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Abstract
Background/aim Insulin resistance (IR) is a major predictor of treatment failure in patients with hepatitis C virus (HCV) infection treated with peginterferon/ribavirin. The aim of this study was to evaluate the short-term effect of an HCV protease inhibitor monotherapy on IR in parallel with an antiviral effect.
Patients/methods In a phase 1b placebo-controlled study, four cohorts of treatment-naïve patients with genotype 1 HCV received danoprevir (ITMN-191/RG7227), a protease inhibitor, or placebo (8/2 patients in each cohort respectively) in a gelatin capsule every 12 h (100, 200 mg) or 8 h (100, 200 mg) for 14 days. A fifth cohort including prior non-responders to peginterferon/ribavirin was similarly randomised to receive placebo or 300 mg danoprevir every 12 h. IR was assessed with the homeostasis model (HOMA-IR) at baseline and days 7, 14 and 15.
Results Serum HCV-RNA and HOMA-IR correlated significantly (Spearman rho=0.379, p<0.0001). At baseline, mean±SD serum HCV-RNA level and mean±SD HOMA-IR score were 6.2±0.5 log10IU/ml and 3.8±1.9, respectively. At the end of 14 days of monotherapy the mean±SD decrease in viral load was 2.2±1.3 log10IU/ml (p<0.0001) in patients who received the active drug (n=40). In parallel, the mean±SD HOMA-IR score also decreased in these patients by 1.6±1.1 (p<0.0001), with a close correlation between the extent of HOMA-IR improvement and the decrease in viral load. By contrast, serum HCV-RNA and HOMA-IR remained unchanged in patients who received placebo (n=10; 6.3±0.5 log10IU/ml and 3.8±2.5, respectively).
Conclusion HCV protease inhibitor may restore insulin sensitivity in patients with genotype 1 HCV. The place of insulin sensitisers remains to be determined in the era of triple therapy.
- HOMA-IR
- insulin resistance
- SVR
- hepatitis C
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Significance of this study
What is already known about the subject?
There is growing evidence linking hepatitis C virus (HCV) infection to insulin resistance and diabetes mellitus.
Insulin resistance is a major predictor of treatment failure in patients with genotype 1 HCV infection treated with peginterferon plus ribavirin.
Reducing IR using insulin sensitising agents does not improve treatment outcomes in these patients.
What are the new findings?
This study represents the first trial to date to address the direct effect of specific antiviral therapy on insulin resistance in patients with genotype 1 chronic hepatitis C.
The results of this study provide original information about the efficacy of the new specific antiviral dugs to overcome insulin resistance without the need of insulin sensitising agents.
The results also emphasise the pivotal role of the NS3-4A protease among the HCV proteins.
The results of this study also provide definitive evidence for the link between HCV infection and insulin resistance in humans.
How might it impact on clinical practice in the foreseeable future?
HCV protease inhibitor may restore insulin sensitivity in patients with genotype 1 chronic hepatitis C. The place of insulin sensitisers remains to be determined in the era of triple therapy.
Introduction
There is growing evidence linking hepatitis C virus (HCV) infection to insulin resistance (IR) and diabetes mellitus, so chronic hepatitis C (CHC) can be considered a metabolic disease.1 2 Recent studies have shown that IR may increase the progression of liver fibrosis and induce histological lesions of non-alcoholic steatohepatitis in patients with CHC.3–8 Moreover, IR has been shown to be a major predictor of non-response to treatment in patients with CHC who received peginterferon and ribavirin.9–13 Finally, studies have shown that, in patients with CHC who responded to peginterferon and ribavirin, there was a reduction in levels of IR.11 14 This improvement in insulin sensitivity was maintained for patients with a sustained virological response (SVR) and resulted in a reduced risk of subsequent diabetes mellitus.15 16
Correcting IR therefore seems to be a rational and attractive option for patients with CHC—at least theoretically—especially for those who are candidates for peginterferon and ribavirin therapy. Clinical trials are underway to determine whether reducing IR using insulin sensitising agents improves treatment outcomes. Unfortunately, preliminary data from trials adding pioglitazone or metformin to peginterferon and ribavirin have been disappointing.17–19 These results highlight the complexity and interactions between host-related and virus-related factors associated with the development of IR in patients with CHC.20 Targeting viral factors associated with IR may be an alternative option for insulin sensitising pharmacotherapy. Regarding specific viral factors, the non-structural NS3-4A protease may be an excellent therapeutic target owing to its essential role in the HCV life cycle.21 22 The aim of this study was thus to evaluate the short-term effect of an HCV protease inhibitor monotherapy on IR in parallel with the antiviral effect in patients with genotype 1 CHC.
Methods
Patient population
This study is derived from a double-blind placebo-controlled trial which was conducted in 2007–8 to evaluate the safety, tolerability and antiviral activity of multiple ascending oral doses of danoprevir (ITMN-191/RG7227), a highly potent and selective inhibitor of NS3/4A HCV serine protease activity, in treatment-naïve patients and non-responders to peginterferon/ribavirin with genotype 1 CHC.
Five cohorts of patients participated. Each cohort included 10 patients, 8 of whom received the active study drug (danoprevir) in monotherapy and 2 of whom received placebo every 12 h or every 8 h. Patients in the first four cohorts were treatment-naïve and were dosed for 14 days starting with 100 mg every 12 h and increasing as follows: 100 mg every 8 h, 200 mg every 12 h, 200 mg every 8 h. The final cohort included non-responders to peginterferon/ribavirin and was similarly randomised to receive placebo or 300 mg danoprevir every 12 h.
All patients were observed in a research facility from the night before the first dose until approximately 48 h following the last dose of study drug. Meals and activity levels were standardised across research facilities.
Eligibility criteria for the study were age 18–65 years, body mass index (BMI) 18–30 kg/m2, absence of diabetes mellitus, absence of drug or alcohol abuse, absence of HIV infection, absence of concomitant aetiologies of viral or non-viral liver disease and absence of cirrhosis (liver histology or non-invasive procedure). All patients gave their written informed consent.
Study procedures
The serum HCV RNA concentration was determined using the Roche COBAS TaqMan HCV test. Serum insulin was determined by electrochemiluminescence immunoassay (Elecsys 2010; Roche Diagnostics, Indianapolis, Indiana, USA) retrospectively using frozen serum samples (−80°C) collected before dosing in the fasting state, at baseline and at days 7, 14 and 15. IR was assessed using the homeostasis model (HOMA-IR) and calculated on the basis of fasting values of plasma glucose and insulin: HOMA-IR=fasting insulin (mIU/l)×fasting glucose (mmol/l)/22.5.
Statistical analyses
Serum HCV RNA levels (log10IU/ml) and HOMA-IR values were expressed as mean±SD. Virological response was defined as ‘continuous decline’ if the viral load decreased across the different study period times (baseline, days 7, 14 and 15), ‘plateau’ if the viral load did not increase from the nadir by more than the variability observed in the placebo + 1 SD (0.7 log10IU/ml) and ‘rebound’ if the viral load increased from the nadir by more than the variability observed in the placebo + 1 SD (0.7 log10IU/ml). The Kruskal–Wallis test was used to compare serum HCV RNA levels and HOMA-IR values across the different study period times (baseline, days 7, 14 and 15) in the whole study population. The extent of the changes in the serum HCV RNA levels and HOMA-IR values was also assessed according to the pattern of virological response. The Spearman rank correlation method was used to assess the correlation between serum HCV RNA and HOMA-IR. All tests were two-sided and used a significance level of 0.05. Data analysis and handling were performed with SPSS software for Windows Version 17 (SPSS Inc, Chicago, Illinois, USA).
Results
Baseline characteristics
Fifty patients were included in the study, 40 of whom were men. The mean±SD age was 48±11 years, mean±SD BMI 24±3 kg/m2, mean±SD alanine transaminase (ALT) level 74±36 U/l, mean±SD triglyceride level 1.05±0.42 mmol/l, mean±SD serum HCV RNA 6.2±0.5 log10IU/ml and mean±SD HOMA-IR score 3.8±1.9.
Virological response
Serum HCV RNA did not change during the study period in the 10 patients who received placebo (6.3±0.4, 6.4±0.5, 6.3±0.5 and 6.5±0.3 log10IU/ml at baseline and days 7, 14 and 15, respectively, p=0.906; figure 1).
Patterns of virological response. Four groups of patients: placebo (10 patients), continuous decline (14 patients), plateau (12 patients) and rebound (14 patients).
Among the 40 patients who received the active drug, 14 achieved a continuous decline, 12 showed a plateau while 14 patients developed a rebound in viral load during the study period. Serum HCV RNA levels (log10IU/ml) at baseline, during treatment (days 7, and 14) and after the end of treatment (day 15) are shown in figure 1: 6.3±0.7, 3.5±0.9, 2.8±0.8 and 3.2±0.9 log10IU/ml, respectively, for the continuous decline group (p<0.0001); 6.1±0.3, 4.2±0.8, 4.2±0.7 and 4.9±0.6 log10IU/ml, respectively, for the plateau group (p<0.0001); and 6.1±0.5, 3.8±1.2, 5.1±0.7 and 5.5±0.7 log10IU/ml, respectively, for the rebound group (p<0.0001).
It was noteworthy that there was no correlation between the decrease in viral load and baseline HOMA-IR value in patients who received the active drug (Spearman rho=0.092, p=0.595). There was also no correlation between the decrease in viral load and the remaining baseline parameters (gender, age, BMI, ALT and triglyceride). There was only a positive and significant correlation with baseline viral load (Spearman rho=0.428, p=0.009).
Insulin resistance
The HOMA-IR score did not change during the study period in the 10 patients who received placebo (3.6±2.0, 3.9±2.2, 3.8±2.5 and 4.0±2.4 at baseline and days 7, 14 and 15, respectively, p=0.945; figure 2A).
Serum hepatitis C virus (HCV) RNA levels and homeostasis model for insulin resistance (HOMA-IR) values for patients in (A) the placebo group, (B) the continuous decline group, (C) the plateau group and (D) the rebound group.
The HOMA-IR score showed a significant decrease in of the 40 patients who received the active drug, regardless of the pattern of virological response. HOMA-IR values at baseline, during treatment (days 7 and 14) and after the end of treatment (day 15) are shown in figure 2: 3.7±1.9, 3.0±1.3, 2.2±1.1 and 3.2±1.7, respectively, for the continuous decline group (p<0.0001, figure 2B); 3.7±2.2, 2.1±1.1, 1.9±1.1 and 2.9±2.0, respectively, for the plateau group (p<0.0001, figure 2C); and 4.0±1.8, 2.0±1.1, 2.3±1.1 and 3.1±1.5, respectively, for the rebound group (p<0.0001, figure 2D).
Twenty-three patients were overweight, all but two of whom received the active drug. At baseline, overweight patients had a higher BMI (27.4±1.8 vs 22.4±2.0 kg/m2, p<0.001), a higher HOMA-IR (5.0±1.9 vs 2.8±1.2, p<0.001) but similar serum HCV RNA (6.3±0.5 vs 6.1±0.6 log10IU/ml, p=0.367) compared with patients with normal BMI. At day 14, overweight patients showed a greater decrease in HOMA-IR (2.1±1.1 vs 1.1±0.8, p<0.001) than patients with normal BMI despite a similar decrease in serum HCV RNA (2.4±1.2 vs 2.1±1.5 log10IU/ml, p=0.563).
Correlation between viral load and IR
The serum HCV RNA level and HOMA-IR score were significantly correlated across the study period (Spearman rho=0.379, p<0.0001). The serum HCV RNA increased significantly according to the HOMA-IR score: 4.1±1.6 log10IU/ml for low HOMA values (<2), 4.9±1.5 log10IU/ml for intermediate HOMA values2–4 and 5.3±1.6 log10IU/ml for high HOMA values2–4 (p<0.0001, figure 3). Interestingly, serum HCV RNA and HOMA-IR levels showed a close parallelism when patients were assessed separately according to the pattern of virological response (figure 2). However, at the individual level (figure 4), these two parameters behaved independently of each other in a subset of patients within each group of patients (figure 4A–C).
Correlation between viral load and insulin resistance: serum hepatitis C virus (HCV) RNA levels increase significantly according to homeostasis model for insulin resistance (HOMA-IR) values (<2, 2–4 and >4, respectively).
Individual data of serum hepatitis C virus (HCV) RNA levels and homeostasis model for insulin resistance (HOMA-IR) scores for patients in (A) the continuous decline group, (B) the plateau group and (C) the rebound group.
Discussion
This study is the first trial to address the direct effect of specific antiviral therapy on IR in patients with genotype 1 CHC. Fifty patients were randomised to receive monotherapy with an HCV NS3-4A protease inhibitor (40 patients) or placebo (10 patients) for 14 days. IR was assessed with HOMA-IR using frozen serum samples collected in the fasting state together with serum HCV RNA at baseline and during and after the end of treatment.
The results of this study provide original information about the efficacy of the new specific antiviral dugs to overcome IR without the need of insulin sensitising agents. In fact, a large number of drugs are in ongoing clinical development for the treatment of patients with genotype 1 CHC to overcome the low SVR rate observed with peginterferon and ribavirin therapy.23 Within a couple of years a triple combination of peginterferon, ribavirin and an HCV inhibitor (probably an NS3/4A protease inhibitor) is likely to become the standard treatment for these patients. Awaiting these new potent molecules, investigators are trying to improve SVR rates with the standard combination therapy by modulating negative predictors, mainly IR. However, adding insulin sensitising agents such as pioglitazone or metformin to peginterferon and ribavirin has shown a major effect on IR but no significant impact on the rapid/early virological response and SVR rates.17–19
The results of this study also provide definitive evidence for the link between HCV infection and IR in humans. In fact, the development of IR in patients with CHC is thought to be due to a combination of both host- and virus-mediated pathways. The molecular mechanisms of the HCV-induced IR are complex and still not completely defined. Initial studies have suggested that IR in patients with CHC is induced by chronic inflammation and increased levels of tumour necrosis factor α.24 However, recent experimental studies have shown that HCV proteins may directly induce IR by impairing the insulin signalling pathway through several possible effectors such as suppressor of cytokine signalling, mammalian target of rapamycin and protein phosphatase 2A.25–28 In our study, patients who received placebo did not show any changes in the HOMA-IR score. By contrast, inhibition of the HCV NS3-4A protease led to a substantial decrease in the HOMA-IR score in those who received the active drug.
Interestingly, serum HCV RNA and HOMA-IR correlated significantly, and the extent of modifications of these two markers showed a close parallelism when assessed according to the pattern of virological response (figure 2). These results are in agreement with previous studies which have shown an association between IR and high HCV viral loads.7 13 29 30 Moreover, a recent report from the HALT-C trial group has found a similar parallel between serum HCV RNA clearance and improvement in the HOMA-IR score as early as week 20 of treatment with peginterferon and ribavirin in patients with genotype non-3 CHC.14 It is noteworthy that insulin resulted in increased amounts of HCV RNA when infused into HCV replicon cells,31 which may explain the decreased effectiveness of the standard combination therapy in the context of IR.
However, when we looked at the correlation between serum HCV RNA and HOMA-IR at the individual level, we found that these two parameters may behave independently of each other in a subset of patients (figure 4). Moreover, when we performed a subgroup analysis for overweight patients, we found that they had a greater decrease in HOMA-IR than patients with normal BMI, despite a similar decrease in serum HCV RNA, highlighting again the imperfect correlation between these two parameters. In this respect, a potential anti-inflammatory or insulin sensitising effect of the drug may explain these results, but remains hypothetical.
Finally, this study emphasises the pivotal role of the NS3-4A protease among the HCV proteins.21 22 The high efficacy of NS3-4A protease inhibitors observed in clinical trials has been explained by their ability to restore innate immune signalling in addition to their known direct antiviral effects. Interestingly, similar enzymes (kinases) are involved in the activation of the immune regulatory pathways and in the insulin signalling pathway.32 33 This similarity may clarify the link between HCV and IR and explain, at least partially, the efficacy of the NS3-4A protease inhibitor to overcome both HCV viral loads and IR observed in this study.
In conclusion, HCV protease inhibitor may restore insulin sensitivity in patients with genotype 1 CHC. The place of insulin sensitisers remains to be determined in the era of triple therapy.
References
Footnotes
Linked articles 222703.
Funding This study was supported by a grant from InterMune Laboratory, Brisbane, California, USA.
Competing interests None.
Ethics approval This study was approved by ethical committees in France and Germany in 2006.
Provenance and peer review Not commissioned; externally peer reviewed.