma. HCV NS4B protein represents a validated target for the identification of new drugs to be added to the combination regimen recently approved. During the last years, NS4B has thus been the object of impressive medicinal chemistry efforts, which led to the identification of promising preclinical candidates. In this context, the present review aims to discuss research published on NS4B functional inhibitors focusing the attention on hit identification, hit-to-lead optimization, ADME profile evaluation, and the structure-activity relationship data raised for each compound family taken into account. The information delivered in this review will be a useful and valuable tool for those medicinal chemists dealing with research programs focused on NS4B and aimed at the identification of innovative anti-HCV compounds.

Interferon-free regimens for the treatment of hepatitis C virus in liver transplant candidates or recipients

The goal of therapy in chronic hepatitis C virus (HCV) infection is sustained virological response (SVR) which reflects HCV eradication. Treatment against HCV has dramatically improved with the recent availability of direct-acting antivirals (DAAs) including sofosbuvir, simeprevir, daclatasvir, ledipasvir/sofosbuvir, paritaprevir/ombitasvir and dasabuvir. Carefully selected combinations of these DAAs offer the potential for highly effective all-oral safe regimens even for patients with decompensated cirrhosis or liver transplant (LT) recipients. Like all current protease inhibitors, simeprevir and paritaprevir should not be used in patients with Child C cirrhosis, while sofosbuvir and ledipasvir/sofosbuvir should not be given in patients with severe renal impairment and glomerular filtration rate less than 30 mL/min. Drug-drug interactions may still occur with the current DAAs particularly in post-LT patients, in whom simeprevir should not be co-administered with cyclosporine and dose adjustments of calcineurin inhibitors are required in case of regimens including the ritonavir boosted paritaprevir. Phase II clinical trials and real life cohort studies have shown that sofosbuvir based combinations are safe and can achieve improvements of clinical status, high SVR rates and even prevention of post-LT HCV recurrence in patients with decompensated cirrhosis or LT-candidates. In the post-LT setting, sofosbuvir based regimens and the combination of paritaprevir/ombitasvir and dasabuvir have been reported to be safe and achieve high SVR rates, similar to those in non-transplant patients, being effective even in cases with cholestatic fibrosing hepatitis. Ongoing clinical trials and rapidly emerging real life data will further clarify the safety and efficacy of the new regimens in these settings.

What does the pharmacological future of treating chronic hepatitis C look like?

Development of direct acting antivirals has revolutionized the standard of care for the treatment of hepatitis C virus. New interferon-free regimens provide sustained virologic response rates of >90% in many genotype 1 patients with only 12 weeks of oral therapy. This review will provide a brief overview of current standards of care with a summary of the evidence supporting the recommended combinations of direct acting antivirals. We will discuss the direction of future therapies, with strategies for shorter durations of therapy and new all-oral combinations in the pipeline.

Hepatitis C virus vaccine development: old challenges and new opportunities

Hepatitis C virus (HCV), an enveloped positive-sense single-stranded RNA virus, can cause chronic and end-stage liver diseases. Approximately 185 million people worldwide are infected with HCV. Tremendous progress has been achieved in the therapeutics of chronic hepatitis C thanks to the development of direct-acting antiviral agents (DAAs), but the worldwide use of these highly effective DAAs is limited due to their high treatment cost. In addition, drug-resistance mutations remain a potential problem as DAAs are becoming a standard therapy for chronic hepatitis C. Unfortunately, no vaccine is available for preventing new HCV infection. Therefore, HCV still imposes a big threat to human public health, and the worldwide eradication of HCV is critically dependent on an effective HCV vaccine. In this review, we summarize recent progresses on HCV vaccine development and present our views on the rationale and strategy to develop an effective HCV vaccine.