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Background: Hepatitis C virus (HCV) infection is common in persons who inject drugs (PWID)., Objective: To evaluate elbasvir-grazoprevir in treating HCV infection in PWID., Design: Randomized, placebo-controlled, double-blind trial. (ClinicalTrials.gov: NCT02105688)., Setting: Australia, Canada, France, Germany, Israel, the Netherlands, New Zealand, Norway, Spain, Taiwan, the United Kingdom, and the United States., Patients: 301 treatment-naive patients with chronic HCV genotype 1, 4, or 6 infection who were at least 80% adherent to visits for opioid agonist therapy (OAT)., Intervention: The immediate-treatment group (ITG) received elbasvir-grazoprevir for 12 weeks; the deferred-treatment group (DTG) received placebo for 12 weeks, no treatment for 4 weeks, then open-label elbasvir-grazoprevir for 12 weeks., Measurements: The primary outcome was sustained virologic response at 12 weeks (SVR12), evaluated separately in the ITG and DTG. Other outcomes included SVR24, viral recurrence or reinfection, and adverse events., Results: The SVR12 was 91.5% (95% CI, 86.8% to 95.0%) in the ITG and 89.5% (95% CI, 81.5% to 94.8%) in the active phase of the DTG. Drug use at baseline and during treatment did not affect SVR12 or adherence to HCV therapy. Among 18 patients with posttreatment viral recurrence through 24-week follow-up, 6 had probable reinfection. If the probable reinfections were assumed to be responses, SVR12 was 94.0% (CI, 89.8% to 96.9%) in the ITG. One patient in the ITG (1 of 201) and 1 in the placebo-phase DTG (1 of 100) discontinued treatment because of an adverse event., Limitation: These findings may not be generalizable to PWID who are not receiving OAT, nor do they apply to persons with genotype 3 infection, a common strain in PWID., Conclusion: Patients with HCV infection who were receiving OAT and treated with elbasvir-grazoprevir had high rates of SVR12, regardless of ongoing drug use. These results support the removal of drug use as a barrier to interferon-free HCV treatment for patients receiving OAT., Primary Funding Source: Merck & Co.

Grazoprevir (GZR) is a second-generation hepatitis C virus NS3/4A protease inhibitor. The aim of this study was to evaluate GZR plus ribavirin (RBV) in patients with HCV GT1 infection. Noncirrhotic, IL28B CC patients with HCV genotype 1 infection were randomized to GZR 100 mg once daily and RBV for 12 or 24 weeks. Patients in the 12-week arm with detectable HCV RNA at treatment week 4 (TW4) had treatment extended to 24 weeks (response-guided therapy, RGT). The primary endpoint was sustained virologic response (SVR12) at follow-up week 12 (HCV RNA <25 IU/mL) in the per-protocol (PP) population (excluding patients with important protocol deviations). Twenty-six patients were randomized and 22 were included in the PP population. SVR12 was 58.3% (7 of 12) and 90% (9 of 10) in the RGT and 24-week arms, respectively. Seven PP patients had virologic failure, including one patient in the 24-week arm who relapsed after follow-up week 12. All three breakthrough patients had wild-type (WT) virus at baseline and developed breakthrough at TW6 or TW12 with Y56H, A156T and D168A/N mutations. Of the five relapse patients, four had WT at baseline (at relapse three had WT and one had V55A and D168A), and one had S122A/T at baseline and S122T at relapse. There were no serious adverse events (AEs), discontinuations due to AEs or grade 3/4 elevations in total and/or direct bilirubin. Grazoprevir plus RBV was associated with a rapid and sustained suppression of HCV RNA. These results support further evaluation of grazoprevir-based regimens (NCT01716156; protocol P039)., (© 2016 John Wiley & Sons Ltd.)

Background and Aim: Vaniprevir is a macrocyclic hepatitis C virus (HCV) non-structural (NS)3/4A protease inhibitor. The objective of these phase 3 multicenter, open-label trials was to evaluate the safety and efficacy of vaniprevir + peginterferon alfa-2b + ribavirin (PR) in Japanese patients with HCV genotype (GT)1 infection who had previously failed treatment with interferon-based regimens., Methods: Japanese patients with chronic HCV GT1 were enrolled. In PN044, patients with previous relapse or virologic breakthrough were randomized to vaniprevir (300 mg twice daily) + PR for 12 weeks followed by PR for another 12 weeks (12-week arm) or vaniprevir + PR for 24 weeks (24-week arm). In PN045, patients with previous partial/null response received vaniprevir + PR for 24 weeks. The primary endpoint was sustained virologic response at 24 weeks after completing treatment (SVR 24 )., Results: In PN044 (n = 51), SVR 24 was 92.0% and 96.2% in the 12- and 24-week arms, respectively. In PN045 (n = 42), SVR 24 was 61.9% in all patients and 55.2% in previous null responders. In both studies, vaniprevir + PR was generally safe and well tolerated; the majority of adverse events were mild/moderate and included pyrexia, decreased hemoglobin, headache, nausea, pruritus, and decreased platelet count. Polymorphisms in the HCV NS3 gene at baseline (Y56, Q80, and V170) did not impact treatment outcome. Virologic failure was principally associated with the on-treatment emergence of R155 or D168 mutations., Conclusions: Vaniprevir + PR is an effective, well-tolerated treatment for Japanese patients with HCV GT1 infection who failed previous interferon-based treatment. ClinicalTrials.gov Identifier NCT01405937 and NCT01405560 (Protocols PN044 and PN045)., (© 2016 The Authors Journal of Gastroenterology and Hepatology published by Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Background: Vaniprevir is a potent macrocyclic hepatitis C virus (HCV) nonstructural protein 3/4A protease inhibitor. This phase III study evaluated the safety and efficacy of vaniprevir in combination with peginterferon alfa-2b and ribavirin (PR) for 24 weeks compared with PR alone for 48 weeks in treatment-naive Japanese patients with HCV genotype 1 infection., Methods: Treatment-naive Japanese patients with HCV genotype 1 infection were randomly assigned to receive vaniprevir (300 mg twice daily) plus PR for 12 weeks then PR alone for 12 weeks, vaniprevir (300 mg twice daily) plus PR for 24 weeks, or PR alone for 48 weeks. The primary end point was sustained virologic response 24 weeks after completion of treatment (SVR24)., Results: In total, 294 patients were randomly assigned to receive treatment. Most patients had HCV genotype 1b infection (98 %, 288 of 294 patients). SVR24 was achieved in 83.7, 84.5, and 55.1 % of the patients in the vaniprevir 12-week, vaniprevir 24-week, and control arms, respectively. The difference in SVR24 rates between each vaniprevir arm and the control arm was statistically significant (p < 0.001 for both). Relapse was commoner in the control arm (29.5 %) than in the vaniprevir arms (8.6 % and 10.5 % for the 12-week and 24-week arms, respectively). Commonly reported adverse events were generally similar across treatment arms, with the exception of an increase in the incidence of gastrointestinal adverse events such as nausea, diarrhea, and vomiting in patients receiving vaniprevir. These events were considered manageable., Conclusion: Vaniprevir is a valuable addition to the therapeutic options available to Japanese patients with HCV genotype 1 infection who are eligible for interferon-based treatment. CLINICALTRIALS., Gov Identifier: NCT01370642.

Background: The phase 2 C-SALVAGE study (Hepatitis C-Salvage Study for Patients who Failed DAA/PR Therapy) demonstrated a 96.2% sustained virologic response at 12 weeks (SVR12) rate using the NS3/4A protease inhibitor grazoprevir and the NS5A inhibitor elbasvir together with ribavirin in treatment-experienced patients with chronic hepatitis C virus (HCV) genotype 1 infection., Methods: C-SALVAGE was a prospective open-label trial of grazoprevir 100 mg once daily and elbasvir 50 mg once daily coadministered with weight-based ribavirin twice daily for 12 weeks in genotype 1-infected cirrhotic and noncirrhotic patients who had failed treatment with ≥ 4 weeks of pegylated interferon and ribavirin plus either boceprevir, telaprevir, or simeprevir. Although the primary efficacy outcome was SVR12, patients were also evaluated 24 weeks after cessation of study therapy. Population sequencing was performed at baseline and periodically in virologic failures throughout the 24-week posttherapy follow-up period., Results: SVR24 rates were 76 of 79 (96.2%) overall, with all 3 relapses occurring by posttherapy week 8. Every NS3 and NS5A variant detected at baseline reappeared at the time of relapse and persisted throughout the available follow-up period. NS3&#95;A156T emerged in virus from each patient at relapse, but rapidly disappeared over the ensuing 2 weeks in 2 patients. NS5A&#95;Y93H emerged in virus from 2 patients at relapse and persisted for the entire follow-up period., Conclusions: Grazoprevir and elbasvir with ribavirin for 12 weeks maintained HCV suppression for at least 24 weeks posttherapy without late relapses. Baseline resistance-associated variants (RAVs) stably reappeared at relapse in all 3 patients with virologic failure. NS5A&#95;RAVs emerging at relapse persisted for the full 24-week follow-up period. If confirmed, this finding could complicate retreatment of the small number of patients failing regimens containing an NS5A inhibitor., Clinical Trials Registration: NCT02105454., (© The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)

Background & Aims: The Phase-2 C-SALVAGE study evaluated an investigational interferon-free combination of grazoprevir (a NS3/4A protease inhibitor) and elbasvir (a NS5A inhibitor) with ribavirin for patients with chronic HCV genotype-1 infection who had failed licensed DAA-containing therapy., Methods: C-SALVAGE was an open-label study of grazoprevir 100 mg and elbasvir 50 mg QD with weight-based ribavirin BID for 12 weeks in cirrhotic and non-cirrhotic patients with chronic HCV genotype-1 infection who had not attained SVR after ⩾4 weeks of peginterferon and ribavirin plus either boceprevir, telaprevir, or simeprevir. Exclusion criteria included decompensated liver disease, hepatocellular carcinoma, and HIV or HBV co-infection. The primary efficacy outcome was SVR12 defined as a HCV RNA level below the assay limit of quantification 12 weeks after the end of treatment., Results: Of the 79 patients treated with ⩾1 dose of study drug, 66 (84%) patients had a history of virologic failure on a regimen containing a NS3/4A protease inhibitor; 12 of the other 13 patients discontinued prior treatment because of adverse experiences. At entry, 34 (43.6%) of 78 evaluable patients harbored NS3 RAVs. SVR12 rates were 76/79 (96.2%) overall, including 28/30 (93.3%) patients with genotype 1a infection, 63/66 (95.5%) patients with prior virologic failure, 43/43 (100%) patients without baseline RAVs, 31/34 (91.2%) patients with baseline NS3 RAVs, 6/8 (75.0%) patients with baseline NS5A RAVs, 4/6 (66.7%) patients with both baseline NS3 and RAVs, and 32/34 (94.1%) cirrhotic patients. None of the five reported serious adverse events were considered drug-related., Conclusions: Grazoprevir and elbasvir plus ribavirin for 12 weeks provides a promising new treatment option for patients after failure of triple therapy containing an earlier-generation protease inhibitor., (Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background: There is a high medical need for an interferon-free, all-oral, short-duration therapy for hepatitis C virus (HCV) that is highly effective across diverse patient populations, including patients with cirrhosis or previous null response to pegylated interferon (peginterferon) plus ribavirin (PR-null responders). We aimed to assess the efficacy, safety, and effective treatment duration of grazoprevir (an HCV NS3/4A protease inhibitor) combined with elbasvir (an HCV NS5A inhibitor) with or without ribavirin in patients with HCV genotype 1 infection with baseline characteristics of poor response., Methods: The C-WORTHY trial is a randomised, open-label phase 2 trial of grazoprevir plus elbasvir with or without ribavirin; here we report findings for two cohorts of previously untreated patients with cirrhosis (cohort 1) and those with previous PR-null response with or without cirrhosis (cohort 2) enrolled in part B of the study. Eligible patients were adults aged 18 years or older with chronic HCV genotype 1 infection and HCV RNA concentrations of 10 000 IU/mL or higher in peripheral blood. We randomly assigned patients to receive grazoprevir (100 mg daily) and elbasvir (50 mg daily) with or without ribavirin for 12 or 18 weeks. Randomisation was done centrally with an interactive voice response system; patients and study investigators were masked to treatment duration up to week 12 but not to treatment allocation. The primary endpoint was the proportion of patients achieving HCV RNA less than 25 IU/mL at 12 weeks after end of treatment (SVR12), assessed by COBAS TaqMan version 2.0. This study is registered with ClinicalTrials.gov, number NCT01717326., Findings: We describe findings for 253 patients enrolled in cohort 1 (n=123) or cohort 2 (n=130). In cohort 1, we randomly assigned 60 patients to the 12-week regimen (31 with ribavirin and 29 with no ribavirin) and 63 to the 18-week regimen (32 with ribavirin and 31 with no ribavirin); in cohort 2, we randomly assigned 65 patients to the 12-week regimen (32 with ribavirin and 33 with no ribavirin) and 65 to the 18-week regimen (33 with ribavirin and 32 with no ribavirin. High SVR12 rates were achieved irrespective of the use of ribavirin or extension of the treatment duration from 12 to 18 weeks; SVR12 rates ranged from 90% (95% CI 74-98; 28/31; cohort 1, 12 weeks, ribavirin-containing) to 100% (95% CI 89-100; 33/33; cohort 2, 18 weeks, ribavirin-containing). Among patients treated for 12 weeks with grazoprevir plus elbasvir without ribavirin, 97% (95% CI 82-100, 28/29) of patients in cohort 1 and 91% (76-98, 30/33) of patients in cohort 2 achieved SVR12. Adverse events reported in more than 10% of patients were fatigue (66 patients, 26% [95% CI 21-32]), headache (58 patients, 23% [95% CI 18-29]), and asthenia (35 patients, 14% [95% CI 10-19])., Interpretation: Treatment with grazoprevir plus elbasvir, both with and without ribavirin and for both 12 and 18 weeks' treatment duration, showed high rates of efficacy in previously untreated patients with cirrhosis and previous PR-null responders with and without cirrhosis. These results support the phase 3 development of grazoprevir plus elbasvir., Funding: Merck & Co, Inc., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Both hepatitis C virus (HCV) mono-infected and HIV/HCV co-infected patients are in need of safe, effective, all-oral HCV regimens. In a phase 2 study we aimed to assess the efficacy and safety of grazoprevir (MK-5172; HCV NS3/4A protease inhibitor) and two doses of elbasvir (MK-8742; HCV NS5A inhibitor) in patients with HCV mono-infection and HIV/HCV co-infection., Methods: The C-WORTHY study is a phase 2, multicentre, randomised controlled trial of grazoprevir plus elbasvir with or without ribavirin in patients with HCV; here, we report findings for previously untreated (genotype 1) patients without cirrhosis who were HCV mono-infected or HIV/HCV co-infected. Eligible patients were previously untreated adults aged 18 years or older with chronic HCV genoype 1 infection and HCV RNA at least 10 000 IU/mL in peripheral blood without evidence of cirrhosis, hepatocellular carcinoma, or decompensated liver disease. In part A of the study we randomly assigned HCV-mono-infected patients to receive 12 weeks of grazoprevir (100 mg) plus elbasvir (20 mg or 50 mg) with or without ribavirin (arms A1-3); in part B we assigned HCV-mono-infected patients to 8 or 12 weeks of grazoprevir (100 mg) plus elbasvir (50 mg) with or without ribavirin (arms B1-3) and HIV/HCV co-infected patients to 12 weeks of therapy with or without ribavirin. The primary endpoint was the proportion of patients achieving HCV RNA less than 25 IU/mL 12 weeks after end of treatment (SVR12). Randomisation was by presence or absence of ribavirin, 8 or 12 weeks of treatment, and dosage of elbasvir. Patients were stratified by gentoype 1a versus 1b. The patients, investigators, and study site personnel were masked to treatment group assignements but the funder was not. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, number NCT01717326., Findings: 218 patients with HCV mono-infection (n=159) and HIV/HCV co-infection (n=59) were enrolled. SVR12 for patients treated for 12 weeks with or without ribavirin ranged from 93-98% in mono-infected and 87-97% in co-infected patients. SVR12 rates in mono-infected and co-infected patients treated for 12 weeks without ribavirin were 98% (95% CI 88-100; 43/44) and 87% (95% CI 69-96; 26/30), respectively, and with ribavirin were 93% (95% CI 85-97; 79/85) and 97% (95% CI 82-100; 28/29), respectively. Among mono-infected patients with genotype 1a infection treated for 8 weeks, SVR12 was 80% (95% CI 61-92; 24/30). Five of six patients who discontinued early for reasons other than virological failure had HCV RNA less than 25 IU/mL at their last study visit. Virological failure among patients treated for 12 weeks occurred in seven patients (7/188, 4%) and was associated with emergence of resistance-associated variants to one or both drugs. The safety profile of grazoprevir plus elbasvir with or without ribavirin was similar in mono-infected and co-infected patients. No patient discontinued due to an adverse event or laboratory abnormality. The most common adverse events were fatigue (51 patients, 23%), headache (44, 20%), nausea (32, 15%), and diarrhoea (21, 10%)., Interpretation: Once-daily grazoprevir plus elbasvir with or without ribavirin for 12 weeks in previously untreated HCV-mono-infected and HIV/HCV-co-infected patients without cirrhosis achieved SVR12 rates of 87-98%. These results support the ongoing phase 3 development of grazoprevir plus elbasvir., Funding: Merck & Co, Inc., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The durability of sustained virologic response (SVR) following boceprevir-based therapy in patients with hepatitis C virus (HCV) infection has not been reported. Furthermore, in patients receiving protease inhibitor-based therapies, development of resistance can contribute to treatment failure. The aim of the present study was to follow the clinical progression of patients treated with boceprevir after treatment in phase 2/3 clinical trials. This was a 3-year, long-term follow-up analysis of patients enrolled in boceprevir phase 2/3 studies. No treatment was administered during follow-up. Patients with SVR were assessed for durability of viral eradication. Non-SVR patients with on-treatment resistance-associated variants (RAVs) were assessed for longevity of RAVs. A total of 1148 patients (SVR, n=696; virologic failure, n=452) were enrolled in this follow-up analysis. The median duration of follow-up was approximately 3.4 years (range of 0.0-4.1 years). Overall, 3 of 696 patients with SVR had detectable HCV RNA during the follow-up period (relapse rate of 0.4% or 1.3 relapses/1000 person-years). The majority of patients who developed RAVs during the initial treatment study (228/314, 73%) reverted to wild-type (WT) within 3 years (RAVs persisted in 27% of patients). The median time for all RAVs to become undetectable was 1.11 years (95% confidence interval 1.05-1.20 years). V36M, T54A, A156S, I/V170A and V36M+R155K appeared to have a faster rate of return to WT (median times to return to WT of ⩽0.9 years); whereas, T54S, R155K, V55A and T54S+R155K had a slower rate of return to WT (median times to return to WT of approximately 1.1 years). Return to WT appeared slightly faster in patients with G1b RAVs compared to those with G1a RAVs, and in patients with previous non-response or relapse versus breakthrough or incomplete virologic response. SVR was durable in most patients treated with boceprevir. Furthermore, most RAVs present at the time of virologic failure reverted to WT over time. Time to return to WT was associated with the phenotype of RAV, presumably a reflection of the fitness of the mutant virus, suggesting that HCV RAVs are not permanently archived, but are replaced in the viral population by WT virus., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background & Aims: Boceprevir with peginterferon/ribavirin (BOC/PR) leads to significantly higher sustained virological response (SVR) rates in patients with chronic hepatitis C and partial response or relapse after prior treatment with peginterferon/ribavirin. We studied the efficacy of BOC/PR in patients with prior treatment failure, including those with a null response (<2-log10 decline in HCV RNA), to peginterferon/ribavirin., Methods: Patients in the control arms of boceprevir Phase 2/3 studies who did not achieve SVR were re-treated with BOC/PR for up to 44 weeks. Patients enrolling >2 weeks after end-of-treatment in the prior study received PR for 4 weeks before adding boceprevir., Results: Of 168 patients enrolled, four discontinued from the PR lead-in and 164 received BOC/PR. Baseline viral load was >800,000 IU/ml in 77% of patients; 62% had HCV genotype 1a, and 10% were cirrhotic. In the ITT analysis (all 168 patients), SVR was achieved in 20 (38%) of 52 patients with prior null response, 57 (67%) of 85 with prior partial response, and 27 (93%) of 29 with prior relapse. In the mITT analysis (164 BOC/PR-treated patients), SVR rates were 41% (20/49), 67% (57/85), and 96% (27/28), respectively. SVR was achieved by 48% of patients with <1-log10 decline in HCV-RNA after lead-in and 76% of those with ⩾ 1-log10 decline or undetectable HCV-RNA after lead-in. The most common adverse events were anemia (49%), fatigue (48%), and dysgeusia (35%); 8% of patients discontinued due to adverse events., Conclusions: Re-treatment with BOC/PR improved SVR rates in all patient subgroups, including those with prior null response., (Copyright © 2014 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background & Aims: To examine the antiviral activity of boceprevir, a hepatitis C virus (HCV) protease inhibitor, in HCV genotype (G) 2/3-infected patients., Methods: We assessed boceprevir and telaprevir activity against an HCV G2 and G3 isolates enzyme panel, in replicon, and in phenotypic cell-based assays. Additionally, a phase I study evaluated the antiviral activity of boceprevir monotherapy (200mg BID, 400mg BID, or 400mg TID) vs. placebo for 14 days in HCV G2/3 treatment-naive patients., Results: Boceprevir and telaprevir similarly inhibited G1 and G2 NS3/4A enzymes and replication in G1 and G2 replicon and cell-based assays. However, telaprevir demonstrated lower potency than boceprevir against HCV G3a enzyme (Ki=75 nM vs. 17 nM), in the G3a replicon assay (EC₅₀=953 nM vs. 159 nM), and against HCV G3a NS3 isolates (IC₅₀=3312 nM vs. 803 nM) in the cell-based assay. In HCV G2/3-infected patients, boceprevir (400 mg TID) resulted in a maximum mean decrease in HCV RNA of -1.60 log vs. -0.21 log with placebo., Conclusions: In vitro, boceprevir is more active than telaprevir against the HCV G3 NS3/4A enzyme in cell-based and biochemical assays and against G3 isolates in replicon assays. In HCV G2/3-infected treatment-naive patients, decreases in HCV RNA levels with boceprevir (400 mg TID) were comparable to those observed with the same dose in HCV treatment-experienced G1-infected patients., (Copyright © 2013. Published by Elsevier B.V.)

The identification of hepatitis C virus (HCV) as the causative agent of non-A and non-B hepatitis, over 20 years ago, fueled an intensive effort to develop direct-acting antivirals targeting the viral polymerase and protease, two key proteins critical for HCV replication. However, it took more than two decades for these efforts to be realized with boceprevir, one of the two HCV protease inhibitors approved for treatment of HCV infection in 2011. The development of boceprevir is a major advancement in the ability to treat HCV infection and a significant step toward the long-term goal of eradicating chronic HCV infection. Both as a first-in-class agent and an entirely new modality for treating HCV infection, many challenges were encountered during the discovery and development of this compound. The lessons learned in overcoming these obstacles offer insights and pave the way for the newly emerging field of HCV antiviral therapeutics. This paper will describe the discovery and development of a first-in-class direct antiviral treatment for chronic hepatitis C infection, boceprevir, marketed around the world as Victrelis™., (© 2013 New York Academy of Sciences.)

Background: Rates of sustained virological response (SVR) to peginterferon-ribavirin are low in patients with hepatitis C virus (HCV) genotype 1 and HIV. We aimed to assess efficacy and safety of triple therapy with boceprevir plus pegylated interferon alfa-2b (peginterferon) and ribavirin, which increases rates of SVR in patients with HCV alone., Methods: In our double-blind, randomised controlled phase 2 trial, we enrolled adults (18-65 years) with untreated HCV genotype 1 infection and controlled HIV (HIV RNA <50 copies per mL) at 30 academic and non-academic study sites. We randomly allocated patients (1:2) according to a computer generated sequence, stratified by Metavir score and baseline HCV RNA level, to receive peginterferon 1·5 μg/kg per week with weight-based ribavirin (600-1400 mg per day) for 4 weeks, followed by peginterferon-ribavirin plus either placebo (control group) or 800 mg boceprevir three times per day (boceprevir group) for 44 weeks. Non-nucleoside reverse-transcriptase inhibitors, zidovudine, and didanosine were not permitted. The primary efficacy endpoint was SVR (defined as undetectable plasma HCV RNA) at follow-up week 24 after end of treatment. We assessed efficacy and safety in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT00959699., Findings: From Jan 15, 2010, to Dec 29, 2010, we enrolled 99 patients, 98 of whom received at least one treatment dose. 40 (63%) of 64 patients in the boceprevir group had an SVR at follow-up week 24, compared with ten (29%) of 34 control patients (difference 33·1%, 95% CI 13·7-52·5; p=0·0008). Adverse events were more common in patients who received boceprevir than in control patients: 26 (41%) versus nine (26%) had anaemia, 23 (36%) versus seven (21%) pyrexia, 22 (34%) versus six (18%) decreased appetite, 18 (28%) versus five (15%) dysgeusia, 18 (28%) versus five (15%) vomiting, and 12 (19%) versus two (6%) neutropenia. Three patients who received boceprevir plus peginterferon-ribavirin and four controls had HIV virological breakthrough., Interpretation: Boceprevir in combination with peginterferon-ribavirin could be an important therapeutic option for patients with HCV and HIV., Funding: Merck., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Resistance to direct-acting antivirals represents a new challenge in the treatment of chronic hepatitis C., Methods: SPRINT-1 was a randomized study of treatment-naive patients with genotype (G) 1 hepatitis C infection (n=595) that evaluated the safety and efficacy of boceprevir (BOC) when added to pegylated interferon-α2b plus ribavirin (PR). Plasma samples collected at protocol-specified visits were analysed by population sequencing for detection of BOC-associated resistance-associated variants (RAVs)., Results: A total of 17/24 (71%) patients randomized to BOC with baseline RAVs achieved sustained virological response (SVR). V55A/I (n=14), Q41H (n=11) and T54S (n=9) were the most frequently detected polymorphisms at baseline. Seven non-SVR patients with baseline RAVs had V55A (relapse, n=3; breakthrough, n=1; and non-response, n=1) and/or R155K (non-response, n=2). In total, 63/144 (44%) patients with sequenced post-baseline samples (2 SVR, 61 non-SVR) had detectable RAVs after BOC treatment (G1a: R155K [39/49; 80%], V36M [37/49; 76%] and T54S [24/49; 49%]; G1b: T54S [3/11; 27%], T54A [4/11; 35%], A156S [2/11; 18%] and V170A [2/11; 18%]). RAV frequency varied according to the virological response: 90%, 67%, 27% and 37% of breakthrough, incomplete virological response, relapse and non-responder patients, respectively, had post-baseline RAVs present. Similar RAVs were identified in both the PR lead-in and no-lead-in arms and the frequency of post-baseline RAVs was highest in the low-dose ribavirin arm., Conclusions: SVR rates were not compromised among patients with RAVs at baseline; however, a lower starting mg/kg dose of ribavirin was associated with a higher frequency of post-baseline RAVs.