Current Treatment Options in Patients with Hepatitis C Virus Genotype 6

In silico analysis of the effect of HCV genotype-specific polymorphisms in Core, NS3, NS5A, and NS5B proteins on T-cell epitope processing and presentation

Background

HCV genotypes are 30-35% polymorphic at the nucleotide level, while subtypes within the same genotype differ by nearly 20%. Although previous studies have shown the immune escape potential of several mutations within the HCV proteins, little is known about the effect of genotype/subtype-specific gene polymorphism on T-cell immunity. Therefore, this study employed several in silico methods to examine the impact of genotype/subtype-specific polymorphisms in Core, NS3, NS5A, and NS5B sequences on T cell epitope processing and HLA-epitope interactions.

Methods

For this study, 8,942, 17,700, 14,645, and 3,277 HCV Core, NS3, NS5A, and NS5B sequences, respectively, from eight genotypes and 21 subtypes were retrieved from the Los Alamos HCV Database. Next, the NetCTL tool was employed to predict Cytotoxic T Lymphocyte (CTL) epitopes based on combined proteasomal cleavage, TAP efficacy, and HLA class I receptor binding scores. PEP-FOLD was used to model selected epitopes, followed by peptide-HLA docking using HPEPDOCK. Finally, molecular dynamics simulations were conducted for 200 ns using Desmond software to analyze differences in HLA-epitope (from different HCV genotypes) interaction kinetics and dynamics.

Results

A total of 3,410, 8,054, 6,532, and 14,015 CTL epitopes were observed in the HCV Core, NS3, NS5A, and NS5B sequences, respectively. Significant genotype/subtype-specific variations in CTL values and docking scores were observed among NS3, NS5A, and NS5B proteins. In silico results reveal that epitopes from genotype 6b (NS3), 6d/r (NS5B), 6o and 6 k (NS5A) exhibit higher immunogenicity than other genotypes, forming more energetically stable complexes with host receptors. These epitopes, compared to those from the same positions but different genotypes, showed binding energies of -144.24 kcal/mol, -85.30 kcal/mol, and - 43 kcal/mol, respectively. Over a 200 ns MD simulation, GT 6b and 6d/r epitopes displayed up to a 40% stronger binding energy with the HLA receptor. These findings suggest that patients infected with GT 6 may experience enhanced T cell responsiveness and broader immunogenicity.

Conclusion

Our study suggests that genotype/subtype-specific polymorphism in HCV may result in altered immune responses by modulating T-cell epitope processing and interaction with HLA receptors. Further experimental studies can be performed to confirm the effect of genotype/subtype-specific polymorphisms on T cell-mediated immune response.

Efficacy and safety of direct-acting antiviral therapy for chronic hepatitis C genotype 6: A meta-analysis

BACKGROUND

Because of the heterogeneity of hepatitis C virus (HCV) distribution of different genotypes, large-scale clinical trials on direct-acting antiviral (DAA) mainly included patients with genotype 1 and genotype 3 infection. Data on the efficacy of direct-acting antiviral agents in patients with chronic genotype 6 HCV infection are limited.

METHODS

The PubMed, Embase, and the Cochrane Libraries were searched comprehensively. All published clinical trials assessing the efficacy of DAA therapy for patients with chronic genotype 6 HCV infection were included. Sustained virological response (SVR) and rapid virological response (RVR) were pooled. Additional meta-analyses were also performed to compare the efficacy of DAA therapy in HCV-6 versus HCV-1 or HCV-3 patients.

RESULTS

Seventeen studies met the inclusion criteria and were included in our meta-analysis. The pooled SVR of all single arms was 95% [95% confidence interval (CI): 0.90-0.97]. The pooled RVR of all single arms was 97% (95% CI: 0.95-0.99). The SVR and RVR were both similar between HCV-6 and HCV-1 or HCV-3. Adverse events were common but rarely caused treatment interruption.

CONCLUSION

Based on the available data, our results indicate that DAA treatment is effective and safe for patients with genotype 6 HCV infection, and the efficacy was similar compared to patients with genotype 1 HCV or genotype 3 HCV infection.

Safety and efficacy of sofosbuvir-based direct-acting antiviral regimens for hepatitis C virus genotype 6 in Southwest China: Real-world experience of a retrospective study

Optional treatments for patients with chronic hepatitis C virus (HCV) genotype (GT) 6 infection have not been extensively studied. This study aimed to evaluate the safety and efficacy of sofosbuvir (SOF)-based direct-acting antiviral agents (DAAs) for HCV GT6. We performed a retrospective study at the West China Hospital of Sichuan University in Southwest China from January 2016 to May 2017. Our study screened 130 treatment-naïve patients with chronic HCV GT6 and without liver cirrhosis. A total of 60 HCV GT6 patients were ultimately enrolled. All patients received SOF-based DAAs therapy, including SOF 400 mg plus daclatasvir (DCV) 60 mg daily or SOF 400 mg plus velpatasvir (VEL) 100 mg daily for 12 weeks. The sustained virological response 12 weeks after treatment (SVR12) was 100% (60/60) in treatment-naïve patients with HCV GT6, including 100% (37/37) of patients receiving SOF plus DCV therapy and 100% (23/23) of patients receiving SOF plus VEL therapy. Measurements of liver stiffness were significantly decreased in patients at week 12 (P = 0.014) and week 24 (P < 0.001) of DAAs treatment compared to baseline values. The serum biomarker aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 score were also significantly reduced at week 12 and week 24 compared to before treatment (both P < 0.001). SOF-based therapy was well-tolerated, and no serious adverse events were reported. In conclusion, SOF plus DCV and SOF plus VEL were safe and achieved a high SVR12 rate for treatment-naïve patients with HCV GT6 without liver cirrhosis.

Open Label Study of 8 vs. 12 Weeks of Ledipasvir/Sofosbuvir in Genotype 6 Treatment Naïve or Experienced Patients

OBJECTIVES

Hepatitis C genotype 6 (HCV-GT6) is one of the most prevalent genotypes in Southeast Asia. Ledipasvir and sofosbuvir fixed-dose combination (LDV/SOF FDC) for 12 weeks has been shown to be effective for multiple HCV genotypes including treatment-naïve HCV-6. Our goal was to examine treatment outcomes in a diverse HCV-6 population.

METHODS

We prospectively enrolled 60 HCV-GT6 patients at four US centers. Treatment -naïve without cirrhosis patients received open-labeled LDV/SOF FDC orally once a day for 8 weeks; All cirrhotic and/or treatment-experienced patients received LDV/SOF FDC for 12 weeks. The primary outcome was sustained virological response 12 weeks after therapy (SVR12). Secondary outcomes were adverse events (AEs) and/or serious adverse events (SAEs). All patients gave written consent.

RESULTS

Overall mean age was 58±10 and 58% were male. All patients were Asian and foreign born. The 8-week group included 20 patients (33.3%) and the 12-week included 40 patients (66.7%). There were 2 (5%) patients with decompensation, 3 with liver cancer (7.5%), and 14 with prior treatment (35%) in the 12-week group. SVR12 was 95.0% for the 8-week group (19/20) and 95.0% for the 12-week group (38/40). AEs included fatigue (5%), insomnia (3.3%), headache (1.7%), and nausea (1.7%); however, all patients completed the intended treatment duration. There were two treatment-unrelated SAEs.

CONCLUSIONS

LDV/SOF FDC for 8 or 12 weeks was safe and effective for patients without cirrhosis or prior treatment failure as well as for patients with cirrhosis and/or prior treatment failure, respectively.

HCV Genotype 6 Increased the Risk for Hepatocellular Carcinoma Among Asian Patients With Liver Cirrhosis

OBJECTIVES

Hepatitis C virus (HCV) infection is a well-documented risk factor for hepatocellular carcinoma (HCC). Seven HCV genotypes have been classified, and the genotypes show a great variety of geographic distribution. HCV genotype 6 is prevalent in Southeast Asia and has been less studied than the other genotypes.

METHODS

This follow-up study was designed to evaluate the natural history of HCV genotype 6. The cohort enrolled 851 Asian patients consisting of 222 with HCV genotype 6 and 629 with other genotypes. The incidence of HCC per 1,000 person-years of various HCV genotypes was estimated by dividing the new HCC cases to the person-years of follow-up. The adjusted hazards ratios (HRs) with 95% confidence intervals (CIs) were estimated by Cox's proportional hazards models.

RESULTS

After 4072 person-years of follow-up, there were 96 newly-developed HCC cases, confirming an incidence of 23.6 per 1000 person-years. By stratifying cirrhosis at study entry, the cumulative risk of HCC among HCV genotype 6 vs. non-6 was 2.9 vs. 2.2% for those without cirrhosis (P=0.45) and 76.2% (95% CI: 55.6-96.8%) vs. 36.2% (95% CI: 28.7-39.1%) for those with cirrhosis (P<0.05), respectively. Among patients with cirrhosis, HCV genotype 6 was significantly associated with HCC compared to patients with non-6 genotypes, with the adjusted HR=2.12 (1.33-3.39), P<0.05. In a model treating patients with genotypes other than 1 or 6 as the reference, the adjusted HR for HCC for HCV genotypes 1 and 6 were 1.13 (0.56-2.27) and 2.34 (1.12-4.86), respectively.

CONCLUSIONS

Among patients with cirrhosis, those with HCV genotype 6 infection should be given high priority for antiviral therapy to decrease HCC risk and for vigilant adherence to HCC surveillance.

American Gastroenterological Association Institute Clinical Practice Update-Expert Review: Care of Patients Who Have Achieved a Sustained Virologic Response After Antiviral Therapy for Chronic Hepatitis C Infection

Chronic hepatitis C virus infection is well-recognized as a common blood-borne infection with global public health impact affecting 3 to 5 million persons in the United States and more than 170 million persons worldwide. Chronic hepatitis C virus infection is associated with significant morbidity and mortality due to complications of liver cirrhosis and hepatocellular carcinoma. Current therapies with all-oral direct-acting antiviral agents are associated with high rates of sustained virologic response (SVR), generally exceeding 90%. SVR is associated with a reduced risk of liver cirrhosis, hepatic decompensation, need for liver transplantation, and both liver-related and all-cause mortality. However, a subset of patients who achieve SVR will remain at long-term risk for progression to cirrhosis, liver failure, hepatocellular carcinoma, and liver-related mortality. Limited evidence is available to guide clinicians on which post-SVR patients should be monitored vs discharged, how to monitor and with which tests, how frequently should monitoring occur, and for how long. In this clinical practice update, available evidence and expert opinion are used to generate best practice recommendations on the care of patients with chronic hepatitis C virus who have achieved SVR.