NS5A Resistance-associated Substitutions Research Articles

Hepatitis C Virus Antiviral Drug Resistance and Salvage Therapy Outcomes Across Australia.

Hepatitis C virus (HCV) infection can now be cured with well-tolerated direct-acting antiviral (DAA) therapy. However, a potential barrier to HCV elimination is the emergence of resistance-associated substitutions (RASs) that reduce the efficacy of antiviral drugs, but real-world studies assessing the clinical impact of RASs are limited. Here, an analysis of the impact of RASs on retreatment outcomes for different salvage regimens in patients nationally who failed first-line DAA therapy is reported. We collected data from 363 Australian patients who failed first-line DAA therapy, including: age, sex, fibrosis stage, HCV genotype, NS3/NS5A/NS5B RASs, details of failed first-line regimen, subsequent salvage regimens, and treatment outcome. Of 240 patients who were initially retreated as per protocol, 210 (87.5%) achieved sustained virologic response (SVR) and 30 (12.5%) relapsed or did not respond. The SVR rate for salvage regimens that included sofosbuvir/velpatasvir/voxilaprevir was 94.3% (n = 140), sofosbuvir/velpatasvir 75.0% (n = 52), elbasvir/grazoprevir 81.6% (n = 38), and glecaprevir/pibrentasvir 84.6% (n = 13). NS5A RASs were present in 71.0% (n = 210) of patients who achieved SVR and in 66.7% (n = 30) of patients who subsequently relapsed. NS3 RASs were detected in 20 patients (20%) in the SVR group and 1 patient in the relapse group. NS5B RASs were observed in only 3 patients. Cirrhosis was a predictor of relapse after retreatment, as was previous treatment with sofosbuvir/velpatasvir. In our cohort, the SVR rate for sofosbuvir/velpatasvir/voxilaprevir was higher than with other salvage regimens. The presence of NS5A, NS5B, or NS3 RASs did not appear to negatively influence retreatment outcomes.

Molecular characterization of patients with chronic hepatitis C virus infection in Jordan: implications on response to direct-acting antiviral therapy

ObjectivesTo investigate the molecular characteristics of Hepatitis C Virus (HCV) detected in patients with chronic HCV infection in Jordan. MethodsThe study included 48 Jordanian treatment-naïve patients with active chronic HCV recruited from seven governorates. HCV genotype and the resistance-associated substitutions (RAS) profile were investigated by next-generation sequencing of the NS5B, NS5A, and NS3 regions of HCV. Results“Unusual genotype 4 subtypes” were detected in four (8.3%) patients (4n-n = 1, 4o-n = 2, 4v-n = 1); one patient (2.1%) was co-infected by genotypes 1b+4a. Overall prevalence of NS5A RASs was 38.3% (3% cutoff); genotype 4a showed the highest NS5A RAS prevalence (n = 11, 55.0%). Overall prevalence of NS3 RASs was 21.8% (7/32), all genotype 1a-infected patients. ConclusionsWe report, for the first time in Jordanian patients with chronic HCV infection, the detection of unusual genotype 4 subtypes 4n, 4o, and 4v. Baseline RASs in NS5A are frequent, with complex RASs patterns in some of the unusual subtypes. Our data support the need for sequencing surveillance programs in sub-Saharan Africa, Asia, and the Middle East and North African region to monitor response to treatment in these subtypes and to facilitate the World Health Organization's 2030 elimination strategy.

Hepatitis C treatment program in Maputo, Mozambique, the challenge of genotypes and key populations: A 5-year retrospective analysis of routine programmatic data.

Hepatitis C (HCV) programs face challenges, especially linked to key populations to achieve World Health Organization (WHO) goals of eliminating hepatitis. Médecins Sans Frontières and Mozambique's Ministry of Health first implemented HCV treatment in Maputo, in 2016 and harm reduction activities in 2017. We retrospectively analyzed routine data of patients enrolled between December 2016 and July 2021. Genotyping was systematically requested up to 2018 and subsequently in cases of treatment failure. Sustainable virological response was assessed 12 weeks after the end of treatment by sofosbuvir-daclatasvir or sofosbuvir-velpatasvir. Two hundred and two patients were enrolled, with 159 (78.71%) males (median age: 41 years [interquartile range (IQR): 37.10, 47.00]). Risk factors included drug use (142/202; 70.29%). One hundred and eleven genotyping results indicated genotype 1 predominant (87/111; 78.37%). Sixteen patients presented genotype 4, with various subtypes. The people who used drugs and HIV coinfected patients were found more likely to present a genotype 1. Intention-to-treat analysis showed 68.99% (89/129) cure rate among the patients initiated and per-protocol analysis, 88.12% (89/101) cure rate. Nineteen patients received treatment integrated with opioid substitution therapy, with a 100% cure rate versus 59.37% (38/64) for initiated ones without substitution therapy (p < 0.001). Among the resistance testing performed, NS5A resistance-associated substitutions were found in seven patients among the nine tested patients and NS5B ones in one patient. We found varied genotypes, including some identified as difficult-to-treat subtypes. People who used drugs were more likely to present genotype 1. In addition, opioid substitution therapy was key for these patients to achieve cure. Access to second-generation direct-acting antivirals (DAAs) and integration of HCV care with harm reduction are crucial to program effectiveness.

Next-generation sequencing analysis of hepatitis C virus resistance-associated substitutions in direct-acting antiviral failure in South Korea.

We used next-generation sequencing (NGS) to analyze resistance-associated substitutions (RASs) and retreatment outcomes in patients with chronic hepatitis C virus (HCV) infection who failed direct-acting antiviral agent (DAA) treatment in South Korea. Using prospectively collected data from the Korean HCV cohort study, we recruited 36 patients who failed DAA treatment in 10 centers between 2007 and 2020; 29 blood samples were available from 24 patients. RASs were analyzed using NGS. RASs were analyzed for 13 patients with genotype 1b, 10 with genotype 2, and one with genotype 3a. The unsuccessful DAA regimens were daclatasvir+asunaprevir (n=11), sofosbuvir+ribavirin (n=9), ledipasvir/sofosbuvir (n=3), and glecaprevir/pibrentasvir (n=1). In the patients with genotype 1b, NS3, NS5A, and NS5B RASs were detected in eight, seven, and seven of 10 patients at baseline and in four, six, and two of six patients after DAA failure, respectively. Among the 10 patients with genotype 2, the only baseline RAS was NS3 Y56F, which was detected in one patient. NS5A F28C was detected after DAA failure in a patient with genotype 2 infection who was erroneously treated with daclatasvir+asunaprevir. After retreatment, 16 patients had a 100% sustained virological response rate. NS3 and NS5A RASs were commonly present at baseline, and there was an increasing trend of NS5A RASs after failed DAA treatment in genotype 1b. However, RASs were rarely present in patients with genotype 2 who were treated with sofosbuvir+ribavirin. Despite baseline or treatment-emergent RASs, retreatment with pan-genotypic DAA was highly successful in Korea, so we encourage active retreatment after unsuccessful DAA treatment.

From the Editor’s Desk…

From the Editor’s Desk…

Selection dynamics of HCV genotype 3 resistance-associated substitutions under direct-acting antiviral therapy pressure.

The chronic hepatitis C (CHC) treatment is currently based on the use of direct-acting antivirals (DAAs), and patients infected with hepatitis C virus genotype 3 (GT3) have emerged as a more difficult-to-cure population. The NS5A inhibitor daclatasvir (DCV) and sofosbuvir (SOF), an NS5B viral polymerase inhibitor, are among the drugs that compose more effective and safer treatment regimens. The virus genetic variability is related to resistance-associated substitutions (RASs) that adversely impact DAAs effectiveness. The aims of this study were to analyze the association of NS5A and NS5B RASs and other clinical factors with DAAs regimens effectiveness in patients with GT3 CHC infection. This was a prospective cohort study performed in a Brazilian university hospital. Individuals older than 18 years with GT3 CHC treated with SOF+DCV ± ribavirin (RBV) or SOF+peginterferon (PEG)+RBV were included. Blood samples were collected at baseline and post-treatment. A total of 121 patients were included. Sustained virological response rates were 87.6% for the SOF+DCV ± RBV group and 80.0% for the SOF+PEG+RBV arm. Cirrhosis, prior treatment with interferon/PEG+RBV, and baseline NS5A RAS were associated with higher risk of treatment failure. The NS5A analysis suggested that A30K, Y93H, and RAS at site 62 were related to failure. Interestingly, a likely compensatory effect was shown between A30K and A62T. Emergence of Y93H was always associated with RAS at position 62. The RASs dynamics comprehension is an important tool to indicate more effective treatment for GT3 patients.

Low Risk of Failing Direct-Acting Antivirals in People With Human Immunodeficiency Virus/Hepatitis C Virus From Sub-Saharan Africa or Southeastern Asia: A European Cross-Sectional Study.

Several studies have reported suboptimal efficacy of direct-acting antivirals (DAAs) to treat hepatitis C virus (HCV) subtypes endemic to sub-Saharan Africa (SSA) and Southeastern Asia (SEA). The extent of this issue in individuals with human immunodeficiency virus (HIV)/HCV from SSA or SEA residing in Europe is unknown. We retrospectively analyzed data from several prospective European cohorts of people living with HIV. We included individuals with HIV/HCV who originated from SSA or SEA, were treated with interferon-free DAAs, and had an available HCV RNA result ≥12 weeks after the end of treatment. The primary outcome was sustained virological response at least 12 weeks after the end of treatment (SVR12). Of the 3293 individuals with HIV/HCV treated with DAA and with available SVR12 data, 142 were from SSA (n = 64) and SEA (n = 78). SVR12 was achieved by 60 (94% [95% confidence interval {CI}, 86%-98%]) individuals from SSA and 76 (97% [95% CI, 92%-99%]) from SEA. The genotypes of the 6 individuals failing DAA treatment were 2, 3a, 3h, 4a, 4c, and 6j. For 2 of the 4 unsuccessfully treated individuals with available sequence data at treatment failure, NS5A resistance-associated substitutions were present (30R/93S in an individual with genotype 4c and 31M in an individual with genotype 6j). SVR12 rates were high in individuals with HIV/HCV residing in Europe and originating from regions where intrinsically NS5A-resistant HCV strains are endemic. HCV elimination for this population in Europe is unlikely to be hampered by suboptimal DAA efficacy.

Long-term persistence of HCV resistance-associated substitutions after DAA treatment failure

Data on the long-term persistence of HCV resistance-associated substitutions (RASs) after treatment with direct acting antivirals (DAAs) are limited. This study evaluated the persistence of NS3, NS5A and NS5B RASs for up to 5 years after the end of treatment (EOT). We included samples from n=678 patients with a HCV GT (genotype) 1 or 3 infection and virologic DAA treatment failure collected in the European Resistance Database. NS3, NS5A and NS5B were sequenced and clinical parameters were evaluated. A total of 242 patients with HCV GT1a (36%), 237 with GT1b (35%) and 199 (29%) with GT3 and a DAA failure were included. After protease inhibitor failure, the frequencies of NS3 RASs were 40-90% after end of treatment (EOT) and RASs disappeared rapidly in GT1b and GT3 after follow-up month 3 (FU3), while in GT1a RASs were stable (≥ 60%) due to Q80K. The SOF-resistant NS5B RAS S282T was only found in individual GT3a patients. Non-nucleoside NS5B RASs were frequent in GT1 (56-80%) and decreased to 30% in GT1a but persisted in GT1b. NS5A RASs were very common in all GTs after NS5A inhibitor failure (88-95%), and even after FU24 their frequency was 65% and higher. However, RASs in GT1b had a stable course, while RASs in GT1a and GT3 declined slightly after FU24 (GT1a, 68%; GT1b, 95%; GT3, 65%), mainly due to the slow decline of high-level resistant Y93H. We found that low to medium-level RASs persisted, while high-level resistant RAS disappeared over time. Different patterns of RAS persistence according to HCV subtype could have implications for retreatment with first generation DAAs and for global HCV elimination goals. The long-term persistence of RASs after DAA failure is largely unknown. RASs in NS3 (with exception of Q80K) and S282T in NS5B generally declined rapidly. NS5A RASs persisted beyond two years after end of treatment, with a slight decrease in GT1a and GT3 compared to GT1b. The different patterns of RAS persistence could be of importance for re-treatment especially in countries with limited medical resources.

Efficacy and safety of direct-acting antiviral therapies and baseline predictors for treatment outcomes in hepatitis C patients: A multicenter, real-world study in Guangdong, China.

The data on direct-acting antivirals (DAAs) in chronic hepatitis C (CHC) patients in southern China with multiple genotypes circulating are limited. This study aims to evaluate the efficacy and safety of DAA regimens among CHC patients in Guangdong, China. A total of 220 patients receiving a variety of DAA were enrolled. The primary outcome was sustained virologic response (SVR) at 12 weeks. Resistance associated substitutions (RASs) were evaluated by deep sequencing. The overall SVR rate was 96.4%, and was 97.7% for genotype 1, 100% for genotype 2, 91.9% for genotype 3, 95.7% for genotype 6, and 100% for untyped. The overall incidence of adverse events (AEs) was 8.2% (18/220) and all the AEs were mild. Nonstructural proteins 5A RAS, 30K/31M, and Y93H were most prevalent at baseline and the end of treatment in non-SVR patients, respectively. Logistics regression showed that elevated alanine aminotransferase(ALT) and aspartate aminotransferase(AST) at baseline were specifically associated with non-SVR in patients with genotype 3 and 6 infections (p = 0.029 and p = 0.017) but not genotype 1 infection (p = 0.746 and p = 0.971), and baseline AST was the best predictor for SVR in genotypes 3 and 6 patients (area under curve = 0.890).Our studies demonstrated all DAA regimens achieved ideal SVR and were well tolerated. NS5A RAS were prevalent in non-SVR patients. Elevated ALT and AST as baseline predictors for non-SVR in genotypes 3 and 6 infections warrant further research in a larger cohort.

Emergence and Persistence of Resistance-Associated Substitutions in HCV GT3 Patients Failing Direct-Acting Antivirals.

Background: The hepatitis C virus has a high mutation rate, which results in the emergence of resistance-associated substitutions (RASs). Despite direct-acting antivirals (DAAs) efforts to treat chronically infected HCV genotype 3 (GT3) patients, there are concerns about the emergence and persistence of RASs in DAA failures. The objective of this study was to determine the prevalence of clinically relevant RASs in HCV NS5A and NS5B regions before and after treatment to better understand the role of RASs in treatment failures. Methods: Viral RNA was extracted before and after treatment from serum samples. NS5A and NS5B regions of HCV were amplified by nested PCR, followed by Sanger sequencing. The nucleotide sequences were aligned against HCV GT3 reference sequences, and amino acid substitutions were analyzed using the geno2pheno [hcv] webserver. Results: A total of 76 patients failing DAA therapy were stratified from the cohort of 1388. RASs were detected at the baseline in 15/76 patients and at relapse in 20/76 patients with cirrhosis and previously treated with interferons. The most prevalent NS5A RAS was Y93H found in all treatment-failing patients (14/54 in DCV vs. 6/22 in VEL), followed by A62S/T and A30K. No RASs were identified in NS5B. RASs that were present at the baseline persisted through the 24-week follow-up period and were enriched with emerging RASs during the treatment. The presence of RASs may be one of the causes of treatment failures in 26.3% of patients. Amino acid substitutions were present at the baseline in most of the patients with RASs against NS5A inhibitors. Patients with the baseline Y93H and/or A30K relapse more frequently than patients harboring A62S/T. Conclusion: Treatment-failing patients harbored NS5A RASs, and the most frequent were A30K (5/20), A62S/T (20/20), and Y93H (20/20). Direct resistance testing is recommended for optimizing re-treatment strategies in treatment-failing patients.

Safety and efficacy of sofosbuvir–velpatasvir–voxilaprevir for re-treatment of chronic hepatitis C virus infection in patients with previous direct-acting antiviral treatment failure in Rwanda (SHARED-3): a single-arm trial

Hepatitis C virus (HCV) genotype 4 non-a/d subtypes, which frequently have NS5A resistance-associated substitutions, are highly prevalent in sub-Saharan Africa. These subtypes, particularly genotype 4r, have been associated with higher rates of failure of treatment regimens containing the NS5A inhibitors ledipasvir or daclatasvir, which are the most accessible direct-acting antivirals in low-income countries. Clinical evidence regarding the efficacy of re-treatment options for these subtypes is limited. We aimed to evaluate the safety and efficacy of sofosbuvir-velpatasvir-voxilaprevir for the treatment of adults in Rwanda with chronic HCV infection, predominantly of genotype 4, and a history of direct-acting antiviral treatment failure. In this single-arm prospective trial, we enrolled adults (aged ≥18 years) with a HCV RNA titre of at least 1000 IU/mL, and a documented history of direct-acting antiviral failure. Patients were assessed for eligibility at a single study site after referral from hospitals with HCV treatment programmes throughout Rwanda, and participants for whom sofosbuvir-ledipasvir treatment had failed in the previous SHARED trial were also included. Participants with decompensated liver disease or hepatitis B virus co-infection were excluded. Participants were treated once daily with an oral fixed-dose combination tablet containing sofosbuvir (400 mg), velpatasvir (100 mg), and voxilaprevir (100 mg) for 12 weeks. The primary endpoint was the proportion of participants with a sustained virological response 12 weeks after completion of treatment (SVR12) in the intention-to-treat population. Viral sequencing of NS3, NS5A, and NS5B genes was done at baseline in all participants and at end of follow-up (week 24) in participants with treatment failure. The study is registered with ClinicalTrials.gov (NCT03888729) and is completed. Between Sept 23, 2019, and Jan 10, 2020, 49 individuals were screened and 40 participants were enrolled. 20 (50%) were female, 20 (50%) were male, median age was 63 years (IQR 56-68), and median HCV viral load was 6·2 log10 IU/mL (5·8-6·5) at baseline. The genotype subtypes identified were 4r (18 [45%] participants), 4k (six [15%]), 4b (five [13%]), 4q (four [10%]), 4l (two [5%]), 4a (one [3%]), 4m (one [3%]), and 3h (one [3%]). One (3%) genotype 4 isolate could not be subtyped, and one (3%) isolate was of unknown genotype. All successfully sequenced isolates (33 [83%]) had at least two NS5A resistance-associated substitutions and 25 (63%) had three or more. 39 (98% [95% CI 87-100]) participants had SVR12. Seven (18%) participants had a total of ten grade 3, 4, or 5 adverse events, including three (8%) cases of hypertension, and one (3%) case each of cataract, diabetes, gastrointestinal bleeding, joint pain, low back pain, vaginal cancer, and sudden death. Four of these events were categorised as serious adverse events resulting in hospitalisation. The one sudden death occurred at home from an unknown cause 4 weeks after the completion of treatment. No serious adverse event was determined to be related to the study drug or resulted in treatment discontinuation. A 12 week course of sofosbuvir-velpatasvir-voxilaprevir is safe and efficacious for the re-treatment of individuals infected with HCV genotype 4 non-a/d subtypes with frequent baseline NS5A resistance-associated substitutions, following failure of previous direct-acting antiviral treatment. Improved affordability and access to sofosbuvir-velpatasvir-voxilaprevir in regions with these subtypes is crucial. Gilead Sciences.

Safety and efficacy of sofosbuvir-velpatasvir to treat chronic hepatitis C virus infection in treatment-naive patients in Rwanda (SHARED-3): a single-arm trial

Hepatitis C virus (HCV) genotype 4 is the predominant type of HCV found in sub-Saharan Africa. Various genotype 4 subtypes, such as 4r, frequently have resistance-associated substitutions that can increase rates of treatment failure with common direct-acting antiviral regimens. In-vitro studies suggest that the NS5A inhibitor velpatasvir is effective against viral isolates containing such resistance-associated substitutions, but its clinical efficacy against genotype 4 non-a/d subtypes in sub-Saharan Africa remains to be confirmed. We aimed to evaluate the safety and efficacy of sofosbuvir-velpatasvir among adults chronically infected with HCV and naive to direct-acting antiviral treatment in Rwanda, where genotype 4 non-a/d subtypes predominate. In this single-arm prospective trial, we enrolled adults (age ≥18 years) in Rwanda who had chronic HCV infection and a plasma HCV RNA titre of at least 1000 IU/mL. Patients were referred from hospitals with HCV treatment programmes throughout Rwanda and were sequentially enrolled and assessed for eligibility at a single study site. Individuals with decompensated liver disease or hepatitis B virus co-infection were excluded. Participants were given an oral fixed-dose combination tablet of sofosbuvir (400 mg) and velpatasvir (100 mg) once-daily for 12 weeks. The primary endpoint was the proportion of participants with a sustained virological response 12 weeks after completion of treatment (SVR12) in the intention-to-treat population. Viral sequencing of the NS5A and NS5B genes was done at baseline for all participants and end of follow-up (week 24) for participants who did not have SVR12. This study is registered with ClinicalTrials.gov (NCT03888729) and is completed. Between Sept 23, 2019, and Jan 10, 2020, 73 individuals were screened for eligibility, of whom 12 (16%) were excluded and 61 (84%) were enrolled. 40 (66%) participants were female, 21 (34%) were male, median age was 64 years (IQR 51-74), and median baseline HCV viral load was 5·7 log10 IU/mL (5·2-6·2). The genotypes identified among the participants were 4k (28 [46%] participants), 4r (11 [18%]), 4v (eight [13%]), 4q (five [8%]), 4l (three [5%]), 4b (one [2%]), 4c (one [2%]), and one undetermined genotype 4 subtype. Three isolates could not be sequenced and were of indeterminate genotype. Of the 55 HCV isolates that were successfully sequenced, all had at least two NS5A resistance-associated substitutions. 59 (97% [95% CI 89-99]) participants had SVR12. 18 (30%) participants had grade 3 adverse events (including 12 [20%] with hypertension), and none had grade 4 adverse events. Four (7%) participants had serious adverse events, including one asthma exacerbation, one abscess, one uterine myoma, and one pelvic fracture related to a motor vehicle accident. No serious adverse events were attributed to the study drug and no adverse event resulted in discontinuation of the study drug. A 12-week regimen of sofosbuvir-velpatasvir is safe and efficacious in treating chronic HCV genotype 4 infection in patients in Rwanda. This regimen could be an effective treatment option in regions known to have a high prevalence of HCV genotype 4 of diverse non-a/d subtypes. Gilead Sciences.

Characteristics of hepatitis C virus resistance in an international cohort after a decade of direct-acting antivirals

Background & AimsDirect-acting antiviral (DAA) regimens provide a cure in >95% of patients with chronic HCV infection. However, in some patients in whom therapy fails, resistance-associated substitutions (RASs) can develop, limiting retreatment options and risking onward resistant virus transmission. In this study, we evaluated RAS prevalence and distribution, including novel NS5A RASs and clinical factors associated with RAS selection, among patients who experienced DAA treatment failure.MethodsSHARED is an international consortium of clinicians and scientists studying HCV drug resistance. HCV sequence linked metadata from 3,355 patients were collected from 22 countries. NS3, NS5A, and NS5B RASs in virologic failures, including novel NS5A substitutions, were examined. Associations of clinical and demographic characteristics with RAS selection were investigated.ResultsThe frequency of RASs increased from its natural prevalence following DAA exposure: 37% to 60% in NS3, 29% to 80% in NS5A, 15% to 22% in NS5B for sofosbuvir, and 24% to 37% in NS5B for dasabuvir. Among 730 virologic failures, most were treated with first-generation DAAs, 94% had drug resistance in ≥1 DAA class: 31% single-class resistance, 42% dual-class resistance (predominantly against protease and NS5A inhibitors), and 21% triple-class resistance. Distinct patterns containing ≥2 highly resistant RASs were common. New potential NS5A RASs and adaptive changes were identified in genotypes 1a, 3, and 4. Following DAA failure, RAS selection was more frequent in older people with cirrhosis and those infected with genotypes 1b and 4.ConclusionsDrug resistance in HCV is frequent after DAA treatment failure. Previously unrecognized substitutions continue to emerge and remain uncharacterized.Lay summaryAlthough direct-acting antiviral medications effectively cure hepatitis C in most patients, sometimes treatment selects for resistant viruses, causing antiviral drugs to be either ineffective or only partially effective. Multidrug resistance is common in patients for whom DAA treatment fails. Older patients and patients with advanced liver diseases are more likely to select drug-resistant viruses. Collective efforts from international communities and governments are needed to develop an optimal approach to managing drug resistance and preventing the transmission of resistant viruses.

The Role of RASs /RVs in the Current Management of HCV.

The approval of combination therapies with direct-acting antiviral (DAA) regimens has led to significant progress in the field of hepatitis C virus (HCV) treatment. Although most patients treated with these agents achieve a virological cure, resistance to DAAs is a major issue. The rapid emergence of resistance-associated substitutions (RASs), in particular in the context of incomplete drug pressure, has an impact on sustained virological response (SVR) rates. Several RASs in NS3, NS5A and NS5B have been linked with reduced susceptibility to DAAs. RAS vary based on HCV characteristics and the different drug classes. DAA-resistant HCV variant haplotypes (RVs) are dominant in cases of virological failure. Viruses with resistance to NS3-4A protease inhibitors are only detected in the peripheral blood in a time frame ranging from weeks to months following completion of treatment, whereas NS5A inhibitor-resistant viruses may persist for years. Novel agents have been developed that demonstrate promising results in DAA-experienced patients. The recent approval of broad-spectrum drug combinations with a high genetic barrier to resistance and antiviral potency may overcome the problem of resistance.

Prevalence of resistance-associated substitutions and phylogenetic analysis of hepatitis C virus infection in Russia

ObjectivesDue to limited hepatitis C virus (HCV) sequence availability from patients in Russia, the relationship between subtypes and baseline resistance-associated substitutions (RAS) to direct antiretroviral treatment outcome is not fully understood. MethodsDeep sequencing of HCV NS3, NS5A, and NS5B sequences was performed on plasma HCV samples from 412 direct-acting antiviral (DAA)-naïve patients from Russia. Phylogenetic analysis was performed to investigate sequence similarities between HCV strains from Russia, Asia, Europe, and North America. Pretreatment HCV RAS was assessed with a 15% cutoff. ResultsHCV genotype GT1b and GT3a sequences in Russia were related to strains in Europe and Asia. The prevalence of GT1a and GT2a was low in Russia. In GT1b, the prevalence of NS5A Y93H was lower in Russia (6%) compared with Asia (15%). The prevalence of NS5B L159F was similar between Russia and Europe (26–39%). GT3a RAS prevalence was similar between Russia and Asia, Europe, and North America. The 2k/1b recombinant strain in Russia was related to strains from Europe. A higher prevalence of the NS5A RAS L31M (10%) was observed in 2k/1b sequences compared to GT1b (1–6%). ConclusionsThe prevalence of RASs and the phylogenetic analysis showed similarities in HCV strains between Russia, Europe, and North America. This information may be useful for HCV regimens in Russia.

Compartmentalization of Resistance-Associated Substitutions in HIV/HCV-Infected Patients: Possible Correlation with Infecting HCV Genotype

Resistance-associated substitutions (RASs) may exist prior to treatment and contribute to the failure of treatment with direct-acting antivirals (DAAs). As the major site of HCV replication, naturally occurring variants with RASs may segregate into the liver. In the present study, we performed viral population sequencing to retrospectively investigate the NS3 and NS5A RAS profiles in 34 HIV/HCV coinfected patients naïve to anti-HCV treatment who underwent diagnostic liver biopsy between 2000 and 2006 and had liver and plasma samples available. Sixteen were infected by HCV genotype (GT) 1a, 11 by GT3a, and 7 by GT4d. The analysis of the NS3 domain in GT1a showed a difference in strain between the liver and plasma in three cases, with a preponderance of specific RASs in the liver compartment. In GT4d samples, 6/7 coupled liver and plasma samples were concordant with no RASs. Sequence analysis of the NS5A domain showed the presence of RASs in the livers of 2/16 patients harboring GT1a but not in the corresponding plasma. In GT4d, NS5A RASs were detected in 7/7 liver tissues and 5/7 plasma samples. NS3 domain and NS5A domain were found to be conserved in plasma and livers of patients infected with GT3a. Thus, RASs within GT1a and GT4d more likely segregate into the liver and may explain the emergence of resistant strains during DAA treatment.

Inferior cure rate in pilot study of 4-week glecaprevir/pibrentasvir treatment with or without ribavirin of chronic hepatitis C.

Shortening the treatment duration for chronic hepatitis C may increase feasibility and reduce the cost of cure. The aims of this study were to compare 4weeks of glecaprevir/pibrentasvir (GLE/PIB) treatment with and without ribavirin for patients with chronic hepatitis C and favourable baseline characteristics and to monitor the development of resistance-associated substitutions (RAS) and re-treatment outcomes if treatment failed. We performed an open-label single-centre randomized controlled trial, in which patients with chronic hepatitis C were randomized 1:1 to GLE/PIB±ribavirin, stratified by genotype 3. The main inclusion criteria were treatment-naive patients, aged 18-49 with all genotypes accepted, and absence of liver fibrosis, determined by liver stiffness measurement less than 8kPa. Viral genome sequences were determined by deep sequencing at baseline and at the time of relapse. A total of 32 patients started treatment. Sustained virological response at week 12 (SVR12) was 59% (10/17) for GLE/PIB without ribavirin and 73% (11/15) for GLE/PIB with ribavirin. Drug target-specific NS5A RAS were detected at baseline for 45% (5/11) of patients with treatment failure and for 14% (3/21) of patients who achieved SVR12. Ten failure patients were retreated 12weeks with sofosbuvir-based regimens; all have been cured. In this pilot study of 4-week treatment with GLE/PIB with and without ribavirin, we found that baseline RAS were more frequent in patients with virological failure. Development of RAS did occur after short treatment but did not result in retreatment failure with a different regimen. EudraCT no: 2017-005179-21.

HCV resistance-associated substitutions following direct-acting antiviral therapy failure - Real-life data from Poland.

This study analysed the NS3 and NS5A mutation frequencies, persistence and drug susceptibility in a cohort of real-life patients, with failed hepatitis C virus (HCV) therapy following directly acting antiviral (DAA) treatment. NS3/NS5A Sanger sequences from 105 patients infected with HCV genotype (G) 1a (6,5.7%), G1b (94,89.5%), G3a (4,3.8%), and G4 (1,1.0%) post DAA treatment failure were analysed. NS3 and NS5A resistance-associated substitutions (RASs) were identified using the geno2pheno algorithm and associated with clinical variables. Time trends were examined using logistic regression. NS5A RAS were found in 87.9% of sequences derived from patients exposed to this class of agents, whereas NS3 RAS was found in 59.1% of HCV protease-exposed subjects. The frequency of the NS3 RAS increased with fibrosis stage, from 40.0% among F0/F1 individuals to 81.8% among patients with liver cirrhosis (F4, p=0.094). NS5A mutation frequencies were 7.6% for 28A/V/M, 10.6% for 30K/Q/R, 42.4% for 31I/F/M/V, and 75.8% for 93H. For NS3, the most common RASs were 56F-23.7%, 168A/E/I/Y/T/V-14.0%, and 117H-5.4%. Susceptibility to glecaprevir/pibrentasvir, velpatasvir/voxlaprevir, and elbasvir/grazoprevir was retained in 92.9%, 43.4%, and, 25.3% of patients, respectively. The frequency of NS3 RAS decreased with time elapsed from failure to sampling (p=0.034 for trend). NS5A RAS frequency remained stable over the 24-months. Following DAA treatment failure, NS5A and NS3 RASs were common with increasing frequency among patients with advanced liver disease. In most cases, despite the presence of RASs, susceptibility to DAA combinations with higher genetic barrier was retained.

Linkage of resistance-associated substitutions in GT1 sofosbuvir + NS5A inhibitor failures treated with glecaprevir/pibrentasvir

Retreatment with glecaprevir/pibrentasvir (G/P) resulted in a rate of sustained virologic response 12 weeks after treatment completion (SVR12) of >90% in HCV genotype 1 (GT1) patients who previously failed a regimen of sofosbuvir plus an NS5A inhibitor (NS5Ai). This study investigated the prevalence and impact of baseline NS3 and NS5A resistance-associated substitutions (RASs) on the efficacy of G/P in prior GT1 sofosbuvir+NS5Ai failures and the persistence of treatment-emergent RASs. Longitudinal samples from 177 patients enrolled in a phase IIIb, randomized pragmatic clinical trial were analyzed. Patients without cirrhosis were randomized to 12 or 16 weeks of G/P, and patients with compensated cirrhosis were randomized to G/P and ribavirin for 12 weeks or G/P for 16 weeks. Linkage of RAS was identified using Primer-ID next-generation sequencing at a 15% cut-off. Of 177 patients, 169 (95.5%) were PI-naïve. All 33 GT1b-infected patients achieved SVR12. In GT1a-infected patients, baseline NS5A RASs were prevalent (74.5%, 105/141) but NS3 RASs were uncommon. Baseline NS3 RASs had no impact on G/P efficacy and patients with baseline NS5A RASs showed a numerically but not statistically significantly lower SVR12 rate compared to those without NS5A RASs (89% vs. 97%). SVR12 was achieved in 34 of 35 (97%) patients without NS5A baseline substitution, and 53 of 57 (93%), 35 of 40 (88%), 5 of 8 (63%) with single, double-linked, and triple-linked NS5A substitutions, respectively. Among 13 patients with virologic failure, 4 acquired treatment-emergent NS3 RASs and 10 acquired NS5A RASs. Baseline NS5A RASs were highly prevalent. The presence of an increasing number of linked NS5A RASs in GT1a showed a trend in decreasing SVR12 rates, although no specific NS5A RASs or their linkage pattern were associated with lower SVR12 rates. Direct-acting antivirals have revolutionized the treatment of chronic hepatitis C infection, but treatment failure occurs in some patients. Retreatment of patients who previously failed a regimen consisting of sofosbuvir and an NS5A inhibitor with a regimen of glecaprevir and pibrentasvir (G/P) is >90% effective. Herein, we analyzed samples from these patients and showed that retreatment efficacy with G/P is lower in patients with double- or triple-linked NS5A resistance mutations than in patients with single or no NS5A resistance mutations. NCT03092375.

Direct-acting Antiviral Regimens for Patients with Chronic Infection of Hepatitis C Virus Genotype 3 in China

Hepatitis C virus (HCV) genotype (GT)3 infection is associated with a more rapid hepatic disease progression than the other genotypes. Hence, early HCV clearance slows down the disease progression and is important for improving prognosis in GT3-infected patients. Nevertheless, compared with other genotypes, GT3 is difficult-to-treat with direct-acting antivirals, especially in the presence of cirrhosis. Current guidelines recommend several regimens which have been proven to be effective in GT3-infected patients from the Western world (North America, Europe, and Oceania). In China, GT3 infection comprises 8.7–11.7% of the 10 million patients infected with HCV and has strikingly different characteristics from that in Western countries. Unlike the Western countries, where GT3a is the predominant subtype, GT3a and 3b each affect roughly half of Chinese GT3-infected patients, with 94–96% of the GT3b-infected patients carrying A30K+L31M double NS5A resistance-associated substitutions. Phase 3 clinical trials including GT3b-infected patients have suggested that GT3b infection is difficult to cure, making the regimen choice for GT3b-infected patients an urgent clinical gap to be filled. This review includes discussions on the epidemiology of HCV GT3 in China, recommendations from guidelines, and clinical data from both Western countries and China. The aim is to provide knowledge that will elucidate the challenges in treating Chinese GT3-infected patients and propose potential solutions and future research directions.