Patterns of Resistance-Associated Substitutions in Patients With Chronic HCV Infection Following Treatment With Direct-Acting Antivirals.

BACKGROUND & AIMS: Little is known about substitutions that mediate resistance of hepatitis C virus (HCV) to direct-acting antivirals (DAAs), due to the small number of patients with treatment failure in approval studies. It is important to identify resistance patterns to select effective salvage treatments. METHODS: We performed a comprehensive analysis for resistance-associated substitutions (RASs) in HCV genes (nonstructural protein [NS]3, NS5A, NS5B) targeted by DAAs. We compared NS3, NS5A, and NS5B sequences from 626 patients in Europe with DAA failure with sequences from 2322 DAA-naïve patients, infected with HCV genotypes 1 to 4. We considered RASs to be relevant if they were associated with DAA failure in patients or conferred a greater than twofold change in susceptibility compared with a reference strain in in vitro replicon assays. Data were collected on pretreatment status, DAA regimen, the treatment initiation date and duration, and virologic response. Patients who received at least 4 weeks of antiviral treatment were included in the analysis. RESULTS: RASs in NS3 associated with simeprevir or paritaprevir failure include R155K and D168E/V. In addition, several RASs were specifically associated with failure of simeprevir (Q80K/R in patients with genotype 1a or 4) or paritaprevir (Y56H in combination with D168V in patients with genotype 1b). Y93H in NS5A was the RAS most frequently associated with failure of daclatasvir, ledipasvir, or ombitasvir in patients with genotype 1b infection, and L31M was associated with failure of daclatasvir or ledipasvir, but not ombitasvir. RASs in NS5A were heterogeneous among patients with HCV genotype 1a or genotype 4 infections. In patients with HCV genotype 3, Y93H was associated with resistance to daclatasvir, but no RASs were associated with ledipasvir failure, pointing to a limited efficacy of ledipasvir in patients with genotype 3. Among patients failed by sofosbuvir-containing regimens, L159F was enriched in patients with genotype 1b (together with C316N) or genotype 3 infection, whereas the RAS S282T was rarely observed. CONCLUSIONS: We compared RASs in NS3, NS5A, and NS5B among patients failed by DAA therapy. Theses varied with the HCV genotype and subtype, and the different drug classes. These findings might be used to select salvage therapies.

Performance of Three Common Hepatitis C Virus (HCV) Genotyping Assays for Identification of HCV Genotype 2/1 Chimeras.

Besides seven major hepatitis C virus (HCV) genotypes (GT), a number of intergenotypic recombinant strains have been described. These so-called chimeras combine genetic characteristics of different HCV genotypes. However, correct genotype classification is important, as choice and duration of direct-acting antiviral (DAA) treatment is mainly based on the viral genotype. Therefore, misclassification of chimeras might lead to suboptimal treatment of patients infected with these strains. For example, 2k/1b chimeras are typically described as HCV genotype 2 strains by commercially available hybridization assays, but real-time PCR-based tests recognizing another HCV region might be more suitable for correct chimera detection. In this study, the analytic capacity of the hybridization-assay Versant HCV Genotype 2.0 (LiPA 2.0) and the real-time PCR-based-assays cobas HCV GT and Abbott RealTime HCV Genotype II were tested in a selected cohort of 230 patients infected with HCV genotype 1 (n = 53) and 2 (n = 177) and 48 patients infected with HCV 2/1 chimeric strains. While the Versant HCV Genotype 2.0 (LiPA 2.0) assay failed to identify chimeras in all of the patients (48/48, 100%), cobas HCV GT and Abbott HCV Genotype II assays identified chimeras correctly in 90% (43/48) and 65% (31/48) of the cases, respectively. In conclusion, while the hybridization-based Versant HCV Genotype 2.0 (LiPA 2.0) assay seems to be unsuitable for detection of HCV 2/1 chimeras, use of the real-time PCR-based assays cobas HCV GT and Abbott RealTime HCV Genotype II led to a higher rate of chimera detection.

Divergent preS Sequences in Virion-Associated Hepatitis B Virus Genomes and Subviral HBV Surface Antigen Particles From HBV e Antigen-Negative Patients.

Background: Hepatitis B virus (HBV) surface proteins (HBsAg) coat the viral particle and form subviral particles (SVPs). Loss of HBsAg represents a functional cure and is an important treatment goal. Methods: We analyzed the impact of the HBV genotypes A-E and pre-S mutations on SVP expression in hepatitis B virus e antigen (HBeAg)-negative chronic HBV-infected patients. A HBV genome harboring a preS1-deletion was analyzed in hepatoma cells. Results: We observed a genotype-specific ratio of the 3 surface proteins (SHBs/MHBs/LHBs), reflecting differences in the morphology and composition of SVPs. Deletions/mutations in the preS1/preS2 domain, detected in released viral genomes, did not affect the molecular weight of MHBs and LHBs in these patients. In contrast, LHB molecular weight was altered in vitro using an HBV genome harboring a preS1-deletion derived from one of these patients. Conclusion: Differences in composition of SVPs may result in genotype-specific immunogenicity and pathogenesis. In the patients with preS-mutations, secreted HBsAg and released viral genomes cannot be derived from the same genetic source. As viral genomes are derived from covalently closed circular DNA (cccDNA), HBsAg is presumably derived from integrated DNA. This important HBsAg source should be considered for novel antiviral strategies in HBeAg-negative chronic HBV-infected patients.

Interferon-free treatment choice according to baseline RASs leads to high SVR rates in HCV genotype 1 infected patients.

AIM: Different combinations of direct antiviral agents (DAA) lead to high SVR rates in HCV genotype 1 infected patients. However, presence of baseline resistance-associated substitutions (RASs) represents a major risk factor for treatment failure. It is unknown whether choice of treatment based on RASs has the potential to decrease virologic failure rates. METHODS: Population-based sequencing of NS3 and NS5A genes was performed in HCV genotype 1 infected patients at a German university hospital. Treatment was individually selected based on resistance analyses. RESULTS: In total, 319 patients (50% treatment-experienced and 30% with cirrhosis) were included. With the treatment choice based on the baseline NS3 and NS5A resistance profile SVR rates between 96 and 100% were observed in all subgroups, including treatment-experienced patients with cirrhosis and HCV genotype 1a infected cirrhotic patients. CONCLUSIONS: The choice of treatment based on the RASs status at baseline may be beneficial for optimizing treatment efficacy in patients with HCV genotype 1 infection and risk factors for treatment failure.

Origin, prevalence and response to therapy of hepatitis C virus genotype 2k/1b chimeras.

BACKGROUND & AIMS: Little is known about the epidemiology and frequency of recombinant HCV genotype 2/1 strains, which may represent a challenge for direct antiviral therapy (DAA). This study aims to identify the epidemiology and phylogeny of HCV genotype 2/1 strains and encourages genotype screening, to select the DAA-regimen that achieves the optimal sustained virologic response. METHODS: Consecutive samples from HCV genotype 2 infected patients, according to commercial genotyping, from Germany, Italy and Israel were re-genotyped by Sanger-based sequencing. Virologic, epidemiological, and phylogenetic analyses including other published chimeras were performed. RESULTS: Sequence analysis of 442 supposed HCV genotype 2 isolates revealed 61 (genotype 2k/1b (n=59), 2a/1b (n=1) or 2b/1a (n=1)) chimeras. No chimeras were observed in Italy, but the frequency was 14% and 25% in Germany and Israel. Treatment of viral chimera with sofosbuvir/ribavirin led to virologic relapse in 25/27 patients (93%). Nearly all patients treated with genotype 1-based DAA-regimens initially (n=8/9), or after relapse (n=13/13), achieved a sustained virologic response. Most patients with 2k/1b chimeras (88%) were originally from eight different areas of the former Soviet Union. All known 2k/1b chimeras harbour the same recombination breakpoint and build one phylogenetic cluster, while all other chimeras have different phylogenies. CONCLUSIONS: The HCV genotype 2k/1b variant derives from one single recombination event most likely in the former Soviet Union, while other chimeras are unique and develop independently. A relatively high frequency has been observed along the migration flows, in Germany and Israel. In countries with little migration from the former Soviet Union the prevalence of 2k/1b chimeras is expected to be low. Treatment with sofosbuvir plus ribavirin is insufficient, but genotype 1-based regimens seem to be effective. Lay summary: The frequency of recombinant HCV is higher than expected. A novel recombinant variant (HCV genotype 2a/1b) was identified. Screening for recombinant viruses would contribute to increased response rates to direct antiviral therapy.

Sofosbuvir and ribavirin for genotype 2 HCV infected patients with cirrhosis: A real life experience.

BACKGROUND & AIMS: Sofosbuvir (SOF) and weight-based ribarivin (RBV) represented until recently the standard of care in hepatitis C virus (HCV) genotype (GT)2 patients. In registration studies 12-16weeks duration were associated with a 90% sustained virological response at 12weeks (SVR12). Real life cohorts showed lower SVR12 rates. METHODS: SVR12 rates attained in an Italian real life cohort and possible benefits of a duration extended up to 20weeks was investigated in HCV GT2 patients with cirrhosis. The role of 2k/1b chimeras as potential predictor of treatment failure was also analysed. RESULTS: Overall, 291 HCV GT2 infected patients with bridging fibrosis or cirrhosis were evaluated. Median age was 68years (18-87); 163 were treatment naïve. Of 168 cirrhotic patients, 149 had Child-Pugh score A and 19 B, 50 platelets count <100,000/mm3 and 62 albumin <3.5g/dl. SVR12 were 95.53% overall, with 99.15% in non-cirrhotic patients and 93.06% in cirrhotic patients. In patients who completed treatment, SVR rates for cirrhotic patients resulted in 94.51%, and 94.94% after 16 or 20weeks respectively. Predictors of SVR were low platelet count and esophageal varices (OR 7.2; 95% CI 1.67-31.25; p=0.0022 and OR 0.1; 95% CI 0.01-0.72; p=0.0079, respectively). Anemia was mild in 12.4%, moderate in 3.4%, and severe in 2.4% of cases. Anemia was slightly more frequent among longer duration but not associated with treatment discontinuations. No 2k/1b strains or genotypes different from those at baseline were identified at relapse. CONCLUSIONS: In GT2 cirrhotic patients, SOF/RBV for 16 or 20weeks is associated with real life SVR12 rates of 95%. LAY SUMMARY: A duration of treatment of 16-20weeks was recommended for treatment of HCV GT2 patients using the combination of sofosbuvir and ribavirin. Real life experiences, where patients received 12weeks of treatment regardless of the severity of liver disease, suggested that response rates are lower than expected, in particular in patients with liver cirrhosis. A misleading genotyping of a 2k/1b strain as GT2 was also hypothesized as a further explanation for less effectiveness. We demonstrated that using the recommended extended duration in patients with more severe disease 95% of patients with severe liver disease including cirrhosis can be cured and that 2k/1b strain plays only a secondary role in specific countries like Germany. Although this combination has been recently replaced by sofosbuvir and velpatasvir fixed dose combination as the standard of care for treating HCV GT2 patients, our findings may inform physicians from countries where the new regimen is not yet available.

Interferon lambda 4 genotypes and resistance-associated variants in patients infected with hepatitis C virus genotypes 1 and 3.

UNLABELLED: Single-nucleotide polymorphisms (SNPs) in the interferon lambda 4 (IFNL4) gene are predictors for treatment success in patients with hepatitis C virus (HCV) infection. For direct-acting antiviral combinations only weak association with IFNL4 SNPs was observed. Little is known about potential selections of resistance-associated variants (RAVs) by the IFNL4 genotype. This study analyzed the prevalence of RAVs to currently approved direct-acting antivirals in a large European population in correlation to SNPs in IFNL4. Samples of 633 patients chronically infected with HCV genotypes 1a (n = 259), 1b (n = 323), and 3 (n = 51) were genotyped for rs12979860 (formerly known as IL28B) and rs368234815. RAVs in NS3, NS5A, and NS5B were detected by population-based sequencing. In addition, IFNL4 SNPs and NS5A RAVs were analyzed including deep sequencing (n = 109) in an independent replication cohort of HCV genotype 1-infected patients (n = 201). No significant correlation was found between IFNL4 SNPs and rare and common RAVs within NS3 and NS5B. In contrast, the NS5A RAV Y93H was detected frequently in HCV genotype 1b (14%) and significantly associated with the beneficial IFNL4 SNPs (P < 0.001 and P = 0.002, respectively). Moreover, the presence of Y93H in HCV genotype 1b patients was significantly associated with the second site variant T83M (P < 0.001). Independent factors significantly associated with the presence of Y93H were IFNL4 genotype and high baseline viral load. CONCLUSION: The NS5A RAV Y93H is significantly associated with the presence of beneficial IFNL4 SNPs and a high baseline viral load in HCV genotype 1-infected patients, which may explain a lack of correlation or even an inverse correlation of treatment response with IFNL4 genotype in some NS5A inhibitor containing IFN-free regimens.

Hepatitis C virus variants resistant to macrocyclic NS3-4A inhibitors subvert IFN-ß induction by efficient MAVS cleavage.

BACKGROUND & AIMS: The hepatitis C virus (HCV) NS3-4A protease is essential for the HCV life cycle and a prime target of antiviral treatment strategies. Protease inhibitors, however, are limited by emergence of resistance-associated amino acid variants (RAVs). The capacity to cleave and inactivate mitochondrial antiviral-signaling protein (MAVS) in the RIG-I-signaling pathway is a cardinal feature of NS3-4A, by which HCV blocks induction of interferon-(IFN)-ß, thereby promoting viral persistence. Here, we aimed to investigate the impact of NS3-4A RAVs on MAVS cleavage. METHODS: The impact of NS3-4A RAVs on MAVS cleavage was assessed using immunoblot analyses, luciferase reporter assays and molecular dynamics simulations to study the underlying molecular principles. IFN-ß was quantified in serum from patients with different NS3-4A RAVs. RESULTS: We show that macrocyclic NS3-4A RAVS with substitutions at residue D168 of the protease result in an increased capacity of NS3-4A to cleave MAVS and suppress IFN-ß induction compared with a comprehensive panel of RAVs and wild type HCV. Mechanistically, we show the reconstitution of a tight network of electrostatic interactions between protease and the peptide substrate that allows much stronger binding of MAVS to D168 RAVs than to the wild-type protease. Accordingly, we could show IFN-ß serum levels to be lower in patients with treatment failure due to the selection of D168 variants compared to R155 RAVs. CONCLUSIONS: Our data constitutes a proof of concept that the selection of RAVs against specific classes of direct antivirals can lead to the predominance of viral variants with possibly adverse pathogenic characteristics.

Evolution of hepatitis C virus quasispecies during repeated treatment with the NS3/4A protease inhibitor telaprevir.

In treating hepatitis B virus (HBV) and human immunodeficiency virus (HIV) infections, the rapid reselection of resistance-associated variants (RAVs) is well known in patients with repeated exposure to the same class of antiviral agents. For chronic hepatitis C patients who have experienced virologic failure with direct-acting antiviral drugs, the potential for the reselection of persistent RAVs is unknown. Nine patients who received 14 days of telaprevir monotherapy were retreated with telaprevir-based triple therapy 4.3 to 5.7 years later. In four patients with virologic failure with both telaprevir-containing regimens, population-based and deep sequencing (454 GS-FLX) of the NS3 protease gene were performed before and at treatment failure (median coverage, 4,651 reads). Using deep sequencing, with a threshold of 1.0% for variant calling, no isolates were found harboring RAVs at the baseline time points. While population-based sequencing uncovered similar resistance patterns (V36M plus R155K for subtype 1a and V36A for subtype 1b) in all four patients after the first and second telaprevir treatments, deep sequencing analysis revealed a median of 7 (range, 4 to 23) nucleotide substitutions on the NS3 backbone of the resistant strains, together with large phylogenetic differences between viral quasispecies, making the survival of resistant isolates highly unlikely. In contrast, in a comparison of the two baseline time points, the median number of nucleotide exchanges in the wild-type isolates was only 3 (range, 2 to 8), reflecting the natural evolution of the NS3 gene. In patients with repeated direct antiviral treatment, a continuous evolution of HCV quasispecies was observed, with no clear evidence of persistence and reselection but strong signs of independent de novo generation of resistance. Antiviral therapy for chronic viral infections, like HIV, hepatitis B virus (HBV), or hepatitis C virus (HCV), faces several challenges. These viruses have evolved survival strategies and proliferate by escaping the host's immune system. The development of direct-acting antiviral agents is an important achievement in fighting these infections. Viral variants conferring resistance to direct antiviral drugs lead to treatment failure. For HIV/HBV, it is well known that viral variants associated with treatment failure will be archived and reselected rapidly during retreatment with the same drug/class of drugs. We explored the mechanisms and rules of how resistant variants are selected and potentially reselected during repeated direct antiviral therapies in chronically HCV-infected patients. Interestingly, in contrast to HIV and HBV, we could not prove long-term persistence and reselection of resistant variants in HCV patients who failed protease inhibitor-based therapy. This may have important implications for the potential to reuse direct-acting antivirals in patients who failed the initial direct antiviral treatment. (The phase IIIb study described in this paper is registered at ClinicalTrials.gov under registration number NCT01054573.).

Clinical significance of residual viremia detected by two real-time PCR assays for response-guided therapy of HCV genotype 1 infection.

BACKGROUND & AIMS: The duration of current standard dual and protease inhibitor-based triple therapies for chronic hepatitis C is determined by assessment of early viral kinetics. Little is known about differences between HCV RNA assays for the use in response guided therapy. METHODS: HCV RNA was assessed by two widely used real-time PCR-based assays, Cobas Ampliprep/Cobas TaqMan (CAP), and Real-Time HCV (ART) in 903 samples of hepatitis C genotype 1 patients treated with dual (n=169) or telaprevir-based triple therapy (n=164) in three European countries. RESULTS: Overall, CAP and ART were in excellent agreement for the determination of HCV-RNA concentrations (mean difference 0.21 log10 IU/ml). For treatment-naïve patients treated with peginterferon-alfa and ribavirin a lower rate of undetectable HCV-RNA at week 4 (RVR) was observed for ART (9%) vs. CAP (16%). Although 11/27 (41%) of patients with shortened treatment (24weeks) had detectable HCV-RNA <12IU/ml by ART at week 4 none of these patients experienced virologic relapse after treatment cessation. In patients who received triple therapy, 67% and 37% had undetectable HCV-RNA at week 4 by CAP and ART, respectively. However, 18/31 (58%) eligible patients for shortened treatment based on CAP had detectable HCV-RNA by ART at week 4. Again, relapse was not observed in these patients. CONCLUSIONS: Lower rates of undetectable HCV-RNA at week 4 were observed with ART compared to CAP in patients treated with dual and triple therapies. For ART, detectable <12IU/ml HCV-RNA levels at week 4 may be sufficient as part of the criteria used for selecting patients who receive a shortened treatment regimen.

Deep sequencing reveals mutagenic effects of ribavirin during monotherapy of hepatitis C virus genotype 1-infected patients.

The preeminent mode of action of the broad-spectrum antiviral nucleoside ribavirin in the therapy of chronic hepatitis C is currently unresolved. Particularly under contest are possible mutagenic effects of ribavirin that may lead to viral extinction by lethal mutagenesis of the hepatitis C virus (HCV) genome. We applied ultradeep sequencing to determine ribavirin-induced sequence changes in the HCV coding region (nucleotides [nt] 330 to 9351) of patients treated with 6-week ribavirin monotherapy (n = 6) in comparison to placebo (n = 6). Baseline HCV RNA levels maximally declined on average by -0.8 or -0.1 log10 IU/ml in ribavirin- versus placebo-treated patients. No general increase in rates of nucleotide substitutions in ribavirin-treated patients was observed. However, more HCV genome positions with high G-to-A and C-to-U transition rates were detected between baseline and treatment week 6 in ribavirin-treated patients in comparison to placebo-treated patients (rate of 0.0041 transitions per base pair versus rate of 0.0022 transitions per base pair; P = 0.049). Similarly, the sensitive detection of low-frequency minority variants by statistical filtering indicated significantly more positions with G-to-A and C-to-U transitions in ribavirin-treated patients than in placebo-treated patients (rate of 0.0331 transitions versus rate of 0.0186 transitions per G/C-containing position at baseline; P = 0.018). In contrast, non-ribavirin-associated A-to-G and U-to-C transitions were not enriched in the ribavirin group (P = 0.152). We conclude that ribavirin exerts a mutagenic effect on the virus in patients with chronic hepatitis C by facilitating G-to-A and C-to-U nucleotide transitions.

Second-generation Cobas AmpliPrep/Cobas TaqMan HCV quantitative test for viral load monitoring: a novel dual-probe assay design.

Hepatitis C virus (HCV) RNA viral load (VL) monitoring is a well-established diagnostic tool for the management of chronic hepatitis C patients. HCV RNA VL results are used to make treatment decisions with the goal of therapy to achieve an undetectable VL result. Therefore, a sensitive assay with high specificity in detecting and accurately quantifying HCV RNA across genotypes is critical. Additionally, a lower sample volume requirement is desirable for the laboratory and the patient. This study evaluated the performance characteristics of a second-generation real-time PCR assay, the Cobas AmpliPrep/Cobas TaqMan HCV quantitative test, version 2.0 (CAP/CTM HCV test, v2.0), designed with a novel dual-probe approach and an optimized automated extraction and amplification procedure. The new assay demonstrated a limit of detection and lower limit of quantification of 15 IU/ml across all HCV genotypes and was linear from 15 to 100,000,000 IU/ml with high accuracy (<0.2-log(10) difference) and precision (standard deviation of 0.04 to 0.22 log(10)). A specificity of 100% was demonstrated with 600 HCV-seronegative specimens without cross-reactivity or interference. Correlation to the Cobas AmpliPrep/Cobas TaqMan HCV test (version 1) was good (n = 412 genotype 1 to 6 samples, R(2) = 0.88; R(2) = 0.94 without 105 genotype 4 samples). Paired plasma and serum samples showed similar performance (n = 25, R(2) = 0.99). The sample input volume was reduced from 1 to 0.65 ml in the second version. The CAP/CTM HCV test, v2.0, demonstrated excellent performance and sensitivity across all HCV genotypes with a smaller sample volume. The new HCV RNA VL assay has performance characteristics that make it suitable for use with currently available direct-acting antiviral agents.

Combined effects of different interleukin-28B gene variants on the outcome of dual combination therapy in chronic hepatitis C virus type 1 infection.

UNLABELLED: In patients with chronic hepatitis C virus (HCV) infection, several variants of the interleukin-28B (IL28B) gene have been shown to correlate significantly with a sustained virologic response (SVR). Recent evidence shows that determination of one single IL28B polymorphism, rs12979860, is sufficient for predicting treatment outcome. We examined whether the combined determination of the IL28B single-nucleotide polymorphisms (SNPs), rs12979860, rs8099917, rs12980275, and rs8103142, might improve the prediction of SVR in patients with HCV. In the study cohort, 54% of 942 patients with chronic HCV type 1 infection had SVR. The IL28B SNPs, rs12979860CC and rs8099917TT, correlated significantly with SVR (68% and 62%). The SNPs, rs12980275 and rs8103142, were in strong linkage disequilibrium with rs12979860 and were not included in further analysis. In homozygous carriers of the rs12979860 responder allele C, additional genotyping of the rs8099917 SNP had no effect on response prediction, whereas in carriers of the rs12979860 nonresponder allele, the rs8099917 SNP improved the response prediction. In heterozygous carriers of the rs12979860 nonresponder T allele, SVR rates were 55% in the presence of the rs8099917TT genotype and 40% in patients carrying the rs8099917 TG or GG genotype. Analysis of an independent confirmation cohort of 377 HCV type 1-infected patients verified the significant difference in SVR rates between the combined genotypes, rs12979860CT/rs8099917TT and rs12979860CT/rs8099917TG (38% versus 21%; P = 0.018). CONCLUSION: Treatment outcome prediction could not be improved in homozygous carriers of the IL28B rs12979860 C responder allele by the additional determination of the rs8099917 SNP. There is evidence that a significant proportion of heterozygous carriers of the rs12979860 T nonresponder allele can profit with respect to SVR prediction by further determination of the rs8099917 SNP. (HEPATOLOGY 2012;55:1700-1710).

Virologic escape during danoprevir (ITMN-191/RG7227) monotherapy is hepatitis C virus subtype dependent and associated with R155K substitution.

Danoprevir is a hepatitis C virus (HCV) NS3/4A protease inhibitor that promotes multi-log(10) reductions in HCV RNA when administered as a 14-day monotherapy to patients with genotype 1 chronic HCV. Of these patients, 14/37 experienced a continuous decline in HCV RNA, 13/37 a plateau, and 10/37 a rebound. The rebound and continuous-decline groups experienced similar median declines in HCV RNA through day 7, but their results diverged notably at day 14. Plateau group patients experienced a lesser, but sustained, median HCV RNA decline. Baseline danoprevir susceptibility was similar across response groups but was reduced significantly at day 14 in the rebound group. Viral rebound in genotype 1b was uncommon (found in 2/23 patients). Population-based sequence analysis of NS3 and NS4A identified treatment-emergent substitutions at four amino acid positions in the protease domain of NS3 (positions 71, 155, 168, and 170), but only two (155 and 168) were in close proximity to the danoprevir binding site and carried substitutions that impacted danoprevir potency. R155K was the predominant route to reduced danoprevir susceptibility and was observed in virus isolated from all 10 rebound, 2/13 plateau, and 1/14 continuous-decline patients. Virus in one rebound patient additionally carried partial R155Q and D168E substitutions. Treatment-emergent substitutions in plateau patients were less frequently observed and more variable. Single-rebound patients carried virus with R155Q, D168V, or D168T. Clonal sequence analysis and drug susceptibility testing indicated that only a single patient displayed multiple resistance pathways. These data indicate the ascendant importance of R155K for viral escape during danoprevir treatment and may have implications for the clinical use of this agent.

Importance of IL28B gene polymorphisms in hepatitis C virus genotype 2 and 3 infected patients.

BACKGROUND & AIMS: Genetic variation in the interleukin 28B (IL28B) gene has been associated with the response to interferon-alfa/ribavirin therapy in hepatitis C virus (HCV) genotype 1-infected patients. The importance of three IL28B single nucleotide polymorphisms (rs8099917, rs12980275 and rs12979860) for HCV genotype 2/3-infected patients is unknown. METHODS: In patients with chronic hepatitis C genotype 2/3 (n=267), IL28B host genotypes (rs8099917, rs12980275 and rs12979860) were analyzed for associations with sustained virologic response (SVR) to antiviral therapy with (pegylated) interferon-alfa and ribavirin and with respect to epidemiological, biochemical, and virological parameters. For comparison, hepatitis C genotype 1 patients (n=378) and healthy controls (n=200) were included. RESULTS: The rs12979860 CC genotype, lower age, and genotype 2 were significantly associated with SVR in HCV genotype 2/3-infected patients (p=0.01, p=0.03 and p=0.03, respectively). No association was observed for rs8099917 and rs12980275. In addition, an SVR in patients with rapid virologic response (RVR) was associated with the rs12979860 CC genotype (p=0.05), while for non-RVR no association was found. Furthermore, a significant association with a higher baseline viral load was observed for all three IL28B genotypes in genotype 1/2/3-infected patients. Finally, increasing frequencies of the rs12979860 CC genotypes were observed in genotype 1- (33.9%), genotype 3- (38.9%), and genotype 2-infected (51.9%) patients in comparison with healthy controls (49.0%) (p<0.01). CONCLUSIONS: In genotype 2/3-infected patients, rs12979860 was significantly associated with SVR. The frequency of the rs12979860 CC genotype is lower in HCV genotype 1 vs. genotype 2/3 patients. All major IL28B genotypes are associated with HCV-RNA concentration.

HVR-1 heterogeneity during treatment with telaprevir with or without pegylated interferon alfa-2a.

BACKGROUND: The extensive heterogeneity of the hypervariable region-1 (HVR-1) of hepatitis C virus (HCV) evidences the high genetic flexibility of HCV and was shown to be associated with virologic response to interferon-α-based therapies. However, the evolution of HVR-1 heterogeneity during treatment with directly acting antivirals has not been studied. METHODS: Clonal sequence analysis of HVR-1 quasispecies in the serum of patients who were treated with telaprevir (3 × 750 mg/day) alone, telaprevir plus pegylated interferon-α-2a (pegIFN-α-2a), or pegIFN-α-2a plus placebo for 14 days was performed. HVR-1 heterogeneity, expressed as Shannon complexity and Hamming distance, was analyzed with virologic response and with the emergence of variants associated with resistance to telaprevir. RESULTS: HVR-1 heterogeneity at baseline was not associated with response to telaprevir-based therapy (Shannon complexity 0.34 vs. 0.55, p = 0.38; Hamming distance 0.15 vs. 0.23, p = 0.51; for patients with or without viral breakthrough, respectively). No significant changes in HVR-1 complexity were observed from baseline to day 4 of therapy in patients in whom a continued decline in HCV RNA was observed (Shannon complexity = 0.55 vs. 0.51, p = 0.67; Hamming distance = 0.23 vs. 0.25, p = 0.81, respectively). This was similar in patients with viral breakthrough associated with telaprevir-resistant variants (Shannon complexity = 0.34 vs. 0.42, p = 0.68; Hamming distance = 0.15 vs. 0.2, p = 0.50, at baseline and day 4, respectively). CONCLUSIONS: Baseline and on-treatment HVR-1 heterogeneity are not associated with early viral response to telaprevir-based therapy.

Characterization of resistance to the protease inhibitor boceprevir in hepatitis C virus-infected patients.

UNLABELLED: Boceprevir is a hepatitis C virus (HCV) nonstructural protein (NS) 3/4A protease inhibitor that is currently being evaluated in combination with peginterferon alfa-2b and ribavirin in phase 3 studies. The clinical resistance profile of boceprevir is not characterized in detail so far. The NS3 protease domain of viral RNA was cloned from HCV genotype 1-infected patients (n = 22). A mean number of 47 clones were sequenced before, at the end, and after treatment with 400 mg boceprevir twice or three times daily for 14 days for genotypic, phenotypic, and viral fitness analysis. At the end of treatment, a wild-type an NS3 protease sequence was observed with a mean frequency of 85.9%. In the remaining isolates, five previously observed resistance mutations (V36M/A, T54A/S, R155K/T, A156S, V170A) and one mutation (V55A) with unknown resistance to boceprevir were detected either alone or in combination. Phenotypic analysis in the HCV replicon assay showed low (V36G, T54S, R155L; 3.8- to 5.5-fold 50% inhibitory concentration [IC(50)]), medium (V55A, R155K, V170A, T54A, A156S; 6.8- to 17.7-fold IC(50)) and high level (A156T; >120-fold IC(50)) resistance to boceprevir. The overall frequency of resistant mutations and the level of resistance increased with greater declines in mean maximum HCV RNA levels. Two weeks after the end of treatment, the frequency of resistant variants declined and the number of wild-type isolates increased to 95.5%. With the exception of V36 and V170 variants all resistant mutations declined by more than 50%. Mathematical modeling revealed impaired replicative fitness for all single mutations, whereas for combined mutations a relative increase of replication efficiency was suggested. CONCLUSION: During boceprevir monotherapy, resistance mutations at six positions within the NS3 protease were detected by way of clonal sequence analysis. All mutations are associated with reduced replicative fitness estimated by mathematical modeling and show cross-resistance to telaprevir.

Hepatitis C virus genotype 1 and 2 recombinant genomes and the phylogeographic history of the 2k/1b lineage.

Recombination is an important driver of genetic diversity, though it is relatively uncommon in hepatitis C virus (HCV). Recent investigation of sequence data acquired from HCV clinical trials produced twenty-one full-genome recombinant viruses belonging to three putative inter-subtype forms 2b/1a, 2b/1b, and 2k/1b. The 2k/1b chimera is the only known HCV circulating recombinant form (CRF), provoking interest in its genetic structure and origin. Discovered in Russia in 1999, 2k/1b cases have since been detected throughout the former Soviet Union, Western Europe, and North America. Although 2k/1b prevalence is highest in the Caucasus mountain region (i.e., Armenia, Azerbaijan, and Georgia), the origin and migration patterns of CRF 2k/1b have remained obscure due to a paucity of available sequences. We assembled an alignment which spans the entire coding region of the HCV genome containing all available 2k/1b sequences (>500 nucleotides; n = 109) sampled in ninteen countries from public databases (102 individuals), additional newly sequenced genomic regions (from 48 of these 102 individuals), unpublished isolates with newly sequenced regions (5 additional individuals), and novel complete genomes (2 additional individuals) generated in this study. Analysis of this expanded dataset reconfirmed the monophyletic origin of 2k/1b with a recombination breakpoint at position 3,187 (95% confidence interval: 3,172-3,202; HCV GT1a reference strain H77). Phylogeography is a valuable tool used to reveal viral migration dynamics. Inference of the timed history of spread in a Bayesian framework identified Russia as the ancestral source of the CRF 2k/1b clade. Further, we found evidence for migration routes leading out of Russia to other former Soviet Republics or countries under the Soviet sphere of influence. These findings suggest an interplay between geopolitics and the historical spread of CRF 2k/1b.

Ombitasvir/paritaprevir/ritonavir + dasabuvir + ribavirin in HCV genotype 1 infected patients who failed previous protease inhibitor therapy.

AIM OF THE STUDY: Combination of ombitasvir/paritaprevir/ritonavir + dasabuvir ± ribavirin (3DDA±RBV) therapy is shown to be effective in HCV genotype 1 (GT1) infected patients. However, sparse data exist in patients who failed previous boceprevir or telaprevir based therapies. Real life efficacy and safety of this combination were evaluated in HCV GT1b infected patients (mostly cirrhotics) with compensated liver disease who failed previous boceprevir or telaprevir based therapies more than a year before. MATERIAL AND METHODS: Data of previous protease inhibitor failure patients, treated with 3DAA+RBV for 12 weeks (GT1b and/or non-cirrhotics) or 24 weeks (non-GT1b cirrhotics), were retrospectively collected. RESULTS: Population characteristics: boceprevir/telaprevir-failure: 82/45, GT1b: 117, cirrhotic: 111 (87.4%). SVR12/24 was observed in 103/105 patients (98.1%) of those who reached either time point. Four SAEs reported: one death due to myocardial infarction, another due to recurrent hepatocellular carcinoma after achieving SVR12, two hospitalizations (elevation of transaminases, pneumonia). Grade ≥ 3 AEs or laboratory abnormalities were reported in < 10% of patients; they were transient in all patients. No early discontinuation of drugs due to SAE has been reported. CONCLUSIONS: One year after previous failure of boceprevir or telaprevir based therapy, 12 weeks of 3DAA+RBV combination in HCV GT1b infected patients is similarly effective and safe as in those with no previous HCV therapy, even in the presence of cirrhosis. These findings might be of particular interest in settings where alternative therapies for such patients are not available or not affordable.

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

Triple therapy of chronic hepatitis C virus (HCV) infection with boceprevir (BOC) or telaprevir (TVR) leads to virologic failure in many patients which is often associated with the selection of resistance-associated variants (RAVs). These resistance profiles are of importance for the selection of potential rescue treatment options. In this study, we sequenced baseline NS3 RAVs population-based and investigated the sensitivity of NS3 phenotypes in an HCV replicon assay together with clinical factors for a prediction of treatment response in a cohort of 165 German and Swiss patients treated with a BOC or TVR-based triple therapy. Overall, the prevalence of baseline RAVs was low, although the frequency of RAVs was higher in patients with virologic failure compared to those who achieved a sustained virologic response (SVR) (7% versus 1%, P = 0.06). The occurrence of RAVs was associated with a resistant NS3 quasispecies phenotype (P<0.001), but the sensitivity of phenotypes was not associated with treatment outcome (P = 0.2). The majority of single viral and host predictors of SVR was only weakly associated with treatment response. In multivariate analyses, low AST levels, female sex and an IFNL4 CC genotype were independently associated with SVR. However, a combined analysis of negative predictors revealed a significantly lower overall number of negative predictors in patients with SVR in comparison to individuals with virologic failure (P<0.0001) and the presence of 2 or less negative predictors was indicative for SVR. These results demonstrate that most single baseline viral and host parameters have a weak influence on the response to triple therapy, whereas the overall number of negative predictors has a high predictive value for SVR.