Understanding the effect of the HCV polymerase inhibitor mericitabine on early viral kinetics in the phase 2 JUMP-C and PROPEL studies.

AIMS: The aim was to evaluate early viral kinetics in patients receiving mericitabine [hepatitis C virus (HCV) nucleoside polymerase inhibitor] with peginterferon alfa-2a (40KD) and ribavirin in two clinical trials (PROPEL and JUMP-C). METHODS: We examined rapid virological responses (RVRs; week 4 HCV RNA <15 IU ml(-1) ) and complete early virological responses (cEVR; week 12 HCV RNA <15 IU ml(-1) ) in HCV genotype 1/4-infected patients receiving mericitabine (500 or 1000 mg) or placebo twice daily plus peginterferon alfa-2a and ribavirin. RESULTS: Among IL28B rs12979860 CC genotype patients receiving 500 or 1000 mg mericitabine or placebo, respectively, RVR rates were 64.3% (95% confidence interval: 38.8-83.7%), 95.1% (83.9-98.7%) and 33.3% (20.2-49.7%), and cEVR rates were 100% (78.5-100%), 100% (91.4-100%) and 80.6% (65.0-90.3%). Among non-CC genotype patients, RVR rates were 26.5% (14.6-43.1%), 52.3% (43.0-61.3%) and 5.7% (2.2-13.8%), and cEVR rates were 76.5% (60.0-87.6%), 84.6% (76.6-90.1%) and 28.6% (19.3-40.1%), respectively. In multiple regression analysis, IL28B genotype (P < 0.0001), mericitabine dose (P < 0.0001) and bodyweight (P = 0.0009) were associated with first-phase (α) slope (change in log10 HCV RNA from baseline to week 1). CONCLUSIONS: Mericitabine-containing triple therapy reduces the impact of IL28B genotype on RVR and cEVR compared with peginterferon alfa-2a and ribavirin dual therapy. The IL28B genotype, mericitabine dose and bodyweight are the most important factors associated with the α slope, and there is no evidence of a pharmacokinetic drug-drug interaction between mericitabine and ribavirin.

Balapiravir plus peginterferon alfa-2a (40KD)/ribavirin in a randomized trial of hepatitis C genotype 1 patients.

INTRODUCTION: Balapiravir (R1626, RG1626) is the prodrug of a nucleoside analogue inhibitor of the hepatitis C virus (HCV) RNA-dependent RNA polymerase (R1479, RG1479). This phase 2, double-blind international trial evaluated the optimal treatment regimen of balapiravir plus peginterferon alfa-2a (40KD)/ribavirin. MATERIAL AND METHODS: Treatment-naive genotype 1 patients (N = 516) were randomized to one of seven treatment groups in which they received balapiravir 500, 1,000, or 1,500 mg twice daily, peginterferon alfa-2a (40KD) 180 or 90 µg/week and ribavirin 1,000/1,200 mg/day or peginterferon alfa-2a (40KD)/ribavirin. The planned treatment duration with balapiravir was reduced from 24 to 12 weeks due to safety concerns. RESULTS: The percentage of patients with undetectable HCV RNA was consistently higher in all balapiravir groups from week 2 to 12. However, high rates of dose modifications and discontinuations of one/all study drugs compromised the efficacy assessment and resulted in similar sustained virological response rates in the balapiravir groups (range 32-50%) and the peginterferon alfa-2a (40KD)/ribavirin group (43%). Balapiravir was discontinued for safety reasons in 28-36% of patients (most often for lymphopenia) and the percentage of patients with serious adverse events (especially hematological, infection, ocular events) was dose related. Serious hematological adverse events (particularly neutropenia, lymphopenia) were more common in balapiravir recipients. Two deaths in the balapiravir/peginterferon alfa-2a/ribavirin combination groups were considered possibly related to study medication. CONCLUSION: Further development of balapiravir for the treatment of chronic hepatitis C has been halted because of the unacceptable benefit to risk ratio revealed in this study (www.ClinicalTrials.gov NCT 00517439).

R1626 plus peginterferon Alfa-2a provides potent suppression of hepatitis C virus RNA and significant antiviral synergy in combination with ribavirin.

UNLABELLED: R1626, a prodrug of the hepatitis C virus (HCV) RNA polymerase inhibitor R1479, showed time-dependent and dose-dependent reduction of HCV RNA levels in a previous study. The present study evaluated the efficacy and safety of R1626 administered for 4 weeks in combination with peginterferon alfa-2a +/- ribavirin in HCV genotype 1-infected treatment-naive patients. Patients were randomized to: DUAL 1500 (1500 mg R1626 twice daily [bid] + peginterferon alfa-2a; n = 21); DUAL 3000 (3000 mg R1626 bid + peginterferon alfa-2a; n = 32); TRIPLE 1500 (1500 mg R1626 bid + peginterferon alfa-2a + ribavirin; n = 31); or standard of care (SOC) (peginterferon alfa-2a + ribavirin; n = 20). At 4 weeks HCV RNA was undetectable (<15 IU/mL) in 29%, 69%, and 74% of patients in the DUAL 1500, DUAL 3000, and TRIPLE 1500 arms, respectively, compared with 5% of patients receiving SOC, with respective mean reductions in HCV RNA from baseline to week 4 of 3.6, 4.5, 5.2, and 2.4 log(10) IU/mL. Synergy was observed between R1626 and peginterferon alfa-2a and between R1626 and ribavirin. There was no evidence of development of viral resistance. Adverse events (AEs) were mainly mild or moderate; seven patients had nine serious AEs (including one patient with one serious AE in SOC). The incidence of Grade 4 neutropenia was 48%, 78%, 39%, and 10% in DUAL 1500, DUAL 3000, TRIPLE 1500, and SOC, respectively, and was the main reason for dose reductions. CONCLUSION: A synergistic antiviral effect was observed when R1626 was combined with peginterferon alfa-2a +/- ribavirin; up to 74% of patients had undetectable HCV RNA at week 4. Dosing of R1626 was limited by neutropenia; a study of different dosages of R1626 in combination with peginterferon alfa-2a and ribavirin is underway.

Effectiveness and dentin bond strengths of two materials for reinforcing thin-walled roots.

OBJECTIVES: To investigate the effectiveness of two restorative materials for reinforcing thin-walled roots and their microtensile bond strengths to root canal dentin. METHODS: Twenty-one decoronated maxillary central incisor roots were root filled and the canals enlarged to leave approximately 1.0 mm thick dentin walls. The roots were distributed randomly to three equal groups. Group 1 (control): a large tapered cast post-core was fabricated. Group 2 (BIS-CORE): a thick layer of dual-cured composite was placed in the post-hole before fabrication of a small-diameter tapered cast post-core. Group 3 (ChemFil Superior): a thick layer of glass-ionomer was placed, as before. Metal-ceramic crowns were fabricated for all teeth. Microtensile bond strength tests and optical and atomic force microscope observations were employed to examine adhesion between the two restorative materials and the root canal dentin. RESULTS: Mechanical loading (kN) demonstrated that composite 0.64 (S.D. 0.05), but not glass-ionomer 0.49 (0.05), significantly reinforced the fracture resistance of thin-walled roots, P<0.001. Microtensile bond strengths (MPa) were 21.7 (1.6) for composite and 12.9 (1.7) for glass-ionomer, P=002. SIGNIFICANCE: A thick intermediate layer of resin-bonded composite, sandwiched between the root dentin and a small-diameter cast Ni-Cr post or dowel, increased significantly the fracture resistance of the roots.