Review article: the efficacy and safety of sofosbuvir, a novel, oral nucleotide NS5B polymerase inhibitor, in the treatment of chronic hepatitis C virus infection

2'-Fluorinated nucleoside chemistry for new drug discovery: achievements and prospects

Fluorinated nucleosides are an important class of modified nucleosides that have demonstrated therapeutic potential for treating various human diseases, especially viral infections and cancer. Many fluorinated nucleosides have advanced into clinical trials or have been approved by the FDA for use in patients. Among these fluorinated nucleosides, azvudine, developed by us, has been officially approved by the National Medical Products Administration for the treatment of coronavirus disease 2019 (COVID-19) and human immunodeficiency virus, indicating the therapeutic promise of fluorinated nucleosides. In view of the therapeutic promise of fluorinated nucleosides for antiviral and anticancer therapy, in this Review we will provide a comprehensive overview of well-established 2'-fluorinated nucleosides approved for use in the market or those in clinical stages for antiviral and antitumor therapies, highlighting the drug discovery strategies, structure-activity relationship studies, mechanisms of action, and preclinical/clinical studies and also discuss the challenges and future directions for nucleoside-based new drug discovery.

Safety considerations in the management of hepatitis C and HIV co-infection

INTRODUCTION

Both HCV and HIV are highly prevalent infections with current estimates of 57 and 38 million people infected worldwide, respectively. Oral antivirals can be curative for HCV and rescue HIV patients from disease progression. Dual therapy in coinfected patients requires expertise.

AREAS COVERED

Four major issues challenge dual HCV and HIV treatment, including overlapping drug-related side effects, hepatitis B reactivation, immune reconstitution inflammatory syndromes (IRIS), and drug-drug interactions (DDI). A search was conducted in PubMed from January 2010 to March 2023.

EXPERT OPINION

The advent of second-generation direct-acting antivirals (DDA) that depict higher antiviral potency, fewer side effects, pangenotypic activity and are co-formulated has expanded the indication of HCV therapy and particularly in HIV-coinfected individuals. Sequential initiation of antiretrovirals (ARV) followed by DAA is generally preferred to start dual treatment concomitantly. Close monitoring of rare episodes of HBV reactivation and IRIS is warranted. The most frequent DDI between DAA and ARV affect drug metabolism by CYP450 induction/inhibition, leading to abnormal drug exposures. Throughout this mechanism interact most HCV and HIV protease inhibitors and non-nucleoside polymerase inhibitors. Exposure to some HIV and HCV nucleos(t)ide analogues (e.g. tenofovir and sofosbuvir, respectively) is subject to induction/inhibition of drug transporters and requires special attention in patients with renal insufficiency.

Real-world Safety and Effectiveness of 24-week Sofosbuvir and Ribavirin Treatment in Patients Infected with Rare Chronic Hepatitis C Virus Genotypes 3, 4, 5, or 6 in Japan

Objectives Real-world evidence on the safety and effectiveness of direct-acting antivirals in patients infected with chronic hepatitis C virus (HCV) genotypes (GTs) 3, 4, 5, or 6 in Japan is limited. This prospective observational study assesses the real-world safety profile and treatment effectiveness among patients prescribed sofosbuvir with ribavirin (SOF+RBV) for HCV GT3-6 infection in Japan. Methods Adults receiving 24-week SOF+RBV treatment for HCV GT3-6 infection were prospectively enrolled and observed through 24 weeks post-treatment for treatment-emergent adverse events (AEs) considered related to SOF and/or RBV by treating physicians and for a sustained virologic response at 12 and 24 weeks post-treatment (SVR12, SVR24). Incidence rates of related AEs and serious AEs (SAEs) were calculated. Proportions of patients experiencing related AEs/SAEs and those achieving SVR12 and SVR24 were assessed overall and by baseline characteristics, including treatment experience and cirrhosis status. Results Among the 50 patients included in the safety analysis, 92% had GT3 infection. The incidence rates of related AEs and SAEs were low overall (1.52 and 0.25 per 100 person-weeks, respectively), with 6.0% and 14.0% patients experiencing AEs related to SOF or RBV, respectively. There were no marked differences in the occurrence of related AEs/SAEs by patient baseline characteristics. SVR12 and SVR24 were achieved in 83.7% (41/49) and 82.2% (37/45) of patients, respectively. Lower effectiveness was observed among treatment-experienced patients and patients with cirrhosis at baseline. Conclusions This study demonstrated that SOF+RBV treatment for HCV GT3-6 infection was safe, effective, and an important treatment option for this difficult-to-treat patient population in Japan.

Crystal structure of the Rubella virus protease reveals a unique papain-like protease fold

Rubella, a viral disease characterized by a red skin rash, is well controlled because of an effective vaccine, but outbreaks are still occurring in the absence of available antiviral treatments. The Rubella virus (RUBV) papain-like protease (RubPro) is crucial for RUBV replication, cleaving the nonstructural polyprotein p200 into two multifunctional proteins, p150 and p90. This protease could represent a potential drug target, but structural and mechanistic details important for the inhibition of this enzyme are unclear. Here, we report a novel crystal structure of RubPro at a resolution of 1.64 Å. The RubPro adopts a unique papain-like protease fold, with a similar catalytic core to that of proteases from Severe acute respiratory syndrome coronavirus 2 and foot-and-mouth disease virus while having a distinctive N-terminal fingers domain. RubPro has well-conserved sequence motifs that are also found in its newly discovered Rubivirus relatives. In addition, we show that the RubPro construct has protease activity in trans against a construct of RUBV protease-helicase and fluorogenic peptides. A protease-helicase construct, exogenously expressed in Escherichia coli, was also cleaved at the p150-p90 cleavage junction, demonstrating protease activity of the protease-helicase protein. We also demonstrate that RubPro possesses deubiquitylation activity, suggesting a potential role of RubPro in modulating the host's innate immune responses. We anticipate that these structural and functional insights of RubPro will advance our current understanding of its function and help facilitate more structure-based research into the RUBV replication machinery, in hopes of developing antiviral therapeutics against RUBV.

Liver involvement in inflammatory bowel disease: What should the clinician know?

Inflammatory bowel disease (IBD) may show a wide range of extraintestinal manifestations. In this context, liver involvement is a focal point for both an adequate management of the disease and its prognosis, due to possible serious comorbidity. The association between IBD and primary sclerosing cholangitis is the most known example. This association is relevant because it implies an increased risk of both colorectal cancer and cholangiocarcinoma. Additionally, drugs such as thiopurines or biologic agents can cause drug-induced liver damage; therefore, this event should be considered when planning IBD treatment. Additionally, particular consideration should be given to the evidence that IBD patients may have concomitant chronic viral hepatitis, such as hepatitis B and hepatitis C. Chronic immunosuppressive regimens may cause a hepatitis flare or reactivation of a healthy carrier state, therefore careful monitoring of these patients is necessary. Finally, the spread of obesity has involved even IBD patients, thus increasing the risk of non-alcoholic fatty liver disease, which has already proven to be more common in IBD patients than in the non-IBD population. This phenomenon is considered an emerging issue, as it will become the leading cause of liver cirrhosis.

Edoxaban and the Issue of Drug-Drug Interactions: From Pharmacology to Clinical Practice

Edoxaban, a direct factor Xa inhibitor, is the latest of the non-vitamin K antagonist oral anticoagulants (NOACs). Despite being marketed later than other NOACs, its use is now spreading in current clinical practice, being indicated for both thromboprophylaxis in patients with non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE). In patients with multiple conditions, the contemporary administration of several drugs can cause relevant drug-drug interactions (DDIs), which can affect drugs' pharmacokinetics and pharmacodynamics. Usually, all the NOACs are considered to have significantly fewer DDIs than vitamin K antagonists; notwithstanding, this is actually not true, all of them are affected by DDIs with drugs that can influence the activity (induction or inhibition) of P-glycoprotein (P-gp) and cytochrome P450 3A4, both responsible for the disposition and metabolism of NOACs to a different extent. In this review/expert opinion, we focused on an extensive report of edoxaban DDIs. All the relevant drugs categories have been examined to report on significant DDIs, discussing the impact on edoxaban pharmacokinetics and pharmacodynamics, and the evidence for dose adjustment. Our analysis found that, despite a restrained number of interactions, some strong inhibitors/inducers of P-gp and drug-metabolising enzymes can affect edoxaban concentration, just as it happens with other NOACs, implying the need for a dose adjustment. However, our analysis of edoxaban DDIs suggests that given the small propensity for interactions of this agent, its use represents an acceptable clinical decision. Still, DDIs can be significant in certain clinical situations and a careful evaluation is always needed when prescribing NOACs.

Distribution of naturally -occurring NS5B resistance-associated substitutions in Egyptian patients with chronic Hepatitis C

Background

NS5B polymerase inhibitors represent the cornerstone of the present treatment of Hepatitis C virus infection (HCV). Naturally occurring substitution mutations to NS5B inhibitors have been recorded. The current study intended to demonstrate possible natural direct acting antiviral (DAA)—mutations of the HCV NS5B region in HCV patients in Minia governorate, Egypt.

Methods

Samples were collected from 27 treatment-naïve HCV patients and 8 non-responders. Out of 27 treatment-naïve patients, 17 NS5B sequences (amino acids 221–345) from treatment-naïve patients and one sample of non-responders were successfully amplified. Nucleotide sequences have been aligned, translated into amino acids, and compared to drug resistance mutations reported in the literature.

Results

NS5B amino acid sequence analysis ensures several novel NS5B mutations existence (more than 40 substitution mutations) that have not been previously documented to be correlated with a resistant phenotype. It was found that K304R (82.4%), E327D and P300T (76.5% each) substitutions were the most distributed in the tested samples, respectively. S282T, the major resistance mutation that induces high sofosbuvir-resistance level in addition to other reported mutations (L320F/C) and (C316Y/N) were not recognized. Q309R mutation is a ribavirin-associated resistance, which was recognized in one strain (5.9%) of genotype 1g sequences. Besides, one substitution mutation (E237G) was identified in the successfully amplified non-responder sample.

Conclusion

Our study showed various combinations of mutations in the analyzed NS5B genes which could enhance the possibility of therapy failure in patients administered regimens including multiple DAA.

Treatment of Chronic Hepatitis C Genotype 3 With Ledipasvir and Sofosbuvir: An Observational Study

OBJECTIVE

Sofosbuvir/ledipasvir (SOF/LED) is recommended for treatment of genotypes 1, 4, 5 and 6. Despite some preliminary data from the ELECTRON-2 trial regarding use of SOF/LED combination in chronic hepatitis C genotype 3, there are no guidelines recommending this combination in such patients. We conducted this study to evaluate the efficacy of the overall sustained virologic response at 12 weeks (SVR 12) and safety of SOF/LED in chronic hepatitis C genotype 3 infection in our population.

METHODS

It was a prospective, hospital-based observational study. All patients with chronic hepatitis C genotype 3 treated with SOF/LED were divided into two groups: patients with cirrhosis and without cirrhosis. Patients without cirrhosis received SOF/LED (90/400 mg) for 12 weeks; however, patients with cirrhosis received treatment for 24 weeks.

RESULTS

We enrolled 104 patients with chronic hepatitis C over a period of 24 months. Of the total, 66 were women (63.5%) and 38 were men (36.5%). The average age was 40 years (range: 18-76 years). Of 104 patients, 86 (82.7%) were of genotype 3, 15 (14.9%) were of genotype 1 and 3 (2.9%) were of genotype 4. Ninety-two (88%) were noncirrhotic and 12 (11.5%) were cirrhotic. Ninety-five (95.2%) were treatment naïve. Among genotype 1 and 4, all patients achieved rapid virologic response and SVR 12. Of 86 genotype 3 patients, 78 (90.6%) were noncirrhotic and 8 (9.3%) were cirrhotic. Among genotype 3 patients without cirrhosis, 75 (96%) achieved SVR 12 while 6 (75%) with cirrhosis achieved SVR 12. All patients tolerated the combination well; however, some patients experienced nausea (26%), headache (25%) and fatigue (21%). No patient had to discontinue therapy due to adverse drug reactions.

CONCLUSIONS

Single tablet LED and SOF combination is safe and effective in genotype 3 patients without cirrhosis even without ribavirin. Being effective in genotype 3, the combination can be used as a pangenotypic drug in patients without cirrhosis.

Real-World Virological Efficacy and Safety of Ledipasvir and Sofosbuvir in Patients with Chronic Hepatitis C Virus Genotype 2 Infection: A Multicenter Study

INTRODUCTION

The real-world virological efficacy and safety of interferon-free direct-acting antiviral (DAA) therapy with ledipasvir (LDV) plus sofosbuvir (SOF) were assessed in patients who were chronically infected with hepatitis C virus (HCV) genotype 2.

METHODS

A total of 126 patients with chronic hepatitis C due to HCV genotype 2 infection who were treated with the LDV/SOF regimen were enrolled. The sustained virological response (SVR) rate and safety were analyzed. SVR was assessed in the intention-to-treat (ITT) population as well as in the modified intention-to-treat (mITT) population, which excluded patients with non-virological failure, including those who dropped out before the SVR assessment.

RESULTS

The overall SVR rates of the ITT and mITT populations were 87.3% (95% confidence interval [CI] 80.2-92.6) (110/126) and 97.3% (95% CI 92.4-99.4) (110/113), respectively. In the mITT population, the percentages of patients with undetectable HCV RNA at 4, 8, and 12 weeks after the start of therapy were 92.9% (95% CI 86.5-96.9) (105/113), 99.1% (95% CI 95.2-100.0) (112/113), and 100.0% (95% CI 97.4-100.0) (113/113), respectively. Subgroup analyses of the mITT population showed no significant differences in SVR rates according to age, sex, HCV genotype (subtype), history of interferon-based therapy, baseline FIB-4 index, or baseline estimated glomerular filtration rate. In all subpopulations, the SVR rates were > 90%. There were no severe adverse events associated with the treatment.

CONCLUSION

The LDV/SOF regimen showed high virological efficacy and acceptable safety in patients with HCV genotype 2 infection.

TRIAL REGISTRATION

UMIN registration no. 000038604.

Interferon lambda 4 gene polymorphisms as a predicting tool of response to hepatitis C virus genotype 4 patients treated with Sofosbuvir and Ribavirin

The relation between interferon lambda 4 gene (IFNL4) and direct acting antiviral (DAA) regimens in hepatitis C virus (HCV) infected patients is not clear. So, a single nucleotide polymorphisms (SNP) of IFNL4 gene genotypes and its relationship with Sofosbuvir (SOF) and Ribavirin (RBV) treatment response is under consideration. This study aims to investigate the relation between IFNL4 polymorphisms and clearance of HCV genotype 4 for HCV patients. Hence, the appropriate drug can be chosen for each patient. SNP genotyping assay for IFNL4 which formerly known as IL28B (rs368234815) was examined for genomic DNA. The DNA was extracted from whole blood of one hundred patients who documented to have infection with chronic HCV genotype 4 (positive PCR) and treated with SOF and RBV. Patients were diagnosed, previously, as HCV genotype 4 and classified according to drug response into two groups (responders, non-responders). All samples were compared with 50 of non-infected (negative PCR) people (control group). The TT/TT homozygous represents 48% of patients and 66% of non-infected people while the homozygous ∆G/∆G is 21% and 12%, respectively. There is significance to IFNL4 genotypes for the treatment response with the probability value p < 0.001. The percentages of the appearance of genotypes TT/TT, TT/∆G and ∆G/∆G for responders were 60%, 28% and 12%, respectively. There is no significance for gender, age, ALT and PLC to treatment response to SOF and RBV, while INR has.

Efficacy and safety of sofosbuvir-based, interferon-free therapy : The Management of rheumatologic extrahepatic manifestations associated with chronic hepatitis C virus infection

BACKGROUND

The use of pegylated interferon alpha (IFN) has been of concern in chronic hepatitis C virus (HCV) patients with rheumatologic extrahepatic manifestations (EHM) due to the immunostimulatory effects of IFN.

AIM

To study the efficacy and safety of sofosbuvir-based, IFN-free antiviral therapy in chronic HCV patients with rheumatologic EHM.

MATERIAL AND METHODS

Group A included 24 patients with arthropathy (arthralgia or arthritis, n = 15) or vasculitis (n = 9) who received sofosbuvir and ribavirin (n = 17) or sofosbuvir and simeprevir (n = 7). Group B comprised 15 historical controls suffering from arthropathy who had received IFN and ribavirin. All patients were clinically evaluated and by detection of HCV viremia at baseline (V0), at the end of treatment (V1), 12 weeks after end of treatment (V2) and 24 weeks after end of treatment (V3).

RESULTS

Sustained viral response was obtained in all patients of group A (100%) versus 12 out of 15 of group B (80%). In group A, the tender joint count (TJC) and visual analogue scale for pain (VAS) improved (p = 0.001 for both) while the swollen joint count (SJC) decreased at V1 (p = 0.001) but returned to baseline values at V3. All vasculitis patients improved. Purpura, arthralgia and leg ulcers disappeared, but peripheral neuropathy persisted. In group B, TJC, SJC and VAS increased from baseline values (p = 0.034, 0.03 and 0.001, respectively). Side effects in group A were generally mild, but one patient developed deterioration of arthralgia.

CONCLUSION

The use of IFN-free regimens is safe and effective in the treatment of most HCV-related rheumatologic EHM.

Paediatric hepatitis C virus infection and its treatment: Present, past, and future

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease in the world. It is a challenging medico-social problem in the paediatric population. High HCV infection rates are reported in low and middle incomes countries. From the health economic point of view treatment of hepatitis C virus (HCV) with subsequent virus eradication is very effective as it eliminates the long-term sequelae of untreated or maltreated HCV. In this review we summarize the updates and highlight the historical approach of treatment of chronic HCV infection in children in the new era of directly acting antiviral (DAA) agents.

Hepatitis C Virus Genetic Variability, Human Immune Response, and Genome Polymorphisms: Which Is the Interplay?

Hepatitis C virus (HCV) infection is the main cause of chronic hepatitis, affecting an estimated 150 million people worldwide. Initial exposure to HCV is most often followed by chronic hepatitis, with only a minority of individuals spontaneously clearing the virus. The induction of sustained and broadly directed HCV-specific CD4⁺ and CD8⁺ T cell responses, together with neutralizing antibodies (nAb), and specific genetic polymorphism have been associated with spontaneous resolution of the infection. However, due to its high variability, HCV is able to overwhelm the host immune response through the rapid acquisition of mutations in the epitopes targeted by T cells and neutralizing antibodies. In this context, immune-mediated pressure represents the main force in driving HCV evolution. This review summarizes the data on HCV diversity and the current state of knowledge about the contributions of antibodies, T cells, and host genetic polymorphism in driving HCV evolution in vivo.

Design, synthesis and broad-spectrum Bcr-Abl inhibitory activity of novel thiazolamide-benzamide derivatives

Bcr-Abl plays an important role in the pathogenesis and development of chronic myeloid leukemia (CML). But Bcr-Abl is prone to mutation, so it increases the difficulty of clinical treatment. Therefore, it is crucial to design a new class of broad-spectrum Bcr-Abl inhibitors. Herein, forty novel thiazolamide-benzamide derivatives were synthesized and evaluated their broad-spectrum Bcr-Abl inhibitory activities. The newly synthesized compounds were characterized by using spectrum data (1H NMR, APCI-MS and IR) and elemental analysis. The protein kinase results indicated that eight compounds (3a, 3e, 3m, 3n, 3p, 4c, 4f, 4g) showed high activities to wild-type and T315I mutation. The most potent compound 3m exhibited an Abl IC50 value as low as 1.273 μM and showed inhibition to the T315I mutant with IC50 value 39.89 μM. 3m could prove to be a new promising lead compound for the further development of broad-spectrum Bcr-Abl inhibitors to overcome clinical acquired resistance.

Synthesis of 1',2'-methano-2',3'-dideoxynucleosides as potential antivirals

The synthesis of constrained nucleosides has become an important tool to understand the SAR in the interaction between biological and synthetic nucleotides in the context of antisense oligonucleotide therapy. The incorporation of a cyclopropane into a furanose ring of a nucleoside induces some degree of constrain without affecting significantly the steric environment of a nucleoside. Here, we report a new, short and stereocontrolled synthesis of two constrained nucleosides analogues, 1',2'- methano-2',3'-dideoxyuridine 9, and the corresponding cytidine analog 12. X-ray crystallography revealed that the furanose ring in the constrained uridine and cytidine analogues was flattened with virtual loss of pseudorotation. The phosphoramidate esters of the novel constrained uridine and cytidine nucleosides, intended as prodrugs, were tested in cell-based assays for viral replication across the herpes virus family and HIV inhibition courtesy of Merck laboratories, Rahway. They were also tested in antiproliferative assays against colorectal and melanoma cell lines. Unfortunately, none of the compounds showed activity in these assays.

Polymerase assays for lead discovery: An overall review of methodologies and approaches

Polymerases represent an attractive molecular target for antibacterial drug development, antiviral intervention and cancer therapy. Over the past decade, academic groups and scientists from pharmaceutical industry have developed a large plethora of different functional assays to monitor the enzymatic reaction catalyzed by polymerases. These assays were used to enable high-throughput screening (HTS) for lead discovery purposes, as well as hit-to-lead (H2L) drug profiling activities. In both cases the choice of the assay technology is critical and to the best of our knowledge, there is no review available to help scientists to choose the most suitable assay. This review summarizes the most common functional assays developed to monitor the enzymatic activity of polymerases and discusses the advantages and disadvantages of each assay. Assays are presented and evaluated in term of cost, ease of use, high-throughput screening compatibility and liability towards delivering false positives and false negatives.

Effectiveness of sofosbuvir/pegylated-interferon plus ribavirin in treatment of hepatitis C virus genotype 4 patients

INTRODUCTION

New regimens involving direct-acting antiviral agents (DAAs) have recently been approved for the treatment of hepatitis C virus (HCV) genotype 4 (GT4). The current study aims to assess the efficacy and safety of sofosbuvir (SOF) with pegylated interferon (PegINF)/ribavirin (RBV) for chronic HCV GT4 patients at the beginning of the interferon-free era.

MATERIAL AND METHODS

Between March 2015 and November 2015, 99 patients (59 naïve and 40 experienced) infected with HCV GT4 were enrolled in the study. Eligible patients received daily oral 400 mg SOF, RBV (body weight: < 75 kg, 1000 mg; < 75 kg, 1200 mg), the dose modified according to patient tolerability, plus 180 μg PegINFα-2 once weekly for 12 weeks.

RESULTS

Among the patient cohort, sustained virological response 12 weeks after the end of treatment (SVR12) was achieved by 88% (87/99) of all patients, by 93% (55/59) of naïve patients and by 80% (32/40) of experienced patients. Regarding treatment failure, the data recorded 12% (12/99) of patients (4 null responses and 8 relapsers). Otherwise, the most common adverse events observed during the study included headache, nausea, fatigue, dyspnea, influenza-like illness, anemia, and leukopenia.

CONCLUSIONS

SOF combination-based therapies were considered promising choice regimens for chronic HCV infection. The present findings suggest that the combination of the SOF/PegINF/RBV regimen was effective for Egyptian patients with HCV GT4. The recorded adverse events and viral outcome revealed the high need for further efforts to minimize the side effects of the current regimen and/or replace PegINF with additional potent DAA(s) to increase SVR12 to achieve 100%.

Prevalence and sociodemographic disparities of Hepatitis C in Baby Boomers and the US adult population

BACKGROUND

The US Baby Boomer (BB) generation is associated with high rates of Hepatitis C virus (HCV) infection. There is limited literature detailing age-specific risk factors for HCV infection. Using a nationally representative sample, this study examines US adult HCV prevalence and age-specific risk factors for chronic HCV infection.

METHODS

We analyzed data from National Health and Nutrition Examination Survey (NHANES) for years 1999-2012. Age was divided into three categories: BB, younger than BB (YG) and older than BB (OG). HCV status was determined by the presence of a positive HCV antibody and a positive HCV RNA. Sociodemographic variables were analyzed by HCV status. Multivariable logistic regression models adjusting for sociodemographic variables were fitted to identify age-specific risk factors for HCV positivity.

RESULTS

The overall prevalence of chronic HCV was 1.19% with a US population estimate of 2,347,852 US adults. BB had the highest prevalence at 2.23%, accounting for over 74% of all chronic HCV cases. HCV prevalence was highest among all ages (1.83%) and BB (2.71%) in 2001-2002 survey cycle. Among BB, males, non-Hispanic blacks, positive blood transfusion history, current and former smoker, and living below the poverty line were significant predictors of chronic HCV positivity.

CONCLUSION

This study highlights the elevated prevalence of chronic HCV among BB and identifies age-specific risk factors for chronic HCV infection. As the BB population ages, it is important to use these generation-specific risk factors that can guide health professionals in targeted screening and public health prevention efforts.

Drug Interchangeability of Generic and Brand Products of Fixed Dose Combination Tablets of Sofosbuvir and Ledipasvir (400/90 mg): Employment of Reference Scaled Average Bioequivalence Study on Healthy Egyptian Volunteers

BACKGROUND AND OBJECTIVES

The purpose of this study was to apply the reference-scaled average bioequivalence (RSABE) approach to evaluate the bioequivalence and to investigate the pharmacokinetic properties of two formulations of fixed dose combination (FDC) tablet of sofosbuvir (SOF) and ledipasvir (LED) (400/90 mg) in 36 healthy Egyptian volunteers.

METHODS

The study was performed in single-dose, randomized-sequence, open-label, reference-replicated, 3-period crossover design (RTR, TRR, RRT), with a washout period of 2 weeks. A rapid and simple LC-MS/MS method was developed and validated for the simultaneous estimation of SOF and LED using eplerenone as an internal standard (IS).

RESULTS

The results showed that the 90% confidence intervals (CIs) for natural log-transformed ratios of C_max, AUC_last and AUC_∞ of SOF (89.95-115.31, 98.77-109.75 and 98.79-109.75) were within the RSABE acceptance limits. The 90% CIs for natural log-transformed ratios of C_max and AUC_last of LED (87.33-115.15 and 83.82-112.26) were within the FDA bioequivalence limits (80.00-125.00). In addition, the in vitro dissolution study was done and both formulations released > 85% of drug within 15 min in the proposed dissolution medium.

CONCLUSIONS

In conclusion, bioequivalence between the two fixed-dose combination products was demonstrated for both active ingredients.

Sofosbuvir plus Daclatasvir with or without ribavirin for treatment of chronic HCV genotype 4 patients: real-life experience

INTRODUCTION

New regimens involving direct-acting antiviral agents have recently been approved for the treatment of HCV. Our aim was to assess the efficacy and safety of 12 or 24 weeks of Sofosbuvir 400 mg plus Daclatasvir 60 mg, with or without ribavirin (800-1000 mg) in treating chronic hepatitis C genotype 4 patients.

METHODS

This is an open-label observational study that describes the effect of 12 week or 24 weeks of daily oral Sofosbuvir (SOF) 400 mg plus Daclatasvir (DCV) 60 mg with or without ribavirin (RBV) with dose adjustment if indicated. It included the first 1168 patients that fulfilled the inclusion and exclusion criteria and treated in the Egyptian Liver Research Institute and Hospital, Mansoura, Egypt.

RESULTS

Sustained viral response after 12 weeks of end of treatment (SVR12) was achieved in 96.6% (95% CI 95.1-98.2%) of the patients receiving 12 weeks of DCV + SOF treatment, in 95.7% (95% CI 93.6-97.8%) of the patients receiving 12 weeks of DCV + SOF + RBV, in 93.3% (95% CI 90.0-96.6%) of those receiving 24 weeks of DCV + SOF, and in 92.2% (95% CI 85.4-98.9%) of patients receiving 24 weeks of DCV + SOF + RBV treatment. SVR12 rate was significantly higher in patients with no cirrhosis receiving DCV + SOF only for 12 weeks or 24 weeks (97.4 and 97.4%, respectively) than in patients with cirrhosis (91.7 and 88.9%, respectively). The most common adverse events were fatigue, headache, insomnia, and anemia. No treatment-related serious adverse events or death were reported in the studied groups.

CONCLUSION

Treatment with SOF (400 mg) plus DCV (60 mg), with or without RBV (800-1000 mg) for 12 or 24 weeks, was effective and well tolerated in chronic hepatitis C genotype 4 patients. SVR rates were higher for patients with no cirrhosis. Addition of RBV has benefit only in treatment-experienced group receiving 24 weeks.

Real-world effectiveness of sofosbuvir plus ribavirin for chronic hepatitis C genotype 2 in Asia: a systematic review and meta-analysis

BACKGROUND

Sofosbuvir plus ribavirin (SOF+RBV) for 12 weeks is the standard treatment for chronic hepatitis C (CHC) genotype 2 (GT2) in most of Asia despite availability of new CHC medications. SOF-RBV real-world effectiveness has only been reported in small and/or single-centre studies. Our goal was to determine the real-world effectiveness of 12-week SOF+RBV therapy for CHC GT2 in Asia.

METHODS

A systematic search on PubMed and Embase was conducted through 30 June 2017. We identified full articles and conference proceedings of at least 10 adult patients with CHC GT2 treated with SOF+RBV for 12 weeks under real-world setting in Asia.

RESULTS

A total of 2208 patients from 13 studies were included. The pooled sustained virological response 12 weeks after the end of treatment (SVR12) was 95.8% (95% CI 94.6% to 96.9%) with non-significant heterogeneity (I2=34.4%). Anaemia (27.9%) was the most common adverse event (AE), with serious AEs in 2.0% and only 0.7% discontinued therapy prematurely. In subgroup analyses, patients with cirrhosis had 8.7% lower SVR12 than non-cirrhotic patients (P<0.0001), and treatment-experienced patients had 7.2% lower SVR12 than treatment-naïve patients (P=0.0002). Cirrhotic treatment-experienced patients had the lowest SVR12 at 84.5%. There were no significant differences in pooled SVR12 among patient subgroups: RBV dose reduction versus no dose reduction (P=0.30); hepatocellular carcinoma (HCC) versus no HCC (P=0.10); GT 2a versus 2b (P=0.86); and <65 vs ≥65 years of age (P=0.20).

CONCLUSIONS

SOF+RBV for 12 weeks was safe and effective for patients with CHC GT2 in Asia, although those with cirrhosis and prior treatment failure had a lower pooled SVR12 rate.

TRIAL REGISTRATION NUMBER

CRD42017067928.

Ledipasvir-Sofosbuvir Plus Ribavirin in Treatment-Naive Patients With Hepatitis C Virus Genotype 3 Infection: An Open-Label Study

Background

Patients chronically infected with genotype 3 hepatitis C virus (HCV) have faster disease progression and are less responsive to current direct-acting antiviral regimens than patients infected with other genotypes. We conducted an open-label trial to evaluate the safety, tolerability, and efficacy of ledipasvir and sofosbuvir plus ribavirin in patients with genotype 3 HCV infection.

Methods

We enrolled treatment-naive patients with and without compensated cirrhosis at 15 sites in Canada. All patients were treated with ledipasvir-sofosbuvir (90 mg and 400 mg) plus weight-based ribavirin for 12 weeks. The primary endpoint was sustained virologic response 12 weeks after treatment (SVR12). Secondary endpoints included evaluation of baseline and treatment-emergent drug resistance.

Results

Of the 111 patients enrolled, 105 (95%) had subtype 3a HCV and 39 (35%) had compensated cirrhosis. SVR12 was achieved by 99 of 111 patients (89%; 95% confidence interval, 82%-94%). Of the 39 patients with cirrhosis, 31 (79%) achieved SVR12, compared with 68 of 72 (94%) patients without cirrhosis. No treatment-emergent resistance mutations occurred in those who failed treatment. One patient discontinued treatment due to liver cancer and died 22 days after treatment discontinuation. The most common adverse events were fatigue (51%), headache (36%), and nausea (23%).

Conclusions

In this multicenter trial involving treatment-naive patients with genotype 3 HCV, 12 weeks of ledipasvir-sofosbuvir provided a high level of SVR in those without cirrhosis.

Clinical Trials Registration

NCT02413593.

Forecasted impacts of a sofosbuvir-based national hepatitis C treatment programme on Egypt's hepatocellular cancer epidemic: simulation of alternatives

Background

Egypt is experiencing a hepatocellular cancer (HCC) epidemic due to widespread hepatitis C virus (HCV) transmission. The use of sofosbuvir-related therapies producing improved treatment success has permitted an updated, nationwide, HCV treatment programme with expanded coverage. This study simulated the multidecade impacts of the new treatment programme on hepatitis and HCC.

Methods

A Markov model of HCV infection and treatment analysed the HCV-related HCC epidemic between 2009 and 2050, using parameters based on peer-reviewed studies and expert opinion. Comparing the ‘new’ and ‘old’ scenarios, and with the old treatment programme being replaced or not by the new programme in 2015, the annual number, prevalence and incidence of HCC were simulated for representative Egypt populations including HCV-infected patients aged 15–59 years in 2008, healthy people aged 5–59 years in 2008 and 5-year-old children cohorts entering the population each year beginning in 2009. Averted HCC cases were calculated, and sensitivity analyses were performed.

Results

Compared with the old scenario, the estimated number, prevalence and incidence of future HCC cases in the new scenario would peak earlier and at lower levels in 2025 (~29 000), 2023 (~28/100 000) and 2022 (~14/100 000), respectively. The new treatment programme is estimated to avert ~956 000 HCC cases between 2015 and 2050.

Discussion

By reducing cancer cases and shortening the peak epidemic period, the new programme should substantially diminish the HCC epidemic across Egypt. Our timeline forecast for Egypt’s HCC epidemic, and evaluation of various disease and programme components, should be useful to other countries that are developing policies to address HCV-related liver cancer prevention.

Effect of Sofosbuvir Plus Daclatasvir in Hepatitis C Virus Genotype-4 Patients: Promising Effect on Liver Fibrosis

BACKGROUND/PURPOSE

The effect of sofosbuvir and daclatasvir in treatment of genotype 4 Hepatitis C Virus (HCV) is not well documented. This study investigated the safety and efficacy of sofosbuvir plus daclatasvir with or without ribavirin in treatment of HCV genotype 4 patients. The impact of therapy on liver fibrosis as well as the role of IL18 polymorphism in therapeutic outcome was assessed.

METHODS

One hundred HCV genotype 4 patients were categorized into 2 groups. The group 1 comprised treatment naïve patients, with total serum bilirubin ≤ 1.2 mg/10-1 L, serum albumin ≥ 3.5 g/10-1 L, INR ≤ 1.2, and platelet count ≥ 150 × 109/L. This group was treated with sofosbuvir plus daclatasvir for 12 weeks. The group 2 included Peg-IFN-α-or sofosbuvir treatment experienced, or patients with at least 2 of the following findings: total serum bilirubin > 1.2 mg/10-1 L, serum albumin < 3.5 g/10-1 L, INR > 1.2, and platelet count < 150 × 109 L-1. Group 2 was treated with sofosbuvir-daclatasvir + ribavirin for 12 weeks, with the exception of sofosbuvir treatment experienced patients, who were treated with sofosbuvir/daclatasvir + ribavirin for 24 weeks.

RESULTS

Sustained Virological Response (SVR12) (undetectable viremia12 weeks post-treatment), was 93.3% in group 1 and 87.5% in group 2 (total = 91%). Such high efficacy was accompanied with tolerable adverse effects as well as with significant improvement in liver fibrosis. No significant association was observed between IL18 polymorphism (rs1946518) at position -607 and achievement of SVR12 in HCV patients after treatment.

CONCLUSION

Sofosbuvir plus daclatasvir, with or without ribavirin achieved high efficacy and safety in HCV genotype 4 patients. Their effects were accompanied with attenuation of liver fibrosis. Further wider-scale studies are needed to evaluate the actual role of IL18 polymorphisms in treatment response with sofosbuvir/daclatasvir.

Timing Strategies of Direct-Acting Antivirals and Biologics Administration in HCV-Infected Subjects with Inflammatory Bowel Diseases

Background: In the last years, inflammatory bowel disease (IBD) and hepatitis C virus (HCV) infection management has completely changed. However, the role of direct-acting antivirals (DAAs) and the correct timing of antiviral drugs administration in IBD patients needing biologics has not been evaluated. Objective: To discuss the management of HCV-infected IBD patients, focusing our attention on the timing of DAAs administration subjects needing biologics. Methods: Relevant articles addressing HCV management in patients needing biologics were identified by searching from PubMed, MEDLINE and Scopus. Results: Three possible timing strategies were identified: (1) sequential strategy, meaning the choice of treating firstly the active IBD with biologics and then, once the acute phase has been controlled, treating the HCV infection; (2) concomitant strategy, that is the contemporaneous beginning of DAAs and biologics administration; (3) inverted sequential strategy-the administration of antiviral therapy before biologics in HCV-infected IBD patients. The potential pharmacological interactions between biologics and DAAs have also been reported. Conclusions: Clinical management of HCV-infected IBD patients remains a challenging problem for clinicians, especially in terms of timing choice. Recent published data about DAAs are very encouraging also in IBD patients. All strategies could be considered safe and effective. However, further data are immediately required in order to evaluate hepatic toxicity of novel immunosuppressive drugs in IBD.

Safety and efficacy of sofosbuvir-based direct-acting antiviral regimens for hepatitis C virus genotypes 1-4 and 6 in Myanmar: Real-world experience

This open-label, clinical experience investigated the safety and efficacy of direct-acting antiviral (DAA) hepatitis C virus (HCV) therapy in Myanmar; 344 patients completed treatment between June 2015 and May 2016. Patients with HCV genotypes 1-4 and 6 received one of four treatments: (i) Peg-interferon (PEG-IFN)+sofosbuvir (SOF)+ribavirin (RBV) for 12 weeks, (ii) SOF+RBV for 24 weeks, (iii) ledipasvir (LDV)+SOF for 12 weeks or (iv) daclatasvir (DCV)+SOF+RBV for 12 or 24 weeks. Genotype 3 was most common (n=133, 38.7%), followed by genotype 6 (n=122, 35.5%) and genotype 1 (n=86, 25%). Overall, 91% of patients achieved sustained virologic response (SVR); 99% in group 1, (n=148/149), 90% in group 2 (n=95/106), 78% in group 3 (n=65/83) and 100% in group 4 (n=6/6). In group 3, SVR rates were 96.8% in genotype 1 (n=30/31) and 64.1% in genotype 6 (n=25/39). Multivariable regression analysis identified advanced fibrosis (F3-4) (OR=.16 CI: 0.05-0.57, P=.005), genotype 6 (OR=.35, CI: 0.16-0.79, P=.012) and diabetes (OR=.29, CI: 0.12-0.71, P=.007) as negative independent predictors of response. Adverse events were mild with all-oral therapy.

CONCLUSION

DAA therapy ±PEG-IFN achieved high SVR rates. Genotype 6 patients had a low SVR to 12 weeks of LDV and SOF raising the need for other regimens, RBV or longer treatment duration in this population.

Real-life results of sofosbuvir based therapy in chronic hepatitis C -naïve and -experienced patients in Egypt

BACKGROUND

More than ten million Egyptians are infected with HCV. Every one of them is going to infect about three to four persons every year. Treating those patients is a matter of national security. A dramatic improvement in hepatitis C virus (HCV) infection treatment was achieved in the last five years. A new era of direct-acting antivirals is now dawning in Egypt.

OBJECTIVE(S)

We share in this report our clinical experience in treating chronic HCV Egyptian patients with Sofosbuvir based regimens to evaluate its safety and efficacy on real life practical ground.

METHODS

A total of 205 chronic HCV patients (195 naive and 15 experienced) were enrolled in the study. Patient were treated with Sofosbuvir+Ribavirin 24 weeks as standard of care. Two interferon eligible patients were treated with PEG-INF+ Sofosbuvir+Ribavirin for 12 weeks. The primary efficacy endpoint was the proportion of patients with sustained virologic response at 24 weeks after cessation of therapy.

RESULTS

The overall response rate was 97.1%. Sustained virological response rate did not differ among treatment-naive patients and patients with previous history of IFN-based therapy. Portal hypertension, prediabetes, and lack of early virologic response were predictors of non response. No clinically significant treatment-emergent adverse effects were noted. No treatment discontinuation was encountered.

CONCLUSION

In the real-life setting, Sofosbuvir based regimens for 24 weeks has established an efficacious and well tolerated treatment in naïve and experienced patients with chronic HCV genotype 4 infection; although shorter treatment durations may be possible. However, patient follow up should extent to at least 6 months post-treatment and verifying viral load on yearly basis is warranted to track any late relapse.

Treatment of hepatitis C with new fixed dose combinations

INTRODUCTION

The advent of oral direct-acting antivirals (DAA) has revolutionized the hepatitis C virus (HCV) therapeutic landscape providing cure rates over 90%. However, a subset of patients remains at higher risk for treatment failure, including those infected with: i) genotype 3 and cirrhosis; ii) resistance-associated substitutions (RAS) occurring either as natural polymorphisms or selected after prior DAA failure; and iii) poor drug adherence associated with social disabilities (homeless, psychiatric illnesses, injection drug use, alcoholism, etc.). Whereas discovery of new DAA with increased antiviral activity across all genotypes and over RAS may enhance efficacy, development of fixed dose combinations (FDC) may be the best way to improve drug adherence in difficult-to-treat HCV populations. Areas covered: Three FDC regimens are in the last steps of clinical development for treating hepatitis C. Two distinct nucleotide analogues that inhibit the HCV polymerase, sofosbuvir and uprifosbuvir, are part of the FDC from Gilead and Merck, respectively. The AbbVie dual FDC does not include a polymerase inhibitor. All three new FDC include second-generation NS3 protease inhibitors and NS5A inhibitors active across all HCV genotypes and over common RAS. Expert opinion: Hepatitis C cure rates over 95% are expected with all three next-coming DAA, even in the most difficult-to-treat and/or cure patient populations. These regimens would be particularly needed for the growing number of prior DAA failures. Co-formulations and 8-week shorter treatment lengths will help to overcome drug adherence challenges in certain populations.

Cost-Effectiveness Analysis of New HCV Treatments in Egyptian Cirrhotic and Non-Cirrhotic Patients: A Societal Perspective

OBJECTIVES

To evaluate the cost-effectiveness of sofosbuvir (SOF) + ribavirin (RBV), SOF + daclatasvir (DCV), and SOF + ledipasvir (LDV) + RBV compared with SOF + pegylated interferon alfa (pegIFN) + RBV in the treatment of patients infected with hepatitis C virus in Egypt.

METHODS

Two Markov models were developed on the basis of the Egyptian clinical data and practice and were derived from published sources. The clinical parameters were derived from two sources: the Egypt multicenter national treatment program and previously published randomized clinical trials. The utility of the health states was derived using the available published data. Direct medical costs were obtained from the National Liver Institute database.

RESULTS

In noncirrhotic patients, incremental cost-effectiveness ratios of US $2330 per quality-adjusted life-year (QALY) gained for the SOF + LDV + RBV, -US $9043/QALY for the SOF + DCV, and -US $1332/QALY for the SOF + RBV regimens were yielded. In cirrhotic patients, incremental cost-effectiveness ratios of -US $4170/QALY gained for the SOF + LDV + RBV, -US $9515/QALY for the SOF + DCV, and -US $2289/QALY for the SOF + RBV regimens were yielded. The SOF + DCV regimen was the most cost-saving option for cirrhotic and noncirrhotic patients. Deterministic sensitivity analyses remain robust.

CONCLUSIONS

The present study concludes that the SOF + DCV regimen among other currently available regimens is the most cost-saving option that yields the most favorable future health economic outcomes compared with the SOF + pegIFN + RBV regimen across a broad spectrum of patients, including those with cirrhosis.

Efficacy of Ledipasvir Plus Sofosbuvir for 8 or 12 Weeks in Patients With Hepatitis C Virus Genotype 2 Infection

BACKGROUND & AIMS

Patients with chronic hepatitis C virus (HCV) genotype 2 have high rates of response to treatment with sofosbuvir and ribavirin. However, ribavirin is associated with hemolytic events and is poorly tolerated by some patients. We evaluated the effectiveness of sofosbuvir and ledipasvir in treatment-naïve and treatment-experienced patients with HCV genotype 2, comparing 12 versus 8 weeks of treatment.

METHODS

This Phase 2, open-label study included 2 cohorts in New Zealand. The first received a fixed-dose combination tablet of ledipasvir-sofosbuvir (90/400 mg) once daily for 12 weeks. If this cohort had a 90% rate of sustained virologic response (SVR) 4 weeks after treatment, a second cohort receiving 8 weeks of ledipasvir-sofosbuvir was to be enrolled. The primary endpoint in both cohorts was the percentage of patients with HCV RNA <15 IU/mL 12 weeks after therapy (SVR12).

RESULTS

SVR12 rates were 96% (25/26; 95% CI, 80%-100%) for 12 weeks and 74% (20/27; 95% CI, 54%-89%) for 8 weeks of ledipasvir-sofosbuvir. The single patient receiving 12 weeks of ledipasvir-sofosbuvir who did not reach SVR12 did not complete treatment because of withdrawing consent after receiving 1 dose of study drug. Six of the 7 patients who did not reach SVR12 after 8 weeks of treatment experienced virologic relapse after stopping therapy. The most common adverse events were headache (26% of patients), fatigue (21%), and nausea (17%). No patients discontinued treatment because of an adverse event.

CONCLUSIONS

For treatment-naïve and -experienced patients, ledipasvir-sofosbuvir for 12 weeks is highly effective for the treatment of HCV genotype 2 (ClinicalTrials.gov: NCT02202980).

Direct Acting Anti-hepatitis C Virus Drugs: Clinical Pharmacology and Future Direction

Chronic hepatitis C virus (HCV) infection is a leading cause of chronic liver disease. The introduction of direct acting antiviral agents (DAAs) for its treatment represents a major advance in terms of sustained virologic response (SVR) rates and adverse effect profiles. Mechanistically, DAAs inhibit specific HCV non-structural proteins (NS) that are vital for its replication. Boceprevir, telaprevir, simeprevir, asunaprevir, grazoprevir and paritaprevir are NS3/4A inhibitors. Ombitasvir, ledipasvir, daclatasvir, elbasvir and velpatasvir are NS5A inhibitors. Sofosbuvir and dasabuvir are NS5B inhibitors. Currently, a combination of two or more DAAs is the corner stone for the treatment of HCV infection. However, the success of DAA therapy is facing several challenges, including the potential of drug-drug interactions and resistant variance. Moreover, the shortage of relevant clinical pharmacological data and drug interaction regarding DAA is a clinical concern. The present review discusses the clinical pharmacology of DAAs with special emphasis on drug-drug interaction.

Lethal Mutagenesis of Hepatitis C Virus Induced by Favipiravir

Lethal mutagenesis is an antiviral approach that consists in extinguishing a virus by an excess of mutations acquired during replication in the presence of a mutagen. Here we show that favipiravir (T-705) is a potent mutagenic agent for hepatitis C virus (HCV) during its replication in human hepatoma cells. T-705 leads to an excess of G → A and C → U transitions in the mutant spectrum of preextinction HCV populations. Infectivity decreased significantly in the presence of concentrations of T-705 which are 2- to 8-fold lower than its cytotoxic concentration 50 (CC50). Passaging the virus five times in the presence of 400 μM T-705 resulted in virus extinction. Since T-705 has undergone advanced clinical trials for approval for human use, the results open a new approach based on lethal mutagenesis to treat hepatitis C virus infections. If proven effective for HCV in vivo, this new anti-HCV agent may be useful in patient groups that fail current therapeutic regimens.

Ledipasvir plus sofosbuvir for 12 weeks in patients with hepatitis C genotype 4 infection

Genotype 4 hepatitis C virus (HCV) was considered difficult to treat in the era of pegylated interferon-alpha (Peg-IFN-α) and ribavirin regimens. We evaluated the efficacy and safety of therapy with the nonstructural (NS) 5A inhibitor, ledipasvir, combined with the NS5B polymerase inhibitor, sofosbuvir, in patients with HCV genotype 4. In this phase 2, open-label study, 44 patients (22 treatment naïve and 22 treatment experienced) received a fixed-dose combination tablet of 90 mg of ledipasvir and 400 mg of sofosbuvir orally once-daily for 12 weeks. The primary endpoint was the percentage of patients with HCV RNA <15 IU/mL 12 weeks after stopping therapy (SVR12). Among study participants, HCV genotype 4 subtypes were well represented (4a, n = 25; 4d, n = 10; other subtypes, n = 9). Ten patients (23%) had compensated cirrhosis. Of the 22 treatment-experienced patients, 21 (95%) had a non-CC IL-28B genotype. All 44 patients completed the full 12 weeks of dosing. The SVR12 rate was 93% (41 of 44; 95% confidence interval, 81-99). SVR12 rates were similar between treatment-naïve (95%; 21 of 22) and treatment-experienced (91%; 20 of 22) patients. All 3 patients who did not achieve SVR12 had virological relapse within 4 weeks of the end of treatment; all 3 had baseline HCV RNA ≥800,000 IU/mL, a non-CC IL-28B genotype, and pretreatment NS5A resistance-associated variants. None of the patients who relapsed had cirrhosis. The most common adverse events were asthenia, headache, and fatigue. No patients experienced a serious adverse event.

CONCLUSION

The all-oral regimen of ledipasvir and sofosbuvir is an effective and safe treatment for a wide range of HCV 4 subtypes in both treatment-naïve and -experienced patients, including those with compensated cirrhosis. (EudraCT number: 2013-003978-27; Clinicaltrials.gov NCT02081079) (Hepatology 2016;64:1049-1056).

Clinical value of on-treatment HCV RNA levels during different sofosbuvir-based antiviral regimens

BACKGROUND & AIMS

The European Association for the Study of the Liver (EASL) guidelines recommend HCV RNA measurements at specific time points during sofosbuvir(SOF)-therapy. However, it remains unclear, how these results should be interpreted. We aimed to analyze whether on-treatment HCV RNA levels predict relapse comparing the CobasAmpliPrep/CobasTaqMan v2.0 (CAP/CTM) and Abbott RealTime HCV (ART) assays.

METHODS

Samples were collected from 298 patients (HCV genotypes; GT1-5) at weeks (w) 0, 1, 2, 4, 8, 12, 16, 20 and 24 during SOF-based therapy at two university clinics and tested for HCV RNA level by CAP/CTM and ART. Patients were treated with SOF/ribavirin (RBV) 12/24 w (n=99), pegylated-interferon-alfa (PegIFN)/SOF/RBV 12 w (n=51), SOF/simeprevir (SMV)±RBV 12 w (n=69) or SOF/daclatasvir±RBV 12/24 w (n=79).

RESULTS

HCV RNA levels during the first 4weeks of SOF/RBV therapy were significantly lower in GT3 patients who achieved SVR compared with those who relapsed. All GT3 patients with a week 2 result <45IU/ml by CAP/CTM achieved SVR but only 33% of those with ⩾45IU/ml (p=0.0003). Similar results were documented with ART and 60IU/ml as cut-off (SVR: 100% vs. 29%; p=0.0002). In contrast, HCV RNA levels during early treatment phases were not significantly related to relapse in patients treated with other SOF-based regimens. Residual HCV RNA was frequently detected by ART at later stages of therapy. However, SVR rates remained high in these patients. At the end of SOF/SMV±RBV therapy HCV RNA was detectable with ART in 20% of patients, of whom 92% achieved SVR.

CONCLUSIONS

HCV RNA levels assessed at week 2 of SOF/RBV therapy can predict relapse in GT3-patients. Detectable HCV RNA results at later stages during SOF-based therapy may occur frequently with the more sensitive ART. However, this should not lead to treatment extension.

LAY SUMMARY

We analyzed the predictive value of hepatitis C virus (HCV) RNA levels measured at different time points for treatment efficacy. We found that the level of HCV RNA measured at week 2 of antiviral therapy can be used to predict treatment success in patients with HCV genotype 3 infection treated with sofosbuvir and ribavirin but not in patients treated with other sofosbuvir-based regimens. Low level HCV RNA is frequently detected by the RealTime HCV assay during later stages of antiviral therapy. However, this is not associated with reoccurrence of HCV RNA after the end of treatment.

A fluorescence polarization based assay for the identification and characterization of polymerase inhibitors

A homogenous fluorescence polarization (FP) assay was developed to monitor the enzymatic activity of polymerases. Under the optimized conditions established in this study, the assay provides highly robust and reproducible data. Miniaturization of the assay for high-throughput screening and compound testing was also performed. The sensitivity of the newly developed assay was confirmed using 2',3'-dideoxyadenosine-5'-triphosphate (ddATP), a chain-elongating inhibitor of the polymerase reaction. Side-by-side comparison of the presented fluorescence polarization assay with already well established PicoGreen® fluorescence intensity assay revealed that the performance of both formats is comparable with good assay sensitivity. However, the direct ratiometric readout of the presented FP assay makes it superior over existing colorimetric and fluorescence intensity based assays in terms of susceptibility to false positives. Moreover, due to its generic nature the presented FP assay can be applied to other polymerases and is compatible with identification of inhibitors and requirements of hit-to-lead programs.

Multiple Targets of Salicylic Acid and Its Derivatives in Plants and Animals

Salicylic acid (SA) is a critical plant hormone that is involved in many processes, including seed germination, root initiation, stomatal closure, floral induction, thermogenesis, and response to abiotic and biotic stresses. Its central role in plant immunity, although extensively studied, is still only partially understood. Classical biochemical approaches and, more recently, genome-wide high-throughput screens have identified more than two dozen plant SA-binding proteins (SABPs), as well as multiple candidates that have yet to be characterized. Some of these proteins bind SA with high affinity, while the affinity of others exhibit is low. Given that SA levels vary greatly even within a particular plant species depending on subcellular location, tissue type, developmental stage, and with respect to both time and location after an environmental stimulus such as infection, the presence of SABPs exhibiting a wide range of affinities for SA may provide great flexibility and multiple mechanisms through which SA can act. SA and its derivatives, both natural and synthetic, also have multiple targets in animals/humans. Interestingly, many of these proteins, like their plant counterparts, are associated with immunity or disease development. Two recently identified SABPs, high mobility group box protein and glyceraldehyde 3-phosphate dehydrogenase, are critical proteins that not only serve key structural or metabolic functions but also play prominent roles in disease responses in both kingdoms.

Current treatment of chronic hepatitis C in China: Dilemma and potential problems

Major advances have been made in the treatment of chronic hepatitis C virus (HCV) infection with the advent of direct-acting antiviral agents (DAAs). China has the most cases of HCV infection worldwide, but none of the DAAs has been approved in mainland China so far, and interferon (IFN)-α-based treatment remains the standard of care. HCV patients without response or with contraindications to IFN-based therapy have no alternative options. However, many patients buy DAAs, especially the generic forms of sofosbuvir, from other countries or areas. Under these circumstances, the use of these drugs may cause many predictable and unpredictable problems in ethics, law and medical practice. Given the obstacles of legal accessibility to DAAs and the potential problems of obtaining and using DAAs in China, the early launching of the DAAs in China or the legalization of buying drugs from areas outside China and using these drugs in China is an urgent issue and needs to be dealt with as soon as possible, in the interest of the patients.

[New Therapeutic Agent for Chronic Hepatitis C: Direct Acting Agent]

Peg-interferon and ribavirin has been the standard therapy of chronic hepatitis C for the past 15 years in Korea. However, the treatment paradigm is changing. Direct acting agents (DAAs) are oral pills that can be easily taken. In addition, DAAs are more effective and have less adverse reactions compared to the previously used drugs. Chronic hepatitis C is hard to treat because the virus is error-prone virus. Host immunity is helpless against the hepatitis C virus since it evades the host immunity through various complex mechanisms. There are 6 genotypes. Quasispecies can co-exist even in the same patients. The treatment strategy is based on the combination of the individual drug corresponding to each step of viral replication process. NS5B nucleosides are the most powerful and effective drug available until now. Other drugs with different mechanisms of action can be used to provide synergy. NS5A and NS5B inhibition drugs currently belong to the leading group amongst many DAAs. These drugs will soon be available in Korea. We have to know the merits and adverse drug reactions of the new drug.

Lactic acidosis in patients with hepatitis C virus cirrhosis and combined ribavirin/sofosbuvir treatment

BACKGROUND & AIMS

Sofosbuvir (SOF) based interferon-alfa free antiviral therapy has become the treatment of choice for patients with chronic hepatitis C virus (HCV) infection. Little is known about safety of drug combinations using two nucleos(t)ide polymerase inhibitors in patients with HCV associated advanced cirrhosis. Here, we report frequent occurrence of lactic acidosis associated with acute-on-chronic hepatic decompensation during ribavirin (RBV) plus SOF based antiviral therapy.

METHODS

Thirty-five patients with chronic hepatitis C and advanced fibrosis, compensated cirrhosis, and decompensated cirrhosis without and after liver transplantation were treated with SOF based antiviral therapy with and without RBV. Adverse events including lactic acidosis (pH <7.35, lactate >20 mg/dl) were recorded 24 weeks before and during (mean ±SD, 18±11 weeks) antiviral therapy. Efficacy was determined by assessment of serum HCV RNA.

RESULTS

We observed severe adverse events in 15/35 (43%) patients before (24 weeks) and in 12/35 (34%) patients during antiviral therapy, the majority in association with acute-on-chronic hepatic decompensation. Lactic acidosis occurred in 5/35 (14%) patients during therapy, while no event of lactic acidosis was observed prior to therapy. Lactic acidosis was associated with hepatic decompensation including renal failure and infection, and was severe (pH <7.3) in two patients.

CONCLUSIONS

RBV in combination with SOF based antiviral therapy in patients with HCV associated advanced cirrhosis may be associated with the development of lactic acidosis. Impaired renal function, and higher MELD/Child-Pugh scores were identified as potential risk factors.

Hepatic decompensation/serious adverse events in post-liver transplantation recipients on sofosbuvir for recurrent hepatitis C virus

AIM: To determine the safety profile of new hepatitis C virus (HCV) treatments in liver transplant (LT) recipients with recurrent HCV infection.

METHODS: Forty-two patients were identified with recurrent HCV infection that underwent LT at least 12 mo prior to initiating treatment with a Sofosbuvir-based regimen during December 2013-June 2014. Cases were patients who experienced hepatic decompensation and/or serious adverse events (SAE) during or within one month of completing treatment. Controls had no evidence of hepatic decompensation and/or SAE. HIV-infected patients were excluded. Cumulative incidence of decompensation/SAE was calculated using the Kaplan Meier method. Exact logistic regression analysis was used to identify factors associated with the composite outcome.

RESULTS: Median age of the 42 patients was 60 years [Interquartile Range (IQR): 56-65 years], 33% (14/42) were female, 21% (9/42) were Hispanic, and 9% (4/42) were Black. The median time from transplant to treatment initiation was 5.4 years (IQR: 2.1-8.8 years). Thirteen patients experienced one or more episodes of hepatic decompensation and/or SAE. Anemia requiring transfusion, the most common event, occurred in 62% (8/13) patients, while 54% (7/13) decompensated. The cumulative incidence of hepatic decompensation/SAE was 31% (95%CI: 16%-41%). Risk factors for decompensation/SAE included lower pre-treatment hemoglobin (OR = 0.61 per g/dL, 95%CI: 0.40-0.88, P < 0.01), estimated glomerular filtration rate (OR = 0.95 per mL/min per 1.73 m², 95%CI: 0.90-0.99, P = 0.01), and higher baseline serum total bilirubin (OR = 2.43 per mg/dL, 95%CI: 1.17-8.65, P < 0.01). The sustained virological response rate for the cohort of 42 patients was 45%, while it was 31% for cases.

CONCLUSION: Sofosbuvir/ribavirin will continue to be used in the post-transplant population, including those with HCV genotypes 2 and 3. Management of anemia remains an important clinical challenge.

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.

Comparison between alcohol- and hepatitis C virus-related hepatocellular carcinoma: clinical presentation, treatment and outcome

BACKGROUND

Hepatitis C virus (HCV) and alcohol abuse are the main risk factors for hepatocellular carcinoma (HCC) in Western countries.

AIM

To investigate the role of alcoholic aetiology on clinical presentation, treatment and outcome of HCC as well as on each Barcelona Clinic Liver Cancer (BCLC) stage, as compared to HCV-related HCCs.

METHODS

A total of 1642 HCV and 573 alcoholic patients from the Italian Liver Cancer (ITA.LI.CA) database, diagnosed with HCC between January 2000 and December 2012 were compared for age, gender, type of diagnosis, tumour burden, portal vein thrombosis (PVT), oesophageal varices, liver function tests, alpha-fetoprotein, BCLC, treatment and survival. Aetiology was tested as predictor of survival in multivariate Cox regression models and according to HCC stages.

RESULTS

Cirrhosis was present in 96% of cases in both groups. Alcoholic patients were younger, more likely male, with HCC diagnosed outside surveillance, in intermediate/terminal BCLC stage and had worse liver function. After adjustment for the lead-time, median (95% CI) overall survival (OS) was 27.4 months (21.5-33.2) in alcoholic and 33.6 months (30.7-36.5) in HCV patients (P = 0.021). The prognostic role of aetiology disappeared when survival was assessed in each BCLC stage and in the Cox regression multivariate models.

CONCLUSIONS

Alcoholic aetiology affects survival of HCC patients through its negative effects on secondary prevention and cancer presentation but not through a greater cancer aggressiveness or worse treatment result. In fact, survival adjusted for confounding factors was similar in alcoholic and HCV patients.

A model-based meta-analysis of sofosbuvir-based treatments in chronic hepatitis C patients

The objective of this study was to compare the efficacy of sofosbuvir-based treatments in patients with chronic hepatitis C virus (HCV) infection using a model-based meta-analysis (MBMA). A bibliographic search was performed to identify clinical trials involving sofosbuvir as a unique direct-acting antiviral (DAA) agent or together with daclatasvir, ledipasvir or simeprevir for the treatment of diagnosed HCV infection. The time course of the virological response (VR) was modelled to estimate the effect of treatment and the influence of population characteristics on the longitudinal efficacy profile. The model was validated and simulations of 10 different treatment schedules were performed. Data from 19 clinical trials were included in the analysis. According to the developed model, therapy with sofosbuvir+ledipasvir is the most effective therapy in all scenarios, but it does not differ greatly in terms of sustained VR with respect to other combinations of DAA treatments. In conclusion, this MBMA generates knowledge regarding hypothetical head-to-head trials that have not been conducted previously. Therapies with sofosbuvir+ledipasvir are probably the most effective sofosbuvir-based treatments.

Sofosbuvir plus ribavirin for the treatment of patients with chronic genotype 1 or 6 hepatitis C virus infection in Hong Kong

BACKGROUND

In Hong Kong, most patients with hepatitis C virus (HCV) have either genotype 6a or 1b infection.

AIM

To evaluate the efficacy and safety of sofosbuvir with ribavirin in treatment-naïve patients in Hong Kong with HCV genotype 1 or 6.

METHODS

In an open-label study, patients were randomised to sofosbuvir 400 mg once daily plus ribavirin 1000-1200 divided twice daily for 12 (n = 10), 16 (n = 11) or 24 (n = 10) weeks. The primary endpoint was the percentage of patients with HCV RNA < LLOQ (lower limit of quantification, 25 IU/mL) 12 weeks after cessation of therapy (SVR12).

RESULTS

All 31 patients (20 HCV genotype 1 and 11 genotype 6) had HCV RNA < LLOQ by Week 4 of treatment and at their last on-treatment visit. SVR12 rates were high in all treatment groups: 100% (10/10) for 12 weeks, 100% (11/11) for 16 weeks and 90% (9/10) for 24 weeks of therapy. The only patient who did not reach SVR12 had genotype 1 HCV and relapsed at post-treatment Week 4. Sofosbuvir with ribavirin was generally well tolerated. The most common adverse events were malaise (13%) and upper respiratory tract infection (13%), followed by anaemia (10%). No patients experienced serious adverse events. One patient discontinued treatment at Week 16 because of an adverse event. The event, upper respiratory tract infection, was not considered treatment related by the investigator. This subject achieved SVR12.

CONCLUSIONS

The all-oral regimen sofosbuvir plus ribavirin is effective in treatment-naïve patients in Hong Kong with genotype 1 or 6 HCV.

TRIAL REGISTRATION NUMBER

NCT02021643.

Next-Generation Sequencing Reveals Frequent Opportunities for Exposure to Hepatitis C Virus in Ghana

Globally, hepatitis C Virus (HCV) infection is responsible for a large proportion of persons with liver disease, including cancer. The infection is highly prevalent in sub-Saharan Africa. West Africa was identified as a geographic origin of two HCV genotypes. However, little is known about the genetic composition of HCV populations in many countries of the region. Using conventional and next-generation sequencing (NGS), we identified and genetically characterized 65 HCV strains circulating among HCV-positive blood donors in Kumasi, Ghana. Phylogenetic analysis using consensus sequences derived from 3 genomic regions of the HCV genome, 5'-untranslated region, hypervariable region 1 (HVR1) and NS5B gene, consistently classified the HCV variants (n = 65) into genotypes 1 (HCV-1, 15%) and genotype 2 (HCV-2, 85%). The Ghanaian and West African HCV-2 NS5B sequences were found completely intermixed in the phylogenetic tree, indicating a substantial genetic heterogeneity of HCV-2 in Ghana. Analysis of HVR1 sequences from intra-host HCV variants obtained by NGS showed that three donors were infected with >1 HCV strain, including infections with 2 genotypes. Two other donors share an HCV strain, indicating HCV transmission between them. The HCV-2 strain sampled from one donor was replaced with another HCV-2 strain after only 2 months of observation, indicating rapid strain switching. Bayesian analysis estimated that the HCV-2 strains in Ghana were expanding since the 16th century. The blood donors in Kumasi, Ghana, are infected with a very heterogeneous HCV population of HCV-1 and HCV-2, with HCV-2 being prevalent. The detection of three cases of co- or super-infections and transmission linkage between 2 cases suggests frequent opportunities for HCV exposure among the blood donors and is consistent with the reported high HCV prevalence. The conditions for effective HCV-2 transmission existed for ~ 3-4 centuries, indicating a long epidemic history of HCV-2 in Ghana.

Update on hepatitis C: Direct-acting antivirals

Hepatitis C virus (HCV) was discovered 26 years ago. For decades, interferon-based therapy has been the mainstay of treatment for HCV. Recently, several direct-acting antivirals (DAAs) have been approved for treatment of HCV-infected patients and to help combat the virus. These drugs have revolutionized the management of HCV as all-oral regimens with favorable side effect profiles and superior rates of sustained virological response. Emerging real-world data are demonstrating results comparable to registration trials for DAA agents. Suddenly, the potential for eradicating HCV is on the horizon.