Prevalence of resistance-associated substitutions and retreatment of patients failing a glecaprevir/pibrentasvir regimen.

OBJECTIVES: To investigate resistance-associated substitutions (RASs) as well as retreatment efficacies in a large cohort of European patients with failure of glecaprevir/pibrentasvir. METHODS: Patients were identified from three European Resistance Reference centres in Spain, Italy and Germany. Sequencing of NS3, NS5A and NS5B was conducted and substitutions associated with resistance to direct antiviral agents were analysed. Clinical and virological parameters were documented retrospectively and retreatment efficacies were evaluated. RESULTS: We evaluated 90 glecaprevir/pibrentasvir failures [3a (n = 36), 1a (n = 23), 2a/2c (n = 20), 1b (n = 10) and 4d (n = 1)]. Ten patients were cirrhotic, two had previous exposure to PEG-interferon and seven were coinfected with HIV; 80 had been treated for 8 weeks. Overall, 31 patients (34.4%) failed glecaprevir/pibrentasvir without any NS3 or NS5A RASs, 62.4% (53/85) showed RASs in NS5A, 15.6% (13/83) in NS3 and 10% (9/90) in both NS5A and NS3. Infection with HCV genotypes 1a and 3a was associated with a higher prevalence of NS5A RASs. Patients harbouring two (n = 34) or more (n = 8) RASs in NS5A were frequent. Retreatment was initiated in 56 patients, almost all (n = 52) with sofosbuvir/velpatasvir/voxilaprevir. The overall sustained virological response rate was 97.8% in patients with end-of-follow-up data available. CONCLUSIONS: One-third of patients failed glecaprevir/pibrentasvir without resistance. RASs in NS5A were more prevalent than in NS3 and were frequently observed as dual and triple combination patterns, with a high impact on NS5A inhibitor activity, particularly in genotypes 1a and 3a. Retreatment of glecaprevir/pibrentasvir failures with sofosbuvir/velpatasvir/voxilaprevir achieved viral suppression across all genotypes.

A Hyper-Glycosylation of HBV Surface Antigen Correlates with HBsAg-Negativity at Immunosuppression-Driven HBV Reactivation in Vivo and Hinders HBsAg Recognition in Vitro.

Immune-suppression driven Hepatitis B Virus (HBV)-reactivation poses serious concerns since it occurs in several clinical settings and can result in severe forms of hepatitis. Previous studies showed that HBV strains, circulating in patients with HBV-reactivation, are characterized by an enrichment of immune-escape mutations in HBV surface antigen (HBsAg). Here, we focused on specific immune-escape mutations associated with the acquisition of N-linked glycosylation sites in HBsAg (NLGSs). In particular, we investigated profiles of NLGSs in 47 patients with immunosuppression-driven HBV-reactivation and we evaluated their impact on HBsAg-antigenicity and HBV-replication in vitro. At HBV-reactivation, despite a median serum HBV-DNA of 6.7 [5.3-8.0] logIU/mL, 23.4% of patients remained HBsAg-negative. HBsAg-negativity at HBV-reactivation correlated with the presence of >1 additional NLGSs (p < 0.001). These NLGSs are located in the major hydrophilic region of HBsAg (known to be the target of antibodies) and resulted from the single mutation T115N, T117N, T123N, N114ins, and from the triple mutant S113N+T131N+M133T. In vitro, NLGSs strongly alter HBsAg antigenic properties and recognition by antibodies used in assays for HBsAg-quantification without affecting HBsAg-secretion and other parameters of HBV-replication. In conclusion, additional NLGSs correlate with HBsAg-negativity despite HBV-reactivation, and hamper HBsAg-antigenicity in vitro, supporting the role of NGSs in immune-escape and the importance of HBV-DNA for a proper diagnosis of HBV-reactivation.

Hepatitis B virus reactivation sustained by a hepatitis B virus surface antigen immune-escape mutant isolate in a patient who was hepatitis B core antibody positive during treatment with sofosbuvir and velpatasvir for hepatitis C virus infection: a case report.

BACKGROUND: Although several cases of hepatitis B virus reactivation have been described in patients with a history of hepatitis B virus infection while undergoing treatment for hepatitis C virus infection with direct acting antivirals, the question of whether hepatitis B virus surface antigen immune-escape mutations might play a role has not been addressed so far. CASE PRESENTATION: We report a case of hepatitis B virus reactivation in a Caucasian patient infected with hepatitis C virus during treatment with sofosbuvir and velpatasvir. A 50-year-old man with a genotype 1a hepatitis C virus infection was considered for therapy. His serological profile was hepatitis B virus surface antigen-negative, hepatitis B virus core antibody-positive, hepatitis B virus surface antibody-negative, and anti-hepatitis D virus-positive. The detection of hepatitis B virus deoxyribonucleic acid (DNA) indicated active viral replication during the direct acting antiviral treatment that spontaneously returned to undetectable levels after treatment completion. Starting from week 12 after the end of treatment, hepatitis B virus surface antibody titers and hepatitis B virus e antibody developed. Sequencing analysis revealed the hepatitis B virus genotype D3 and the presence of two relevant immune-escape mutations (P120S and T126I) in the major hydrophilic region by analyzing the S region. CONCLUSIONS: We speculate that the presence of the hepatitis B virus surface antigen mutations, endowed with the enhanced capability to elude the immune response, could play a role in hepatitis B virus reactivation. This observation confirms that occult hepatitis B infection should also be carefully monitored, through surveillance of the hepatitis B virus viral load before and during direct acting antiviral treatment of hepatitis C virus.

Establishment of a Seronegative Occult Infection With an Active Hepatitis B Virus Reservoir Enriched of Vaccine Escape Mutations in a Vaccinated Infant After Liver Transplantation.

We describe the establishment of a seronegative occult hepatitis B virus (HBV) infection (OBI) in a successfully vaccinated infant who underwent liver transplantation from an donor positive for antibody to hepatitis B core antigen (anti-HBc). The use of highly sensitive droplet digital polymerase chain reaction assays revealed a not negligible and transcriptionally active intrahepatic HBV reservoir (circular covalently closed DNA, relaxed circular DNA, and pregenomic RNA: 5.6, 2.4, and 1.1 copies/1000 cells, respectively), capable to sustain ongoing viral production and initial liver damage. Next-generation sequencing revealed a peculiar enrichment of hepatitis B surface antigen vaccine-escape mutations that could have played a crucial role in OBI transmission. This clinical case highlights the pathobiological complexity and the diagnostic challenges underlying OBI.

NS5A Gene Analysis by Next Generation Sequencing in HCV Nosocomial Transmission Clusters of HCV Genotype 1b Infected Patients.

Background: The aim of the study was to investigate the intra-host variability through next-generation-sequencing (NGS) of the NS5A-gene in nosocomial transmission-clusters observed in two Italian hospitals among hepatitis C virus (HCV)-genotype-1b infected patients. Methods: HCV-sequencing was performed by Sanger-sequencing (NS3 + NS5A + NS5B) and by NGS (NS5A, MiSeq-Illumina) in 15 HCV-1b infected patients [five acute with onco-hematologic-disease and 10 (4/6 acute/chronic) with ß-thalassemia]. Resistance-associated-substitutions (RAS) were analysed by Geno2pheno-algorithm. Nucleotide-sequence-variability (NSV, at 1%, 2%, 5%, 10% and 15% NGS-cutoffs) and Shannon entropy were estimated. Phylogenetic analysis was performed by Mega6-software and Bayesian-analysis. Results: Phylogenetic analysis showed five transmission-clusters: one involving four HCV-acute onco-hematologic-patients; one involving three HCV-chronic ß-thalassemia-patients and three involving both HCV-acute and chronic ß-thalassemia-patients. The NS5A-RAS Y93H was found in seven patients, distributed differently among chronic/acute patients involved in the same transmission-clusters, independently from the host-genetic IL-28-polymorphism. The intra-host NSV was higher in chronic-patients versus acute-patients, at all cutoffs analyzed (p < 0.05). Even though Shannon-entropy was higher in chronic-patients, significantly higher values were observed only in chronic ß-thalassemia-patients versus acute ß-thalassemia-patients (p = 0.01). Conclusions: In nosocomial HCV transmission-clusters, the intra-host HCV quasispecies divergence in patients with acute-infection was very low in comparison to that in chronic-infection. The NS5A-RAS Y93H was often transmitted and distributed differently within the same transmission-clusters, independently from the IL-28-polymorphism.

Reactivation of Hepatitis B Virus With Immune-Escape Mutations After Ocrelizumab Treatment for Multiple Sclerosis.

Ocrelizumab is an anti-CD20 monoclonal antibody for the treatment of multiple sclerosis (MS) that is closely related to rituximab. We describe a case of hepatitis B virus (HBV) reactivation in an MS patient with resolved HBV infection receiving ocrelizumab. HBV reactivation was monitored with HBV-DNA and HBV surface antigen periodic assessment. Anti-HBV treatment with entecavir was started after HBV-DNA detection. Ocrelizumab can reactivate viral replication in patients with resolved HBV infection. HBV reactivation monitoring seems an effective and safe option for the management of these patients. More studies are needed to assess the optimal management of HBV reactivation in MS patients on ocrelizumab treatment.

Prevalence of Single and Multiple Natural NS3, NS5A and NS5B Resistance-Associated Substitutions in Hepatitis C Virus Genotypes 1-4 in Italy.

Natural resistance-associated substitutions (RASs) are reported with highly variable prevalence across different HCV genotypes (GTs). Frequency of natural RASs in a large Italian real-life cohort of patients infected with the 4 main HCV-GTs was investigated. NS3, NS5A and NS5B sequences were analysed in 1445 HCV-infected DAA-naïve patients. Sanger-sequencing was performed by home-made protocols on 464 GT1a, 585 GT1b, 92 GT2c, 199 GT3a, 16 GT4a and 99 GT4d samples. Overall, 20.7% (301/1455) of patients showed natural RASs, and the prevalence of multiclass-resistance was 7.3% (29/372 patients analysed). NS3-RASs were particularly common in GT1a and GT1b (45.2-10.8%, respectively), mainly due to 80K presence in GT1a (17%). Almost all GTs showed high prevalence of NS5A-RASs (range: 10.2-45.4%), and especially of 93H (5.1%). NS5A-RASs with fold-change >100x were detected in 6.8% GT1a (30H/R-31M-93C/H), 10.3% GT1b (31V-93H), 28.4% GT2c (28C-31M-93H), 8.5% GT3a (30K-93H), 45.5% GT4a (28M-30R-93H) and 3.8% GT4d (28V-30S-93H). Sofosbuvir RAS 282T was never detected, while the 159F and 316N RASs were found in GT1b (13.4-19.1%, respectively). Natural RASs are common in Italian patients infected with HCV-GTs 1-4. High prevalence of clinically-relevant RASs (such as Y93H) supports the appropriateness of HCV resistance-test to properly guide DAA-based therapy.

HCV very late relapse following an atypical viral kinetics in a HIV patient treated for hepatitis C with direct-acting antivirals.

Direct-acting antivirals (DAAs) for the treatment of HCV have dramatically increased the rate of sustained virological response: patients not achieving sustained virological response represent a challenge and rates of late recurrent viremia are very low. We describe here the first case of a very late HCV relapse, following an atypical kinetics (characterized by a spontaneous but transient HCV clearance after an early virological relapse), in a HIV co-infected patient treated with DAAs. Optimal adherence to the therapy was well documented and a phylogenetic analysis ruled out a possible reinfection from a different HCV strain. In conclusion, our case underlines the importance of a long follow-up (> 48 weeks) after DAAs therapies in HCV-HIV co-infected patients who might benefit the most from a very rigorous virological surveillance.

Optimal cure rate by personalized HCV regimens in real-life: a proof-of-concept study.

BACKGROUND: Pretreatment evaluation of HCV-infected patients is a complex interplay between multiple clinical and viral parameters, leading to a tailored approach that may bring real-life sustained virological response (SVR) rates close to 98%-99%. OBJECTIVES: As proof-of-concept, we evaluated the efficacy of all-oral direct-acting antiviral (DAA) regimens in patients whose personalization included pre-therapy evaluation of natural resistance-associated substitutions (RASs), in addition to international guideline recommendations. METHODS: One hundred and thirty-one patients who started a first-line all-oral DAA regimen between April 2015 and December 2016 were tested for baseline NS3 and NS5A RASs by Sanger sequencing. SVR12 was defined as HCV-RNA undetectability 12 weeks after treatment discontinuation. RESULTS: Compatibly with a real-life context, 74.0% (97 of 131) of patients presented ≥2 pretreatment risk factors for failure to achieve SVR12 (infection by GT-1a/GT-3a; cirrhosis; previous treatment experience; HCV-RNA ≥800 000 IU/mL) and 33.6% had ≥3 risk factors. Natural RASs were frequently detected (32.1% prevalence), with substantial prevalence of NS5A RASs (15.3%), mostly represented by Y93H in GT-1b (3 of 36, 8.3%) and GT-3a (3 of 25, 12.0%) and F28C in GT-2c (2 of 11, 18.2%). Overall, personalized treatment led to 100% SVR12, even in those patients for whom treatment strategy was either strengthened (by ribavirin inclusion and/or duration increase) or simplified (by ribavirin exclusion and/or duration reduction), thanks to baseline RAS evaluation. CONCLUSIONS: Even with newer DAA regimens, an integrated interpretation of clinical and virological pretreatment parameters, including natural RASs, may play a relevant role in bringing SVR rates close to the highest achievable. Treatment tailoring can be foreseen in 'hard-to-treat' patients, but also in 'easy' patients with favourable indicators, whereby a simplification/shortening of recommended regimens can be indicated.

Implications of hepatitis C virus subtype 1a migration patterns for virus genetic sequencing policies in Italy.

BACKGROUND: In-depth phylogeographic analysis can reveal migration patterns relevant for public health planning. Here, as a model, we focused on the provenance, in the current Italian HCV subtype 1a epidemic, of the NS3 resistance-associated variant (RAV) Q80K, known to interfere with the action of NS3/4A protease inhibitor simeprevir. HCV1a migration patterns were analysed using Bayesian phylodynamic tools, capitalising on newly generated and publicly available time and geo-referenced NS3 encoding virus genetic sequence data. RESULTS: Our results showed that both immigration and local circulation fuel the current Italian HCV1a epidemic. The United States and European continental lineages dominate import into Italy, with the latter taking the lead from the 1970s onwards. Since similar migration patterns were found for Q80K and other lineages, no clear differentiation of the risk for failing simeprevir can be made between patients based on their migration and travel history. Importantly, since HCV only occasionally recombines, these results are readily transferable to the genetic sequencing policy concerning NS5A RAVs. CONCLUSIONS: The patient migration and travel history cannot be used to target only part of the HCV1a infected population for drug resistance testing before start of antiviral therapy. Consequently, it may be cost-effective to expand genotyping efforts to all HCV1a infected patients eligible for simeprevir-based therapies.

Multiclass HCV resistance to direct-acting antiviral failure in real-life patients advocates for tailored second-line therapies.

BACKGROUND & AIMS: Despite the excellent efficacy of direct-acting antivirals (DAA) reported in clinical trials, virological failures can occur, often associated with the development of resistance-associated substitutions (RASs). This study aimed to characterize the presence of clinically relevant RASs to all classes in real-life DAA failures. METHODS: Of the 200 virological failures that were analyzed in 197 DAA-treated patients, 89 with pegylated-interferon+ribavirin (PegIFN+RBV) and 111 without (HCV-1a/1b/1g/2/3/4=58/83/1/6/24/25; 56.8% treatment experienced; 65.5% cirrhotic) were observed. Sanger sequencing of NS3/NS5A/NS5B was performed by home-made protocols, at failure (N=200) and whenever possible at baseline (N=70). RESULTS: The majority of the virological failures were relapsers (57.0%), 22.5% breakthroughs, 20.5% non-responders. RAS prevalence varied according to IFN/RBV use, DAA class, failure type and HCV genotype/subtype. It was 73.0% in IFN group vs 49.5% in IFN free, with the highest prevalence of NS5A-RASs (96.1%), compared to NS3-RASs (75.9% with IFN, 70.5% without) and NS5B-RASs (66.6% with IFN, 20.4% without, in sofosbuvir failures). In the IFN-free group, RASs were higher in breakthrough/non-responders than in relapsers (90.5% vs 40.0%, P<.001). Interestingly, 57.1% of DAA IFN-free non-responders had a misclassified genotype, and 3/4 sofosbuvir breakthroughs showed the major-RAS-S282T, while RAS-L159F was frequently found in sofosbuvir relapsers (18.2%). Notably, 9.0% of patients showed also extra target RASs, and 47.4% of patients treated with ≥2 DAA classes showed multiclass resistance, including 11/11 NS3+NS5A failures. Furthermore, 20.0% of patients had baseline-RASs, which were always confirmed at failure. CONCLUSIONS: In our failure setting, RAS prevalence was remarkably high in all genes, with a partial exception for NS5B, whose limited resistance is still higher than previously reported. This multiclass resistance advocates for HCV resistance testing at failure, in all three genes for the best second-line therapeutic tailoring.

Consequences of inaccurate hepatitis C virus genotyping on the costs of prescription of direct antiviral agents in an Italian district.

Available commercial assays may yield inaccurate hepatitis C virus (HCV) genotype assignment in up to 10% of cases. We investigated the cost-effectiveness of re-evaluating HCV genotype by population sequencing, prior to choosing a direct acting antiviral (DAA) regimen. Between March and September 2015, HCV sequence analysis was performed in order to confirm commercial LiPA-HCV genotype (Versant® HCV Genotype 2.0) in patients eligible for treatment with DAAs. Out of 134 consecutive patients enrolled, sequencing yielded 21 (15.7%) cases of discordant results. For three cases of wrong genotype assignment, the putative reduction in efficacy was gauged between 15% and 40%. Among the eight cases for whom G1b was assigned by commercial assays instead of G1a, potentially suboptimal treatments would have been prescribed. Finally, for five patients with G1 and indeterminate subtype, the choice of regimens would have targeted the worst option, with a remarkable increase in costs, as in the case of the four mixed HCV infections for whom pan-genotypic regimens would have been mandatory. Precise assignment of HCV genotype and subtype by sequencing may, therefore, be more beneficial than expected, until more potent pan-genotypic regimens are available for all patients.

Multiple Hepatitis B Virus (HBV) Quasispecies and Immune-Escape Mutations Are Present in HBV Surface Antigen and Reverse Transcriptase of Patients With Acute Hepatitis B.

BACKGROUND: This study characterizes and defines the clinical value of hepatitis B virus (HBV) quasispecies with reverse transcriptase and HBV surface antigen (HBsAg) heterogeneity in patients with acute HBV infection. METHODS: Sixty-two patients with acute HBV infection (44 with genotype D infection and 18 with genotype A infection) were enrolled from 2000 to 2010. Plasma samples obtained at the time of the first examination were analyzed by ultradeep pyrosequencing. The extent of HBsAg amino acid variability was measured by Shannon entropy. RESULTS: Median alanine aminotransferase and serum HBV DNA levels were 2544 U/L (interquartile range, 1938-3078 U/L) and 5.88 log10 IU/mL (interquartile range, 4.47-7.37 log10 IU/mL), respectively. Although most patients serologically resolved acute HBV infection, only 54.1% developed antibody to HBsAg (anti-HBs). A viral population with ≥1 immune-escape mutation was found in 53.2% of patients (intrapatient prevalence range, 0.16%-100%). Notably, by Shannon entropy, higher genetic variability at HBsAg amino acid positions 130, 133, and 157 significantly correlated with no production of anti-HBs in individuals infected with genotype D (P < .05). Stop codons were detected in 19.3% of patients (intrapatient prevalence range, 1.6%-47.5%) and occurred at 11 HBsAg amino acid positions, including 172 and 182, which are known to increase the oncogenic potential of HBV.Finally, ≥1 drug resistance mutation was detected in 8.1% of patients (intrapatient prevalence range, 0.11%-47.5% for primary mutations and 10.5%-99.9% for compensatory mutations). CONCLUSIONS: Acute HBV infection is characterized by complex array of viral quasispecies with reduced antigenicity/immunogenicity and enhanced oncogenic potential. These viral variants may induce difficult-to-treat HBV forms; favor HBV reactivation upon iatrogenic immunosuppression, even years after infection; and potentially affect the efficacy of the current HBV vaccination strategy.

Hepatitis B surface antigen genetic elements critical for immune escape correlate with hepatitis B virus reactivation upon immunosuppression.

UNLABELLED: Hepatitis B virus (HBV) reactivation during immunosuppression can lead to severe acute hepatitis, fulminant liver failure, and death. Here, we investigated hepatitis B surface antigen (HBsAg) genetic features underlying this phenomenon by analyzing 93 patients: 29 developing HBV reactivation and 64 consecutive patients with chronic HBV infection (as control). HBsAg genetic diversity was analyzed by population-based and ultradeep sequencing (UDS). Before HBV reactivation, 51.7% of patients were isolated hepatitis B core antibody (anti-HBc) positive, 31.0% inactive carriers, 6.9% anti-HBc/anti-HBs (hepatitis B surface antibody) positive, 6.9% isolated anti-HBs positive, and 3.4% had an overt HBV infection. Of HBV-reactivated patients, 51.7% were treated with rituximab, 34.5% with different chemotherapeutics, and 13.8% with corticosteroids only for inflammatory diseases. In total, 75.9% of HBV-reactivated patients (vs. 3.1% of control patients; P<0.001) carried HBsAg mutations localized in immune-active HBsAg regions. Of the 13 HBsAg mutations found in these patients, 8 of 13 (M103I-L109I-T118K-P120A-Y134H-S143L-D144E-S171F) reside in a major hydrophilic loop (target of neutralizing antibodies [Abs]); some of them are already known to hamper HBsAg recognition by humoral response. The remaining five (C48G-V96A-L175S-G185E-V190A) are localized in class I/II-restricted T-cell epitopes, suggesting a role in HBV escape from T-cell-mediated responses. By UDS, these mutations occurred in HBV-reactivated patients with a median intrapatient prevalence of 73.3% (range, 27.6%-100%) supporting their fixation in the viral population as a predominant species. In control patients carrying such mutations, their median intrapatient prevalence was 4.6% (range, 2.5%-11.3%; P<0.001). Finally, additional N-linked glycosylation (NLG) sites within the major hydrophilic loop were found in 24.1% of HBV-reactivated patients (vs. 0% of chronic patients; P<0.001); 5 of 7 patients carrying these sites remained HBsAg negative despite HBV reactivation. NLG can mask immunogenic epitopes, abrogating HBsAg recognition by Abs. CONCLUSION: HBV reactivation occurs in a wide variety of clinical settings requiring immune-suppressive therapy, and correlates with HBsAg mutations endowed with enhanced capability to evade immune response. This highlights the need for careful patient monitoring in all immunosuppressive settings at reactivation risk and of establishing a prompt therapy to prevent HBV-related clinical complications.

Specific mutations in the C-terminus domain of HBV surface antigen significantly correlate with low level of serum HBV-DNA in patients with chronic HBV infection.

BACKGROUND: To define HBsAg-mutations correlated with different serum HBV-DNA levels in HBV chronically-infected drug-naive patients. METHODS: This study included 187 patients stratified into the following ranges of serum HBV-DNA:12-2000 IU/ml, 2000-100,000 IU/ml, and >100,000 IU/ml. HBsAg-mutations were associated with HBV-DNA levels by applying a Bayesian-Partitional-Model and Fisher-exact test. Mutant and wild-type HBV genotype-D genomes were expressed in Huh7 cells and HBsAg-production was determined in cell-supernatants at 3 days-post-transfection. RESULTS: Specific HBsAg-mutations (M197T,-S204N-Y206C/H-F220L) were significantly correlated with serum HBV-DNA <2000 IU/ml (posterior-probability>90%, P < 0.05). The presence of Y206C/H and/or F220L was also associated with lower median (IQR) HBsAg-levels and lower median (IQR) transaminases (for HBsAg:250[115-840] IU/ml for Y206C/H and/or F220L versus 4300[640-11,838] IU/ml for wild-type, P = 0.023; for ALT:28[21-40] IU/ml versus 53[34-90] IU/ml, P < 0.001). These mutations were localized in the HBsAg C-terminus, known to be involved in virion and/or HBsAg secretion. The co-occurrence of Y206C + F220L was found significant by cluster-analysis, (P = 0.02). In addition, in an in-vitro model Y206C + F220L determined a 2.8-3.3 fold-reduction of HBsAg-amount released in supernatants compared to single mutants and wt (Y206C + F220L = 5,679 IU/ml; Y206H = 16,305 IU/ml; F220L = 18,368 IU/ml; Y206C = 18,680 IU/ml; wt = 14,280 IU/ml, P < 0.05). CONCLUSIONS: Specific HBsAg-mutations (compartmentalized in the HBsAg C-terminus) correlated with low-serum HBV-DNA and HBsAg-levels. These findings can be important to understand mechanisms underlying low HBV replicative potential including the inactive-carrier state.

Hepatitis C virus RNA levels at week-2 of telaprevir/boceprevir administration are predictive of virological outcome.

BACKGROUND: Triple therapy with telaprevir/boceprevir + pegylated-interferon+ribavirin can achieve excellent antiviral efficacy, but it can be burdened with resistance development at failure. AIMS: To evaluate kinetics of hepatitis C virus (HCV) RNA decay and early resistance development, in order to promptly identify patients at highest risk of failure to first generation protease inhibitors. METHODS: HCV-RNA was prospectively quantified in 158 patients receiving pegylated-interferon+ribavirin+telaprevir (N = 114) or+boceprevir (N = 44), at early time-points and during per protocol follow-up. Drug resistance was contextually evaluated by population sequencing. RESULTS: HCV-RNA at week-2 was significantly higher in patients experiencing virological failure to triple-therapy than in patients with sustained viral response (2.3 [1.9-2.8] versus 1.2 [0.3-1.7]log IU/mL, p < 0.001). A 100 IU/mL cut-off value for week-2 HCV-RNA had the highest sensitivity (86%) in predicting virological success. Indeed, 23/23 (100%) patients with undetectable HCV-RNA reached success, versus 26/34 (76.5%) patients with HCV-RNA<100 IU/mL, and only 11/31 (35.5%) with HCV-RNA > 100 IU/mL (p < 0.001). Furthermore, differently from failing patients, none of the patient with undetectable HCV-RNA at week-2 had baseline/early resistance. CONCLUSIONS: With triple therapy based on first generation protease inhibitors, suboptimal HCV-RNA decay at week-2 combined with early detection of resistance can help identifying patients with higher risk of virological failure, thus requiring a closer monitoring during therapy.