HCV genotype 4, 5 and 6: Distribution of viral subtypes and sustained virologic response rates in clinical trials of approved direct-acting antiviral regimens

'Unusual' HCV genotype subtypes: origin, distribution, sensitivity to direct-acting antiviral drugs and behaviour on antiviral treatment and retreatment

The high genetic diversity of hepatitis C virus (HCV) has led to the emergence of eight genotypes and a large number of subtypes in limited geographical areas. Currently approved pangenotypic DAA regimens have been designed and developed to be effective against the most common subtypes (1a, 1b, 2a, 2b, 2c, 3a, 4a, 5a and 6a). However, large populations living in Africa and Asia, or who have migrated from these regions to industrialised countries, are infected with 'unusual', non-epidemic HCV subtypes, including some that are inherently resistant to currently available direct-acting antiviral (DAA) drugs due to the presence of natural polymorphisms at resistance-associated substitution positions. In this review article, we describe the origin and subsequent global spread of HCV genotypes and subtypes, the current global distribution of common and unusual HCV subtypes, the polymorphisms naturally present in the genome sequences of unusual HCV subtypes that may confer inherently reduced susceptibility to DAA drugs and the available data on the response of unusual HCV subtypes to first-line HCV therapy and retreatment. We conclude that the problem of unusual HCV subtypes that are inherently resistant to DAAs and its threat to the global efforts to eliminate viral hepatitis are largely underestimated and warrant vigorous action.

Biomedical Applications of Antiviral Nanohybrid Materials Relating to the COVID-19 Pandemic and Other Viral Crises

The COVID-19 pandemic has driven a global research to uncover novel, effective therapeutical and diagnosis approaches. In addition, control of spread of infection has been targeted through development of preventive tools and measures. In this regard, nanomaterials, particularly, those combining two or even several constituting materials possessing dissimilar physicochemical (or even biological) properties, i.e., nanohybrid materials play a significant role. Nanoparticulate nanohybrids have gained a widespread reputation for prevention of viral crises, thanks to their promising antimicrobial properties as well as their potential to act as a carrier for vaccines. On the other hand, they can perform well as a photo-driven killer for viruses when they release reactive oxygen species (ROS) or photothermally damage the virus membrane. The nanofibers can also play a crucial protective role when integrated into face masks and personal protective equipment, particularly as hybridized with antiviral nanoparticles. In this draft, we review the antiviral nanohybrids that could potentially be applied to control, diagnose, and treat the consequences of COVID-19 pandemic. Considering the short age of this health problem, trivially the relevant technologies are not that many and are handful. Therefore, still progressing, older technologies with antiviral potential are also included and discussed. To conclude, nanohybrid nanomaterials with their high engineering potential and ability to inactivate pathogens including viruses will contribute decisively to the future of nanomedicine tackling the current and future pandemics.

Resistance-associated substitutions in patients with chronic hepatitis C virus genotype 4 infection

Data on the prevalence of resistance-associated substitutions (RASs) and their implications for treatment with direct-acting antivirals (DAAs) are sparse in European patients with HCV genotype 4. This study investigated RASs before and after DAA failure in different genotype 4 subtypes and evaluated retreatment efficacies. Samples of 195 genotype 4-infected patients were collected in the European Resistance Database and investigated for NS3, NS5A and NS5B RASs. Retreatment efficacies in DAA failure patients were analysed retrospectively. After NS5A inhibitor (NS5Ai) failure, subtype 4r was frequent (30%) compared to DAA-naïve patients (5%) and the number of NS5A RASs was significantly higher in subtype 4r compared to 4a or 4d (median three RASs vs no or one RAS, respectively, P < .0001). RASsL28V, L30R and M31L pre-existed in subtype 4r and were maintained after NS5Ai failure. Typical subtype 4r RASs were located in subdomain 1a of NS5A, close to membrane interaction and protein-protein interaction sites that are responsible for multimerization and hence viral replication. Retreatment of 37 DAA failure patients was highly effective with 100% SVR in prior SOF/RBV, PI/SOF and PI/NS5Ai failures. Secondary virologic failures were rare (n = 2; subtype 4d and 4r) and only observed in prior NS5Ai/SOF failures (SVR 90%). In conclusion, subtype 4r harboured considerably more RASs compared to other subtypes. A resistance-tailored retreatment using first- and second-generation DAAs was highly effective with SVR rates ≥90% across all subtypes and first-line treatment regimens.

Efficacy and safety of glecaprevir/pibrentasvir in patients with HCV genotype 5/6: An integrated analysis of phase 2/3 studies

BACKGROUND & AIMS

Hepatitis C virus (HCV) has high genetic diversity with six major genotypes (GT) GT1-6 and global distribution. HCV GT5 and 6 are rare with < 10 million people infected worldwide. Data on direct-acting antiviral use in these rare HCV genotypes are limited. The study aimed to evaluate the efficacy and safety of glecaprevir/pibrentasvir (G/P) in a pooled analysis of phase 2/3 trials in HCV GT5 or 6-infected patients without cirrhosis or with compensated cirrhosis.

METHODS

Patients with chronic HCV GT5 or 6 infection received oral G/P (300 mg/120 mg) once daily for 8 or 12 weeks. The primary efficacy endpoint was sustained virological response at post-treatment week 12 (SVR12) in the intention-to-treat population.

RESULTS

One hundred eighty-one patients were evaluated; 56 with HCV GT5 and 125 with HCV GT6. The majority were treatment-naïve (88%) and non-cirrhotic (85%). Overall SVR12 rate with 8- or 12-week G/P treatment was 98% (178/181). Eight-week treatment with G/P yielded SVR12 rates of 95% (21/22) in HCV GT5- and 99% (69/70) in HCV GT6-infected non-cirrhotic patients. Eight- and 12-week treatment of patients with compensated cirrhosis achieved SVR12 rates of 100% (10/10) and 94% (17/18) respectively. The G/P regimen was well-tolerated; 3% (6/181) Grade 3 or higher adverse events, and no serious adverse events were attributed to G/P or led to study drug discontinuation.

CONCLUSIONS

This integrated dataset demonstrates a high SVR12 rate following 8-week G/P treatment in patients with HCV GT5 (96%) or GT6 (99%) infection without cirrhosis or with compensated cirrhosis.

Antiviral Activity of Chitosan Nanoparticles Encapsulating Curcumin Against Hepatitis C Virus Genotype 4a in Human Hepatoma Cell Lines

Purpose

Current direct-acting antiviral agents for treatment of hepatitis C virus genotype 4a (HCV-4a) have been reported to cause adverse effects, and therefore less toxic antivirals are needed. This study investigated the role of curcumin chitosan (CuCs) nanocomposite as a potential anti-HCV-4a agent in human hepatoma cells Huh7.

Methods

Docking of curcumin and CuCs nanocomposite and binding energy calculations were carried out. Chitosan nanoparticles (CsNPs) and CuCs nanocomposite were prepared with an ionic gelation method and characterized with TEM, zeta size and potential, and HPLC to calculate encapsulation efficiency. Cytotoxicity studies were performed on Huh7 cells using MTT assay and confirmed with cellular and molecular assays. Anti-HCV-4a activity was determined using real-time PCR and Western blot.

Results

The strength of binding interactions between protein ligand complexes gave scores with NS3 protease, NS5A polymerase, and NS5B polymerase of -124.91, -159.02, and -129.16, for curcumin respectively, and -68.51, -54.52, and -157.63 for CuCs nanocomposite, respectively. CuCs nanocomposite was prepared at sizes 29-39.5 nm and charges of 33 mV. HPLC detected 4% of curcumin encapsulated into CsNPs. IC50 was 8 µg/mL for curcumin and 25 µg/mL for the nanocomposite on Huh7 but was 25.8 µg/mL and 34 µg/mL on WISH cells. CsNPs had no cytotoxic effect on tested cell lines. Apoptotic genes' expression revealed the caspase-dependent pathway mechanism. CsNPs and CuCs nanocomposite demonstrated 100% inhibition of viral entry and replication, which was confirmed with HCV core protein expression.

Conclusion

CuCs nanocomposite inhibited HCV-4a entry and replication compared to curcumin alone, suggesting its potential role as an effective therapeutic agent.

Genetic diversity of genotype 6 HCV infections in France: Epidemiology and consequences for treatment strategy

Genotype-6 hepatitis C virus (GT6-HCV) exhibits a high genetic diversity. GT6 prevalence, diversity and real-life response to treatment were studied among 14 603 HCV mono-infected patients from the French ANRS-CO22-Hepather cohort. NS3, NS5A and NS5B-HCV genes were amplified and sequenced for all GT6-infections identified in the database. Following phylogenic characterization, resistance-associated substitution polymorphisms were identified. GT6-infected patients (n = 36; 0.25%) did not differ from patients infected with other genotypes with regard to gender, age or liver fibrosis. GT6e was the most prevalent (27.8%), followed by 6a (22.2%), 6q (11.1%) and 6o (8.3%). Each subtype p and xc were found in two patients (5.6%) and subtypes f/h/r and t were each detected in one patient. Four strains (11.1%) clustered with unclassified reference sequences. Concordant genotype determination throughout NS3, NS5A and NS5B-genes is consistent with lack of recombination within this genomic region. All, but three patients were born in Asia, Cambodia (44.4%), Vietnam (38.9%) or Laos (8.3%). GT6a were found in 42.8% of Vietnamese and 6e in 37.5% of Cambodian. GT6q, 6p and 6r were only found in Cambodian patients. Resistance-associated polymorphisms for each DAA classes were identified in baseline sequences. Twenty-seven patients were treated with sofosbuvir-based combinations and 3 with glecaprevir/pibrentasvir. All treated patients, whether naïve or previously treated, achieved a sustained viral response. In conclusion, GT6-infections are uncommon in France and their genetic diversity likely reflects infection within the country of origin. Despite residue variability at DAA resistance-associated positions, sustained viral response was obtained in all treated patients.

Impact of Preexisting Hepatitis C Virus Genotype 6 NS3, NS5A, and NS5B Polymorphisms on the In Vitro Potency of Direct-Acting Antiviral Agents

HCV genotype 6 (GT-6) is found predominantly in East and Southeast Asia. Clinical studies have focused on patients infected with hepatitis C virus (HCV) GT-6a, where high sustained virologic response (SVR) rates to direct-acting antivirals (DAAs) have been achieved. However, GT-6 is highly diverse, with 29 reported subtypes. We explored the diversity of GT-6 polymorphisms at residues associated with DAA resistance, their impact on DAA in vitro potency when evaluated in a GT-6a consensus replicon, and their association with specific GT-6 subtypes. GT-6 sequences from 25 patient-derived samples and 105 sequences from the U.S. HCV database were compared, and substitutions at resistance-associated residue positions were phenotyped against different DAAs. Preexisting resistance-associated substitutions (RASs) to NS3 protease (A156V and D168E) and NS5B nucleotide (L159F and S282C) inhibitors were rare (<4%). Preexisting RASs to NS5A inhibitors were common, especially at L28 (A/F/G/M/T/V) and R30 (E/N/S). In vitro susceptibilities of NS5A-L28A and -L28T were dramatically reduced against all tested NS5A drugs (90% effective concentration [EC₉₀] range, 119 to 2,032 nM) compared with susceptibilities against a GT-6a consensus replicon (EC₉₀ range, 0.1 to 19 nM). These L28 RASs preexisted in combination with R30S (EC₉₀ [L28A-R30S] of ≥720 nM or EC₉₀ [L28T-R30S] of ≥128 nM against tested DAAs) or as L28T-L31I (EC₉₀ [tested DAAs] of >5,000 nM) and were detected in evaluated GT-6b and -6f sequences. NS5A-L28A-R30A, observed in GT-6r, did not replicate. In conclusion, HCV GT-6b, GT-6f, and GT-6r sequences harbored highly resistant RASs to all evaluated NS5A drugs. Therefore, monitoring SVR in patients infected with these GT-6 subtypes treated with NS5A drug-containing regimens is suggested to confirm any association between noted NS5A polymorphisms and treatment failure.

Direct-acting antiviral therapy for chronic hepatitis C virus genotype 4 infection: Exploring new regimens

The optimal antiviral regimen for hepatitis C virus (HCV) genotype 4 is still a subject of investigation. The report in this issue of Health Science Reports by Asselah and colleagues investigated the additional benefit of extending treatment duration of the ombitasvir/paritaprevir/ritonavir plus ribavirin regimen to up to 24 weeks for patients with HCV genotype 4 and compensated cirrhosis.

Frequent Antiviral Treatment Failures in Patients Infected With Hepatitis C Virus Genotype 4, Subtype 4r

Hepatitis C virus (HCV) genotype 4 is highly heterogeneous. HCV subtype 4r has been suggested to be less responsive to direct-acting antiviral (DAA) drug treatment than other genotype 4 subtypes. Among 537 DAA-treated patients who experienced a virological failure (VF) in France between 2015 and 2018, 121 (22.5%) were infected with genotype 4 and 27 of them (22.3%) with subtype 4r; subtype 4r was thus over-represented as compared to its prevalence in the French general population. Population sequencing of the nonstructural protein (NS) 3, NS5A, and NS5B genes was performed in all subtype 4r patients at treatment failure and in 6 at baseline, whereas full-length HCV genome sequencing was performed in two baseline and three treatment failure samples by means of an original shotgun metagenomics method based on deep sequencing. At treatment failure, all subtype 4r patients harbored two to three dominant NS5A resistance-associated substitutions (RASs), including at least L28A/C/I/M/V and L30R. Among 13 patients exposed to sofosbuvir and an NS5A inhibitor (daclatasvir, ledipasvir, or velpatasvir), 5 (38.5%) also harbored NS5B S282C/T RASs at treatment failure. An additional patient harbored S282C/T RASs at treatment failure by deep sequencing. Prevalence of S282C/T RASs at treatment failure was significantly higher in patients infected with genotype 4r than with other genotypes, including other subtypes of genotype 4. Conclusion: The lower rates of sustained virological response in patients infected with subtype 4r are related to the frequent preexistence at treatment baseline and subsequent selection by DAA treatment of both NS5A and NS5B S282 RASs. Our study suggests that these patients should be identified and receive a triple DAA combination regimen as first-line treatment.

Efficacy and safety of glecaprevir/pibrentasvir in patients with chronic hepatitis C virus genotype 5 or 6 infection (ENDURANCE-5,6): an open-label, multicentre, phase 3b trial

BACKGROUND

The pangenotypic direct-acting antiviral regimen of glecaprevir coformulated with pibrentasvir is approved to treat chronic hepatitis C virus (HCV) genotype 1-6 infection in adults. In registrational studies, 84 (99%) of 85 patients with HCV genotype 5 or 6 infection achieved a sustained virological response (SVR) with glecaprevir/pibrentasvir, with no virological failures. To increase the body of data for these less prevalent genotypes, ENDURANCE-5,6 evaluated the efficacy and safety of glecaprevir/pibrentasvir exclusively in patients infected with HCV genotype 5 or 6.

METHODS

ENDURANCE-5,6 was a phase 3b, single-arm, open-label, multicentre trial done in 24 hospitals or clinics in Europe, Oceania, North America, South Africa, and southeast Asia. Adults with chronic HCV genotype 5 or 6 infection who were previously untreated or treatment-experienced were eligible to be enrolled. Glecaprevir/pibrentasvir (300 mg/120 mg) was given orally once daily for 8 weeks (for patients without cirrhosis) or 12 weeks (for patients with compensated cirrhosis). The primary efficacy endpoint was SVR12 (ie, HCV RNA <15 IU/mL at 12 weeks post-treatment), assessed within each HCV genotype, and analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02966795.

FINDINGS

Between Feb 9, 2017, and Aug 28, 2018, 84 patients were enrolled: 23 with genotype 5 infection and 61 with genotype 6 infection. Overall, 82 (97·6%, 95% CI 94·4-100·0) of the 84 patients achieved SVR12. 22 (95·7%, 95% CI 87·3-100·0) of 23 patients with genotype 5 infection achieved SVR12, as did 60 (98·4%, CI 95·2-100·0) of 61 with genotype 6 infection. One patient with an HCV genotype 6f infection and cirrhosis had on-treatment virological failure at treatment week 12, and one patient with HCV genotype 5a without cirrhosis who had achieved SVR at post-treatment week 4 relapsed at post-treatment week 12. Five (6%) patients had serious adverse events, none of which were deemed related to glecaprevir/pibrentsavir or led to discontinuation. Fatigue (11 [13%] patients) and headache (11 [13%]) were the only adverse events that occurred in 10% or more of patients. No post-baseline grade 3 or higher increases in aminotransferase concentrations were reported.

INTERPRETATION

Glecaprevir/pibrentasvir achieved high SVR12 rates, comparable with data reported in registrational studies, and was well tolerated in patients with HCV genotype 5 or 6 infection with compensated liver disease.

FUNDING

AbbVie.