Treatment of chronic hepatitis D with peginterferon lambda-the phase 2 LIMT-1 clinical trial.

BACKGROUND AND AIMS: HDV infection leads to the most aggressive form of human viral hepatitis for which there is no FDA-approved therapy. PEG IFN-lambda-1a (Lambda) has previously demonstrated a good tolerability profile in HBV and HCV patients compared to PEG IFN-alfa. The goal of Phase 2 LIMT-1 trial was to evaluate the safety and efficacy of Lambda monotherapy in patients with HDV. APPROACH AND RESULTS: An open-label study of Lambda 120 or 180 mcg, administered once weekly by subcutaneous injections for 48 weeks, followed by 24 weeks of posttreatment follow-up. Thirty-three patients were allocated to Lambda 180 mcg (n=14) or 120 mcg (n=19). Baseline mean values: HDV RNA 4.1 log10 IU/mL (SD±1.4); ALT 106 IU/L (35-364); and bilirubin 0.5 mg/dL (0.2-1.2). Intention-to-treat rates of virologic response to Lambda 180 mcg and 120 mcg, 24 weeks following treatment cessation were 5 of 14(36%) and 3 of 19 (16%), respectively. The posttreatment response rate of 50% was seen in low BL viral load (≤4 log10) on 180 mcg. Common on-treatment adverse events included flu-like symptoms and elevated transaminase levels. Eight (24%) cases of hyperbilirubinemia with or without liver enzyme elevation, leading to drug discontinuation, were mainly observed in the Pakistani cohort. The clinical course was uneventful, and all responded favorably to dose reduction or discontinuation. CONCLUSIONS: Treatment with Lambda in patients with chronic HDV may result in virologic response during and following treatment cessation. Clinical phase 3 development of Lambda for this rare and serious disease is ongoing.

Antiviral Activity, Safety, and Pharmacokinetics of Capsid Assembly Modulator NVR 3-778 in Patients with Chronic HBV Infection.

BACKGROUND & AIMS: NVR 3-778 is a first-in-class hepatitis B virus (HBV) capsid assembly modulator that can inhibit HBV replication. We performed a proof-of-concept study to examine the safety, pharmacokinetics, and antiviral activity of NVR 3-778 in patients with chronic HBV infection. METHODS: We performed a phase 1 study in 73 hepatitis B envelope antigen (HBeAg)-positive patients with chronic HBV infection without cirrhosis. In a 2-part study (part 1 in New Zealand and part 2 in Hong Kong, Singapore, Taiwan, Korea, and the United States), patients were randomly assigned to groups that were given oral NVR 3-778 (100 mg, 200 mg, or 400 mg daily or 600 mg or 1000 mg twice daily) or placebo for 4 weeks. Additional groups received combination treatment with pegylated interferon (pegIFN) and NVR 3-778 (600 mg twice daily) or pegIFN with placebo. RESULTS: Reductions in serum levels of HBV DNA and HBV RNA were observed in patients receiving ≥1200 mg/d NVR 3-778. The largest mean reduction in HBV DNA was observed in the group given NVR 3-778 plus pegIFN (1.97 log10 IU/mL), compared with the groups given NVR 3-778 or pegIFN alone (1.43 log10 IU/mL and 1.06 log10 IU/mL, respectively). The mean reduction in HBV RNA was also greatest in the group given NVR 3-778 plus pegIFN (2.09 log10 copies/mL), compared with the groups given NVR 3-778 or pegIFN alone (1.42 log10 copies/mL and 0.89 log10 copies/mL, respectively). There was no significant mean reduction in HBsAg during the 4-week treatment period. There were no discontinuations and no pattern of dose-related adverse effects with NVR 3-778. CONCLUSIONS: In a phase 1 study of HBeAg-positive patients with chronic HBV infection without cirrhosis, NVR 3-778 was well tolerated and demonstrated antiviral activity. The agent reduced serum levels of HBV DNA and HBV RNA, to the greatest extent in combination with pegIFN. The observed reductions in HBV RNA confirmed the novel mechanism of NVR 3-778. Clinicaltrials.gov no. NCT02112799 (single-center) and NCT02401737 (multicenter).

Treating chronic hepatitis delta: The need for surrogate markers of treatment efficacy.

Chronic hepatitis delta represents the most severe form of chronic viral hepatitis. The current treatment of hepatitis delta virus (HDV) infection consists of the use of interferons and is largely unsatisfactory. Several new compounds are currently in development for the treatment of HDV infection. However, surrogate markers that can be used to develop clinical endpoints in HDV infection are not well defined. In the current manuscript, we aimed to evaluate the existing data on treatment of HDV infection and to suggest treatment goals (possible "trial endpoints") that could be used across different clinical trials.

Simeprevir with peginterferon α-2a/ribavirin for chronic hepatitis C virus genotype 1 infection in treatment-experienced patients: an open-label, rollover study.

BACKGROUND: This Phase 3, open-label, rollover study (NCT01323244) investigated the efficacy and safety of simeprevir plus peginterferon α-2a (PegIFNα-2a) and ribavirin (RBV) in a well-characterized population of HCV genotype 1 (GT1)-infected treatment-experienced patients. METHODS: Patients who had failed PegIFNα/RBV treatment in the placebo arm of a previous Phase 2/3 simeprevir study (Phase 2/3 group, n = 125), or had been exposed to HCV direct-acting antivirals (simeprevir or other) for up to 14 days in a selected Phase 1 study (Phase 1 group, n = 16), were eligible. Phase 2/3 group patients were classified according to prior relapse, breakthrough, or non-response (null response, partial response, non-classifiable non-response) to PegIFNα/RBV. Eight patients in the Phase 1 group received short-term (≤14 days) simeprevir. Treatment comprised simeprevir 150 mg once daily (QD) plus PegIFNα-2a/RBV for 12 weeks followed by PegIFNα-2a/RBV for 12 or 36 weeks (using response-guided therapy [RGT] to determine total treatment duration in Phase 2/3 prior relapsers or breakthrough) or 36 weeks fixed (Phase 2/3 group non-responders and Phase 1 group). The primary endpoint was sustained virologic response 12 weeks after planned end of treatment (SVR12). RESULTS: Phase 2/3 group: SVR12 rate was 69.6% (87/125) overall; 92.7% (51/55), 60.0% (6/10), 64.3% (18/28), and 36.7% (11/30) in patients with prior relapse, viral breakthrough, partial response, or null response, respectively. SVR12 rates were similar for patients with HCV GT1a (66.0% [33/50]) and GT1b infection (72.0% [54/75]) and among HCV GT1a-infected patients with/without a baseline Q80K polymorphism (66.7% [8/12] and 65.8% [25/38], respectively). The majority of RGT-eligible patients (prior viral relapse or breakthrough) met RGT criteria (89.2% [58/65]); of these, 89.7% (52/58) achieved SVR12. Overall, 16.0% (20/125) of patients experienced on-treatment failure and 14.4% (18/125) experienced post-treatment failure (15 relapses, 3 missing data). Phase 1 group (simeprevir-naïve and -experienced patients combined): SVR12 rate was 37.5% (6/16). Safety and tolerability findings were comparable to those of the feeder studies. CONCLUSIONS: The majority of RGT-eligible patients met criteria for shortening treatment to 24 weeks in total. Simeprevir 150 mg QD with PegIFNα-2a/RBV led to a high SVR rate among prior relapsers with HCV GT1 infection. No new safety signals were noted. TRIAL REGISTRATION: NCT01323244 . (date of registration: March 24, 2011).

Nucleotide polymerase inhibitor sofosbuvir plus ribavirin for hepatitis C.

BACKGROUND: The standard treatment for hepatitis C virus (HCV) infection is interferon, which is administered subcutaneously and can have troublesome side effects. We evaluated sofosbuvir, an oral nucleotide inhibitor of HCV polymerase, in interferon-sparing and interferon-free regimens for the treatment of HCV infection. METHODS: We provided open-label treatment to eight groups of patients. A total of 40 previously untreated patients with HCV genotype 2 or 3 infection were randomly assigned to four groups; all four groups received sofosbuvir (at a dose of 400 mg once daily) plus ribavirin for 12 weeks. Three of these groups also received peginterferon alfa-2a for 4, 8, or 12 weeks. Two additional groups of previously untreated patients with HCV genotype 2 or 3 infection received sofosbuvir monotherapy for 12 weeks or sofosbuvir plus peginterferon alfa-2a and ribavirin for 8 weeks. Two groups of patients with HCV genotype 1 infection received sofosbuvir and ribavirin for 12 weeks: 10 patients with no response to prior treatment and 25 with no previous treatment. We report the rate of sustained virologic response 24 weeks after therapy. RESULTS: Of the 40 patients who underwent randomization, all 10 (100%) who received sofosbuvir plus ribavirin without interferon and all 30 (100%) who received sofosbuvir plus ribavirin for 12 weeks and interferon for 4, 8, or 12 weeks had a sustained virologic response at 24 weeks. For the other patients with HCV genotype 2 or 3 infection, all 10 (100%) who received sofosbuvir plus peginterferon alfa-2a and ribavirin for 8 weeks had a sustained virologic response at 24 weeks, as did 6 of 10 (60%) who received sofosbuvir monotherapy. Among patients with HCV genotype 1 infection, 21 of 25 previously untreated patients (84%) and 1 of 10 with no response to previous therapy (10%) had a sustained virologic response at 24 weeks. The most common adverse events were headache, fatigue, insomnia, nausea, rash, and anemia. CONCLUSIONS: Sofosbuvir plus ribavirin for 12 weeks may be effective in previously untreated patients with HCV genotype 1, 2, or 3 infection. (Funded by Pharmasset and Gilead Sciences; ClinicalTrials.gov number, NCT01260350.).

Sofosbuvir for previously untreated chronic hepatitis C infection.

BACKGROUND: In phase 2 trials, the nucleotide polymerase inhibitor sofosbuvir was effective in previously untreated patients with chronic hepatitis C virus (HCV) genotype 1, 2, or 3 infection. METHODS: We conducted two phase 3 studies in previously untreated patients with HCV infection. In a single-group, open-label study, we administered a 12-week regimen of sofosbuvir plus peginterferon alfa-2a and ribavirin in 327 patients with HCV genotype 1, 4, 5, or 6 (of whom 98% had genotype 1 or 4). In a noninferiority trial, 499 patients with HCV genotype 2 or 3 infection were randomly assigned to receive sofosbuvir plus ribavirin for 12 weeks or peginterferon alfa-2a plus ribavirin for 24 weeks. In the two studies, the primary end point was a sustained virologic response at 12 weeks after the end of therapy. RESULTS: In the single-group study, a sustained virologic response was reported in 90% of patients (95% confidence interval, 87 to 93). In the noninferiority trial, a sustained response was reported in 67% of patients in both the sofosbuvir-ribavirin group and the peginterferon-ribavirin group. Response rates in the sofosbuvir-ribavirin group were lower among patients with genotype 3 infection than among those with genotype 2 infection (56% vs. 97%). Adverse events (including fatigue, headache, nausea, and neutropenia) were less common with sofosbuvir than with peginterferon. CONCLUSIONS: In a single-group study of sofosbuvir combined with peginterferon-ribavirin, patients with predominantly genotype 1 or 4 HCV infection had a rate of sustained virologic response of 90% at 12 weeks. In a noninferiority trial, patients with genotype 2 or 3 infection who received either sofosbuvir or peginterferon with ribavirin had nearly identical rates of response (67%). Adverse events were less frequent with sofosbuvir than with peginterferon. (Funded by Gilead Sciences; FISSION and NEUTRINO ClinicalTrials.gov numbers, NCT01497366 and NCT01641640, respectively.).

Efficacy and safety of danoprevir-ritonavir plus peginterferon alfa-2a-ribavirin in hepatitis C virus genotype 1 prior null responders.

Danoprevir (DNV) is a hepatitis C virus (HCV) protease inhibitor that achieves high sustained virologic response (SVR) rates in combination with peginterferon alfa-2a-ribavirin in treatment-naive HCV genotype 1 (G1)-infected patients. This study explored the efficacy and safety of ritonavir-boosted DNV (DNVr) plus peginterferon alfa-2a-ribavirin in G1-infected prior peginterferon-ribavirin null responders. Null responders (<2-log10 reduction in HCV RNA level at week 12) were given an open-label combination of 100 mg of ritonavir and 100 mg of DNV (100/100 mg DNVr) every 12 h (q12h) plus peginterferon alfa-2a-ribavirin for 12 weeks. All patients achieving an early virologic response (EVR; ≥2-log10 decrease in HCV RNA by week 12) continued treatment with peginterferon alfa-2a-ribavirin; those without an EVR discontinued all study drugs. Twenty-four prior null responders were enrolled; 16 patients (67%) were infected with HCV G1b, and 8 (33%) were infected with G1a. Ninety-six percent of patients had an IL28B non-CC genotype. A sustained virologic response at 24 weeks posttreatment (SVR24) was achieved in 67% of patients, with a higher rate in G1b-infected (88%) than G1a-infected (25%) patients. Resistance-related breakthrough occurred in 4/8 G1a and 1/16 G1b patients through the DNV resistance-associated variant (RAV) NS3 R155K. NS3 R155K was also detected in 2/2 G1a patients who relapsed. Treatment was well tolerated. Two patients withdrew prematurely from study medications due to adverse events. Two serious adverse events were reported; both occurred after completion of DNVr therapy and were considered unrelated to treatment. No grade 3 or 4 alanine aminotransferase (ALT) elevations were observed. DNVr plus peginterferon alfa-2a-ribavirin demonstrated high SVR24 rates in HCV G1b-infected prior null responders and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. NCT01185860.).

A phase 2B study of MK-7009 (vaniprevir) in patients with genotype 1 HCV infection who have failed previous pegylated interferon and ribavirin treatment.

BACKGROUND & AIMS: MK-7009 (vaniprevir) is a non-covalent competitive inhibitor of the hepatitis C virus (HCV) NS3/4A protease. This report presents the primary analysis results (safety and sustained viral response) of a phase 2b study of MK-7009 given in combination with peginterferon (PegIFN) alfa2a 180 µg weekly and ribavirin (RBV) 1000-1200 mg/day, for 24-48 weeks to non-cirrhotic patients who have failed previous PegIFN and RBV treatment. METHODS: We present results of a randomized, placebo-controlled, double-blind study of MK-7009 administered for 24-48 weeks in combination with PegIFN and RBV in 4 regimens to at least 40 patients per arm. Stratification by prior response to PegIFN and RBV was as follows: null response, partial response, breakthrough and relapse. HCV RNA was determined by Roche Cobas Taqman with a lower limit of detection (LLoD) of 10 IU/ml and a lower limit of quantification (LLoQ) of 25 IU/ml. RESULTS: SVR24 in patients on MK-7009+PegIFN and ribavirin (P/R) was statistically superior to placebo+P/R in all treatment groups (p<0.001). MK-7009 at 300 mg b.i.d. and 600 mg b.i.d. is generally well tolerated for use for up to 48 weeks of therapy. Patients in MK-7009 regimens had higher rates of gastrointestinal adverse events as compared to control (mostly mild to moderate). There were no significant differences in rates of anemia and rash between the MK-7009 regimens and control. CONCLUSIONS: In conclusion, patients treated with MK-7009 plus P/R experienced significant improvement in SVR compared to P/R control in a population of GT 1 experienced patients.

Safety of peginterferon alfa-2a plus ribavirin in a large multinational cohort of chronic hepatitis C patients.

BACKGROUND & AIMS: Peginterferon plus ribavirin has been the standard of care for chronic hepatitis C for a decade and an essential component of combination regimens for this disease. This large multinational open-label study aimed to better define the incidence of serious adverse events (SAEs) and non-serious adverse events of special interest in patients receiving peginterferon alfa-2a/ribavirin. METHODS: Patients were assigned at the investigator's discretion to 24- or 48-week treatment with peginterferon alfa-2a 180 µg/week and ribavirin 800 mg/day or 1000/1200 mg/day. All AEs, defined as SAEs and non-SAEs of special interest, were recorded during treatment and for 12 weeks thereafter. Non-SAEs of special interest included those leading to dose reduction/discontinuation, neutropenia, thrombocytopenia, anaemia, ALT elevations leading to dose modification and unknown/unexpected AEs. RESULTS: Of 1675 and 7178 patients assigned to 24 and 48 weeks of treatment, respectively, 87.6 and 68.3% completed therapy, whereas 6.4 and 10.3% prematurely stopped peginterferon alfa-2a treatment because of AEs. Among patients assigned to 24 and 48 weeks, 37.4 and 46.9%, respectively, reported any AE (SAE or non-SAE of special interest); 4.2 and 6.6% reported SAEs and 35.2 and 44.0% reported non-SAEs of special interest. Female gender, increasing age and cirrhosis were significantly associated with dose reductions of either drug. Increasing age (and female gender in the case of ribavirin) was significantly associated with treatment discontinuation. CONCLUSION: This study confirmed the safety and tolerability profile of peginterferon alfa-2a/ribavirin and identified patient subgroups at higher risk of dose reductions and discontinuations, thus allowing optimum management of AEs.

Antiviral activity, safety, and pharmacokinetics of danoprevir/ritonavir plus PEG-IFN α-2a/RBV in hepatitis C patients.

BACKGROUND & AIMS: Danoprevir (RG7227; ITMN-191) is a potent inhibitor of the HCV NS3/4A serine protease. The aims of this double-blind, placebo-controlled, multiple-ascending dose phase Ib study were to evaluate safety, tolerability, antiviral activity, resistance, and pharmacokinetics of once- and twice-daily danoprevir in the presence of low-dose ritonavir (danoprevir/r) and in combination with peginterferon alfa-2a (40KD)/ribavirin in treatment-naive HCV genotype 1 patients. METHODS: Thirty eligible patients were enrolled into three cohorts and treated with danoprevir/r or placebo/r all in combination with peginterferon alfa-2a (40KD)/ribavirin for 15 days. Cohort 1 received danoprevir/r at 100/100mg twice daily; Cohort 2 200/100mg once daily; and Cohort 3 200/100mg twice daily. RESULTS: The median reductions in HCV RNA from baseline after 14 days of treatment (day 15) were -5.1, -4.8, and -4.6 log(10)IU/ml in Cohorts 1, 2, and 3, respectively, and -2.7 log(10) in placebo/r and peginterferon alfa-2a (40KD)/ribavirin recipients. Viral breakthrough was not observed in any patient. On day 15, HCV RNA was undetectable (<15IU/ml) in 6/9 (67%), 4/8 (50%), and 8/8 (100%) patients in Cohorts 1, 2, and 3, respectively. When co-administered with low dose ritonavir, danoprevir concentrations reached a steady state between 6 to 10 days of dosing. Danoprevir exposures increased more than dose proportionally between 100/100mg and 200/100mg. Danoprevir/r plus peginterferon alfa-2a (40KD)/ribavirin was well-tolerated with no safety-related discontinuations. CONCLUSIONS: Danoprevir/r plus peginterferon alfa-2a (40KD)/ribavirin provides profound and robust reductions in serum HCV RNA, at substantially lower systemic exposures compared to those observed with higher doses of danoprevir in the absence of ritonavir. These results support further studies of danoprevir/r.

Oral combination therapy with a nucleoside polymerase inhibitor (RG7128) and danoprevir for chronic hepatitis C genotype 1 infection (INFORM-1): a randomised, double-blind, placebo-controlled, dose-escalation trial.

BACKGROUND: Present interferon-based standard of care treatment for chronic hepatitis C virus (HCV) infection is limited by both efficacy and tolerability. We assessed the safety, tolerability, and antiviral activity of an all-oral combination treatment with two experimental anti-HCV drugs-RG7128, a nucleoside polymerase inhibitor; and danoprevir, an NS3/4A protease inhibitor-in patients with chronic HCV infection. METHODS: Patients from six centres in New Zealand and Australia who were chronically infected with HCV genotype 1 received up to 13 days oral combination treatment with RG7128 (500 mg or 1000 mg twice daily) and danoprevir (100 mg or 200 mg every 8 h or 600 mg or 900 mg twice daily) or placebo. Eligible patients were sequentially enrolled into one of seven treatment cohorts and were randomly assigned by interactive voice or web response system to either active treatment or placebo. Patients were separately randomly assigned within each cohort with a block size that reflected the number of patients in the cohort and the ratio of treatment to placebo. The random allocation schedule was computer generated. Dose escalation was started in HCV treatment-naive patients; standard of care treatment-experienced patients, including previous null responders, were enrolled in higher-dose danoprevir cohorts. Investigators, personnel at the study centre, and patients were masked to treatment allocation. However, the pharmacist who prepared the doses, personnel involved in pharmacokinetic sample analyses, statisticians who prepared data summaries, and the clinical pharmacologists who reviewed the data before deciding to initiate dosing in the next cohort were not masked to treatment allocation. The primary outcome was change in HCV RNA concentration from baseline to day 14 in patients who received 13 days of combination treatment. All patients who completed treatment with the study drugs were included in the analyses. This study is registered with ClinicalTrials.gov, NCT00801255. FINDINGS: 88 patients were randomly assigned to a study drug treatment regimen (n=74 over seven treatment groups; 73 received at least one dose of study drug) or to placebo (n=14, all of whom received at least one dose). The median change in HCV RNA concentration from baseline to day 14 ranged from -3·7 to -5·2 log(10) IU/mL in the cohorts that received 13 days of combination treatment. At the highest combination doses tested (1000 mg RG7128 and 900 mg danoprevir twice daily), the median change in HCV RNA concentration from baseline to day 14 was -5·1 log(10) IU/mL (IQR -5·6 to -4·7) in treatment-naive patients and -4·9 log(10) IU/mL in previous standard of care null responders (-5·2 to -4·5) compared with an increase of 0·1 log(10) IU/mL in the placebo group. The combination of RG7128 and danoprevir was well tolerated with no treatment-related serious or severe adverse events, no grade 3 or 4 changes in laboratory parameters, and no safety-related treatment discontinuations. INTERPRETATION: This oral combination of a nucleoside analogue polymerase inhibitor and protease inhibitor holds promise as an interferon-free treatment for chronic HCV. FUNDING: Roche Palo Alto.

Efficacy and safety of peginterferon alfa-2a (40KD) plus ribavirin in hepatitis C patients with advanced fibrosis and cirrhosis.

UNLABELLED: The objective of this study is to determine the efficacy and safety of peginterferon alfa-2a (40 KD)/ribavirin in patients with advanced fibrosis. Data from 341 genotype 1/4 patients (99 with bridging fibrosis/cirrhosis) treated for 48 weeks and 1547 genotype 2/3 patients (380 with bridging fibrosis/cirrhosis) treated for 16 or 24 weeks enrolled in three randomized international studies were analyzed. Sustained virological response (SVR) rates decreased progressively from 60% in genotype 1/4 patients without advanced fibrosis to 51% in those with bridging fibrosis and 33% in those with cirrhosis (trend test P = 0.0028); and from 76% to 61% and 57%, respectively, in genotype 2/3 patients treated for 24 weeks (trend test P < 0.0001). Irrespective of genotype, patients without advanced fibrosis were more likely to have an earlier response to treatment that was associated with higher SVR rates and lower relapse rates during untreated follow-up. Among patients with or without a diagnosis of advanced fibrosis, rates of SVR and relapse were similar for patients with similar responses in the first 12 weeks. CONCLUSION: Compared with patients with less severe disease, SVR rates are significantly lower in patients with advanced fibrosis. However, irrespective of genotype and degree of fibrosis, the time to become hepatitis C virus (HCV) RNA undetectable was the strongest predictor of SVR.

Ritonavir-boosted danoprevir-based regimens in treatment-naive and prior null responders with HCV genotype 1 or 4 and compensated cirrhosis.

BACKGROUND AND AIM: Effective and safe antiviral treatment regimens are needed for patients with chronic hepatitis C (CHC) and cirrhosis. METHODS: An international open-label trial was conducted in CHC patients with genotype (G)1/4 infection, compensated cirrhosis, HCV RNA ≥ 50,000 IU/mL and body mass index 18-35 kg/m(2). Treatment-naive patients (Cohort 1) received a triple therapy regimen [danoprevir/r 100/100 mg twice daily (bid), ribavirin 1000/1200 mg/day and peginterferon alfa-2a 180 µg/week] for 24 weeks. Prior null responders (Cohort 2) received a quadruple therapy regimen (danoprevir/r 100/100 mg bid, mericitabine 1000 mg bid and peginterferon alfa-2a/ribavirin). The primary efficacy outcome was sustained virological response (HCV RNA < limit of quantification, target not detected) at end of the 24-week follow-up period (SVR24). RESULTS: In Cohort 1 (n = 23), 73.9 and 65.2 % of patients had a virological response at Weeks 4 and 24, respectively; 39.1 % achieved SVR24 (G1a = 1/13; G1b = 8/9; G4 = 0/1). In Cohort 2 (n = 20), 100 % achieved virological response at Weeks 4 and 24; 65 % achieved SVR24 (G1a = 4/8; G1b = 7/10; G4 = 2/2). Treatment failure was more common in G1a than G1b-infected patients and less common in patients receiving quadruple therapy. Treatment failure was associated with emergence of resistance to danoprevir, but not mericitabine. The safety profile was typical of that associated with peginterferon alfa-2a/ribavirin. No deaths/episodes of hepatic decompensation occurred. CONCLUSIONS: Treatment with danoprevir/r-based regimens for 24 weeks is safe and well tolerated in CHC patients with compensated cirrhosis. A quadruple therapy regimen (danoprevir/r, mericitabine, peginterferon alfa/ribavirin) produced high SVR24 rates in prior null responders, particularly among G1b patients.