Investigation of NS3 Protease Resistance-Associated Variants and Phenotypes for the Prediction of Treatment Response to HCV Triple Therapy

Water-soluble extracts from edible mushrooms (Agaricus bisporus) as inhibitors of hepatitis C viral replication

Hepatitis C virus (HCV) is the main agent responsible for chronic liver disease. Recent advances in anti-HCV treatment strategies have significantly increased the viral clearance rate (>90%). However, sustained antiviral responses vary in different cohorts, and high costs limit the broad use of direct-acting antivirals (DAAs). The goal of this study is to evaluate the inhibitory ability of well characterized (LC-QTOF-MS/MS) aqueous extracts obtained from edible mushrooms (Agaricus bisporus) to diminish HCV viral replication. Our data have demonstrated an in vitro inhibitory effect of A. bisporus extracts on NS3/4A protease and HCV replication. Fractionation by ultra-filtration and sequential liquid-liquid extraction showed that the compounds responsible for the inhibition are water-soluble with low molecular weights (<3 kDa) and that action could be through the following five compounds: ergothioneine, adenine, guanine, hypoxanthine, and xanthine, which are present in all fractions (UF-3, AqF-3 kDa and organic fractions) showing NS3/4A inhibition. Low molecular weight aqueous extracts (<3 kDa) from A. bisporus have potential applications in the prophylaxis and treatment of HCV, especially for patients who do not have access to the last generation of DAAs. They may be useful as well for other flaviviruses, which also possess a NS3 serine protease.

Hepatitis C virus cell culture models: an encomium on basic research paving the road to therapy development

Chronic hepatitis C virus (HCV) infections affect 71 million people worldwide, often resulting in severe liver damage. Since 2014 highly efficient therapies based on directly acting antivirals (DAAs) are available, offering cure rates of almost 100%, if the infection is diagnosed in time. It took more than a decade to discover HCV in 1989 and another decade to establish a cell culture model. This review provides a personal view on the importance of HCV cell culture models, particularly the replicon system, in the process of therapy development, from drug screening to understanding of mode of action and resistance, with a special emphasis on the contributions of Ralf Bartenschlager's group. It summarizes the tremendous efforts of scientists in academia and industry required to achieve efficient DAAs, focusing on the main targets, protease, polymerase and NS5A. It furthermore underpins the importance of strong basic research laying the ground for translational medicine.

HCV genotype-1 subtypes and resistance-associated substitutions in drug-naive and in direct-acting antiviral treatment failure patients

BACKGROUND

Direct-acting antiviral (DAA) treatment regimens and response rates of patients with HCV genotype-1 (GT1) are currently considered subtype-dependent. Identification of clinically relevant resistance-associated substitutions (RASs) in the NS3 and NS5A proteins at baseline and in DAA failures, may also impact clinical decisions.

METHODS

In a multicentre cohort study (n=308), NS3 or NS5B sequencing (n=248) was used to discriminate between GT1 subtypes. The correlation between baseline NS3 and NS5A RASs on the 12-week sustained virological response (SVR12) rates of 160 of the patients treated with second-generation DAAs was also assessed. Post-treatment resistance analysis was performed on samples from 58 patients exhibiting DAA virological failure.

RESULTS

GT1a, GT1b and GT1d subtypes were identified in 23.0%, 75.4% and 1.2% of tested samples. GT1b was most prevalent (97.7%, 128/131) among patients born in the former Soviet Union. The Q80K NS3 RAS was identified in 17.5% (10/57) of the GT1a carriers, most of whom were Israeli-born. NS3 and NS5A baseline RASs showed a negligible correlation with SVR12 rates. Treatment-emergent RASs were observed among 8.9% (4/45) and 76.9% (10/13) of first- and second-generation DAA failures, respectively, with D168V/E (NS3), Y93H and L31M (NS5A) being the most prevalent mutations.

CONCLUSIONS

NS3 sequencing analysis can successfully discriminate between GT1 subtypes and identify NS3 amino acid substitutions. While pre-treatment NS3 and NS5A RASs marginally affect second-generation DAA SVR12 rates, post-treatment resistance analysis should be considered prior to re-therapy.

Real-world effectiveness and predictors of sustained virological response with all-oral therapy in 21,242 hepatitis C genotype-1 patients

BACKGROUND

Predictors of sustained virological response (SVR) to all-oral HCV regimens can inform nuanced treatment decisions. We evaluated effectiveness and identified predictors of SVR for ledipasvir/sofosbuvir ± ribavirin (LDV/SOF ±RBV) and ombitasvir/paritaprevir/ritonavir + dasabuvir (OPrD) ±RBV in patients treated in routine practice.

METHODS

Observational, intent-to-treat cohort of 21,142 genotype-1 patients initiating 8 or 12 weeks of LDV/SOF ±RBV or 12 weeks of OPrD ±RBV at any Veterans Affairs facility. Multivariate logistic regression models were constructed to model SVR and identify predictors.

RESULTS

SVR was 91.2% (9,781/10,720) for LDV/SOF, 89.6% (3,266/3,646) for LDV/SOF+RBV, 91.7% (1,197/1,306) for OPrD and 87.8% (3,365/3,832) for OPrD+RBV. For LDV/SOF ±RBV, reduced odds of SVR occurred in African-Americans (0.80, 95% CI 0.70, 0.92, P<0.001), body mass index (BMI)<25 (0.77, 95% CI 0.66, 0.90, P<0.001), BMI≥30 (0.77, 95% CI 0.67, 0.89, P<0.001), proton pump inhibitors (PPIs; 0.81, 95% CI 0.71, 0.92, P<0.001), decompensated liver disease (0.58, 95% CI 0.45, 0.74, P<0.001) and FIB4>3.25 (0.60, 95% CI 0.53, 0.69, P<0.001). For OPrD ±RBV, FIB-4>3.25 negatively predicted SVR (0.72, 95% CI 0.59, 0.88, P<0.001). Detectable 4-week on-treatment HCV RNA≥15 IU/ml reduced SVR odds for both regimens (LDV/SOF ±RBV OR 0.49, 95% CI 0.41, 0.58, P<0.001; OPrD ±RBV OR 0.38, 95% CI 0.29, 0.50, P<0.001). Receipt of OPrD+RBV compared to LDV/SOF reduced odds of SVR (OR 0.70, 95% CI 0.62, 0.80, P<0.001). Mental health diagnosis did not impact likelihood of SVR.

CONCLUSIONS

The diversity and size of this cohort allowed for extensive examination of regimen-specific predictors of SVR. FIB-4>3.25 and detectable 4-week on-treatment HCV RNA had the greatest negative impact. African-American race, low or high BMI, and PPIs negatively impacted odds of SVR for LDV/SOF ±RBV. Mental health diagnoses did not.