Potency, safety, and pharmacokinetics of the NS3/4A protease inhibitor BI201335 in patients with chronic HCV genotype-1 infection

Therapeutic Intervention of Serine Protease Inhibitors against Hepatitis C Virus

Hepatitis C virus (HCV) is a globally prevalent and hazardous disorder that is responsible for inducing several persistent and potentially fatal liver diseases. Current treatment strategies offer limited efficacy, often accompanied by severe and debilitating adverse effects. Consequently, there is an urgent and compelling need to develop novel therapeutic interventions that can provide maximum efficacy in combating HCV while minimizing the burden of adverse effects on patients. One promising target against HCV is the NS3-4A serine protease, a complex composed of two HCV-encoded proteins. This non-covalent heterodimer is crucial in the viral life cycle and has become a primary focus for therapeutic interventions. Although peginterferon, combined with ribavirin, is commonly employed for HCV treatment, its efficacy is hampered by significant adverse effects that can profoundly impact patients' quality of life. In recent years, the development of direct-acting antiviral agents (DAAs) has emerged as a breakthrough in HCV therapy. These agents exhibit remarkable potency against the virus and have demonstrated fewer adverse effects when combined with other DAAs. However, it is important to note that there is a potential for developing resistance to DAAs due to alterations in the amino acid position of the NS3-4A protease. This emphasizes the need for ongoing research to identify strategies that can minimize the emergence of resistance and ensure long-term effectiveness. While the combination of DAAs holds promise for HCV treatment, it is crucial to consider the possibility of drug-drug interactions. These interactions may occur when different DAAs are used concurrently, potentially compromising their therapeutic efficacy. Therefore, carefully evaluating and monitoring potential drug interactions are vital to optimize treatment outcomes. In the pursuit of novel therapeutic interventions for HCV, the field of computational biology and bioinformatics has emerged as a valuable tool. These advanced technologies and methodologies enable the development and design of new drugs and therapeutic agents that exhibit maximum efficacy, reduced risk of resistance, and minimal adverse effects. By leveraging computational approaches, researchers can efficiently screen and optimize potential candidates, accelerating the discovery and development of highly effective treatments for HCV, treatments.

Discovery of New Inhibitors of Hepatitis C Virus NS3/4A Protease and Its D168A Mutant

Hepatitis C virus (HCV) is a human pathogen with high morbidity. The HCV NS3/4A protease is essential for viral replication and is one of the top three drug targets. Several drugs targeting the protease have been developed, but drug-resistant mutant strains emerged. Here, we screened a library and synthesized a novel class of small molecules based on a tryptophan derivative scaffold identified as HCV NS3/4A protease inhibitors that are active against both wild type and mutant form of the protease. Only the compounds with predicted binding poses not affected by the most frequent mutations in the active site were selected for experimental validation. The antiviral activities were evaluated by replicon and enzymatic assays. Twenty-two compounds were found to inhibit HCV with EC50 values ranging between 0.64 and 63 μM with compound 22 being the most active. In protease assays, 22 had a comparable inhibition profile for the common mutant HCV GT1b D168A and the wild-type enzyme. However, in the same assay, the potency of the approved drug, simeprevir, decreased 5.7-fold for the mutant enzyme relative to the wild type. The top three inhibitors were also tested against four human serine proteases and were shown to be specific to the viral protease. The fluorescence-based cell viability assay demonstrated a sufficient therapeutic range for the top three candidates.

The outcome of combined treatment with ombitasvir-paritaprevir-ritonavir, sofosbuvir with or without ribavirin as salvage therapy for Egyptian HCV experienced patients: A single center study

We aimed to investigate the efficacy and safety of combination of sofosbuvir with ombitasvir, paritaprevir, and ritonavir ± ribavirin as a retreatment option for experienced Egyptian patients who failed previous sofosbuvir, daclatasvir ± ribavirin therapy. A total of 75 treatment-experienced patients were allocated for the completion of their treatment period according to criteria formed by the national committee for control of viral hepatitis. The enrolled patients were followed up throughout treatment, at the end of treatment and 3 months after the end of the treatment by clinical evaluation and laboratory investigations. 27 patients were treated with sofosbuvir with ombitasvir, paritaprevir, and ritonavir plus ribavirin for 12 weeks while 48 patients were treated with sofosbuvir with ombitasvir, paritaprevir, and ritonavir without ribavirin for 24 weeks. The per-protocol sustained virological response at week 12 (SVR12) rate was 100% in both groups while the intention-to-treat SVR12 was 93.4% in all patients, 97.9% in the 24 weeks group and 85.2% in the 12 weeks group. The regimen was well tolerated and the most common adverse effects observed across treatment and during follow-up period included fatigue (38.6%) and headache (29.3%), withdrawal due to adverse effects occurred in 6.6%. We can conclude that retreatment with sofosbuvir with ombitasvir, paritaprevir, and ritonavir ± ribavirin is well tolerated and achieved high SVR12 rates in chronic HCV Egyptian patients with previous sofosbuvir plus daclatasvir treatment failure. Ribavirin free regimen for 24 weeks exerted significant lesser adverse effects.

Identification of 19 Novel Hepatitis C Virus Subtypes-Further Expanding HCV Classification

Background

Hepatitis C virus (HCV) is currently classified into 8 genotypes and 86 subtypes. The objective of this study was to characterize novel HCV subtypes and to investigate the impact of subtypes on treatment outcome.

Methods

Full-genome sequencing was performed on HCV plasma samples with <85% sequence homology of NS3, NS5A, and/or NS5B to HCV genotype (GT) 1–8 reference strains.

Results

A total of 14 653 patients with GT1–6 HCV infection were enrolled in clinical studies of sofosbuvir-based regimens. For the majority of the patients, a specific subtype could be assigned based on a close genetic relationship to previously described subtypes. However, for 19 patients, novel subtypes were identified with <85% homology compared with previously described subtypes. These novel subtypes had the following genotypes: 9 in GT2, 5 in GT4, 2 in GT6, and 1 each in GT1, GT3, and GT5. Despite the presence of polymorphisms at resistance-associated substitution positions, 18 of the 19 patients treated with sofosbuvir-containing therapy achieved SVR12.

Conclusions

Nineteen novel HCV subtypes were identified, suggesting an even greater genetic diversity of HCV subtypes than previously recognized.

Interferon-Free Regimen: Equally Effective in Treatment Naive and Experienced HCV Patients

INTRODUCTION AND AIM

Interferon-free regimen has been reported to be highly efficient in treatment of HCV infection, including patients with compensated cirrhosis. We compared the efficacy of Ombitasvir, Paritaprevir, Ritonavir, Dasabuvir and Ribavirin (OBT/PTV/r, with DSV and RBV) therapy in patients with chronic HCV genotype 1b infection and compensated cirrhosis with and without prior treatment experience with pegylated interferon and ribavirin (IFN/RBV).

MATERIAL AND METHODS

A prospective two-center study was conducted in Mures County Hospital and Brasov County Hospital, Romania in period November 2015-July 2016. Both treatment naïve and PegIFN/RBV experienced patients with chronic HCV genotype 1b infection received 12 weeks of OBT/PTV/r, with DSV and RBV. Sustained virologic response 12 weeks after the treatment and eventual discontinuation of therapy due to adverse events were assessed in order to estimate safety and efficiency of therapeutic regimen.

RESULTS

Fifty nine patients were included in study, 35 (59.3%) of them were previously treated with IFN/RBV. Forty four (74.5%) patients were previously diag-nosed with cirrhosis Child Pugh score 5, while 15 (25.4%) with Child Pugh score 6. All 59 patients achieved a SVR12 of 100% and one patient from treatment naïve cohort discontinued the therapy due to hyperbilirubinemia and encephalopathy. However viral load assessed at 12 weeks after discontinuation of therapy in this patient was undetectable. Conclusion An all-oral regimen of co-for-mulated OBT/PTV/r with DSV and RBV results in high rate of sustained virologic response at post-treatment week 12 among HCV GT1b infected patients associated with compensated cirrhosis, regardless of previous treatment experience with PegIFN/RBV.

Antiviral Activity, Safety, and Tolerability of Multiple Ascending Doses of Elbasvir or Grazoprevir in Participants Infected With Hepatitis C Virus Genotype-1 or -3

PURPOSE

Elbasvir (MK-8742) and grazoprevir (MK-5172; Merck & Co, Inc, Kenilworth, New Jersey) are hepatitis C virus (HCV)-specific inhibitors of the nonstructural protein 5A phosphoprotein and the nonstructural protein 3/4A protease, respectively. The aims of these studies were to evaluate the antiviral activity and safety of different doses of elbasvir or grazoprevir each administered as monotherapy to participants infected with either HCV genotype (GT) 1 or GT3.

METHODS

These 2 double-blind, randomized, placebo-controlled, sequential-panel, multiple ascending dose studies were conducted to assess the safety and pharmacodynamics of 5 days of once-daily elbasvir or 7 days of once-daily grazoprevir in adult male participants chronically infected with either HCV GT1 or GT3.

FINDINGS

Oral administration of elbasvir or grazoprevir once daily exhibited potent antiviral activity in participants with chronic GT1 or GT3 HCV infections. HCV RNA levels declined rapidly (within 1 day for elbasvir and 2 days for grazoprevir). At 50 mg of elbasvir once daily, the mean maximum reductions in HCV RNA from baseline were 5.21, 4.17, and 3.12 log₁₀ IU/mL for GT1b-, GT1a-, and GT3-infected participants, respectively. At 100 mg of grazoprevir once daily, the mean maximum reductions in HCV RNA from baseline were 4.74 and 2.64 log₁₀ IU/mL for GT1- and GT3-infected participants.

IMPLICATIONS

The results in the elbasvir monotherapy study showed that 10 to 50 mg of elbasvir was associated with a rapid decline in HCV viral load; the results in the grazoprevir monotherapy study suggest that doses of 50 mg of grazoprevir and higher are on the maximum response plateau of the dose-response curve for GT1-infected participants. The results of these proof-of-concept studies provided preliminary data for the selection of the dosages of elbasvir and grazoprevir to test in Phase II and III clinical studies. ClinicalTrials.gov identifiers: NCT00998985 (Protocol 5172-004) and NCT01532973 (Protocol 8742-002).

Pharmacokinetic Interaction between Faldaprevir and Cyclosporine or Tacrolimus in Healthy Volunteers: A Prospective, Open-Label, Fixed-Sequence, Crossover Study

Faldaprevir (FDV) is a potent, orally administered inhibitor of hepatitis C virus. In this single-centre, open-label, fixed-sequence, crossover study of 32 healthy adult male and female volunteers, subjects received either a single dose of cyclosporine (CsA) 50 mg (N = 16) or tacrolimus (TAC) 0.5 mg (N = 16), followed by a washout of at least 14 days. Each subject then received a loading dose of FDV 240 mg followed by 120 mg FDV once daily for 6 days. FDV 120 mg was then co-administered with an additional single dose of CsA (50 mg) or TAC (0.5 mg), followed by an additional 6 days of FDV 120 mg once daily. Intensive blood sampling was performed to assess the PK interaction potential. Assessment of relative BA indicated that exposure to CsA co-administered with FDV was similar to CsA alone. However, the AUC_τ,ss and C_max,ss of FDV were increased by 23% and 41%, respectively, when FDV was co-administered with CsA. Exposure to TAC was slightly increased (AUC_0-∞ increased by 27%, no change in C_max ) when TAC was co-administered with FDV. In contrast, exposure to FDV co-administered with TAC was similar to FDV alone. No unexpected safety findings arose from the trial. The limitations of the study (use of single, low dose of TAC and CsA, and only healthy volunteers in the trial) are discussed.

Direct-acting antivirals for chronic hepatitis C

BACKGROUND

Millions of people worldwide suffer from hepatitis C, which can lead to severe liver disease, liver cancer, and death. Direct-acting antivirals (DAAs), e.g. sofosbuvir, are relatively new and expensive interventions for chronic hepatitis C, and preliminary results suggest that DAAs may eradicate hepatitis C virus (HCV) from the blood (sustained virological response). Sustained virological response (SVR) is used by investigators and regulatory agencies as a surrogate outcome for morbidity and mortality, based solely on observational evidence. However, there have been no randomised trials that have validated that usage.

OBJECTIVES

To assess the benefits and harms of DAAs in people with chronic HCV.

SEARCH METHODS

We searched for all published and unpublished trials in The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, LILACS, and BIOSIS; the Chinese Biomedical Literature Database (CBM), China Network Knowledge Information (CNKI), the Chinese Science Journal Database (VIP), Google Scholar, The Turning Research into Practice (TRIP) Database, ClinicalTrials.gov, European Medicines Agency (EMA) (www.ema.europa.eu/ema/), WHO International Clinical Trials Registry Platform (www.who.int/ictrp), the Food and Drug Administration (FDA) (www.fda.gov), and pharmaceutical company sources for ongoing or unpublished trials. Searches were last run in October 2016.

SELECTION CRITERIA

Randomised clinical trials comparing DAAs versus no intervention or placebo, alone or with co-interventions, in adults with chronic HCV. We included trials irrespective of publication type, publication status, and language.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were hepatitis C-related morbidity, serious adverse events, and health-related quality of life. Our secondary outcomes were all-cause mortality, ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, hepatocellular carcinoma, non-serious adverse events (each reported separately), and SVR. We systematically assessed risks of bias, performed Trial Sequential Analysis, and followed an eight-step procedure to assess thresholds for statistical and clinical significance. We evaluated the overall quality of the evidence, using GRADE.

MAIN RESULTS

We included a total of 138 trials randomising a total of 25,232 participants. The trials were generally short-term trials and designed primarily to assess the effect of treatment on SVR. The trials evaluated 51 different DAAs. Of these, 128 trials employed matching placebo in the control group. All included trials were at high risk of bias. Eighty-four trials involved DAAs on the market or under development (13,466 participants). Fifty-seven trials administered DAAs that were discontinued or withdrawn from the market. Study populations were treatment-naive in 95 trials, had been exposed to treatment in 17 trials, and comprised both treatment-naive and treatment-experienced individuals in 24 trials. The HCV genotypes were genotype 1 (119 trials), genotype 2 (eight trials), genotype 3 (six trials), genotype 4 (nine trials), and genotype 6 (one trial). We identified two ongoing trials.We could not reliably determine the effect of DAAs on the market or under development on our primary outcome of hepatitis C-related morbidity or all-cause mortality. There were no data on hepatitis C-related morbidity and only limited data on mortality from 11 trials (DAA 15/2377 (0.63%) versus control 1/617 (0.16%); OR 3.72, 95% CI 0.53 to 26.18, very low-quality evidence). We did not perform Trial Sequential Analysis on this outcome.There is very low quality evidence that DAAs on the market or under development do not influence serious adverse events (DAA 5.2% versus control 5.6%; OR 0.93, 95% CI 0.75 to 1.15 , 15,817 participants, 43 trials). The Trial Sequential Analysis showed that there was sufficient information to rule out that DAAs reduce the relative risk of a serious adverse event by 20% when compared with placebo. The only DAA that showed a lower risk of serious adverse events when meta-analysed separately was simeprevir (OR 0.62, 95% CI 0.45 to 0.86). However, Trial Sequential Analysis showed that there was not enough information to confirm or reject a relative risk reduction of 20%, and when one trial with an extreme result was excluded, the meta-analysis result showed no evidence of a difference.DAAs on the market or under development may reduce the risk of no SVR from 54.1% in untreated people to 23.8% in people treated with DAA (RR 0.44, 95% CI 0.37 to 0.52, 6886 participants, 32 trials, low quality evidence). Trial Sequential Analysis confirmed this meta-analysis result.Only 1/84 trials on the market or under development assessed the effects of DAAs on health-related quality of life (SF-36 mental score and SF-36 physical score).There was insufficient evidence from trials on withdrawn or discontinued DAAs to determine their effect on hepatitis C-related morbidity and all-cause mortality (OR 0.64, 95% CI 0.23 to 1.79; 5 trials, very low-quality evidence). However, these DAAs seemed to increase the risk of serious adverse events (OR 1.45, 95% CI 1.22 to 1.73; 29 trials, very low-quality evidence). Trial Sequential Analysis confirmed this meta-analysis result.None of the 138 trials provided useful data to assess the effects of DAAs on the remaining secondary outcomes (ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, and hepatocellular carcinoma).

AUTHORS' CONCLUSIONS

The evidence for our main outcomes of interest come from short-term trials, and we are unable to determine the effect of long-term treatment with DAAs. The rates of hepatitis C morbidity and mortality observed in the trials are relatively low and we are uncertain as to how DAAs affect this outcome. Overall, there is very low quality evidence that DAAs on the market or under development do not influence serious adverse events. There is insufficient evidence to judge if DAAs have beneficial or harmful effects on other clinical outcomes for chronic HCV. Simeprevir may have beneficial effects on risk of serious adverse event. In all remaining analyses, we could neither confirm nor reject that DAAs had any clinical effects. DAAs may reduce the number of people with detectable virus in their blood, but we do not have sufficient evidence from randomised trials that enables us to understand how SVR affects long-term clinical outcomes. SVR is still an outcome that needs proper validation in randomised clinical trials.

Direct-acting antivirals for chronic hepatitis C

BACKGROUND

Millions of people worldwide suffer from hepatitis C, which can lead to severe liver disease, liver cancer, and death. Direct-acting antivirals (DAAs) are relatively new and expensive interventions for chronic hepatitis C, and preliminary results suggest that DAAs may eradicate hepatitis C virus (HCV) from the blood (sustained virological response). However, it is still questionable if eradication of hepatitis C virus in the blood eliminates hepatitis C in the body, and improves survival and leads to fewer complications.

OBJECTIVES

To assess the benefits and harms of DAAs in people with chronic HCV.

SEARCH METHODS

We searched for all published and unpublished trials in The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, LILACS, and BIOSIS; the Chinese Biomedical Literature Database (CBM), China Network Knowledge Information (CNKI), the Chinese Science Journal Database (VIP), Google Scholar, The Turning Research into Practice (TRIP) Database, ClinicalTrials.gov, European Medicines Agency (EMA) (www.ema.europa.eu/ema/), WHO International Clinical Trials Registry Platform (www.who.int/ictrp), the Food and Drug Administration (FDA) (www.fda.gov), and pharmaceutical company sources for ongoing or unpublished trials. Searches were last run in October 2016.

SELECTION CRITERIA

Randomised clinical trials comparing DAAs versus no intervention or placebo, alone or with co-interventions, in adults with chronic HCV. We included trials irrespective of publication type, publication status, and language.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were hepatitis C-related morbidity, serious adverse events, and quality of life. Our secondary outcomes were all-cause mortality, ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, hepatocellular carcinoma, non-serious adverse events (each reported separately), and sustained virological response. We systematically assessed risks of bias, performed Trial Sequential Analysis, and followed an eight-step procedure to assess thresholds for statistical and clinical significance. The overall quality of the evidence was evaluated using GRADE.

MAIN RESULTS

We included a total of 138 trials randomising a total of 25,232 participants. The 138 trials assessed the effects of 51 different DAAs. Of these, 128 trials employed matching placebo in the control group. All included trials were at high risk of bias. Eighty-four trials involved DAAs on the market or under development (13,466 participants). Fifty-seven trials administered withdrawn or discontinued DAAs. Trial participants were treatment-naive (95 trials), treatment-experienced (17 trials), or both treatment-naive and treatment-experienced (24 trials). The HCV genotypes were genotype 1 (119 trials), genotype 2 (eight trials), genotype 3 (six trials), genotype 4 (nine trials), and genotype 6 (one trial). We identified two ongoing trials.Meta-analysis of the effects of all DAAs on the market or under development showed no evidence of a difference when assessing hepatitis C-related morbidity or all-cause mortality (OR 3.72, 95% CI 0.53 to 26.18, P = 0.19, I² = 0%, 2,996 participants, 11 trials, very low-quality evidence). As there were no data on hepatitis C-related morbidity and very few data on mortality (DAA 15/2377 (0.63%) versus control 1/617 (0.16%)), it was not possible to perform Trial Sequential Analysis on hepatitis C-related morbidity or all-cause mortality.Meta-analysis of all DAAs on the market or under development showed no evidence of a difference when assessing serious adverse events (OR 0.93, 95% CI 0.75 to 1.15, P = 0.52, I² = 0%, 15,817 participants, 43 trials, very low-quality evidence). The Trial Sequential Analysis showed that the cumulative Z-score crossed the trial sequential boundary for futility, showing that there was sufficient information to rule out that DAAs compared with placebo reduced the relative risk of a serious adverse event by 20%. The only DAA that showed a significant difference on risk of serious adverse events when meta-analysed separately was simeprevir (OR 0.62, 95% CI 0.45 to 0.86). However, Trial Sequential Analysis showed that there was not enough information to confirm or reject a relative risk reduction of 20%, and when one trial with an extreme result was excluded, then the meta-analysis result showed no evidence of a difference.DAAs on the market or under development seemed to reduce the risk of no sustained virological response (RR 0.44, 95% CI 0.37 to 0.52, P < 0.00001, I² = 77%, 6886 participants, 32 trials, very low-quality evidence) and Trial Sequential Analysis confirmed this meta-analysis result.Only 1/84 trials on the market or under development assessed the effects of DAAs on health-related quality of life (SF-36 mental score and SF-36 physical score).Withdrawn or discontinued DAAs had no evidence of a difference when assessing hepatitis C-related morbidity and all-cause mortality (OR 0.64, 95% CI 0.23 to 1.79, P = 0.40, I² = 0%; 5 trials, very low-quality evidence). However, withdrawn DAAs seemed to increase the risk of serious adverse events (OR 1.45, 95% CI 1.22 to 1.73, P = 0.001, I² = 0%, 29 trials, very low-quality evidence), and Trial Sequential Analysis confirmed this meta-analysis result.Most of all outcome results were short-term results; therefore, we could neither confirm nor reject any long-term effects of DAAs. None of the 138 trials provided useful data to assess the effects of DAAs on the remaining secondary outcomes (ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, and hepatocellular carcinoma).

AUTHORS' CONCLUSIONS

Overall, DAAs on the market or under development do not seem to have any effects on risk of serious adverse events. Simeprevir may have beneficial effects on risk of serious adverse event. In all remaining analyses, we could neither confirm nor reject that DAAs had any clinical effects. DAAs seemed to reduce the risk of no sustained virological response. The clinical relevance of the effects of DAAs on no sustained virological response is questionable, as it is a non-validated surrogate outcome. All trials and outcome results were at high risk of bias, so our results presumably overestimate benefit and underestimate harm. The quality of the evidence was very low.

Safety and efficacy of faldaprevir in combination with pegylated interferon α-2b and ribavirin in Japanese patients with genotype-1 chronic hepatitis C virus infection

AIM

We evaluated the safety and efficacy of the hepatitis C virus (HCV) NS3/4A A protease inhibitor faldaprevir plus pegylated interferon α-2b and ribavirin (PegIFNα-2b/RBV) in Japanese patients with HCV genotype-1 infection.

METHODS

Treatment-naïve patients were randomized (1:1) to faldaprevir 120 mg q.d. for 12 or 24 weeks (response-guided therapy [RGT], n = 44), or faldaprevir 240 mg q.d. for 12 weeks (n = 43), each combined with PegIFNα-2b/RBV for 24 or 48 weeks (RGT). Response-guided therapy was based on early treatment success (HCV RNA <25 IU/mL at week 4 and <25 IU/mL undetected at week 8). Treatment-experienced patients received 240 mg q.d. for 24 weeks, plus PegIFNα-2b/RBV RGT (24 or 48 weeks, prior relapsers, n = 29) or PegIFNα-2b/RBV (48 weeks, 5 prior partial responders/breakthroughs, 10 prior null responders). The primary objective was safety; sustained virologic response 12 weeks post-treatment (SVR12) was a secondary end-point.

RESULTS

All except one patient experienced drug-related adverse events. Adverse events led to faldaprevir discontinuation in 1 (2%), 13 (20%), and 3 (6.8%) patients on faldaprevir 120 mg, faldaprevir 240 mg 12 weeks, and faldaprevir 240 mg 24 weeks, respectively. The SVR12 rates were: 86% with faldaprevir 120 mg and 74% with faldaprevir 240 mg among treatment-naïve patients; and 86%, 60%, and 40% among prior relapsers, partial responders/breakthroughs, and null responders, respectively.

CONCLUSIONS

In treatment-naïve Japanese patients, faldaprevir 120 mg q.d. plus PegIFNα-2b/RBV was better tolerated than faldaprevir 240 mg q.d. plus PegIFNα-2b/RBV, with at least comparable efficacy. In treatment-experienced patients, most prior relapsers achieved SVR12 with 24 weeks of faldaprevir 240 mg q.d. plus PegIFNα-2b/RBV. Clinicaltrials.gov NCT01579474.

Faldaprevir, pegylated interferon, and ribavirin for treatment-naïve HCV genotype-1: pooled analysis of two phase 3 trials

INTRODUCTION & AIM

Faldaprevir is a potent once-daily (q.d.) hepatitis C virus (HCV) NS3/4A protease inhibitor. The STARTVerso1 and STARTVerso2 phase 3 studies evaluated faldaprevir plus peginterferon alfa-2a/ribavirin (PegIFN/RBV) in treatment-naïve patients with chronic HCV genotype-1 infection.

MATERIAL AND METHODS

Patients were randomized 1:2:2 to receive placebo, faldaprevir 120 mg q.d. (12 or 24 weeks) or faldaprevir 240 mg q.d. (12 weeks) all with PegIFN/RBV (24-48 weeks). Faldaprevir 120 mg for 12 weeks only (STARTVerso1 only) required early treatment success (ETS, HCV RNA < 25 IU/mL at week 4 and undetected at week 8). All faldaprevir-treated patients with ETS stopped PegIFN/RBV at week 24. Primary endpoint: sustained virologic response 12 weeks post-treatment (SVR12).

RESULTS

SVR12 rates were significantly higher for patients treated with faldaprevir 120 or 240 mg (72% and 73%, respectively) compared with placebo (50%); estimated differences (adjusted for trial, race, and genotype-1 subtype) faldaprevir 120 mg 24% (95% CI: 17-31%, P < 0.0001), faldaprevir 240 mg 23% (95% CI: 16-30%, P < 0.0001). Subgroup analyses consistently showed higher SVR12 rates for patients receiving faldaprevir compared with placebo. The incidence of adverse events (AEs) was similar in faldaprevir 120-mg and placebo groups and slightly higher in the faldaprevir 240-mg group. Serious Aes were reported in 6%, 7%, and 8% of patients in placebo, faldaprevir 120-mg, and faldaprevir 240-mg groups, respectively.

CONCLUSION

Addition of faldaprevir to PegIFN/RBV increased SVR12 in patients with HCV genotype-1, and was well tolerated. Faldaprevir 120 mg is effective in the treatment of HCV genotype-1. ClinicalTrials.gov: NCT01343888 and NCT01297270.

HCVerso3: An Open-Label, Phase IIb Study of Faldaprevir and Deleobuvir with Ribavirin in Hepatitis C Virus Genotype-1b-Infected Patients with Cirrhosis and Moderate Hepatic Impairment

This study evaluated the interferon-free, oral combination of deleobuvir (non-nucleoside HCV NS5-RNA-polymerase inhibitor) and faldaprevir (HCV NS3/4A-protease inhibitor) with ribavirin in patients with HCV genotype-1b and moderate (Child-Pugh B [CPB], n = 17) or mild hepatic impairment (Child-Pugh A [CPA], n = 18). Patients received faldaprevir 120 mg and deleobuvir (600 mg [CPA], 400 mg [CPB]) twice-daily with weight-based ribavirin for 24 weeks. Baseline characteristics were similar between groups. Among CPA patients, 13/18 completed treatment; discontinuations were for adverse events (AEs, n = 1), lack of efficacy (n = 3) and withdrawal (n = 1). Among CPB patients, 8/17 completed treatment; discontinuations were for AEs (n = 6), withdrawal (n = 1) and ‘other’ (n = 2). Sustained virologic response at post-treatment Week 12 (SVR12) was achieved by 11 (61%) CPA patients (95% confidence interval: 38.6%–83.6%) and 9 (53%) CPB patients (95% confidence interval: 29.2%–76.7%), including most CPA (11/16) patients with Week 4 HCV RNA <25 IU.mL^-1 (target detected or not detected) and most CPB (8/9) patients with Week 4 HCV RNA <25 IU.mL^-1 (target not detected); 0/4 CPB patients with Week 4 HCV RNA <25 IU.mL^-1 (target detected) achieved SVR12. The most common AEs in both groups were nausea, diarrhoea and vomiting. Serious AEs were observed in 9 (53%) CPB patients and 1 (6%) CPA patient. Plasma trough concentrations of deleobuvir and faldaprevir were not substantially different between the CPA and CPB groups. In conclusion, in this small study the safety and efficacy profiles for 24 weeks of treatment with faldaprevir+deleobuvir+ribavirin in patients with mild or moderate hepatic impairment were consistent with the safety and efficacy profile of this regimen in non-cirrhotic patients. Faldaprevir+deleobuvir+ribavirin resulted in SVR12 in 53–61% of patients: proportions achieving SVR4 but not SVR12 were higher than in non-cirrhotic patients and overall response rates were lower than rates reported with other all-oral regimens in patients with cirrhosis.

Trial Registration: ClinicalTrials.gov NCT01830127.

HCVerso1 and 2: faldaprevir with deleobuvir (BI 207127) and ribavirin for treatment-naïve patients with chronic hepatitis C virus genotype-1b infection

The interferon-free combination of once-daily faldaprevir 120 mg, twice-daily deleobuvir 600 mg, and weight-based ribavirin was evaluated in two Phase III studies (HCVerso1, HCVerso2) in hepatitis C virus genotype-1b-infected, treatment-naïve patients, including those ineligible for peginterferon (HCVerso2). Patients without cirrhosis were randomized to 16 weeks (Arm 1; n=208 HCVerso1, n=213 HCVerso2) or 24 weeks (Arm 2; n=211 in both studies) of faldaprevir + deleobuvir + ribavirin. Patients with compensated cirrhosis received open-label faldaprevir + deleobuvir + ribavirin for 24 weeks (Arm 3; n=51, n=72). Primary endpoints were comparisons of adjusted sustained virologic response (SVR) rates with historical rates: 71% (HCVerso1) and 68% (HCVerso2). Adjusted SVR12 rates were significantly greater than historical controls for Arms 1 and 2 in HCVerso2 (76%, 95% confidence interval [CI] 71-81, P=0.002; 81%, 95% CI 76-86, P<0.0001) and Arm 2 in HCVerso1 (81%, 95% CI 77-86, P<0.0001), but not for Arm 1 of HCVerso1 (72%, 95% CI 66-77, P=0.3989). Unadjusted SVR12 rates in Arms 1, 2, and 3 were 71.6%, 82.5%, and 72.5%, respectively, in HCVerso1 and 75.6%, 82.0%, and 73.6%, respectively, in HCVerso2. Virologic breakthrough and relapse occurred in 24-week arms in 8%-9% and 1% of patients, respectively, and in 16-week arms in 7%-8% and 9%-11% of patients, respectively. The most common adverse events were nausea (46%-61%) and vomiting (29%-35%). Adverse events resulted in discontinuation of all medications in 6%-8% of patients. In treatment-naïve patients with hepatitis C virus genotype-1b infection, with or without cirrhosis, faldaprevir + deleobuvir + ribavirin treatment for 24 weeks resulted in adjusted SVR12 rates significantly higher than historical controls. Both studies were registered in ClinicalTrials.gov (NCT01732796, NCT01728324).

Resistance Analyses of HCV NS3/4A Protease and NS5B Polymerase from Clinical Studies of Deleobuvir and Faldaprevir

Background & Aim

The resistance profile of anti-hepatitis C virus (HCV) agents used in combination is important to guide optimal treatment regimens. We evaluated baseline and treatment-emergent NS3/4A and NS5B amino-acid variants among HCV genotype (GT)-1a and -1b-infected patients treated with faldaprevir (HCV protease inhibitor), deleobuvir (HCV polymerase non-nucleoside inhibitor), and ribavirin in multiple clinical studies.

Methods

HCV NS3/4A and NS5B population sequencing (Sanger method) was performed on all baseline plasma samples (n = 1425 NS3; n = 1556 NS5B) and on post-baseline plasma samples from patients with virologic failure (n = 113 GT-1a; n = 221 GT-1b). Persistence and time to loss of resistance-associated variants (RAVs) was estimated using Kaplan–Meier analysis.

Results

Faldaprevir RAVs (NS3 R155 and D168) and deleobuvir RAVs (NS5B 495 and 496) were rare (<1%) at baseline. Virologic response to faldaprevir/deleobuvir/ribavirin was not compromised by common baseline NS3 polymorphisms (e.g. Q80K in 17.5% of GT-1a) or by NS5B A421V, present in 20% of GT-1a. In GT-1b, alanine at NS5B codon 499 (present in 15% of baseline sequences) was associated with reduced response. Treatment-emergent RAVs consolidated previous findings: NS3 R155 and D168 were key faldaprevir RAVs; NS5B A421 and P495 were key deleobuvir RAVs. Among on-treatment virologic breakthroughs, RAVs emerged in both NS3 and NS5B (>90%). Virologic relapse was associated with RAVs in both NS3 and NS5B (53% GT-1b; 52% GT-1b); some virologic relapses had NS3 RAVs only (47% GT-1a; 17% GT-1b). Median time to loss of GT-1b NS5B P495 RAVs post-treatment (5 months) was less than that of GT-1b NS3 D168 (8.5 months) and GT-1a R155 RAVs (11.5 months).

Conclusion

Faldaprevir and deleobuvir RAVs are more prevalent among virologic failures than at baseline. Treatment response was not compromised by common NS3 polymorphisms; however, alanine at NS5B amino acid 499 at baseline (wild-type in GT-1a, polymorphism in GT-1b) may reduce response to this deleobuvir-based regimen.

Ombitasvir, paritaprevir, and ritonavir plus ribavirin for chronic hepatitis C virus genotype 4 infection in Egyptian patients with or without compensated cirrhosis (AGATE-II): a multicentre, phase 3, partly randomised open-label trial

BACKGROUND

In Egypt, chronic hepatitis C virus (HCV) infection occurs in around 10% of the population (about 8 million individuals), and is a leading cause of liver cirrhosis, hepatocellular carcinoma, and mortality. Although HCV genotype 4 constitutes about 20% of HCV infections worldwide, the prevalence in Egypt is more than 90%. We assessed the efficacy and safety of the two direct-acting antiviral drugs ombitasvir, an NS5A inhibitor, and paritaprevir, an NS3/4A protease inhibitor dosed with ritonavir, plus ribavirin in treatment of chronic HCV infection in Egypt.

METHODS

AGATE-II was a phase 3, open-label, partly randomised trial in patients with chronic HCV genotype 4 infection recruited from five academic and hepatology centres in Egypt. Patients were HCV treatment-naive or treatment-experienced with interferon-based regimens. Eligible patients were aged 18 years or older, and had been chronically infected with HCV genotype 4 for at least 6 months with a plasma HCV RNA concentration of more than 1000 IU/mL at screening. Patients without cirrhosis were assigned to receive 12 weeks of 25 mg ombitasvir, 150 mg paritaprevir, and 100 mg ritonavir orally once daily plus weight-based ribavirin. Patients with compensated cirrhosis were randomly assigned (1:1) to receive the same treatment for either 12 weeks or 24 weeks. Randomisation was stratified by previous pegylated interferon and ribavirin treatment experience using a web-based interactive response technology system and computer-generated schedules prepared by personnel from the funder's statistics department. Investigators were masked to randomisation schedules and were informed of each patient's assigned treatment by the interactive response technology system immediately after allocation. The primary endpoint was the proportion of patients with a sustained virological response (HCV RNA <15 IU/mL) 12 weeks after the last dose of study drug (SVR12). All patients who received at least one dose of study drugs were included in the primary and safety analysis. This study is registered with ClinicalTrials.gov, number NCT02247401.

FINDINGS

Between Nov 4, 2014, and March 16, 2015, we screened 182 patients with HCV infection, of whom 160 were eligible for inclusion; 100 patients were assessed as not having cirrhosis and were given 12 weeks of treatment, and 60 patients assessed as having cirrhosis were randomly assigned to the 12-week treatment group (n=31) or the 24-week treatment group (n=29). 94 (94%; 95% CI 88-97) of 100 patients in the without cirrhosis group, 30 (97%; 84-99) of 31 patients in the cirrhosis 12-week treatment group, and 27 (93%; 78-98) of 29 patients in the cirrhosis 24-week treatment group achieved SVR12. The most common adverse events in patients without cirrhosis were headache (41 [41%]) and fatigue (35 [35%]). Fatigue occurred in nine (29%) patients in the cirrhosis 12-week treatment group and 11 (38%) patients in the cirrhosis 24-week treatment group, and headache occurred in nine (29%) patients in the cirrhosis 12-week treatment group and in 10 (35%) patients in the cirrhosis 24-week treatment group. Adverse events were predominantly mild or moderate in severity, and laboratory abnormalities were not clinically meaningful. No patients discontinued treatment because of an adverse event. One serious adverse event in the group without cirrhosis was attributed to study drugs by the investigators; the patient had deep venous thrombosis.

INTERPRETATION

Ombitasvir, paritaprevir, and ritonavir plus ribavirin for 12 weeks achieved SVR12 in a high proportion of patients and was well tolerated in Egyptian patients with HCV genotype 4 infection with or without compensated cirrhosis. Extension of treatment to 24 weeks in patients with cirrhosis did not improve the proportion of patients achieving SVR12. A shorter duration regimen could be useful to address the significant burden of HCV genotype 4 infection in patients with compensated cirrhosis.

FUNDING

AbbVie.

Investigation of the effect of food and omeprazole on the relative bioavailability of a single oral dose of 240 mg faldaprevir, a selective inhibitor of HCV NS3/4 protease, in an open-label, randomized, three-way cross-over trial in healthy participants

Objectives

This study was conducted to investigate the effect of food and coadministration of omeprazole on the relative bioavailability (BA) of faldaprevir (FDV).

Methods

Fifteen healthy participants participated in this open-label, randomized, three-way cross-over study. Faldaprevir was administered as a 240 mg single dose during fasting state, following intake of a high-fat breakfast, or following omeprazole 40 mg q.d. dosing for 5 days. PK samples were collected on the day of faldaprevir administration.

Key findings

We found geometric mean (gMean) AUC0–∞ values for faldaprevir of 48 200, 37 900 and 36 000 ng h/ml under the fed, fasted and omeprazole coadministration conditions respectively. Similarly, gMean Cmax values for faldaprevir were 2600, 2030, 1920 ng/ml under the same respective conditions. The adjusted gMean ratio between the fed and fasted condition was approximately 120% for both AUC0–∞ and Cmax, while the ratio of omeprazole coadministration to fasted condition was approximately 94%. Faldaprevir was safe and well tolerated in the study.

Conclusions

Administration of a single dose of 240 mg faldaprevir after high-fat breakfast led to a modest, clinically irrelevant increase in faldaprevir exposure, while coadministration of omeprazole did not influence faldaprevir exposure.

Open-label phase 2 study of faldaprevir, deleobuvir and ribavirin in Japanese treatment-naive patients with chronic hepatitis C virus genotype 1 infection

AIM

The safety and efficacy of the NS3/4A protease inhibitor faldaprevir in combination with the non-nucleoside NS5B polymerase inhibitor deleobuvir and ribavirin in Japanese treatment-naive patients with chronic genotype 1 hepatitis C virus (HCV) infection was evaluated.

METHODS

In this multicenter, open-label phase 2 study, patients were assigned to 8 weeks of treatment with 80 mg (group 1) or 120 mg (group 2) faldaprevir once daily (q.d.) in combination with deleobuvir 600 mg twice daily and weight-based ribavirin. This was followed by a 24-week treatment with faldaprevir 120 mg q.d. in combination with peginterferon-α-2a and ribavirin. The primary objective was safety; virological response at weeks 4 and 8 was a secondary endpoint.

RESULTS

Twelve and 13 patients were treated in group 1 and 2, respectively; all were infected with HCV genotype 1b. All patients experienced a drug-related adverse event (AE). The frequency of individual events was generally numerically greater in group 2 than 1. The most common AEs were nausea (66.7%, group 1; 76.9%, group 2) and vomiting (33.3%, group 1; 61.5%, group 2). Virological response at weeks 4 and 8 was achieved by 11 (91.7%) patients in group 1; in group 2, 12 (92.3%) patients achieved virological response at week 4 and all at week 8. All patients who achieved the week 8 endpoint achieved sustained virological response at week 12.

CONCLUSION

Faldaprevir 80 or 120 mg q.d. in combination with deleobuvir and ribavirin was tolerable and had similar efficacy in Japanese patients with HCV genotype 1 infection. ClinicalTrials.gov: NCT01528735.

Efficacy and safety of ombitasvir/paritaprevir/r and dasabuvir compared to IFN-containing regimens in genotype 1 HCV patients: The MALACHITE-I/II trials

BACKGROUND & AIMS

Telaprevir plus pegylated interferon/ribavirin (TPV+PegIFN/RBV) remains a therapeutic option for chronic hepatitis C virus (HCV) genotype (GT) 1 infection in many regions. We conducted two open-label, phase IIIb trials comparing safety and efficacy of all-oral ombitasvir/paritaprevir/ritonavir and dasabuvir±ribavirin (OBV/PTV/r+DSV±RBV) and TPV+PegIFN/RBV.

METHODS

Treatment-naïve (MALACHITE-I) or PegIFN/RBV-experienced (MALACHITE-II) non-cirrhotic, chronic HCV GT1-infected patients were randomized to OBV/PTV/r+DSV+weight-based RBV, OBV/PTV/r+DSV (treatment-naïve, GT1b-infected patients only), or 12weeks of TPV+PegIFN+weight-based RBV and 12-36 additional weeks of PegIFN/RBV. The primary endpoint was sustained virologic response 12weeks post-treatment (SVR12). Patient-reported outcome questionnaires evaluated mental and physical health during the studies.

RESULTS

Three hundred eleven treatment-naïve and 148 treatment-experienced patients were randomized and dosed. Among treatment-naïve patients, SVR12 rates were 97% (67/69) and 82% (28/34), respectively, in OBV/PTV/r+DSV+RBV and TPV+PegIFN/RBV-treated GT1a-infected patients; SVR12 rates were 99% (83/84), 98% (81/83), and 78% (32/41) in OBV/PTV/r+DSV+RBV, OBV/PTV/r+DSV, and TPV+PegIFN/RBV-treated GT1b-infected patients. Among treatment-experienced patients, SVR12 rates were 99% (100/101) and 66% (31/47) with OBV/PTV/r+DSV+RBV and TPV+PegIFN/RBV. Mental and physical health were generally better with OBV/PTV/r+DSV±RBV than TPV+PegIFN/RBV. Rates of discontinuation due to adverse events (0-1% and 8-11%, respectively, p<0.05) and rates of hemoglobin decline to <10g/dl (0-4% and 34-47%, respectively, p<0.05) were lower for OBV/PTV/r+DSV±RBV than TPV+PegIFN/RBV.

CONCLUSIONS

Among non-cirrhotic, HCV GT1-infected patients, SVR12 rates were 97-99% with 12week, multi-targeted OBV/PTV/r+DSV±RBV regimens and 66-82% with 24-48 total weeks of TPV+PegIFN/RBV. OBV/PTV/r+DSV±RBV was associated with a generally better mental and physical health, more favorable tolerability, and lower rates of treatment discontinuation due to adverse events.

Baseline Polymorphisms and Emergence of Drug Resistance in the NS3/4A Protease of Hepatitis C Virus Genotype 1 following Treatment with Faldaprevir and Pegylated Interferon Alpha 2a/Ribavirin in Phase 2 and Phase 3 Studies

Analysis of data pooled from multiple phase 2 (SILEN-C1 to 3) and phase 3 studies (STARTVerso1 to 4) of the hepatitis C virus (HCV) nonstructural protein 3/4A (NS3/4A) protease inhibitor faldaprevir plus pegylated interferon alpha/ribavirin (PR) provides a comprehensive evaluation of baseline and treatment-emergent NS3/4A amino acid variants among HCV genotype-1 (GT-1)-infected patients. Pooled analyses of GT-1a and GT-1b NS3 population-based pretreatment sequences (n = 3,124) showed that faldaprevir resistance-associated variants (RAVs) at NS3 R155 and D168 were rare (<1%). No single, noncanonical NS3 protease or NS4A cofactor baseline polymorphism was associated with a reduced sustained virologic response (SVR) to faldaprevir plus PR, including Q80K. The GT-1b NS3 helicase polymorphism T344I was associated with reduced SVR to faldaprevir plus PR (P < 0.0001) but was not faldaprevir specific, as reduced SVR was also observed with placebo plus PR. Among patients who did not achieve SVR and had available NS3 population sequences (n = 507 GT-1a; n = 349 GT-1b), 94% of GT-1a and 83% of GT-1b encoded faldaprevir treatment-emergent RAVs. The predominant GT-1a RAV was R155K (88%), whereas GT-1b encoded D168 substitutions (78%) in which D168V was predominant (67%). The novel GT-1b NS3 S61L substitution emerged in 7% of virologic failures as a covariant with D168V, most often among the faldaprevir breakthroughs; S61L in combination with D168V had a minimal impact on faldaprevir susceptibility compared with that for D168V alone (1.5-fold difference in vitro). The median time to loss of D168 RAVs among GT-1b-infected patients who did not have a sustained virologic response at 12 weeks posttreatment (non-SVR12) after virologic failure was 5 months, which was shorter than the 14 months for R155 RAVs among GT-1a-infected non-SVR12 patients, suggesting that D168V is less fit than R155K in the absence of faldaprevir selective pressure.

Development and application of a fast, reproducible assay to measure HCV NS3 protease activity using Escherichia coli lysate

The hepatitis C virus (HCV) NS3/4A protease is a key target of efforts to develop direct-acting antiviral inhibitors for treatment of chronic HCV infection. In vitro analyses of the effects of NS3/4A mutations and polymorphisms on protease inhibitor (PI) susceptibility are essential to nonclinical and clinical compound characterization, but can be hampered by time and technical limitations of current in vitro methods using replicon or purified protein systems. We have developed a fast and simple method utilizing full-length NS3/4A protease inducibly expressed in Escherichia coli cells. Minimally processed E. coli whole cell lysate was used for analyzing NS3/4A protease activity and inhibition by antiviral compounds. Assay conditions were optimized to develop a reproducible assay that can be used for efficient analysis of NS3 protease mutants with poor replication capacity in the replicon system. IC50 fold-changes for NS3 mutants relative to their wild-types generated by this NS3 assay are comparable to those observed in the replicon system, with an R(2) of 0.82 for the values obtained by the two methods. In addition, we demonstrate that this assay can be successfully used for population and clonal phenotyping of patient samples and characterization of PIs against the NS3/4A protease from HCV genotypes 1-6.

Ombitasvir/paritaprevir/r and dasabuvir plus ribavirin in HCV genotype 1-infected patients on methadone or buprenorphine

BACKGROUND & AIMS

Hepatitis C virus (HCV)-infected patients with a history of injection drug use have low rates of initiation and completion of interferon-based therapies. This study evaluated efficacy, safety, and pharmacokinetics of a 12-week all-oral regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir+ribavirin in HCV genotype 1-infected patients on stable opioid replacement therapy.

METHODS

This was a phase II, multicenter, open-label, single-arm study in treatment-naïve or peginterferon/ribavirin treatment-experienced HCV genotype 1-infected patients on methadone or buprenorphine±naloxone. Patients received 12weeks of co-formulated ombitasvir/paritaprevir/ritonavir (25mg/150mg/100mg once daily) and dasabuvir (250mg twice daily)+weight-based ribavirin. The primary efficacy endpoint was sustained virologic response 12 weeks post-treatment.

RESULTS

Thirty-eight non-cirrhotic patients on chronic methadone (n=19) or buprenorphine (n=19) were enrolled. A total of 37 patients (97.4%) had a sustained virologic response 12 weeks post-treatment. No patient had a viral breakthrough or relapse. One patient discontinued due to serious adverse events unrelated to study drug (cerebrovascular accident and sarcoma). The most frequent adverse events were nausea, fatigue, and headache. Eight patients had on-treatment hemoglobin concentrations <10g/dl. Pharmacokinetic analyses indicated no clinically meaningful impact of methadone or buprenorphine on ombitasvir, paritaprevir, ritonavir, dasabuvir, or dasabuvir M1 metabolite exposures. No dose adjustments of methadone or buprenorphine were required.

CONCLUSIONS

The interferon-free regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir+ribavirin for 12weeks was well tolerated and achieved sustained virologic response in 97.4% of patients on opioid substitution therapy in this study. This all-oral regimen may provide an effective alternative to interferon-based therapies for HCV-infected patients with a history of injection drug use.

STARTVerso1: A randomized trial of faldaprevir plus pegylated interferon/ribavirin for chronic HCV genotype-1 infection

BACKGROUND & AIMS

The efficacy and tolerability of faldaprevir, a potent hepatitis C virus (HCV) NS3/4A protease inhibitor, plus peginterferon (PegIFN) and ribavirin (RBV) was assessed in a double-blind, placebo-controlled phase 3 study of treatment-naïve patients with HCV genotype-1 infection.

METHODS

Patients were randomly assigned (1:2:2) to PegIFN/RBV plus: placebo (arm 1, n = 132) for 24 weeks; faldaprevir (120 mg, once daily) for 12 or 24 weeks (arm 2, n = 259); or faldaprevir (240 mg, once daily) for 12 weeks (arm 3, n = 261). In arms 2 and 3, patients with early treatment success (HCV-RNA <25 IU/ml at week 4 and undetectable at week 8) stopped all treatment at week 24. Other patients received PegIFN/RBV until week 48 unless they met futility criteria. The primary endpoint was sustained virologic response 12 weeks post-treatment (SVR12).

RESULTS

SVR12 was achieved by 52%, 79%, and 80% of patients in arms 1, 2, and 3, respectively (estimated difference for arms 2 and 3 vs. arm 1: 27%, 95% confidence interval 17%-36%; and 29%, 95% confidence interval, 19%-38%, respectively; p < 0.0001 for both). Early treatment success was achieved by 87% (arm 2) and 89% (arm 3) of patients, of whom 86% and 89% achieved SVR12. Adverse event rates were similar among groups; few adverse events led to discontinuation of all regimen components.

CONCLUSIONS

Faldaprevir plus PegIFN/RBV significantly increased SVR12, compared with PegIFN/RBV, in treatment-naïve patients with HCV genotype-1 infection. No differences were seen in responses of patients given faldaprevir once daily at 120 or 240 mg.

Hepatitis C in HIV-infected patients: impact of direct-acting antivirals

Approximately 30% of HIV-infected patients are co-infected with hepatitis C virus (HCV). After the release of highly active antiretroviral therapy, liver disease has become the leading cause of morbidity and mortality in HIV patients. Prior to 2011, HCV treatment with pegylated-interferon and ribavirin in HCV/HIV co-infected patients only allowed 14-38% of patients with HCV genotype 1 to achieve a sustained virologic response (SVR). Additionally, treatment was commonly discontinued as a result of adverse events. Recently, simeprevir and sofosbuvir have been approved by the US Food and Drug Administration (FDA) for HCV mono-infection. Sofosbuvir has been given FDA approval in co-infected patients offering unprecedented SVR rates and the potential for interferon-free therapy. HCV therapies that are in the pipeline offer improved treatment times, safety profiles, and rates of SVR. Despite these improvements, several new issues including adherence, drug-drug interactions with antiretroviral therapies, adverse events, resistance, and patient selection may complicate therapy. This article reviews the current status of direct-acting antivirals (DAA)-containing regimens for HIV/HCV co-infected patients in the USA. New results investigating telaprevir and boceprevir are also discussed as they are relevant for locations where new DAAs are not available. The impact future interferon-free therapies may have on co-infected patients is also discussed.

Faldaprevir and pegylated interferon α-2a/ribavirin in individuals co-infected with hepatitis C virus genotype-1 and HIV

OBJECTIVE

Faldaprevir is a potent, once-daily hepatitis C virus (HCV) NS3/4A protease inhibitor. STARTVerso4 assessed the efficacy and safety of faldaprevir and response-guided pegylated interferon α-2a/ribavirin (PegIFN/RBV) in individuals with HCV/HIV co-infection.

DESIGN

A phase 3 open-label study (NCT01399619).

METHODS

Individuals (N = 308) co-infected with HCV genotype 1 (treatment-naive or prior interferon relapsers) and HIV [96% on antiretroviral therapy (ART)] received faldaprevir 120 mg (N = 123) or 240 mg (N = 185) and PegIFN/RBV. Those receiving a protease inhibitor or efavirenz ART were assigned to faldaprevir 120 or 240 mg, respectively. Individuals achieving early treatment success (ETS; HCV RNA <25 IU/ml at week 4 and undetectable at week 8) were randomized to 24 or 48 weeks of PegIFN/RBV. The primary endpoint was sustained virologic response 12 weeks after treatment (SVR12).

RESULTS

SVR12 was achieved in 221 (72%) individuals, and the rates were comparable across faldaprevir doses. ETS was achieved in 80%, and of these 86% achieved SVR12, with comparable rates with 24 and 48 weeks of PegIFN/RBV (87 and 94%, respectively). In multivariate analysis, age below 40 years, IL28B CC genotype, and baseline HCV RNA below 800 000 IU/ml were associated with SVR12 (P = 0.027, P < 0.0001, and P = 0.0002, respectively), whereas treatment (ART regimen and faldaprevir dose), liver cirrhosis, and genotype 1 subtype were not. The safety profile was comparable to that of faldaprevir in HCV-monoinfected individuals.

CONCLUSIONS

High SVR12 rates were achieved with faldaprevir and PegIFN/RBV in HIV/HCV co-infected individuals, regardless of faldaprevir dose and background ART, HCV genotype 1 subtype, or cirrhosis status. SVR rates mirrored those obtained with similar regimens in HCV monoinfected individuals.

Faldaprevir for the treatment of hepatitis C

The current treatments for chronic hepatitis C virus (HCV) genotype 1 infection are combinations of direct-acting antivirals, and faldaprevir is one of the new generation of HCV NS3/4A protease inhibitors. At the end of 2013, the US Food and Drug Administration (FDA) approved the HCV NS3/4A protease inhibitor simeprevir and the HCV NS5B polymerase inhibitor sofosbuvir. Simeprevir or sofosbuvir in combination with pegylated interferon and ribavirin are available for clinical use. Faldaprevir, another HCV NS3/4A protease inhibitor that also has fewer adverse events than telaprevir or boceprevir, is under development. Of interest, faldaprevir in combination with pegylated interferon and ribavirin, and interferon-free treatment with faldaprevir in combination with deleobuvir plus ribavirin provides high sustained virological response rates for HCV genotype 1 infection. The aim of this article is to review these data concerning faldaprevir. Faldaprevir in combination with pegylated interferon and ribavirin treatment appears to be associated with fewer adverse events than telaprevir or boceprevir in combination with pegylated interferon and ribavirin, and may be one of the therapeutic options for treatment-naive patients with HCV genotype 1. The interferon-free combination of faldaprevir and deleobuvir with ribavirin was effective for HCV genotype 1 infection and may hold promise for interferon-ineligible and interferon-intolerant patients.

Faldaprevir for the treatment of genotype-1 hepatitis C virus

Historically, pegylated interferon in combination with ribavirin was the standard of care in hepatitis C virus; however, this combination is often poorly tolerated, has a significant side-effect profile and is of limited efficacy in hepatitis C virus genotype-1. More recently, pegylated interferon/ribavirin has been combined with direct acting antiviral agents such as the first generation NS3/4A protease inhibitors. Faldaprevir, a first generation, second-wave protease inhibitor, when used with a pegylated interferon/ribavirin regimen, has also been shown to increase treatmentsuccess while shortening treatment duration; however, second generation direct acting antiviral agents offer even betterefficacy and tolerability. Various direct acting antiviral agent combinations in interferon-free regimens have been effective in over 95% of patients and are now in licensed use. While faldaprevir was a pioneering drug, by the time it reached late phase development it was superseded by newer agents.

Interactions of the hepatitis C virus protease inhibitor faldaprevir with cytochrome P450 enzymes: in vitro and in vivo correlation

The potential inhibition of the major human cytochrome P450 (CYP) enzymes by faldaprevir was evaluated both in vitro and in clinical studies (healthy volunteers and hepatitis C virus [HCV] genotype 1-infected patients). In vitro studies indicated that faldaprevir inhibited CYP2B6, CYP2C9, and CYP3A, and was a weak-to-moderate inactivator of CYP3A4. Faldaprevir 240 mg twice daily in healthy volunteers demonstrated moderate inhibition of hepatic and intestinal CYP3A (oral midazolam: 2.96-fold increase in AUC(0-24 h)), weak inhibition of hepatic CYP3A (intravenous midazolam: 1.56-fold increase in AUC(0-24 h)), weak inhibition of CYP2C9 ([S]-warfarin: 1.29-fold increase in AUC(0-120 h)), and had no relevant effects on CYP1A2, CYP2B6, or CYP2D6. Faldaprevir 120 mg once daily in HCV-infected patients demonstrated weak inhibition of hepatic and intestinal CYP3A (oral midazolam: 1.52-fold increase in AUC(0-∞)), and had no relevant effects on CYP2C9 or CYP1A2. In vitro drug-drug interaction predictions based on inhibitor concentration ([I])/inhibition constant (Ki) ratios tended to overestimate clinical effects and a net-effect model provided a more accurate approach. These studies suggest that faldaprevir shows a dose-dependent inhibition of CYP3A and CYP2C9, and does not induce CYP isoforms.

Pharmacokinetics, safety, and tolerability of faldaprevir in patients with renal impairment

Faldaprevir is a potent hepatitis C virus (HCV) NS3/4A protease inhibitor with negligible urinary excretion. We assessed the pharmacokinetics and safety of a single oral dose of faldaprevir (480 mg) in 32 HCV-negative subjects with renal impairment or normal renal function. Compared with subjects with normal renal function, the adjusted geometric mean ratios (90% confidence intervals in parentheses) for overall exposure area under the concentration-time curve from zero to infinity (AUC0-∞) were 113.6% (41.6 to 310.2%), 178.3% (85.2 to 373.0%), and 169.2% (73.2 to 391.2%) for subjects with mild, moderate, and severe renal impairment, respectively. Overall, 5/8 (63%) subjects with normal renal function and 20/24 (83%) subjects with renal impairment reported adverse events, with gastrointestinal events being the most common. No severe or serious adverse events or deaths were reported. These results suggest that moderate or severe renal impairment can result in a modest increase in faldaprevir exposure. The increase in exposure may be related to decrease in the activity of the liver uptake transporter OATP1B1 as a result of renal impairment. Given this relatively slight increase in exposure, a dose adjustment in HCV patients with renal impairment is not warranted. (This study has been registered at ClinicalTrials.gov under registration number NCT01957657.).

Effect of the hepatitis C virus protease inhibitor faldaprevir on the pharmacokinetics of an oral contraceptive containing ethinylestradiol and levonorgestrel in healthy female volunteers

Faldaprevir is a potent hepatitis C virus (HCV) NS3/4A protease inhibitor. Faldaprevir is known to inhibit P-glycoprotein, CYP3A4, and UDP-glucuronosyltransferase 1A1. This study evaluated the effect of steady-state 240 mg faldaprevir on the pharmacokinetics (PK) of an oral contraceptive containing ethinylestradiol (EE) and levonorgestrel (LNG) in healthy premenopausal women. In period 1, subjects received EE/LNG once daily (QD) for 14 days. Blood samples were taken on days 1, 11, and 12, with intensive PK blood sampling for EE and LNG on day 13. In period 2, subjects received EE-LNG QD and 240 mg faldaprevir QD on days 14 to 21 (240 mg faldaprevir twice daily on day 14). Blood samples were taken on days 14, 19, and 20, with PK profiling samples obtained for EE and LNG on day 21. A total of 15/16 subjects completed the study. Overall, EE and LNG exposure (assessed by the area under the curve) was approximately 1.4-fold higher when EE and LNG were coadministered with faldaprevir than when administered alone. Median t1/2 (terminal half-life in plasma at steady state) values were prolonged for both EE (2.4 h longer) and LNG (4.7 h longer) when EE and LNG were coadministered with faldaprevir. The mean oral clearance and apparent volume of distribution of both EE and LNG were lower (∼ 30%) when EE and LNG were coadministered with faldaprevir. Coadministration of faldaprevir and an oral contraceptive resulted in a moderate increase in exposure to both EE and LNG. However, this increase was not considered clinically meaningful, and no dose adjustment of oral contraceptives was deemed necessary. (This study has been registered at ClinicalTrials.gov under registration number NCT01570244.).

Efficacy and safety of faldaprevir, deleobuvir, and ribavirin in treatment-naive patients with chronic hepatitis C virus infection and advanced liver fibrosis or cirrhosis

Patients with advanced hepatic fibrosis or cirrhosis with chronic hepatitis C virus (HCV) infection represent an unmet need. The HCV NS3/4A inhibitor, faldaprevir, was evaluated in combination with the nonnucleoside NS5B inhibitor, deleobuvir, with or without ribavirin in treatment-naive patients with HCV genotype 1 infection in the SOUND-C2 study. Here, the efficacy and safety of this interferon-free regimen in a subset of patients with advanced liver fibrosis, including those with compensated cirrhosis, were assessed. Patients (n=362) were randomized to once-daily faldaprevir with either twice-daily (BID) or three-times-daily (TID) deleobuvir for 16 (TID16W), 28 (TID28W and BID28W), or 40 (TID40W) weeks with or without ribavirin (TID28W-NR). Patients were classified according to fibrosis stage (F0 to F2 versus F3 to F4) and the presence of cirrhosis (yes/no). In total, 85 (24%) patients had advanced fibrosis/cirrhosis (F3 to F4) and 33 (9%) had cirrhosis. Within each treatment arm, differences in rates of sustained virologic response 12 weeks after completion of treatment (SVR12) between patients with mild to moderate fibrosis (F0 to F2) versus F3 to F4 did not show a consistent pattern and were not statistically significant (63% versus 47% for TID16W, 53% versus 76% for TID28W, 48% versus 67% for TID40W, 70% versus 67% for BID28W, and 40% versus 36% for TID28W-NR, respectively; P > 0.05 for each arm). The most frequent adverse events in patients with/without cirrhosis were gastrointestinal and skin events, which were mostly mild or moderate in intensity. The degree of liver fibrosis did not appear to affect the probability of achieving SVR12 following treatment with the interferon-free regimen of faldaprevir, deleobuvir, and ribavirin. (This study has been registered at ClinicalTrials.gov under registration no. NCT01132313.).

Effect of faldaprevir on raltegravir pharmacokinetics in healthy volunteers

Faldaprevir is a potent hepatitis C virus (HCV) NS3/4A protease inhibitor and an inhibitor of UDP-glucuronosyltransferase-1A1 (UGT1A1), which is involved in raltegravir clearance. Raltegravir, an HIV integrase inhibitor, may be used in combination with HCV treatment in HCV/HIV co-infected patients. In this open-label, 2-period, fixed-sequence study, 24 healthy volunteers (12 males) received faldaprevir 240 mg and raltegravir 400 mg in 2 treatment schedules (A and B) separated by a washout phase of ≥7 days: (A) twice-daily raltegravir (Days 1-3), once-daily raltegravir (Day 4); (B) twice-daily raltegravir and twice-daily faldaprevir (loading dose, Day 1), twice-daily raltegravir and once-daily faldaprevir (Days 2-5), once-daily raltegravir and once-daily faldaprevir (Day 6). Pharmacokinetics and safety were assessed over 132 hours post-dosing. Compared with raltegravir alone, co-administration with faldaprevir led to 2.7-fold and 2.5-fold increases in raltegravir geometric mean AUC(τ,ss) and C(max,ss), respectively, and a similar increase in raltegravir glucuronide metabolite exposure. No serious adverse events (AEs) were reported and no subject discontinued due to AEs. Faldaprevir and raltegravir co-administration was well tolerated and resulted in a moderate increase in raltegravir exposure.

Flaviviruses, an expanding threat in public health: focus on dengue, West Nile, and Japanese encephalitis virus

The flaviviruses dengue, West Nile, and Japanese encephalitis represent three major mosquito-borne viruses worldwide. These pathogens impact the lives of millions of individuals and potentially could affect non-endemic areas already colonized by mosquito vectors. Unintentional transport of infected vectors (Aedes and Culex spp.), traveling within endemic areas, rapid adaptation of the insects into new geographic locations, climate change, and lack of medical surveillance have greatly contributed to the increase in flaviviral infections worldwide. The mechanisms by which flaviviruses alter the immune and the central nervous system have only recently been examined despite the alarming number of infections, related deaths, and increasing global distribution. In this review, we will discuss the expansion of the geographic areas affected by flaviviruses, the potential threats to previously unaffected countries, the mechanisms of pathogenesis, and the potential therapeutic interventions to limit the devastating consequences of these viruses.

[New direct-acting antiviral agents for the treatment of chronic hepatitis C in 2014]

BACKGROUND

The development of direct-acting antiviral agents (DAA) against the hepatitis C virus (HCV) has seen enormous progress in recent years. In 2011, the first protease inhibitors boceprevir (BOC) and telaprevir (TLV) were approved, which still need to be combined with pegylated interferon α (PEG-IFN α) and ribavirin (RBV) and are used only in patients with genotype 1. With sofosbuvir (SOF) and simeprevir (SMV), two new DAA are available. More DAA are in clinical development.

OBJECTIVES

Which changes in the treatment of chronic hepatitis C infection can be expected with the approval of the new DAA in 2014? Relevant phase IIb and phase III studies for the approval in 2014 were considered for drugs approved by the FDA or EMA at the editorial deadline.

CURRENT DATA

For patients with genotype 1, the combination of SOF, SMV or faldaprevir with PEG-IFN α and RBV was successfully evaluated in phase III studies. In contrast to previous treatment with PEG-IFN α, RBV and telaprevir (TLV) or boceprevir (BOC), therapy can be shortened in most cases with a significantly improved side-effect profile. Cure rates above 80 % are possible. Data are also available for an interferon-free therapy with either SOF and RBV or SOF and SMV in GT-1 patients. SVR rates exceeding 60 % and up to 90 % are possible. However, treatment experience with these combinations is low and an unrestricted interferon-free therapy for genotype 1 should not be expected before 2015. For patients with genotypes 2 and 3, valid data for interferon-free therapies are available. The combination of SOF and RBV for 12 weeks in genotype 2 and 24 weeks for genotype 3 is effective and shows equal or superior cure rates with fewer side effects than the PEG-IFN α/RBV therapy.

CONCLUSION

For patients with genotype 1, the duration of therapy can be further reduced with better side effect profile. In certain situations, therapy without PEG-IFN α is possible and should be considered. For patients with genotypes 2 and 3, an interferon-free therapy will be standard of care in 2014.

Structural analysis of asunaprevir resistance in HCV NS3/4A protease

Asunaprevir (ASV), an isoquinoline-based competitive inhibitor targeting the hepatitis C virus (HCV) NS3/4A protease, is very potent in vivo. However, the potency is significantly compromised by the drug resistance mutations R155K and D168A. In this study three crystal structures of ASV and an analogue were determined to analyze the structural basis of drug resistance susceptibility. These structures revealed that ASV makes extensive contacts with Arg155 outside the substrate envelope. Arg155 in turn is stabilized by Asp168, and thus when either residue is mutated, the enzyme’s interaction with ASV’s P_2* isoquinoline is disrupted. Adding a P₁–P₃ macrocycle to ASV enhances the inhibitor’s resistance barrier, likely due to poising the inhibitor to its bound conformation. Macrocyclic inhibitors with P_2* extension moieties avoiding interaction with the protease S₂ residues including Arg155 must be chosen for future design of more robust protease inhibitors.

Ombitasvir (ABT-267), a novel NS5A inhibitor for the treatment of hepatitis C

INTRODUCTION

Chronic hepatitis C infection is a global disease with 160 million people infected worldwide. Until recently, therapy was characterized by long duration, suboptimal success rates and significant adverse drug reactions. The development of direct-acting antivirals initiated a dramatic change in the treatment of hepatitis C.

AREAS COVERED

This review covers the development of the novel NS5A inhibitor ombitasvir (ABT-267) and its clinical evaluation in Phase I to III trials as monotherapy and in combination with the NS3/4A inhibitor ABT-450/r and the non-nucleoside NS5B inhibitor dasabuvir (ABT-333) ± ribavirin.

EXPERT OPINION

Ombitasvir (ABT-267) is a potent inhibitor of the hepatitis C virus protein NS5A, has favorable pharmacokinetic characteristics and is active in the picomolar range against genotype 1 - 6. In patients with genotype 1 and 4, 12-week combination treatment with ombitasvir, dasabuvir and ABT-450/r plus ribavirin was highly effective and resulted in 12-week sustained virological response rates higher than 95% in treatment-naöve and treatment-experienced patients. In liver transplant recipients with genotype 1 hepatitis C, success rates in the same range can be expected after 24 weeks of treatment according to preliminary trial results. Genotype 1a patients with compensated cirrhosis who were prior nonresponders benefit from a treatment duration of 24 weeks.

Exploratory trial of ombitasvir and ABT-450/r with or without ribavirin for HCV genotype 1, 2, and 3 infection

OBJECTIVES

To examine the safety and efficacy of ombitasvir and ABT-450 with ritonavir (ABT-450/r) ± ribavirin (RBV) in treatment-naïve, non-cirrhotic adults with chronic HCV genotype 1-3 infection.

METHODS

Patients in this open-label, exploratory, phase 2, multicenter study received ombitasvir (25 mg QD) and ABT-450/r (200/100 mg QD) ± RBV for 12 weeks. Primary efficacy endpoint was HCV RNA < lower limit of quantitation (LLOQ) from week 4 through 12. Sustained virologic response 12 weeks post-treatment (SVR12) was a secondary endpoint.

RESULTS

Sixty-one patients were enrolled. Among genotype 1-, 2-, and 3-infected patients, respectively, HCV RNA was<LLOQ from week 4 through 12 in 10 (100%; 95% CI 69-100), 9 (90%; 56-100), and 7 (70%; 35-93) receiving the RBV-containing regimen and 9 (90%; 56-100), 8 (80%; 44-97), and 2 (18%; 2-52) receiving the RBV-free regimen. Among genotype 1-, 2-, and 3-infected patients, respectively, SVR12 was achieved by 10 (100%), 8 (80%), and 5 (50%) receiving the RBV-containing regimen, and 6 (60%), 6 (60%), and 1 (9%) receiving the RBV-free regimen. The most common adverse events were fatigue, nausea, and headache. One patient discontinued due to an adverse event.

CONCLUSIONS

In this study, ombitasvir and ABT-450/r ± RBV regimens were generally well-tolerated. Sustained virologic response was achieved in most patients with HCV genotype 1 or 2 infection, but low SVR rates were observed in HCV genotype 3-infected patients.

Mechanisms underlying benign and reversible unconjugated hyperbilirubinemia observed with faldaprevir administration in hepatitis C virus patients

Faldaprevir, an investigational agent for hepatitis C virus treatment, is well tolerated but associated with rapidly reversible, dose-dependent, clinically benign, unconjugated hyperbilirubinemia. Multidisciplinary preclinical and clinical studies were used to characterize mechanisms underlying this hyperbilirubinemia. In vitro, faldaprevir inhibited key processes involved in bilirubin clearance: UDP glucuronosyltransferase (UGT) 1A1 (UGT1A1) (IC50 0.45 µM), which conjugates bilirubin, and hepatic uptake and efflux transporters, organic anion-transporting polypeptide (OATP) 1B1 (IC50 0.57 µM), OATP1B3 (IC50 0.18 µM), and multidrug resistance-associated protein (MRP) 2 (IC50 6.2 µM), which transport bilirubin and its conjugates. In rat and human hepatocytes, uptake and biliary excretion of [(3)H]bilirubin and/or its glucuronides decreased on coincubation with faldaprevir. In monkeys, faldaprevir (≥20 mg/kg per day) caused reversible unconjugated hyperbilirubinemia, without hemolysis or hepatotoxicity. In clinical studies, faldaprevir-mediated hyperbilirubinemia was predominantly unconjugated, and levels of unconjugated bilirubin correlated with the UGT1A1*28 genotype. The reversible and dose-dependent nature of the clinical hyperbilirubinemia was consistent with competitive inhibition of bilirubin clearance by faldaprevir, and was not associated with liver toxicity or other adverse events. Overall, the reversible, unconjugated hyperbilirubinemia associated with faldaprevir may predominantly result from inhibition of bilirubin conjugation by UGT1A1, with inhibition of hepatic uptake of bilirubin also potentially playing a role. Since OATP1B1/1B3 are known to be involved in hepatic uptake of circulating bilirubin glucuronides, inhibition of OATP1B1/1B3 and MRP2 may underlie isolated increases in conjugated bilirubin. As such, faldaprevir-mediated hyperbilirubinemia is not associated with any liver injury or toxicity, and is considered to result from decreased bilirubin elimination due to a drug-bilirubin interaction.

Response-guided therapy in patients with genotype 1 hepatitis C virus: current status and future prospects

On-treatment responses to antiviral therapy are used to determine duration of therapy in patients being treated for genotype 1 hepatitis C virus infection. Such use of response-guided therapy has successfully reduced exposure of patients to the side-effects of pegylated interferon and ribavirin without jeopardizing overall treatment success. Response-guided therapy is an integral part of treatment using the current standard treatments involving the direct-acting antiviral (DAA) agents--boceprevir or telaprevir--combined with pegylated interferon/ribavirin. Improvements in our understanding of the kinetics of viral load during antiviral therapy have shown us that more potent suppression of viral replication increases the rate of viral eradication, providing impetus for the development of more potent DAAs. Emerging results from clinical trials of these agents--including trials of interferon-free DAA combinations--suggest that very high rates of viral eradication are achievable, even in patients who failed to respond to previous courses of interferon-based therapy. Furthermore, because of these high rates of treatment success, on-treatment assessment of viral response may become unnecessary. The field of hepatitis C virus therapy is evolving rapidly and current trends indicate that the era of simple treatment regimens with high rates of success and good tolerability are near.

HCV genome-wide genetic analyses in context of disease progression and hepatocellular carcinoma

Hepatitis C virus (HCV) is a major cause of hepatitis and hepatocellular carcinoma (HCC) world-wide. Most HCV patients have relatively stable disease, but approximately 25% have progressive disease that often terminates in liver failure or HCC. HCV is highly variable genetically, with seven genotypes and multiple subtypes per genotype. This variation affects HCV's sensitivity to antiviral therapy and has been implicated to contribute to differences in disease. We sequenced the complete viral coding capacity for 107 HCV genotype 1 isolates to determine whether genetic variation between independent HCV isolates is associated with the rate of disease progression or development of HCC. Consensus sequences were determined by sequencing RT-PCR products from serum or plasma. Positions of amino acid conservation, amino acid diversity patterns, selection pressures, and genome-wide patterns of amino acid covariance were assessed in context of the clinical phenotypes. A few positions were found where the amino acid distributions or degree of positive selection differed between in the HCC and cirrhotic sequences. All other assessments of viral genetic variation and HCC failed to yield significant associations. Sequences from patients with slow disease progression were under a greater degree of positive selection than sequences from rapid progressors, but all other analyses comparing HCV from rapid and slow disease progressors were statistically insignificant. The failure to observe distinct sequence differences associated with disease progression or HCC employing methods that previously revealed strong associations with the outcome of interferon α-based therapy implies that variable ability of HCV to modulate interferon responses is not a dominant cause for differential pathology among HCV patients. This lack of significant associations also implies that host and/or environmental factors are the major causes of differential disease presentation in HCV patients.

Hepatitis C virus: standard-of-care treatment

Hepatitis C virus (HCV) infection is curable by therapy. The antiviral treatment of chronic hepatitis C has been based for decades on the use of interferon (IFN)-α, combined with ribavirin. More recently, new therapeutic approaches that target essential components of the HCV life cycle have been developed, including direct-acting antiviral (DAA) and host-targeted agents (HTA). A new standard-of-care treatment has been approved in 2011 for patients infected with HCV genotype 1, based on a triple combination of pegylated IFN-α, ribavirin, and either telaprevir or boceprevir, two inhibitors of the HCV protease. New triple and quadruple combination therapies including pegylated IFN-α, ribavirin, and one or two DAAs/HTAs, respectively, are currently being evaluated in Phase II and III clinical trials. In addition, various options for all-oral, IFN-free regimens are currently being evaluated. This chapter describes the characteristics of the different drugs used in the treatment of chronic hepatitis C and those currently in development and provides an overview of the current and future standard-of-care treatments of chronic hepatitis C.

Treatment of HCV with ABT-450/r-ombitasvir and dasabuvir with ribavirin

BACKGROUND

The interferon-free combination of the protease inhibitor ABT-450 with ritonavir (ABT-450/r) and the NS5A inhibitor ombitasvir (also known as ABT-267) plus the nonnucleoside polymerase inhibitor dasabuvir (also known as ABT-333) and ribavirin has shown efficacy against the hepatitis C virus (HCV) in patients with HCV genotype 1 infection. In this phase 3 trial, we evaluated this regimen in previously untreated patients with HCV genotype 1 infection and no cirrhosis.

METHODS

In this multicenter, randomized, double-blind, placebo-controlled trial, we assigned previously untreated patients with HCV genotype 1 infection, in a 3:1 ratio, to an active regimen consisting of a single-tablet coformulation of ABT-450/r-ombitasvir (at a once-daily dose of 150 mg of ABT-450, 100 mg of ritonavir, and 25 mg of ombitasvir), and dasabuvir (250 mg twice daily) with ribavirin (in doses determined according to body weight) (group A) or matching placebos (group B). The patients received the study treatment during a 12-week double-blind period. The primary end point was sustained virologic response at 12 weeks after the end of treatment. The primary analysis compared the response rate in group A with the response rate (78%) in a historical control group of previously untreated patients without cirrhosis who received telaprevir with peginterferon and ribavirin. Adverse events occurring during the double-blind period were compared between group A and group B.

RESULTS

A total of 631 patients received at least one dose of the study drugs. The rate of sustained virologic response in group A was 96.2% (95% confidence interval, 94.5 to 97.9), which was superior to the historical control rate. Virologic failure during treatment and relapse after treatment occurred in 0.2% and 1.5%, respectively, of the patients in group A. The response rates in group A were 95.3% among patients with HCV genotype 1a infection and 98.0% among those with HCV genotype 1b infection. The rate of discontinuation due to adverse events was 0.6% in each study group. Nausea, pruritus, insomnia, diarrhea, and asthenia occurred in significantly more patients in group A than in group B (P<0.05 for all comparisons). Reductions in the hemoglobin level were all of grade 1 or 2; reductions of grade 1 and 2 occurred in 47.5% and 5.8%, respectively, of the patients in group A, whereas grade 1 reductions occurred in 2.5% of the patients in group B.

CONCLUSIONS

In previously untreated patients with HCV genotype 1 infection and no cirrhosis, a 12-week multitargeted regimen of ABT-450/r-ombitasvir and dasabuvir with ribavirin was highly effective and was associated with a low rate of treatment discontinuation. (Funded by AbbVie; SAPPHIRE-I ClinicalTrials.gov number, NCT01716585.).

Retreatment of HCV with ABT-450/r-ombitasvir and dasabuvir with ribavirin

BACKGROUND

In this phase 3 trial we evaluated the efficacy and safety of the interferon-free combination of ABT-450 with ritonavir (ABT-450/r), ombitasvir (also known as ABT-267), dasabuvir (also known as ABT-333), and ribavirin for the retreatment of HCV in patients who were previously treated with peginterferon-ribavirin.

METHODS

We enrolled patients with HCV genotype 1 infection and no cirrhosis who had previously been treated with peginterferon-ribavirin and had a relapse, a partial response, or a null response. Patients were randomly assigned in a 3:1 ratio to receive coformulated ABT-450/r-ombitasvir (at a once-daily dose of 150 mg of ABT-450, 100 mg of ritonavir, and 25 mg of ombitasvir) and dasabuvir (250 mg twice daily) with ribavirin (1000 or 1200 mg daily) or matching placebos during the 12-week double-blind period. The primary end point was the rate of sustained virologic response 12 weeks after the end of study treatment. The primary efficacy analysis compared this rate among patients assigned to the active regimen with a historical response rate (65%) among previously treated patients with HCV genotype 1 infection and no cirrhosis who had received retreatment with telaprevir and peginterferon-ribavirin.

RESULTS

A total of 394 patients received at least one study-drug dose. In the active-regimen group, 286 of 297 patients had a sustained virologic response at post-treatment week 12, for an overall rate of 96.3% (95% confidence interval, 94.2 to 98.4). This rate was noninferior and superior to the historical control rate. Rates were 95.3% among patients with a prior relapse (82 of 86 patients), 100% among patients with a prior partial response (65 of 65 patients), and 95.2% among patients with a prior null response (139 of 146 patients). Pruritus occurred more frequently with the active regimen (in 13.8% of patients) than with placebo (5.2%, P=0.03). Three patients in the active-regimen group (1.0%) discontinued the study drugs owing to adverse events. Hemoglobin values of grade 2 (8.0 to <10.0 g per deciliter) and grade 3 (6.5 to <8.0 g per deciliter) occurred in 4.7% and 0.3% of patients in the active-regimen group, respectively.

CONCLUSIONS

Rates of response to a 12-week interferon-free combination regimen were more than 95% among previously treated patients with HCV genotype 1 infection, including patients with a prior null response. (Funded by AbbVie; SAPPHIRE-II ClinicalTrials.gov number, NCT01715415.).

SILEN-C3, a phase 2 randomized trial with faldaprevir plus pegylated interferon α-2a and ribavirin in treatment-naive hepatitis C virus genotype 1-infected patients

Faldaprevir is an investigational hepatitis C virus (HCV) NS3/4A protease inhibitor which, when administered for 24 weeks in combination with pegylated interferon α-2a and ribavirin (PegIFN/RBV) in treatment-naive patients in a prior study (SILEN-C1; M. S. Sulkowski et al., Hepatology 57:2143–2154, 2013, doi:10.1002/hep.26276), achieved sustained virologic response (SVR) rates of 72 to 84%. The current randomized, open-label, parallel-group study compared the efficacy and safety of 12 versus 24 weeks of 120 mg faldaprevir administered once daily, combined with 24 or 48 weeks of PegIFN/RBV, in 160 treatment-naive HCV genotype 1 patients. Patients with maintained rapid virologic response (HCV RNA of <25 IU/ml at week 4 and undetectable at weeks 8 and 12) stopped all treatment at week 24, otherwise they continued PegIFN/RBV to week 48. SVR was achieved by 67% and 74% of patients in the 12-week and 24-week groups, respectively. Virologic response rates were lower in the 12-week group from weeks 2 to 12, during which both groups received identical treatment. SVR rates were similar in both groups for patients achieving undetectable HCV RNA. Most adverse events were mild or moderate, and 6% of patients in each treatment group discontinued treatment due to adverse events. Once-daily faldaprevir at 120 mg for 12 or 24 weeks with PegIFN/RBV resulted in high SVR rates, and the regimen was well tolerated. Differences in the overall SVR rates between the 12-week and 24-week groups were not statistically significant and possibly were due to IL28B genotype imbalances; IL28B genotype was not tested, as its significance was not known at the time of the study. These results supported phase 3 evaluation. (This study has been registered at ClinicalTrials.gov under registration no. NCT00984620).

Drug-drug interactions with oral anti-HCV agents and idiosyncratic hepatotoxicity in the liver transplant setting

Studies of boceprevir and telaprevir based antiviral therapy in liver transplant (LT) recipients with hepatitis C genotype 1 infection have demonstrated dramatic increases in tacrolimus, cyclosporine, and mTOR inhibitor exposure. In addition to empiric dose reductions, daily monitoring of immunosuppressant blood levels is required when initiating as well as discontinuing the protease inhibitors to maximize patient safety. Although improved suppression of HCV replication is anticipated, 20 to 40% of treated subjects have required early treatment discontinuation due to various adverse events including anemia (100%), infection (30%), nephrotoxicity (20%) and rejection (5 to 10%). Simeprevir and faldaprevir will likely have improved efficacy and safety profiles but potential drug interactions with other OATP1B1 substrates and unconjugated hyperbilirubinemia are expected. In contrast, sofosbuvir and daclatasvir based antiviral therapy are not expected to lead to clinically significant drug-drug interactions in LT recipients but confirmatory studies are needed. Liver transplant recipients may also be at increased risk of developing drug induced liver injury (DILI). Establishing a diagnosis of DILI in the transplant setting is very difficult with the variable latency, laboratory features and histopathological manifestations of hepatotoxicity associated with a given drug, the need to exclude competing causes of allograft injury, and the lack of an objective and verifiable confirmatory test. Nonetheless, a heightened awareness of the possibility of DILI is warranted in light of the large number of medications used in LT recipients and the potential adverse impact that DILI may have on patient outcomes.

Importance of HCV genotype 1 subtypes for drug resistance and response to therapy

The treatment for patients infected with hepatitis C virus (HCV) genotype 1 has undergone major changes with the availability of direct-acting antivirals. Triple therapy, containing telaprevir or boceprevir, first-wave NS3 protease inhibitors, in combination with peginterferon and ribavirin, improved rates of sustained virologic response compared with peginterferon and ribavirin alone in patients with HCV genotype 1. However, the development of drug-resistant variants is a concern. In patients treated with telaprevir or boceprevir, different patterns of resistance are observed for the two major HCV genotype 1 subtypes, 1a and 1b. Genotype 1b is associated with a lower rate of resistant variant selection and better response to triple therapy compared with genotype 1a. Similar subtype-specific patterns have been observed for investigational direct-acting antivirals, including second-wave NS3 protease inhibitors, NS5A inhibitors and non-nucleoside NS5B inhibitors. This review explores resistance to approved and investigational direct-acting antivirals for the treatment of HCV, focusing on the differences between genotype 1a and genotype 1b. Finally, given the importance of HCV genotype 1 subtype on resistance and treatment outcomes, clinicians must also be aware of the tests currently available for genotype subtyping and their limitations.

MK-5172 : a second-generation protease inhibitor for the treatment of hepatitis C virus infection

INTRODUCTION

Approximately 170 million people worldwide are chronic carriers of the hepatitis C virus (HCV). Twenty-five percent of them develop liver cirrhosis and hepatocellular carcinoma during their life. Successful antiviral treatment dramatically reduces the risk of disease progression. HCV infection is treated with pegylated interferon and ribavirin; the addition of a protease inhibitor (boceprevir or telaprevir) can also be considered for patients with genotype 1.

AREAS COVERED

This review summarizes the data about the pharmacokinetics, pharmacodynamics, efficacy and safety of MK-5172 , a second-generation inhibitor of HCV NS3/4A protease.

EXPERT OPINION

The pharmacokinetic profile allows for once-a-day administration. Combined with pegylated interferon and ribavirin, MK-5172 results in a high rate of HCV eradication (in about 90% of cases) and a better outcome than boceprevir-based triple therapy. Also in interferon-free combinations, MK-5172-associated eradication rates are very high (89 - 100%). MK-5172 has a higher barrier to resistance than first-generation protease inhibitors and is active against most variants associated with resistance to first-generation protease inhibitors. Tolerability and safety profile are good. Although data are limited, MK-5172 appears to overcome most of the drawbacks of the first-generation protease inhibitors and is thus a very promising agent to be used in combination with other antivirals to eradicate HCV infection.

Phase 2b trial of interferon-free therapy for hepatitis C virus genotype 1

BACKGROUND

An interferon-free combination of the protease inhibitor ABT-450 with ritonavir (ABT-450/r), the nonnucleoside polymerase inhibitor ABT-333, and ribavirin showed efficacy against the hepatitis C virus (HCV) in a pilot study involving patients with HCV genotype 1 infection. The addition of another potent agent, the NS5A inhibitor ABT-267, may improve efficacy, especially in difficult-to-treat patients. This study was designed to evaluate multiple regimens of direct-acting antiviral agents and ribavirin in patients with HCV genotype 1 infection who had not received therapy previously or who had no response to prior therapy with pegylated interferon and ribavirin.

METHODS

In this phase 2b, open-label study with 14 treatment subgroups, 571 patients without cirrhosis who had not received treatment previously or who had not had a response to prior therapy were randomly assigned to a regimen of ABT-450/r, combined with ABT-267 or ABT-333 or both, for 8, 12, or 24 weeks and received at least one dose of therapy. All the subgroups but 1 also received ribavirin (dose determined according to body weight). The primary end point was sustained virologic response at 24 weeks after the end of treatment. The primary efficacy analysis compared rates between previously untreated patients who received three direct-acting antiviral agents and ribavirin for 8 weeks and those who received the same therapy for 12 weeks.

RESULTS

Among previously untreated patients who received three direct-acting antiviral agents (with the ABT-450/r dose administered as 150 mg of ABT-450 and 100 mg of ritonavir) plus ribavirin, the rate of sustained virologic response at 24 weeks after treatment was 88% among those who received the therapy for 8 weeks and 95% among those who received the therapy for 12 weeks (difference, -7 percentage points; 95% confidence interval, -19 to 5; P=0.24). The rates of sustained virologic response across all treatment subgroups ranged from 83 to 100%. The most frequent adverse events were fatigue, headache, nausea, and insomnia. Eight patients (1%) discontinued treatment owing to adverse events.

CONCLUSIONS

In this phase 2b study, all-oral regimens of antiviral agents and ribavirin were effective both in patients with HCV genotype 1 infection who had not received therapy previously and in those who had not had a response to prior therapy. (Funded by AbbVie; ClinicalTrials.gov number, NCT01464827.).

Safety and efficacy of faldaprevir with pegylated interferon alfa-2a and ribavirin in Japanese patients with chronic genotype-1 hepatitis C infection

BACKGROUND & AIMS

Faldaprevir (BI 201335) is a potent once-daily (QD) NS3/4A protease inhibitor for the treatment of patients with genotype-1 (GT-1) hepatitis C virus (HCV). The aim of this study was to evaluate the safety, pharmacokinetics and efficacy of faldaprevir plus pegylated interferon alfa-2a (PegIFN) and ribavirin (RBV) in Japanese patients infected with chronic GT-1 HCV.

METHODS

Part 1 of this phase II study was a randomized, double-blind, placebo-controlled, dose-ascending study. Treatment-naïve patients received faldaprevir 120 or 240 mg QD, or placebo, plus PegIFN/RBV for 4 weeks, then PegIFN/RBV alone for 44 weeks. In Part 2 (open label), treatment-experienced patients received faldaprevir 240 mg QD plus PegIFN/RBV for 4 weeks, then PegIFN/RBV alone for 44 weeks. Efficacy was assessed using sustained virological response (SVR) 24 weeks after treatment completion. The pharmacokinetics, safety and tolerability of faldaprevir were also assessed.

RESULTS

SVR was achieved by 4/6 (67%) treatment-naïve patients treated with faldaprevir 120 mg QD, 5/6 (83%) patients treated with faldaprevir 240 mg QD and 2/4 (50%) patients who received placebo. Of the treatment-experienced patients, 3/6 (50%) achieved SVR. Faldaprevir was well tolerated. There was one serious adverse event, which was not considered to be treatment related. Rash and hyperbilirubinaemia were more frequently reported with faldaprevir than with placebo in treatment-naïve patients, but no cases were severe or serious and none led to discontinuation. Steady-state plasma concentrations of faldaprevir were reached within 7 days of QD dosing.

CONCLUSIONS

Faldaprevir with PegIFN/RBV was efficacious and well tolerated, supporting further evaluation of this combination in Japanese patients.