Sofosbuvir/Velpatasvir: A Review in Chronic Hepatitis C

The Burden of Inappropriate Prescriptions and Predictors for Hospitalized Patients with Liver Cirrhosis in Ethiopia

Background

Pathophysiological alterations in liver cirrhosis affect how medications are metabolized and eliminated. Therefore, when prescribing medicines for patients with cirrhosis, appropriate prescription of medication is an accepted standard of practice. Since patients with cirrhosis require a complex therapy plan, it necessitates regular reviews of medication utilization. However, no research was conducted in Ethiopia. The aim of this study was to figure out the predictors of inappropriate prescriptions and the pattern of prescription in patients with cirrhosis.

Patients and methods

A cross-sectional study design was carried out at Felege-Hiwot, a specialized and comprehensive referral hospital, from June 30, 2022, to November 30, 2022, in 123 hospitalized patients with cirrhosis. Patients were recruited using a simple random sampling procedure, and data were collected using an interviewer-administered questionnaire. For the purpose of identifying determinants of inappropriate prescription, logistic regression analyses have been carried out and statistical significance was defined by a p-value of less than 0.05 and a 95% confidence range.

Results

The burden of inappropriate prescriptions among patients with cirrhosis was 35.8%. An increased number of medications prescribed (AOR = 4.88 (1.05-22.68)), prescription by a general practitioner (AOR = 3.57 (95% CI 1.07-11.44)), increased level of bilirubin (AOR = 3.54 (95% CI 1.95-6.45)), and decreased level of albumin (AOR = 0.18 (95% CI 0.04-0.72)) were predictors for an inappropriate prescription.

Conclusion

It has been found that there were inappropriate prescriptions among patients with liver cirrhosis. Prescribers should pay close attention to patients who have prescribed with higher number of medications, increased level of bilirubin and decreased level of albumin. Moreover, educational level of prescribers needs to be upgraded in order to adopt evidence-based medication prescriptions and adhere to recommended practices.

An insight into the hepatoprotective role of Velpatasvir and Sofosbuvir per se and in combination against carbon tetrachloride-induced hepatic fibrosis in rats

Hepatitis C is a global health issue. Hepatitis C Virus (HCV) induces fibrosis by redox reactions, which involve the deposition of collagen in extracellular matrix (ECM). This study aimed to examine the antifibrotic effect of direct-acting antivirals; Sofosbuvir and Velpatasvir, per se and in combination against carbon tetrachloride (CCl4)-induced fibrosis in rats. Carbon tetrachloride (intraperitoneal; 0.5 ml/kg) twice weekly for six weeks was used to induce hepatic fibrosis in rats. After two weeks of CCl4, oral administration of Sofosbuvir (20 mg/kg/d) and Velpatasvir (10 mg/kg/d) was administered to rats for the last four weeks. Liver function tests (LFTs), renal function tests (RFTs), oxidative stress markers, and the levels of TNF-a, NF-κB, and IL-6 were measured through ELISA and western blotting at the end of the study. CCl4 significantly ameliorated the values of RFTs, LFTs and lipid profiles in the diseased group, which were normalized by the SOF and VEL both alone and in combination. These drugs produced potent antioxidant effects by significantly increasing antioxidant enzymes. From the histopathology of hepatic tissues of rats treated with drugs, the antifibrotic effect was further manifested, which showed suppression of hepatic stellate cells (HSCs) in treated rats, as compared to the disease control group. The antifibrotic effect was further demonstrated by significantly decreasing the levels of TNF-a, NF-κB and IL-6 in serum and hepatic tissues of treated rats as compared to the disease control group. Sofosbuvir and Velpatasvir alone and in combination showed marked inhibition of fibrosis in the CCl4-induced non-HCV rat model, which was mediated by decreased levels of TNF-a/NF-κB and the IL-6 signaling pathway. Thus, it can be concluded that Sofosbuvir and Velpatasvir might have an antifibrotic effect that appears to be independent of their antiviral activity.

Asymmetric Synthesis of US-FDA Approved Drugs over Five Years (2016–2020): A Recapitulation of Chirality

Chirality is a major theme in the design, discovery, and development of new drugs. Historically, pharmaceuticals have been synthesized as racemic mixtures. However, the enantiomeric forms of drug molecules have distinct biological properties. One enantiomer may be responsible for the desired therapeutic effect (eutomer), whereas the other may be inactive, interfere with the therapeutic form, or exhibit toxicity (distomer). Classical chemical synthesis usually leads to a racemic mixture unless stereospecific synthesis is employed. To meet the requirements of single-enantiomeric drugs, asymmetric synthesis has evolved at the forefront of drug discovery. Asymmetric synthesis involves the conversion of an achiral starting material into a chiral product. This review emphasizes the methods used for synthesizing FDA-approved chiral drugs during 2016–2020, with a special focus on asymmetric synthesis by means of chiral induction, resolution, or chiral pool.

A simple and sensitive HPLC-FL method for bioanalysis of velpatasvir, a novel hepatitis C virus NS5A inhibitor, in rat plasma: Investigation of factors determining its oral bioavailability

Velpatasvir is a novel inhibitor of hepatitis C virus nonstructural protein 5A that received US Food and Drug Administration approval for the treatment of patients with chronic hepatitis C virus genotypes 1-6. In the present study, a sensitive bioanalytical method for velpatasvir was developed using high-performance liquid chromatography coupled with a fluorescence detector system, which was applied to elucidate the factors determining the oral bioavailability and disposition of velpatasvir. This method offered sufficient sensitivity, with a lower limit of quantification of 0.5 ng/mL, which is comparable to previously reported methods using liquid chromatography coupled with tandem mass spectrometry. Velpatasvir exhibited low oral bioavailability, moderate intestinal permeability, and significant biliary excretion in rats. It was also found to be significantly metabolized in the liver, with a low-to-moderate extraction ratio; however, its intestinal metabolism and enterohepatic circulation did not occur. Thus, our present results demonstrate that the oral bioavailability of velpatasvir is primarily dependent on gut absorption and hepatic first-pass metabolism. The fractions of velpatasvir dose unabsorbed from the gut and eliminated by the liver before reaching the systemic circulation following oral administration were estimated to be 32.8%-58.6% and 4.74%-30.54% of the oral dose, respectively. To our knowledge, this is the first systematic study to investigate the contributory roles of biopharmaceutical and pharmacokinetic factors on the oral bioavailability of velpatasvir, together with a new bioanalytical method for velpatasvir.

Impact of direct-acting antiviral regimens on hepatic and extrahepatic manifestations of hepatitis C virus infection

Hepatitis C virus (HCV) is a common cause of liver disease and is associated with various extrahepatic manifestations (EHMs). This mini-review outlines the currently available treatments for HCV infection and their prognostic effect on hepatic manifestations and EHMs. Direct-acting antiviral (DAA) regimens are considered pan-genotypic as they achieve a sustained virological response (SVR) > 85% after 12 wk through all the major HCV genotypes, with high percentages of SVR even in advanced fibrosis and cirrhosis. The risk factors for DAA failure include old males, cirrhosis, and the presence of resistance-associated substitutions (RAS) in the region targeted by the received DAAs. The effectiveness of DAA regimens is reduced in HCV genotype 3 with baseline RAS like A30K, Y93H, and P53del. Moreover, the European Association for the Study of the Liver recommended the identification of baseline RAS for HCV genotype 1a. The higher rate of hepatocellular carcinoma (HCC) after DAA therapy may be related to the fact that DAA regimens are offered to patients with advanced liver fibrosis and cirrhosis, where interferon was contraindicated to those patients. The change in the growth of pre-existing subclinical, undetectable HCC upon DAA treatment might be also a cause. Furthermore, after DAA therapy, the T cell-dependent immune response is much weaker upon HCV clearance, and the down-regulation of TNF-α or the elevated neutrophil to lymphocyte ratio might increase the risk of HCC. DAAs can result in reactivation of hepatitis B virus (HBV) in HCV co-infected patients. DAAs are effective in treating HCV-associated mixed cryoglobulinemia, with clinical and immunological responses, and have rapid and high effectiveness in thrombocytopenia. DAAs improve insulin resistance in 90% of patients, increase glomerular filtration rate, and decrease proteinuria, hematuria and articular manifestations. HCV clearance by DAAs allows a significant improvement in atherosclerosis and metabolic and immunological conditions, with a reduction of major cardiovascular events. They also improve physical function, fatigue, cognitive impairment, and quality of life. Early therapeutic approach with DAAs is recommended as it cure many of the EHMs that are still in a reversible stage and can prevent others that can develop due to delayed treatment.

Real-world effectiveness of direct-acting antivirals in people living with human immunodeficiency virus and hepatitis C virus genotype 6 infections

BACKGROUND

Hepatitis C virus (HCV) genotype 6 (HCV-6) infection is prevalent predominantly in Southeast Asia, and the data on the virologic response of HCV-6 to direct-acting antivirals (DAAs) are sparse in people living with human immunodeficiency virus (HIV) (PLWH).

AIM

To assess the virologic response of HCV-6 to DAAs in PLWH.

METHODS

From September 2016 to July 2019, PLWH coinfected with HCV-6 initiating DAAs were included. Laboratory investigations were performed at baseline, the end of treatment, and 12 wk off-therapy.

RESULTS

Of the 349 PLWH included (mean age 48.9 years, 82.5% men), 80.5% comprised people who inject drugs, 18.1% men who have sex with men, and 1.4% heterosexuals. Coexistent hepatitis B virus infection was present in 12.3% of the included PLWH, liver cirrhosis 10.9%, hepatocellular carcinoma 0.9%, and previous HCV treatment experience 10.9%. The mean baseline plasma HCV RNA was 6.2 log₁₀ IU/mL. Treatment with glecaprevir/pibrentasvir was initiated in 51.9%, sofosbuvir/ledipasvir 41.5%, sofosbuvir/velpatasvir 6.3%, and sofosbuvir/daclatasvir 0.3%. At DAA initiation, antiretroviral therapy containing tenofovir alafenamide was given in 26.4%, tenofovir disoproxil fumarate 34.4%, non-tenofovir alafenamide/tenofovir disoproxil fumarate 39.3%, non-nucleoside reverse-transcriptase inhibitors 30.4%, protease inhibitors 4.0%, and integrase strand transfer inhibitors 66.8%; 94.8% of the included patients had CD4 counts ≥ 200 cells/mm³ and 96.0% had plasma HIV RNA < 50 copies/mL. Overall, 96.8% achieved undetectable plasma HCV RNA (< 30 IU/mL) at end of treatment; and 92.3% achieved sustained virologic response 12 wk off-therapy in the intention-to-treat analysis (93.5% in patients receiving sofosbuvir-based DAAs and 91.2% in those receiving glecaprevir/pibrentasvir).

CONCLUSION

Similar to the observation made in HIV-negative patients, sustained virologic response 12 wk off-therapy with DAAs is high in PLWH coinfected with HCV-6.

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.

Sofosbuvir/velpatasvir with or without low-dose ribavirin for patients with chronic hepatitis C virus infection and severe renal impairment

OBJECTIVE

Data regarding the real-world effectiveness and safety of sofosbuvir/velpatasvir (SOF/VEL) with or without low-dose ribavirin (RBV) in patients with chronic hepatitis C virus (HCV) infection and severe renal impairment (RI) are limited. We evaluated the performance of SOF/VEL with or without low-dose RBV in HCV-infected patients with chronic kidney disease stage 4 or 5.

DESIGN

191 patients with compensated (n=181) and decompensated (n=10) liver diseases receiving SOF/VEL (400/100 mg/day) alone and SOF/VEL with low-dose RBV (200 mg/day) for 12 weeks were retrospectively recruited at 15 academic centres in Taiwan. The effectiveness was determined by sustained virological response at off-treatment week 12 (SVR₁₂) in evaluable (EP) and per-protocol populations (PP). The safety profiles were assessed.

RESULTS

The SVR₁₂ rates by EP and PP analyses were 94.8% (95% CI 90.6% to 97.1%) and 100% (95% CI 97.9% to 100%). In patients with compensated liver disease, the SVR₁₂ rates were 95.0% and 100% by EP and PP analyses. In patients with decompensated liver disease, the SVR₁₂ rates were 90.0% and 100% by EP and PP analyses. Ten patients who failed to achieve SVR₁₂ were attributed to non-virological failures. Among the 20 serious adverse events (AEs), none were judged related to SOF/VEL or RBV. The AEs occurring in ≥10% included fatigue (14.7%), headache (14.1%), nausea (12.6%), insomnia (12.0%) and pruritus (10.5%). None had ≥grade 3 total bilirubin or alanine aminotransferase elevations.

CONCLUSION

SOF/VEL with or without low-dose RBV is effective and well-tolerated in HCV-infected patients with severe RI.

Sensitive Determination of SARS-COV-2 and the Anti-hepatitis C Virus Agent Velpatasvir Enabled by Novel Metal-Organic Frameworks

Herein, we report on the electrochemical determination of velpatasvir (VLP) as the main constituent of Epclusa, a SARS-COV-2 and anti-hepatitis C virus (HCV) agent, using a novel metal-organic framework (MOF). The NH2-MIL-53(Al) MOF was successfully modified with 5-bromo-salicylaldehyde to synthesize 5-BSA=N-MIL-53(Al) MOF. The synthesized MOF has been characterized using Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The modified MOF showed higher electrochemical activity and response than the bare NH2-MIL-53(Al) MOF. Compared to the bare carbon paste electrode (CPE), the 5-BSA=N-MIL-53(Al)/CPE platform was shown to enhance the electrochemical oxidation and detection of the anti-SARS-COV-2 and anti-HCV agent. Under optimized conditions, the 5-BSA=N-MIL-53(Al)/CPE platform showed a linear range of 1.11 × 10-6 to 1.11 × 10-7 and 1.11 × 10-7 to 25.97 × 10-6 M Britton-Robinson buffer (pH 7) with a detection limit and limit of quantification of 8.776 × 10-9 and 2.924 × 10-8 M, respectively. Repeatability, storage stability, and reproducibility in addition to selectivity studies and interference studies were conducted to illustrate the superiority of the electrode material. The study also included a highly accurate platform for the determination of VLP concentrations in both urine and plasma samples with reasonable recovery.

Sofosbuvir/velpatasvir for the treatment of hepatitis C in pediatric patients

Introduction: Sofosbuvir/velpatasvir is a combination of direct-acting antivirals with pangenotypic activity for treatment of chronic hepatitis C virus infection. It was approved in 2020 for use in children aged 6-17 years and in June 2021 by the United States Food and Drug Administration for the age group 3-5 years.Areas covered: A literature search of PUBMED and EMBASE was conducted on April 30th and updated on June 10th. Other citations were identified in references of available literature and from ClinicalTrials.gov. The aim of the present research was to outline and discuss the pharmacokinetics, clinical efficacy, tolerability and safety of sofosbuvir/velpatasvir, exploring its actual and potential use in children and adolescents with chronic hepatitis C virus infection.Expert opinion: Five combinations of direct-acting antivirals, of whom three with pangenotypic activity, are now approved for children. No major differences in efficacy and safety profile have been described. Limited access to treatment still is a major issue, especially in low and middle-income countries.

The current state of validated small molecules inhibiting SARS-CoV-2 nonstructural proteins

The current COVID-19 outbreak has had a profound influence on public health and daily life. Despite all restrictions and vaccination programs, COVID-19 still can lead to fatality due to a lack of COVID-19-specific treatments. A number of studies have demonstrated the feasibility to develop therapeutics by targeting underlying components of the viral proteome. Here we reviewed recently developed and validated small molecule inhibitors of SARS-CoV-2's nonstructural proteins. We described the validation level of identified compounds specific for SARS-CoV-2 in the presence of in vitro and in vivo supporting data. The mechanisms of pharmacological activity, as well as approaches for developing improved SARS-CoV-2 NSP inhibitors have been emphasized.

SARS-CoV-2 RNA-dependent RNA polymerase as a therapeutic target for COVID-19

Introduction: The current SARS-CoV-2 pandemic urgently demands for both prevention and treatment strategies. RNA-dependent RNA-polymerase (RdRp), which has no counterpart in human cells, is an excellent target for drug development. Given the time-consuming process of drug development, repurposing drugs approved for other indications or at least successfully tested in terms of safety and tolerability, is an attractive strategy to rapidly provide an effective medication for severe COVID-19 cases.Areas covered: The currently available data and upcominSg studies on RdRp which can be repurposed to halt SARS-CoV-2 replication, are reviewed.Expert opinion: Drug repurposing and design of novel compounds are proceeding in parallel to provide a quick response and new specific drugs, respectively. Notably, the proofreading SARS-CoV-2 exonuclease activity could limit the potential for drugs designed as immediate chain terminators and favor the development of compounds acting through delayed termination. While vaccination is awaited to curb the SARS-CoV-2 epidemic, even partially effective drugs from repurposing strategies can be of help to treat severe cases of disease. Considering the high conservation of RdRp among coronaviruses, an improved knowledge of its activity in vitro can provide useful information for drug development or drug repurposing to combat SARS-CoV-2 as well as future pandemics.

Sofosbuvir/velpatasvir for patients with chronic hepatitis C virus infection and compensated liver disease: real-world data in Taiwan

BACKGROUND

Data regarding the real-world effectiveness and safety of sofosbuvir/velpatasvir (SOF/VEL) for East Asian patients with chronic hepatitis C virus (HCV) infection and compensated liver disease are limited. We evaluated the performance of SOF/VEL for 12 weeks for HCV-infected patients with compensated liver disease in a large real-world cohort in Taiwan.

METHODS

Between July 2019 and March 2020, 1880 HCV-infected patients with compensated liver disease who received SOF/VEL 400/100 mg once daily for 12 weeks were included at 15 academic centers in Taiwan. The sustained virologic response at off-treatment week 12 (SVR₁₂) was assessed for evaluable (EP) and per-protocol populations (PP). The tolerance was also reported.

RESULTS

The SVR₁₂ rates by EP and PP analyses were 95.6% [1798 of 1880 patients; 95% confidence interval (CI) 94.6-96.5%] and 99.3% (1798 of 1811 patients; 95% CI 98.8-99.6%), respectively. Among 82 patients who failed to achieve SVR₁₂, 13 (15.9%) were attributed to virologic failures. The SVR₁₂ rates were comparable regardless of baseline characteristics. A total of 1859 (98.9%) patients completed 12-week SOF/VEL treatment. Four (0.2%) patients discontinued treatment due to adverse events (AEs). All patients with serious AEs or deaths were judged not related to SOF/VEL. The AEs occurring in ≥ 10% included headache (16.8%), fatigue (16.2%), nausea (11.8%), and insomnia (11.1%). Nine (0.5%) and 2 (0.1%) patients had grade 3 total bilirubin and alanine aminotransferase elevations.

CONCLUSIONS

SOF/VEL for 12 weeks is efficacious and well-tolerated by chronic HCV-infected patients with compensated liver disease in Taiwan.

In silico identification of available drugs targeting cell surface BiP to disrupt SARS-CoV-2 binding and replication: Drug repurposing approach

Aims

Cell surface binding immunoglobin protein (csBiP) is predicted to be susceptible to SARS-CoV-2 binding. With a substrate-binding domain (SBD) that binds to polypeptides and a nucleotide-binding domain (NBD) that can initiate extrinsic caspase-dependent apoptosis, csBiP may be a promising therapeutic target for COVID-19. This study aims to identify FDA-approved drugs that can neutralize viral binding and prevent viral replication by targeting the functional domains of csBiP.

Methods

In silico screening of 1999 FDA-approved drugs against the functional domains of BiP were performed using three molecular docking programs to avoid bias from individual docking programs. Top ligands were selected by averaging the ligand rankings from three programs. Interactions between top ligands and functional domains of BiP were analyzed.

Key findings

The top 10 SBD-binding candidates are velpatasvir, irinotecan, netupitant, lapatinib, doramectin, conivaptan, fenoverine, duvelisib, irbesartan, and pazopanib. The top 10 NBD-binding candidates are nilotinib, eltrombopag, grapiprant, topotecan, acetohexamide, vemurafenib, paritaprevir, pixantrone, azosemide, and piperaquine-phosphate. Among them, Velpatasvir and paritaprevir are antiviral agents that target the protease of hepatitis C virus. Netupitant is an anti-inflammatory drug that inhibits neurokinin-1 receptor, which contributes to acute inflammation. Grapiprant is an anti-inflammatory drug that inhibits the prostaglandin E₂ receptor protein subtype 4, which is expressed on immune cells and triggers inflammation. These predicted SBD-binding drugs could disrupt SARS-CoV-2 binding to csBiP, and NBD-binding drugs may falter viral attachment and replication by locking the SBD in closed conformation and triggering apoptosis in infected cells.

Significance

csBiP appears to be a novel therapeutic target against COVID-19 by preventing viral attachment and replication. These identified drugs could be repurposed to treat COVID-19 patients.

Second direct-acting antiviral therapy for hepatitis C virus infection after umbilical cord blood transplantation: A case report

Hepatitis C virus (HCV) infection has an adverse impact on outcomes after allogeneic hematopoietic stem cell transplantation (HSCT). It is recommended that HSCT candidates infected with HCV receive the treatment prior to transplantation. Although the recent approval of direct-acting antivirals (DAAs) has led to great advances in the treatment of HCV infection, little information is available on the efficacy and safety of DAA therapy in patients receiving allogeneic HSCT. Herein, we report the clinical course of an umbilical cord blood (UCB) recipient treated with DAAs for HCV infection. The patient achieved HCV RNA negativity with glecaprevir and pibrentasvir after consolidation therapy for acute myeloid leukemia (AML), and underwent transplantation before confirming sustained virological response (SVR) at 12 weeks. The HCV viral load became detectable on day +28 after transplantation and second HCV treatment with sofosbuvir, velpatasvir, and ribavirin was required. It is important to confirm SVR prior to transplantation, but it is often difficult. If early transplantation is required, close monitoring of HCV RNA after transplantation is needed. Further investigation is required to clarify the optimal management of HCV infection for allogeneic HSCT recipients in the DAA era.

Eco-friendly analytical methods for the determination of compounds with disparate spectral overlapping: application to antiviral formulation of sofosbuvir and velpatasvir

Green analytical chemistry is one of the newest trends in analytical chemistry nowadays targeting the concept of green laboratory practices on chemists and environment. In this text, green practices are proposed in this work for the determination of sofosbuvir (SF) and velpatasvir (VP) in their pharmaceutical formulation. The analysis of SF in a binary mixture with VP represents an analytical challenge due to the complete overlapping of the UV spectrum of SF by that of VP. Therefore, the direct absorbance and derivative measurements cannot resolve such interference and failed to determine SF. In this paper, three direct and simple methods were developed for the analysis of SF without any interference from VP without sample pre-treatment. The proposed methods include measuring the second derivative amplitude of the ratio spectrum of the mixture using VP as a divisor, measuring the absorbance difference of the mixture in NaOH solution against its HCl solution, and using the derivative compensation technique. On the other hand, VP was determined specifically in presence of SF by two methods. Firstly, by its reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) where the reaction product was measured spectrophotometrically and spectrofluorometrically and secondly through the reaction of VP with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH). The calibration curves showed good correlation coefficient (r2 > 0.999). The developed methods were highly precise with RSD% values less than 2%. The method greenness profile was compared with other published methods by applying the eco-scale protocol. Assessment results proved that our analytical procedure is greener than other reported methods. Moreover, upon comparison with other methods, the proposed methods showed better or comparable sensitivity in addition to being inexpensive and ecofriendly. Accordingly, these methods could be readily applied for quality control purposes as an eco-friendly, simple and efficient analytical tool.

Development and Clinical Application of Phosphorus-Containing Drugs

Phosphorus-containing drugs belong to an important class of therapeutic agents and are widely applied in daily clinical practices. Structurally, the phosphorus-containing drugs can be classified into phosphotriesters, phosphonates, phosphinates, phosphine oxides, phosphoric amides, bisphosphonates, phosphoric anhydrides, and others; functionally, they are often designed as prodrugs with improved selectivity and bioavailability, reduced side effects and toxicity, or biomolecule analogues with endogenous materials and antagonistic endoenzyme supplements. This review summarized the phosphorus-containing drugs currently on the market as well as a few promising molecules at clinical studies, with particular emphasis on their structural features, biological mechanism, and indications.

Cost-utility of sofosbuvir/velpatasvir versus other direct-acting antivirals for chronic hepatitis C genotype 1b infection in China

OBJECTIVE

This study aimed to estimate the cost-utility of sofosbuvir/velpatasvir (SOF/VEL) compared with other direct-acting antivirals (DAAs) in Chinese patients with hepatitis C virus (HCV).

DESIGN

A Markov model was developed to estimate the disease progression of patients with HCV over a lifetime horizon from the healthcare system perspective. Efficacy, clinical inputs and utilities were derived from the published literature. Drug costs were from the market price survey, and health costs for Markov health states were sourced from a Chinese study. Costs and utilities were discounted at an annual rate of 5%. One-way and probabilistic sensitivity analyses were conducted to test the impact of input parameters on the results.

INTERVENTIONS

SOF/VEL was compared with sofosbuvir+ribavirin (SR), sofosbuvir+dasabuvir (SD), daclatasvir+asunaprevir (DCV/ASV), ombitasvir/paritaprevir/ritonavir+dasabuvir (3D) and elbasvir/grazoprevir (EBR/GZR).

PRIMARY AND SECONDARY OUTCOMES

Costs, quality-adjusted life years (QALYs) and incremental cost-utility ratios (ICURs).

RESULTS

SOF/VEL was economically dominant over SR and SD. However, 3D was economically dominant compared with SOF/VEL. Compared with DCV/ASV, SOF/VEL was cost-effective with the ICUR of US$1522 per QALY. Compared with EBR/GZR, it was not cost-effective with the ICUR of US$369 627 per QALY. One-way sensitivity analysis demonstrated that reducing the cost of SOF/VEL to the lower value of CI resulted in dominance over EBR/GZR and 3D. Probabilistic sensitivity analysis demonstrated that 3D was cost-effective in 100% of iterations in patients with genotype (GT) 1b and SOF/VEL was not cost-effective.

CONCLUSIONS

Compared with other oral DAA agents, SOF/VEL treatment was not the most cost-effectiveness option for patients with chronic HCV GT1b in China. Lower the price of SOF/VEL will make it cost-effective while simplifying treatment and achieving the goal of HCV elimination.

RNA-dependent RNA polymerase of SARS-CoV-2 as a therapeutic target

The global pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), named coronavirus disease 2019, has infected more than 8.9 million people worldwide. This calls for urgent effective therapeutic measures. RNA-dependent RNA polymerase (RdRp) activity in viral transcription and replication has been recognized as an attractive target to design novel antiviral strategies. Although SARS-CoV-2 shares less genetic similarity with SARS-CoV (~79%) and Middle East respiratory syndrome coronavirus (~50%), the respective RdRps of the three coronaviruses are highly conserved, suggesting that RdRp is a good broad-spectrum antiviral target for coronaviruses. In this review, we discuss the antiviral potential of RdRp inhibitors (mainly nucleoside analogs) with an aim to provide a comprehensive account of drug discovery on SARS-CoV-2.

Thin-layer chromatography/fluorescence detection approach for sensitive and selective determination of hepatitis C virus antiviral (velpatasvir): application to human plasma

A validated thin-layer chromatography (TLC) method combined with fluorescence detection mode was developed for the selective determination of a recently approved anti-hepatitis C virus (HCV) drug (velpatasvir). The separation was performed on silica gel 60 F₂₅₄ plates using ethylacetate:methanol:triethylamine (48:1.5:1.0, v/v/v) as a mobile phase. Plates were scanned in the fluorescence mode after excitation at 335 nm. This method provided an excellent separation of velpatasvir from sofosbuvir with R_F values of 0.22 and 0.46 for velpatasvir and sofosbuvir, respectively, after scanning the developed plates in the ultraviolet detection mode at 335 nm. The calibration curve was linear over the range 4-40 ng/band with a correlation coefficient of 0.9994. The developed procedure was validated according to ICH guidelines with a detection limit of 1.30 ng/band and quantitation limit of 3.95 ng/band. The suggested method could selectively determine velpatasvir with high sensitivity in a synthetic tablet powder containing a co-formulated anti-HCV drug (sofosbuvir) without any interference from excipients or sofosbuvir. In addition, the method was successfully applied for determination of velpatasvir in spiked human plasma with adequate % recovery.

Real-world Effectiveness of Sofosbuvir/Velpatasvir for Treatment of Chronic Hepatitis C in British Columbia, Canada: A Population-Based Cohort Study

Background

Clinical trials show high efficacy of sofosbuvir/velpatasvir (SOF/VEL), but there are limited data from “real-world” settings. We aimed to evaluate SOF/VEL effectiveness for all hepatitis C virus (HCV) genotypes (GTs) in British Columbia (BC), Canada.

Methods

We used the BC Hepatitis Testers Cohort, which includes all HCV cases in the province (1990–2015) linked to administrative databases, including prescriptions to end of 2018. We measured sustained virologic response (SVR; negative RNA ≥10 weeks after treatment end) and identified characteristics associated with non-SVR. Conservatively, we excluded individuals with no assessment for SVR if their last RNA test after treatment initiation was negative (but included if positive).

Results

Of 2821 eligible participants, most were infected with GT1 (1076, 38.1%) or GT3 (1072, 38.0%), and a minority (278, 9.9%) were treated with RBV. SVR was 94.6% (2670/2821) overall and 94.5% (1017/1076) for GT1, 96.4% (512/531) for GT2, and 93.7% (1004/1072) for GT3. When disaggregated by GT, treatment regimen, and cirrhosis/treatment experience, SVR was lowest (30/40, 75.0%) among treatment-experienced GT3 individuals treated with RBV. Characteristics associated with non-SVR in multivariable analysis included younger age, RBV addition, and being a person with HIV (PWH) or who injects/injected drugs (PWID). When treatment regimen (±RBV) was removed from multivariable model, treatment experience was associated with non-SVR for GT3. Of 151 non-SVR individuals, 56.3% were nonvirological failures (treatment incomplete/no assessment for SVR) and 43.7% were virological failures (nonresponse/relapse). A disproportionately high percentage of non-SVR among PWID was due to nonvirological failure.

Conclusions

SOF/VEL was highly effective in this “real-world” population-based cohort. Additional support is required for PWID/PWH to reach SVR.

Direct-acting antiviral interactions with opioids, alcohol or illicit drugs of abuse in HCV-infected patients

The hepatitis C virus (HCV) prevalence is extremely high in patients who consume and inject illicit drugs. Concerns about poor adherence and fear of interaction with drugs of abuse could constitute further disincentive for treatment initiation in these patients. We discussed the pharmacokinetics (PKs) and pharmacodynamics (PD) of currently prescribed direct antiviral agents (NSA5 inhibitors: daclatasvir, elbasvir, ledipasvir, pibrentasvir, velpatasvir; NS5B inhibitor: sofosbuvir; NS3/4A protease inhibitors: glecaprevir, grazoprevir, voxilaprevir) and most common substances of abuse (opioids: buprenorphine, fentanyl, heroin, methadone, morphine, oxycodone; stimulants: amphetamines, cathinones, cocaine; cannabinoids; ethanol). Overall, most direct-acting antivirals (DAAs) are substrates and inhibitors of the transmembrane transporter P-glycoprotein (P-gp), and several of them are metabolized by cytochrome P450 enzymes. Clinically relevant interactions are associated with P-gp and CYP3A modulators. Most substances of abuse are eliminated by Phase I and Phase II metabolizing enzymes, but none of them are either major inhibitors or inducers. PK studies did not show any relevant interactions between DAA and methadone or buprenorphine. Based on pharmacological considerations, neither efficacy loss nor adverse drug event associated with detrimental interaction are expected with opioids, stimulants, cannabinoids and ethanol. In summary, our literature review shows that the interaction potential of DAA with most opioids and illicit drugs is limited and should not be a hurdle to the initiate DAA.

Accelerating the repurposing of FDA-approved drugs against coronavirus disease-19 (COVID-19)

The recent release of the main protein structures belonging to SARS CoV-2, responsible for the coronavirus disease-19 (COVID-19), strongly pushed for identifying valuable drug treatments. With this aim, we show a repurposing study on FDA-approved drugs applying a new computational protocol and introducing a novel parameter called IVS_ratio. Starting with a virtual screening against three SARS CoV-2 targets (main protease, papain-like protease, spike protein), the top-ranked molecules were reassessed combining the Inverse Virtual Screening novel approach and MM-GBSA calculations. Applying this protocol, a list of drugs was identified against the three investigated targets. Also, the top-ranked selected compounds on each target (rutin vs. main protease, velpatasvir vs. papain-like protease, lomitapide vs. spike protein) were further tested with molecular dynamics simulations to confirm the promising binding modes, obtaining encouraging results such as high stability of the complex during the simulation and a good protein–ligand interaction network involving some important residues of each target. Moreover, the recent outcomes highlighting the inhibitory activity of quercetin, a natural compound strictly related to rutin, on the SARS-CoV-2 main protease, strengthened the applicability of the proposed workflow.

New computational protocol applied to a repurposing campaign against SARS-CoV-2.

High sustained virologic response in genotypes 3 and 6 with generic NS5A inhibitor and sofosbuvir regimens in chronic HCV in myanmar

Exclusive HCV therapy clinical trials with genotype 6 patients in high prevalence areas have been sparse. We analysed the safety and efficacy of two generic, pangenotypic NS5A/NS5B combination oral DAA regimens, primarily in genotypes 3 and 6, in a real-world setting: (a) daclatasvir/sofosbuvir (DCV/SOF) ± ribavirin (RBV) and (b) Velpatasvir/sofosbuvir (VEL/SOF ± RBV). Between December 2015 and November 2017, data from 522 patients were analysed, 311 of whom were treated with DCV/SOF ± RBV for 12/24 weeks (genotype 3: n = 193, genotype 6: n = 89) and 211 were treated with VEL/SOF ± RBV for 12/24 weeks (genotype 3: n = 83, genotype 6: n = 77). Overall SVR rates were high for both DCV/SOF ± RBV (96.1%, n = 299/311) and VEL/SOF ± RBV (95.3%, n = 201/211), and there was a good adverse event profile. Treatment naïve status and inclusion of RBV (in advanced fibrosis/cirrhosis) were significant independent predictors of achieving SVR12, while type of DAA regimen was not predictive. In this large cohort of genotypes 3 (n = 276) and 6 (n = 166; n = 127 unique subtype of 6c-l), high SVR rates of 94.9% (n = 262/276) and 95.2% (n = 158/166), respectively, were noted. In conclusion, generic and pangenotypic DCV/SOF and VEL/SOF ± RBV regimens were highly effective and safe, in genotypes 3 and 6 chronic HCV in Myanmar. These efficacious pangenotypic regimens suggest that baseline genotype testing can be eliminated moving forward. While RBV may still be needed for those with advanced fibrosis/cirrhosis, in a global elimination strategy it would not be practical even if it does compromise SVR in a minority with difficult to treat characteristics.

SVR12 rates higher than 99% after sofosbuvir/velpatasvir combination in HCV infected patients with F0-F1 fibrosis stage: A real world experience

Background and objectives

The pangenotypic single tablet regimen of NS5B inhibitor sofobuvir (SOF) and NS5A inhibitor velpatasvir (VEL) is advised for 12 weeks in HCV-infected patients including those with compensated cirrhosis. Addition of ribavirin (RBV) may be considered in genotype 3 (GT3) with compensated and is recommended in decompensated cirrhosis. Real-life results with SOF/VEL are limited. To evaluate efficacy and safety in a large real-world-cohort including patients with different GTs and various fibrosis stages.

Design

In total, 1429 patients were treated with SOF/VEL 400/100 mg for 12 weeks in the Puglia registry between June 2017 and May 2018. 1319 (92.3%) reached week 12 post-treatment (SVR12) at the moment. Only 41 received RBV. Diagnosis of cirrhosis was based on transient elastography and/or APRI or FIB-4 scores. Sensitivity analysis in the population including all patients except non virological failure was conducted. Primary efficacy endpoint was the percentage of patients with SVR12.

Results

Patients’ mean age was 63.8 years, 42.3% had GT1. The majority were naïve and 735 (55.5%) F0/F2. Of the remaining 587, 282 had cirrhosis. SVR12 was 98.5%, 98.0% in GT1, 99.4% in GT2, 97.1% in GT3, 100% in GT4. Overall, SVR12 by sensitivity analysis was 99.4%; 99.7% among F0-F1. Among 218 PWID, SVR12 was 94.5%. Discontinuation rates were 3.7% among PWID and 0.7% among non-PWID (p = 0.004).

Conclusions

SOF/VEL treatment of chronic HCV infection reaches very high cure rates in a variety of patients; including those with F0/F1 and PWID.

Synthesis of New Indanyl Nucleoside Analogues and their Biological Evaluation on Hepatitis C Virus (HCV) Replicon

Here, we report a convenient synthetic procedure for the preparation of four novel indanyl carbanucleoside derivatives in the racemic form. The action of these compounds against hepatitis C virus was evaluated in vitro using the replicon cell line, Huh7.5 SG. Contrary to our expectations, all these compounds did not inhibit, but rather promoted HCV genotype 1b (HCVg1b) replication. Similar effects have been reported for morphine in the replicon cell lines, Huh7 and Huh8. Several biological experiments and computational studies were performed to elucidate the effect of these compounds on HCVg1b replication. Based on all the experiments performed, we propose that the increase in HCVg1b replication could be mediated, at least in part, by a similar mechanism to that of morphine on the enhancement of this replication. The presence of opioid receptors in Huh7.5 SG cells was indirectly determined for the first time in this work.

Sofosbuvir/Velpatasvir/Voxilaprevir: A Review in Chronic Hepatitis C

A fixed-dose combination of the hepatitis C virus (HCV) NS5B polymerase inhibitor sofosbuvir, the HCV NS5A inhibitor velpatasvir and the HCV NS3/4A protease inhibitor voxilaprevir (sofosbuvir/velpatasvir/voxilaprevir; Vosevi^®) is approved in the EU for the treatment of chronic HCV genotype 1, 2, 3, 4, 5 or 6 infection in adults. In the phase III POLARIS trials, in patients who had HCV genotype 1-6 infection with or without compensated cirrhosis, overall rates of sustained virological response at 12 weeks post-treatment (SVR₁₂) with sofosbuvir/velpatasvir/voxilaprevir were high after 8 weeks of treatment in direct-acting antiviral (DAA)-naïve patients and 12 weeks of treatment in DAA-experienced patients. However, 8 weeks of sofosbuvir/velpatasvir/voxilaprevir was inferior to 12 weeks of sofosbuvir/velpatasvir in cirrhotic or non-cirrhotic DAA-naïve patients with HCV genotype 1, 2, 4, 5 or 6 infection and non-cirrhotic DAA-naïve patients with HCV genotype 3 infection, mostly due to an insufficient treatment period. Sofosbuvir/velpatasvir/voxilaprevir was generally well tolerated, with most adverse events being of mild or moderate intensity. The most common adverse events included headache, fatigue, nausea and diarrhoea. In conclusion, sofosbuvir/velpatasvir/voxilaprevir is an important and effective option for the treatment of HCV genotype 1-6 infection in adults, especially those who have previously failed a DAA therapy with or without an HCV NS5A inhibitor.

Real-World Efficacy and Safety of Pangenotypic Direct-Acting Antivirals Against Hepatitis C Virus Infection

BACKGROUND

Advances in the development of Direct-Acting Antivirals (DAAs), particularly pangenotypic drugs, have led to a high rate of hepatitis C virus (HCV) eradication. Notably, real- world studies have confirmed the efficacy and safety of pangenotypic DAA combinations reported in registration trials. The aim of this study was to review the treatment recommendations, and the efficacy and safety data of anti-HCV pangenotypic drugs reported in registration clinical trials and in recent real-life cohort studies.

METHODS

We reviewed the efficacy and safety data of pangenotypic anti-HCV drug combinations reported in original articles and in online conference abstracts.

RESULTS

Current pangenotypic drug combinations resulted in very high rates of sustained virologic response and few adverse reactions in real-life settings. SVR12 rates in real-life studies ranged from 90-100% depending on the pangenotypic combination, the HCV genotype and the stage of liver disease. Most adverse reactions reported in real-life settings were mild in intensity and rarely led to treatment discontinuation. These results are in accordance with those of clinical trials.

CONCLUSION

Pangenotypic DAAs result in very high rates of sustained virologic responses and are well tolerated. However, they are contraindicated in patients with decompensated cirrhosis or advanced chronic kidney disease who failed previous DDA-based treatment. Further research is required to customize treatment to "unpackage" current DAA combinations and to develop generic drugs against HCV.

Drug-Drug Interactions Potential of Direct-Acting Antivirals for the treatment of Chronic Hepatitis C Virus infection

The advent of direct-acting antiviral agents (DAAs) has transformed the hepatitis C virus (HCV) therapeutic landscape in terms of efficacy and safety, with a cure rate of more than 90%. However, an important potential for drug-drug interactions (DDIs) is expected with these combinations, particularly in patients with other comorbidities (e.g. HIV co-infection, cardiovascular diseases). Each DAA can be a substrate, an inhibitor and/or an inducer of metabolic enzymes and drug efflux transporters. DAAs can act as both victims and perpetrators of DDIs and can sometimes increase the risk and/or intensity of side effects or limit the efficacy of treatment. Therefore, knowledge and management of DDIs with DAAs should be considered a key issue of HCV therapy. This review describes the pharmacokinetic profile of currently used and recommended DAA regimens and summarizes available data regarding DDIs to optimize HCV treatment in clinical practice.

Study on fluorescence properties of HCV antiviral (velpatasvir) and its fluorimetric determination in presence of sofosbuvir; application to stability study and human plasma

Velpatasvir (VLP) is a new, oral, direct-acting antiviral with potent inhibitory activity against all hepatitis C virus (HCV) genotypes. A highly sensitive, simple, fast and specific one fluorometric method for determination of VLP in the presence of sofosbuvir was developed and validated. The fluorescence behavior of VLP in different organic solvents was examined and explained. Methanol was concluded to be the best sensitizing reagent. The native fluorescence intensity of VLP was accomplished at 383 nm with 339 nm for excitation wavelength. The impacts of experimental variables included pH, various organized media, and time of stability were examined and optimized. A linear relationship was achieved between the VLP concentration and the fluorescence intensity in a range of 5 to 5 × 10³ ng mL^-1 with 0.70 and 0.23 ng mL^-1 , for quantitation and detection limits respectively. The proposed method was utilized for analyzing of VLP in human plasma and additionally expanded to examine the stability of VLP after its exposure to various stress conditions, like oxidative, alkaline, acidic, UV, daylight and sunlight conditions, according to ICH guidelines. Furthermore, the kinetics of acidic and oxidative degradations of VLP was examined. Moreover, the half-life times of the reaction (t_1/2 ) and the first-order reaction rate constants were estimated. Finally, a suggestion for the degradation pathway was presented.

Chronic Hepatitis C in Elderly Patients: Current Evidence with Direct-Acting Antivirals

Since the introduction of direct-acting antivirals (DAAs), the outcomes of hepatitis C (HCV) treatment have shown an improvement in cure rates with minimal side effects. However, to date, the safety and efficacy of DAAs have not been specifically examined in elderly patients. The treatment of HCV in the era of pegylated interferon and ribavirin was more challenging among elderly patients due to the increased prevalence of multiple comorbid conditions associated with an increased risk of side effects, including anemia, and high rates of discontinuation, likely as a result of poor tolerability, resulting in lower rates of sustained virologic response (SVR). The advent of highly efficacious all-oral DAA agents with minimal adverse events has provided more data on the outcomes of treatment in the elderly population. The current evidence shows that DAA agents have been effective and safe in the elderly population, with comparable rates of SVR. The aim of this article was to review the safety and efficacy of commonly prescribed DAA agents in the management of chronic HCV in the elderly population.

Depression, fatigue and neurocognitive deficits in chronic hepatitis C

Patients with chronic hepatitis C virus (HCV) infection experience a range of symptoms including depression, fatigue and neurocognitive deficits, impairing quality of life. Depression, in particular, may be reactive to increased psychosocial stress, and the physical symptoms of advanced HCV or associated comorbidities. However, even patients at an early stage of HCV infection, with minimal hepatic inflammation or comorbidities, report more depressive symptoms and fatigue than the general population. Similarly, specific neurocognitive deficits occur in early stage HCV infection and are independent of the presence of depression or encephalopathy. Therefore, intracerebral neurobiological changes associated with HCV may potentially explain these symptoms. These changes may arise from infiltration of the brain by peripherally induced cytokines, as well as direct neuropathic effects of HCV viral particles penetrating the blood-brain barrier. These phenomena parallel those reported in human immunodeficiency virus (HIV) infection. HCV-associated intracerebral changes include upregulated inflammatory responses, altered neurotransmitter levels, hormonal dysregulation, and release of neurotoxic substances. These may subsequently lead to abnormal neuronal conduction and function in areas of the brain governing affective responses, emotional processing, motivation, attention and concentration. Although direct-acting antiviral medications lead to high rates of HCV clearance, intracerebral changes may not be subsequently reversed and symptoms of depression, fatigue and neurocognitive deficits may persist. There is an ongoing role for multidisciplinary care and pharmacotherapy to manage these symptoms in HCV patients. Furthermore, there may be opportunities for future therapies to specifically target and ameliorate HCV-associated intracerebral changes.

HCV Genotype 6a Escape From and Resistance to Velpatasvir, Pibrentasvir, and Sofosbuvir in Robust Infectious Cell Culture Models

BACKGROUND & AIMS

Chronic liver diseases caused by hepatitis C virus (HCV) genotype 6 are prevalent in Asia, and millions of people require treatment with direct-acting antiviral regimens, such as NS5A inhibitor velpatasvir combined with the NS5B polymerase inhibitor sofosbuvir. We developed infectious cell culture models of HCV genotype 6a infection to study the effects of these inhibitors and the development of resistance.

METHODS

The consensus sequences of strains HK2 (MG717925) and HK6a (MG717928), originating from serum of patients with chronic HCV infection, were determined by Sanger sequencing of genomes amplified by reverse-transcription polymerase chain reaction. In vitro noninfectious full-length clones of these 6a strains were subsequently adapted in Huh7.5 cells, primarily by using substitutions identified in JFH1-based Core-NS5A and Core-NS5B genotype 6a recombinants. We studied the efficacy of NS5A and NS5B inhibitors in concentration-response assays. We examined the effects of long-term culture of Huh7.5 cells incubated with velpatasvir and sofosbuvir singly or combined following infection with passaged full-length HK2 or HK6a recombinant viruses. Resistance-associated substitutions (RAS) were identified by Sanger and next-generation sequencing, and their effects on viral fitness and in drug susceptibility were determined in reverse-genetic experiments.

RESULTS

Adapted full-length HCV genotype 6a recombinants HK2cc and HK6acc had fast propagation kinetics and high infectivity titers. Compared with an HCV genotype 1a recombinant, HCV genotype 6a recombinants of strains HK2 and HK6a were equally sensitive to daclatasvir, elbasvir, velpatasvir, pibrentasvir, and sofosbuvir, but less sensitive to ledipasvir, ombitasvir, and dasabuvir. Long-term exposure of HCV genotype 6a-infected Huh7.5 cells with a combination of velpatasvir and sofosbuvir resulted in clearance of the virus, but the virus escaped the effects of single inhibitors via emergence of the RAS L31V in NS5A (conferring resistance to velpatasvir) and S282T in NS5B (conferring resistance to sofosbuvir). Engineered recombinant genotype 6a viruses with single RAS mediated resistance to velpatasvir or sofosbuvir. HCV genotype 6a viruses with RAS NS5A-L31V or NS5B-S282T were however, able to propagate and escape in Huh7.5 cells exposed to the combination of velpatasvir and sofosbuvir. Further, HCV genotype 6a with NS5A-L31V was able to propagate and escape in the presence of pibrentasvir with emergence of NS5A-L28S, conferring a high level of resistance to this inhibitor.

CONCLUSIONS

Strains of HCV genotype 6a isolated from patients can be adapted to propagate in cultured cells, permitting studies of the complete life cycle for this important genotype. The combination of velpatasvir and sofosbuvir is required to block propagation of original HCV genotype 6a, which quickly becomes resistant to single inhibitors via the rapid emergence and persistence of RAS. These features of HCV genotype 6a could compromise treatment.

Development of robust genotype 1a hepatitis C replicons harboring adaptive mutations for facilitating the antiviral drug discovery and study of virus replication

The hepatitis C virus (HCV) subgenomic replicon is a valuable tool for studying virus replication and HCV drug development. Despite the fact that HCV genotype 1a (HCV1a) is the most prevalent genotype in the United States, few HCV1a reporter replicon constructs have been reported, and their replication capacities are not as efficient as those of HCV1b or 2a, especially in transient expression. In this study, we selected efficient HCV1a replicons and characterized the novel adaptive mutations derived from stable HCV1a (strain H77) replicon cells after G418 selection. These novel adaptive mutations were scored in NS3 (A1065V, C1073S, N1227D, D1431Y, and E1556G), NS4A (I1694T and E1709V), and NS4B (G1871C). The D1431Y mutation alone or combinations of other adaptive mutations introduced into the parental HCV1a replicon construct was observed to differentially enhance either transient or stable expression of replicon. In particular, two replicon mutants VDYG (A1065V, N1227D, D1431Y, and E1556G within NS3) and VDYGRG, VDYG with two additional adaptive mutations (NS4A-K1691R and NS4B-E1726G), displayed robust replication and exhibited no impairment in the susceptibility of replicon activity to various known HCV inhibitors.

Enhanced dispersive solid phase extraction assisted by cloud point strategy prior to fluorometric determination of anti-hepatitis C drug velpatasvir in pharmaceutical tablets and body fluids

An innovative spectrofluorometric method was developed for the analysis of a recently FDA approved anti-hepatitis C velpatasvir (VELP). The developed method was relied on dispersive solid phase extraction (dSPE) using synergistic effect of reduced graphene oxide (RGO) and cobalt hydroxide nanoparticles (CHNPs) in addition to cloud point extraction (CPE) using polyethylene glycol 6000 (PEG 6000) as non-ionic surfactant. This method combines the merits of preconcentration and interferences elimination achieved by dSPE and CPE, respectively. All relevant parameters such as surfactant concentration, ionic strength, pH, incubation time and others were thoroughly investigated and optimized. Fluorometric detection of VELP was carried out at excitation wavelength of 350 nm and emission wavelength of 415 nm. Under the optimum conditions, a linear calibration curve was achieved in the range of 0.5–45 ng mL⁻¹. Limits of detection (LOD) and quantification (LOQ) based on three and ten times the standard deviation of the blank were 0.040 and 0.112 ng mL⁻¹, respectively. This method was successfully applied for determination of VELP in real samples such as tablets, human plasma and urine samples with good recoveries.

Highly sensitive and selective solid phase extraction method combined with cloud point extraction strategy was developed for analysis of velpatasvir in its pharmaceutical tablets and biological fluids.

Global elimination of hepatitis C virus infection: Progresses and the remaining challenges

Today, with the introduction of interferon-free direct-acting antivirals and outstanding progresses in the prevention, diagnosis and treatment of hepatitis C virus (HCV) infection, the elimination of HCV infection seems more achievable. A further challenge is continued transmission of HCV infection in high-risk population specially injecting drug users (IDUs) as the major reservoir of HCV infection. Considering the fact that most of these infections remain undiagnosed, unidentified HCV-infected IDUs are potential sources for the rapid spread of HCV in the community. The continuous increase in the number of IDUs along with the rising prevalence of HCV infection among young IDUs is harbinger of a forthcoming public health dilemma, presenting a serious challenge to control transmission of HCV infection. Even the changes in HCV genotype distribution attributed to injecting drug use confirm this issue. These circumstances create a strong demand for timely diagnosis and proper treatment of HCV-infected patients through risk-based screening to mitigate the risk of HCV transmission in the IDUs community and, consequently, in the society. Meanwhile, raising general awareness of HCV infection, diagnosis and treatment through public education should be the core activity of any harm reduction intervention, as the root cause of failure in control of HCV infection has been lack of awareness among young drug takers. In addition, effective prevention, comprehensive screening programs with a specific focus on high-risk population, accessibility to the new anti-HCV treatment regimens and public education should be considered as the top priorities of any health policy decision to eliminate HCV infection.

Hepatitis C virus infection in Jeddah city, Saudi Arabia: Seroprevalence and knowledge

The infection rate of the hepatitis C virus (HCV) in Saudi Arabia is among the lowest in the world. However, it is likely that poor knowledge and awareness of HCV infection could minimize the effectiveness of prevention and control programs in the kingdom. Thus, the study objective was to estimate the prevalence of HCV infection, and to assess current knowledge about it, in the targeted population. Data on 5482 Saudi people attending primary healthcare centers in Jeddah City in 2014/2015 were analyzed in this cross-sectional study. Questions that covered the natural history, risk behavior, and prevention, and treatment of HCV were collected using a predesigned questionnaire. HCV seroprevalence was assessed using an enzyme-linked immunosorbent assay. HCV prevalence of 0.38% (95% confidence interval: 0.22-0.54) was found. The level of knowledge of the natural history, risk behavior, and prevention and treatment of HCV was poor among the participants. The lowest level of knowledge for all participants pertained to its prevention and treatment. The prevalence of HCV was low in Saudi Arabia (0.38%). However, adequate knowledge of HCV was lacking. Thus, the need to increase knowledge and awareness of HCV in the Saudi population is warranted.

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.

Updates on hepatitis C virus therapy in the direct-acting antiviral era

PURPOSE OF REVIEW

Hepatitis C virus (HCV) is a major cause of clinical burden in the United States and worldwide, as a percentage of patients can develop complications such as cirrhosis and hepatocellular carcinoma.

RECENT FINDINGS

Therapy for chronic HCV infection was previously interferon-based, but with the advent of direct-acting antivirals (DAAs), there has been a dramatic improvement in eradicating the virus with favourable side effect profiles.

SUMMARY

Emerging data are demonstrating new successful agents in difficult-to-manage populations. This review is aimed to provide a brief overview of currently accepted therapy, as well providing new information on upcoming therapeutic agents available for practioners going forward.

Profile of Roche's cobas® HCV tests

INTRODUCTION

Molecular assays for detection and accurate quantitation of hepatitis C virus (HCV) RNA have been important for identification and management of the hepatitis C. Furthermore, the HCV genotype should be assessed prior to treatment initiation. Recently, Roche developed the cobas® HCV tests for use on the cobas® 6800/8800 Systems and the cobas® 4800 System and the cobas® HCV genotyping (GT) test for use on the cobas® 4800 System. Areas covered: The analytic and clinical performance of the newly-developed tests is described according to the currently existing literature. Both tests for detection and quantitation of HCV RNA have been shown to be sensitive and linear, and correlate well with established Roche tests used in the routine diagnostic laboratory. The cobas® HCV GT test shows a good performance and is suitable for identification of HCV genotypes 1 to 6 and genotype 1 subtypes a and b in clinical specimens from individuals with chronic HCV infection. Expert commentary: The new tests are effective in screening for hepatitis C infection and in the management of patients with chronic HCV infection ensuring full HCV genotype coverage. They will replace the established Roche tests within the next few years.

Pharmacokinetic drug evaluation of velpatasvir plus sofosbuvir for the treatment of hepatitis C virus infection

INTRODUCTION

The fixed-dose combination therapy of sofosbuvir (SOF) plus velpatasvir (VEL) is the first pangenotypic, direct-acting antiviral (DAA), single-treatment regimen (STR) for the treatment of hepatitis C virus (HCV) infection to be commercialized. It is approved for the treatment of HCV genotypes 1, 2, 3, 4, 5, and 6. Following approval in 2016, new pharmacokinetic and pharmacodynamic data were reported, which led to important clinical applications. Areas covered: This review provides a summary of the pharmacokinetics, pharmacodynamics, efficacy and safety of SOF/VEL therapy for treatment of HCV infection. The topics covered include data regarding the drug's absorption, distribution, metabolism, excretion and antiviral activity strategies, such as clinical dose selection and treatment duration. Expert opinion: This novel combination therapy containing 400 mg of SOF plus 100 mg of VEL, taken orally, once daily, with or without food, has an excellent pharmacokinetic and pharmacodynamic profile. SOF/VEL achieved very high rates of sustained virological response in treatment-naive and treatment-experienced patients with chronic HCV genotype 1-6 infection, including those with compensated cirrhosis or HIV-1 co-infection.