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Background: Telaprevir and boceprevir are highly selective hepatitis C virus (HCV) NS3/4A proteaseinhibitors in phase 3 development. Viral breakthrough during mono- and triple-therapies with PEG-interferon and ribavirin and relapse is associated with resistance., Objectives: Potential persistence of resistance mutations during long-term follow-up should be analyzed., Study Design: Clonal sequence analysis of the NS3-protease gene was performed at long-term follow-up in HCV genotyp-1 infected patients who received telaprevir or boceprevir within phase-1b studies for comparison with resistant variants present directly after the end-of-treatment., Results: After a median follow-up of 4.2 years in 28 of 82 patients HCV-RNA was still detectable. Resistance variants were detected in two of 14 telaprevir- and in four of 14 boceprevir-treated patients. For telaprevir patients two low-level (V36M, V36A) and one high-level (A156T) mutation associated with resistance were detected at low frequencies (4-9% of the clones). In five boceprevir-treated patients four low level mutations (V36A, T54A/S, V55A) were observed at low frequencies (1-10%) while in one patient additionally a combined variant (T54S+R155K) was detected at 94%. Presence of resistant variants at long-term follow-up was not predictable by variants detected at the end-of-treatment. In one patient a V55A variant which was dominant already at baseline was still detectable at long-term follow-up., Conclusions: In the majority of patients after short-term treatment with telaprevir or boceprevir wild-type NS3-protease isolates are detectable by clonal sequencing at long-term follow-up. Detectable resistance mutations in single patients are not predictable by initial frequencies of variants., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: In patients with chronic infection with hepatitis C virus (HCV) genotype 1, treatment with peginterferon alfa and ribavirin for 48 weeks results in rates of sustained virologic response of 40 to 50%. Telaprevir is a specific inhibitor of the HCV serine protease and could be of value in HCV treatment., Methods: A total of 334 patients who had chronic infection with HCV genotype 1 and had not been treated previously were randomly assigned to receive one of four treatments involving various combinations of telaprevir (1250 mg on day 1, then 750 mg every 8 hours), peginterferon alfa-2a (180 microg weekly), and ribavirin (dose according to body weight). The T12PR24 group (81 patients) received telaprevir, peginterferon alfa-2a, and ribavirin for 12 weeks, followed by peginterferon alfa-2a and ribavirin for 12 more weeks. The T12PR12 group (82 patients) received telaprevir, peginterferon alfa-2a, and ribavirin for 12 weeks. The T12P12 group (78 patients) received telaprevir and peginterferon alfa-2a without ribavirin for 12 weeks. The PR48 (control) group (82 patients) received peginterferon alfa-2a and ribavirin for 48 weeks. The primary end point, a sustained virologic response (an undetectable HCV RNA level 24 weeks after the end of therapy), was compared between the control group and the combined T12P12 and T12PR12 groups., Results: The rate of sustained virologic response for the T12PR12 and T12P12 groups combined was 48% (77 of 160 patients), as compared with 46% (38 of 82) in the PR48 (control) group (P=0.89). The rate was 60% (49 of 82 patients) in the T12PR12 group (P=0.12 for the comparison with the PR48 group), as compared with 36% (28 of 78 patients) in the T12P12 group (P=0.003; P=0.20 for the comparison with the PR48 group). The rate was significantly higher in the T12PR24 group (69% [56 of 81 patients]) than in the PR48 group (P=0.004). The adverse events with increased frequency in the telaprevir-based groups were pruritus, rash, and anemia., Conclusions: In this phase 2 study of patients infected with HCV genotype 1 who had not been treated previously, one of the three telaprevir groups had a significantly higher rate of sustained virologic response than that with standard therapy. Response rates were lowest with the regimen that did not include ribavirin. (ClinicalTrials.gov number, NCT00372385.), (2009 Massachusetts Medical Society)

Almost half of the patients who have chronic hepatitis C cannot be cured with the current standard treatment. Recent progress in structure determination of HCV proteins and development of a subgenomic replicon system and a cell culture infectious HCV clone enabled the development of a specifically targeted antiviral therapy for hepatitis C (STAT-C). Many HCV-specific compounds are under investigation in preclinical and clinical trials. The development of agents in different classes may allow construction of antiviral combinations that enhance the effectiveness of antiviral treatment, reduce the duration of treatment, and, eventually, may even avoid the use of interferon-alfa.

Unlabelled: Telaprevir (VX-950) is an orally active, specifically targeted antiviral therapy for hepatitis C virus (HCV) that has been shown to profoundly reduce plasma HCV RNA in genotype 1 patients. Using a highly sensitive sequencing assay that detects minor populations of viral variants (>or=5%), mutations were identified that conferred low-level (V36M/A, T54A, or R155K/T) or high-level (A156V/T and 36/155) resistance to telaprevir in vitro. We report a detailed kinetic analysis of these variants in 16 patients given telaprevir or telaprevir + pegylated interferon-alpha-2a (PEG-IFN-alpha-2a) for 14 days. In 4 patients who had a viral rebound on telaprevir alone, the R155K/T and A156V/T variants were detected during the initial steep decline in HCV RNA. During the rebound phase, the R155K/T and A156V/T variants were replaced by V36(M/A)/R155(K/T) double mutant variants. In the remaining 12 patients given telaprevir alone or with telaprevir/PEG-IFN-alpha-2a, the A156V/T variant was detected in some patients, but viral levels continued to decline in all patients., Conclusion: These studies suggest that the initial antiviral response to telaprevir is due to a sharp reduction in wild-type virus, which uncovers pre-existing telaprevir-resistant variants. In patients given telaprevir alone, viral rebound can result from the selection of variants with greater fitness. However, the combination of telaprevir and PEG-IFN-alpha-2a inhibited both wild-type and resistant variants. In the present study, every patient who began PEG-IFN-alpha-2a and ribavirin after the 14-day dosing period had undetectable HCV RNA levels at 24 weeks, indicating that telaprevir-resistant variants are sensitive to PEG-IFN-alpha-2a and ribavirin.

Unlabelled: Telaprevir (VX-950), an inhibitor of the hepatitis C virus (HCV) NS3/4A protease, substantially decreased plasma HCV RNA levels in a prior clinical study. The present study evaluated viral kinetics and safety during dosing with telaprevir alone and in combination with peginterferon alfa-2a for 14 days. Previously untreated patients with genotype 1 hepatitis C were randomized to receive placebo and peginterferon alfa-2a (n = 4); telaprevir (n = 8); or telaprevir and peginterferon alfa-2a (n = 8). Telaprevir was given as 750 mg oral doses every 8 hours; peginterferon alfa-2a was given as weekly 180 mug subcutaneous injections. The median change in HCV RNA from baseline to day 15 was -1.09 log(10) (range, -2.08 to -0.46) in the placebo and peginterferon alfa-2a group; -3.99 log(10) (range, -5.28 to -1.26) in the telaprevir group, and -5.49 log(10) (range, -6.54 to -4.30) in the telaprevir and peginterferon alfa-2a group. Day 15 HCV RNA levels were undetectable in 4 patients who received telaprevir and peginterferon alfa-2a and in 1 patient who received telaprevir alone. No viral breakthrough occurred in patients who received telaprevir and peginterferon alfa-2a. The majority of adverse events were mild. There were no serious adverse events or premature discontinuations. Twelve weeks after starting off-study standard therapy, HCV RNA was undetectable in all 8 patients in the telaprevir and peginterferon alfa-2a group, 5 patients in the telaprevir group, and 1 patient in the placebo and peginterferon alfa-2a group., Conclusion: This study confirmed the substantial antiviral effects of telaprevir and showed an increased antiviral effect of telaprevir combined with peginterferon alfa-2a.

Background & Aims: SCH 503034 is a novel and potent oral hepatitis C virus (HCV) protease inhibitor. In this phase Ib study, we assessed safety parameters and virologic response of combination of SCH 503034 plus pegylated (PEG) interferon (IFN) alpha-2b in patients with HCV genotype 1 infections who were previously nonresponders to PEG-IFN-alpha-2b +/- ribavirin therapy., Methods: This was a multicenter, open-label, 2-dose level, 3-way crossover, randomized (to crossover sequence) study carried out in 3 medical centers in Europe. Adult patients received SCH 503034 200 mg (n = 14) or 400 mg (n = 12) 3 times daily orally and PEG-IFN-alpha-2b 1.5 microg/kg subcutaneously once each week. Patients received SCH 503034 as monotherapy for 1 week, PEG-IFN-alpha-2b as monotherapy for 2 weeks, and combination therapy for 2 weeks with washout periods between each treatment period., Results: Combination therapy with SCH 503034 and PEG-IFN-alpha-2b was well tolerated, with no clinically significant changes in safety parameters. Mean maximum log(10) changes in HCV RNA were -2.45 +/- 0.22 and -2.88 +/- 0.22 for PEG-IFN-alpha-2b plus 200 mg and 400 mg SCH 503034, respectively, compared with -1.08 +/- 0.22 and -1.61 +/- 0.21 for SCH 503034 200 mg and 400 mg, respectively, and -1.08 +/- 0.22 and -1.26 +/- 0.20 for PEG-IFN-alpha-2b alone in the 200 mg and 400 mg SCH 503034 groups, respectively., Conclusions: SCH 503034 plus PEG-IFN-alpha-2b was well tolerated in patients with HCV genotype 1 nonresponders to PEG-IFN-alpha-2b +/- ribavirin. These preliminary results of antiviral activity of the combination suggest a potential new therapeutic option for this hard-to-treat, nonresponder patient population.

Background & Aims: VX-950 specifically inhibits the NS3.4A protease of hepatitis C and has antiviral activity in vitro. This phase I, placebo-controlled, double-blind study evaluated the antiviral activity, pharmacokinetics, and safety of VX-950 in patients with chronic hepatitis C (CHC)., Methods: Thirty-four patients with genotype 1 CHC were randomized to receive placebo or VX-950 at doses of 450 mg or 750 mg every 8 hours or 1250 mg every 12 hours for 14 days. Of the 34 participants, 27 (79%) had failed prior treatment. Patients were monitored for safety and tolerability of VX-950. Plasma VX-950 concentrations and HCV RNA levels were measured., Results: VX-950 was well tolerated and had substantial antiviral effects: viral loads dropped > or =2 log(10) in all 28 patients treated with VX-950 and > or =3 log(10) in 26 (93%) of the 28 patients. In the 750-mg-dose group, which had the highest trough plasma drug concentrations, the median reduction of HCV RNA was 4.4 log(10) after 14 days. In the 450-mg and 1250-mg groups, the maximal effect was seen between days 3 and 7 of dosing, and median HCV RNA increased between days 7 and 14; median reductions at day 14 were 2.4 log(10) and 2.2 log(10), respectively. Median alanine aminotransferase levels decreased during dosing in all VX-950 groups., Conclusions: VX-950 was well tolerated and demonstrated substantial antiviral activity. Some patients had viral breakthrough during dosing, related to selection of variants with decreased sensitivity to VX-950. The results support further studies of VX-950 in patients with CHC.