Clinical trial: exposure to ribavirin predicts EVR and SVR in patients with HCV genotype 1 infection treated with peginterferon alpha-2a plus ribavirin

Does Epoetin Beta Still Have a Place in Peginterferon Alpha-2a Plus Ribavirin Treatment Strategies for Chronic Hepatitis C?

To investigate the impact of epoetin beta (EPO) on sustained virological response (SVR) in hepatitis C virus (HCV)-infected patients treated with peginterferon-ribavirin (RBV). Controlled, randomized, pragmatic multicenter study to assess 2 strategies, ie, the use (EPO group) or nonuse (control group) of EPO in terms of achieving SVR in treatment-naive, genotype non-2/non-3 HCV-infected patients receiving a 48-week treatment regimen of pegylated interferon α-2a (peg-IFN) plus RBV (randomization 2:1). The single-nucleotide polymorphisms of interferon lambda 3 (IFNL3) (rs12979860 and rs8099917), interferon lambda 4 (IFNL4) (ss469415590), and inosine triphosphatase (ITPA) (rs1127354 and rs7270101) were determined retrospectively. Two hundred twenty-seven patients were included in the study. In the global population (n = 227), the overall SVR rate was 52% (118/227). Nonresponse and relapse occurred in respectively 46/227 (20.3%) and 42/227 (18.5%) patients. In the intention-to-treat analysis, 55.5% of patients with anemia (n = 164) had a SVR, specifically 57.4% in the EPO group versus 52.4% in the control group, but the difference was not statistically significant. In the anemic population, independent factors associated with SVR were IFNL3 and IFNL4 polymorphisms, pretreatment HCV RNA level, iron level, and aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio. EPO has little impact on SVR in patients treated with peg-IFN+RBV and should be recommended only for patients with severe anemia.

Telaprevir and ribavirin interaction: higher ribavirin levels are not only due to renal dysfunction during triple therapy

A higher incidence of anemia has been observed during the treatment of hepatitis C virus genotype 1 (HCV-1) infection with pegylated alpha interferon (pegIFN-α), ribavirin, and telaprevir. We assessed the impacts that concomitant administration of telaprevir and changes in the glomerular filtration rate have on ribavirin plasma levels. The minimum concentrations of ribavirin in plasma (ribavirin Cmin) determined during triple therapy including telaprevir were compared with those observed after telaprevir withdrawal and those observed in the same subjects and in a large cohort during a previous course of pegIFN-α plus ribavirin. Intensive pharmacokinetic sampling for ribavirin was performed at steady state during the triple-therapy phase. Ribavirin levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Twenty-seven HCV-1/HIV-coinfected patients were enrolled. The median ribavirin Cmin for triple therapy (4.08 μg/ml; range, 2.14 to 5.56 μg/ml) was higher than that observed after telaprevir withdrawal (1.96 μg/ml; range, 0.41 to 3.45 μg/ml) (P < 0.001) and that observed for 125 HCV-1/HIV-coinfected patients treated only with pegIFN-α plus ribavirin (1.65 μg/ml; range, 0.41 to 5.56 μg/ml) (P < 0.001). The estimated glomerular filtration rate (eGFR) decreased >20% from the baseline value in 11 of 27 patients and became normal after telaprevir removal in almost all cases. There was a negative correlation between eGFR and ribavirin clearance (r(2) = 0.257; P = 0.064) but not the ribavirin area under the concentration-time curve from 0 to 12 h (AUC0-12) (r(2) = 0.001; P = 0.455). Thus, there is a significant pharmacokinetic interaction between telaprevir and ribavirin that results in very high ribavirin levels, which explains the excess of toxicity observed with this drug combination. A blockade of the proximal tubular transporters might be implicated in both the increase in plasma creatinine and the high ribavirin levels. (This study has been registered at ClinicalTrials.gov under registration no. NCT01818856.).

Impact of the peginterferon-α 2a and ribavirin plasma levels on viral kinetics and sustained virological response in genotype 1 HCV/HIV-co-infected patients with the unfavourable non-CC IL28B genotypes

Studies on the association between the peginterferon-α and ribavirin levels and sustained virological response (SVR) have shown yielded conflicting results, but most of them were performed before the influence of IL28B polymorphisms was known. Our aim was to assess the effects of peginterferon-α 2a and ribavirin plasma levels on viral kinetics and SVR in hepatitis C virus genotype 1 HCV-1/HIV-co-infected patients according to IL28B genotype. This was a cohort study of HCV-1/HIV-co-infected patients who were HCV-treatment naïve and for whom the efficacy of peginterferon-α 2a plus ribavirin was evaluated by per-protocol analysis. The peginterferon-α 2a and ribavirin levels were measured by ELISA and HPLC-UV, respectively. The relationships among host and viral factors, the trough drugs levels and virological responses were analysed by multivariate regression analyses. A total of 131 Caucasian patients were included (cirrhosis:38.9%). Overall, SVR rate was 39.6%. In patients with CC IL28B genotype, SVR was related neither to peginterferon-α 2a nor to ribavirin plasma levels, while higher levels of both drugs were the only variables independently associated with SVR in individuals with CT/TT IL28B genotypes (OR, 5.02; CI95 , 1.45-17.1; P = 0.001 and 4.0; CI95 , 1.08-14.7; P = 0.038, respectively). Moreover, faster viral declines were observed in CT/TT patients when pegIFN-α 2a and ribavirin plasma levels were greater than 3400 pg/mL and 1.6 μg/mL, respectively. In contrast to the results for CC patients, the results in patients carrying the unfavourable CT/TT IL28B genotypes showed that plasma levels of both drugs have significant effects on viral kinetics and SVR.

Pegylated versus standard interferon plus ribavirin in chronic hepatitis C genotype 4: A systematic review and meta-analysis

AIM

Treatment of hepatitis C genotype 4 (HCV-G4) with pegylated interferon (PEG IFN) has not been adequately studied and is considered to be challenging. The aim of this meta-analysis is to systematically review and evaluate the effectiveness of 48 weeks of combined PEG IFN plus ribavirin (RBV) compared to standard interferon (IFN) plus RBV. The outcome of interest is sustained virological response (SVR).

METHODS

We searched for eligible randomized controlled trials (RCT) through May 2012. Random effects meta-analysis was used to pool the risk ratio (RR) of achieving SVR across trials.

RESULTS

Five RCT enrolling 386 patients were included. The PEG IFN/RBV group had increased likelihood of achieving SVR (RR = 1.51, 95% confidence interval [CI] = 1.08-2.10). SVR was significantly higher in PEG IFN-α-2a compared to the -α-2b group (P = 0.02). There was no statistically significant effect of ribavirin dosage on SVR (P = 0.55). The quality of evidence was moderate overall and limited by heterogeneity.

CONCLUSION

In treatment-naive patients with HCV-G4, treatment with PEG IFN plus RBV achieves higher SVR rate than treatment with IFN plus RBV.

Treatment extension may benefit female genotype 1 chronic hepatitis C patients with complete early virological response to peginterferon-alpha-2b and ribavirin combination therapy

AIM

  Little is known about the appropriate use of peginterferon-α-2b (PEG IFN-α-2b) or ribavirin (RBV) in genotype 1 chronic hepatitis C (CH-C) patients with complete early virological response (cEVR). Female patients, especially the older, are known to experience inferior treatment outcomes.

METHOD

  A total of 150 CH-C patients with cEVR treated for 48 weeks (n = 104) or 52-64 weeks (n = 46) with PEG IFN-α-2b and RBV combination therapy were retrospectively analyzed to evaluate the benefits of extended treatment.

RESULTS

  In the 48-week group, patients without a sustained virological response (SVR) were more often female (P = 0.004) and had received a significantly lower total RBV dose (P = 0.003) than those with SVR. The SVR rate in these female patients was similar to males with hepatitis C virus (HCV) RNA negativity at treatment week 8 (P = 0.413); however, it was lower than that in males with HCV RNA negativity at treatment week 12 (P = 0.005). In the 52-64-week group, although the total RBV dose (mg/kg) after treatment week 48 was less in females than in males (P = 0.027), the SVR rate in females was equivalent to that in males (P = 0.604).

CONCLUSION

  Genotype 1 CH-C patients treated with PEG IFN-α-2b and RBV combination therapy without SVR were more often female and had received a lower total RBV dose than males. The smaller SVR rate in female patients with cEVR compared to males may be overcome by extending treatment even if the RBV dose is lowered due to anemia.

Impact of ribavirin dose on retreatment of chronic hepatitis C patients

AIM: To study the efficacy and factors associated with a sustained virological response (SVR) in chronic hepatitis C (CHC) relapsing patients.

METHODS: Out of 1228 CHC patients treated with pegylated interferon (PEG-IFN) and ribavirin (RBV), 165 (13%) had a relapse. Among these, 62 patients were retreated with PEG-IFN-α2a or -α2b and RBV. Clinical, biological, virological and histological data were collected. Initial doses and treatment modifications were recorded. The efficacy of retreatment and predictive factors for SVR were analyzed.

RESULTS: An SVR was achieved in 42% of patients. SVR was higher in young (< 50 years) (61%) than old patients (27%) (P = 0.007), and in genotype 2 or 3 (57%) than in genotype 1 or 4 (28%) patients (P = 0.023). Prolonging therapy for at least 24 wk more than the previous course was associated with higher SVR rates (53% vs 28%, P = 0.04). Also, a better SVR rate was observed with RBV dose/body weight > 15.2 mg/kg per day (70% vs 35%, P = 0.04). In logistic regression, predictors of a response were age (P = 0.018), genotype (P = 0.048) and initial RBV dose/body weight (P = 0.022). None of the patients without a complete early virological response achieved an SVR (negative predictive value = 100%).

CONCLUSION: Retreatment with PEG-IFN/RBV is eff-ective in genotype 2 or 3 relapsers, especially in young patients. A high dose of RBV seems to be important for the retreatment response.

Impact of ribavirin on HCV replicon RNA decline during treatment with interferon-α and the protease inhibitors boceprevir or telaprevir

BACKGROUND

Ribavirin increases early and sustained virological response rates in patients chronically infected with HCV who receive pegylated interferon-α and novel HCV protease inhibitors.

METHODS

To better characterize antiviral efficacies of these upcoming therapies, Huh7 cells harbouring a subgenomic HCV replicon system were cultivated with various doses and combinations of ribavirin, interferon-α, and the protease inhibitors boceprevir and telaprevir. Antiviral efficacy parameters were estimated from HCV RNA decay, and synergistic effects of combination therapies were analysed with the Bliss independency model.

RESULTS

Single-drug antiviral activities showed dose-dependent HCV RNA reductions in replicon cells (50% inhibitory concentration of 386.16 μM, 81.67 IU, 0.44 μM and 0.81 μM after 48 h for ribavirin, interferon-α, boceprevir and telaprevir, respectively). For the dual combination of ribavirin with either boceprevir or telaprevir, no deviation from additivity was observed whereas the reduction of HCV RNA was synergistic for ribavirin with interferon-α (P<0.001). Triple combinations with ribavirin, interferon-α and protease inhibitors showed the most profound HCV RNA decay.

CONCLUSIONS

The beneficial in vitro antiviral effect of ribavirin with interferon-α and novel HCV protease inhibitors demonstrates that ribavirin may be required as an antiviral backbone in the near future.

The treatment response of chronically hepatitis C virus-infected patients depends on interferon concentration but not on interferon gene expression in peripheral blood mononuclear cells

The current treatment of chronic hepatitis C is based on pegylated alpha interferon (PEG-IFN-α) and ribavirin. The aim of this study was to identify biological and clinical variables related to IFN therapy that could predict patient outcome. The study enrolled 47 patients treated with PEG-IFN and ribavirin combined therapy. The interferon concentration was measured in serum by a bioassay. The expression of 93 interferon-regulated genes in peripheral blood mononuclear cells was quantified by real-time quantitative reverse transcription-PCR (RT-PCR) before and after 1 month of treatment. The interferon concentration in the serum was significantly lower in nonresponders than in sustained virological responders. Moreover, a significant correlation was identified between interferon concentration and interferon exposition as well as body weight. The analysis of interferon-inducible genes in peripheral blood mononuclear cells among the genes tested did not permit the prediction of treatment outcome. In conclusion, the better option seems to be to treat patients with weight-adjusted PEG-IFN doses, particularly for patients with high weight who are treated with PEG-IFN-α2a. Although the peripheral blood mononuclear cell samples are the easiest to obtain, the measurement of interferon-inducible genes seems not be the best strategy to predict treatment outcome.

Pharmacological exposure to ribavirin: a key player in the complex network of factors implicated in virological response and anaemia in hepatitis C treatment

Ribavirin remains today a pivotal drug in the treatment of hepatitis C; in standard double therapy, as well as in triple combination with direct antiviral agents, ribavirin reduces relapse and can double the sustained virological response obtained with peginterferon alone or in association with direct antiviral agents. In the complex network of interacting factors determining sustained virological response independently of known predictive factors related to host and virus, two modern tools are emerging: polymorphisms in the IL28B gene and very early exposure to ribavirin. The use of a pharmacokinetic-pharmacodynamic model of early ribavirin exposure to adjust the dose individually would help promote a safer ribavirin use and improve sustained virological response. The variability of the influence of ribavirin exposure on anaemia is probably genetically determined; however, the low prevalence of the implicated protective alleles of the inosine triphosphate pyrophosphatase gene could explain their lack of influence on sustained virological response.

Consensus interferon used to treat prior partial-responders to pegylated interferon plus ribavirin

BACKGROUND

The response to pegylated interferon (peg-IFN) plus ribavirin therapy remains less than ideal with 40-50% of treated subjects failing to clear the virus. Moreover, retreatment is only minimally effective. Consensus interferon (c-IFN) has been shown to be efficacious in HCV genotype 1 patients who have failed therapy with peg-IFN.

AIM

To evaluated the response to re-treatment of peg-IFN plus ribavirin partial-responders with c-IFN plus ribavirin.

METHODS

Forty-two subjects who had previously failed to clear virus after treatment with peg-IFN plus ribavirin were treated with c-IFN (15 μg/day) plus ribavirin (800-1,200 mg/day) until 12 months of therapy or a total of six consecutive months of PCR negativity was achieved.

RESULTS

The study population consisted predominantly of males (71%), Caucasians (76%), with African Americans comprising the remaining 24%, subjects with HCV genotype 1 infection (81%) and 21% had cirrhosis by liver biopsy. The overall SVR rate was 29%. The only pretreatment variable that distinguished responders from partial-responders was the serum triglyceride level.

CONCLUSIONS

The use of c-IFN plus ribavirin in the retreatment of prior peg-IFN plus ribavirin partial responders is essentially twice that achieved in prior re-treatment regimens consisting of a second course of peg-IFN plus ribavirin. These results will need to be evaluated against the use of triple therapy consisting of a peg-IFN plus ribavirin and a protease inhibitor. More studies utilizing c-IFN plus ribavirin with either a protease inhibitor or polymerase inhibitor need to be performed as well.

Redefining baseline demographics: the role of genetic testing in hepatitis C virus infection

The current standard of care for hepatitis C virus (HCV) infection is pegylated interferon and ribavirin. Unfortunately, treatment cures at best only 40% to 50% of patients infected with genotype 1 HCV, the most common HCV genotype in Western countries. Treatment is also expensive and is often poorly tolerated. Therefore, the identification of patients most likely to benefit from treatment is clinically important. Genome-wide association studies have recently identified genetic variants, most notably IL28B and ITPA, which will enhance the ability of clinicians to personalize antiviral therapy for HCV infection.

Plasma/erythrocyte ribavirin x100 ratio as an indicator of sustained virological response in HCV genotype 1 patients with early virological response

BACKGROUND

On-treatment predictors during antiviral therapy of HCV are useful because they allow discontinuation of an unnecessary treatment in non-responders. Our aim was to evaluate the usefulness of plasma and erythrocyte ribavirin levels in predicting sustained virological response (SVR) in HCV genotype 1 patients undergoing antiviral treatment.

METHODS

A total of 40 HCV genotype 1 patients treated with pegylated interferon-alpha2a 180 microg weekly plus ribavirin 1,000 or 1,200 mg daily (according to body weight) were included in the study. Plasma and erythrocyte ribavirin levels were evaluated in all patients at week 12 by HPLC. At week 24, ribavirin levels were reassessed in those achieving early virological response (EVR).

RESULTS

A total of 27 patients achieved EVR, whereas 17 achieved SVR. There was no difference among EVR and non-EVR patients in terms of plasma and erythrocyte ribavirin concentrations at week 12. At week 24, EVR patients obtaining SVR exhibited higher mean +/-sd levels of ribavirin in plasma and lower levels in erythrocytes compared with non-SVR patients (in plasma 12.8 +/-10 versus 5.8 +/-4 microM [P<0.02] and in erythrocytes 1,053 +/-504 versus 1,613 +/-589 microM [P<0.03]). When the plasma ribavirin/erythrocyte ribavirin x100 ratio was compared, the difference was enhanced (1.5 +/-1.3 versus 0.4 +/-0.3 microM; P<0.01). Receiver operating characteristic curve analysis identified a cutoff for plasma ribavirin/erythrocyte ribavirin x100 ratio in predicting SVR of 0.71 with a negative predictive value of 0.8 and a positive predictive value of 0.9, whereas those related to EVR were 1 and 0.6, respectively.

CONCLUSIONS

Plasma ribavirin/erythrocyte ribavirin x100 ratio at week 24 seems to be a good indicator of SVR in HCV genotype 1 patients achieving EVR.

Epoetin alpha improves the response to antiviral treatment in HCV-related chronic hepatitis

BACKGROUND

The conventional antiviral treatment of chronic hepatitis related to hepatitis C virus (HCV) often leads to anemia. In this case, it is necessary to reduce ribavirin dose or stop treatment, thus reducing the rate of sustained virological response.

AIM

We investigated whether epoetin alpha administration improves treatment adherence and leads to higher percentage of response at the end of therapy and sustained virological response.

METHODS

Two hundred and fourteen individuals with genotype 1b HCV-related chronic hepatitis underwent treatment with pegylated (peg)-interferon alpha-2A 180 μg once weekly and ribavirin 1,000-1,200 mg/day; 174 were responders. Forty individuals completed treatment with no hemoglobin reduction; 134 developed anemia during therapy. Anemic responders were distributed randomly into two groups: group 1 continued therapy with epoetin alpha addiction; group 2 continued antiviral therapy with ribavirin reduction only.

RESULTS

Patients in group 1 achieved better control of hemoglobin levels (13.8 ± 1.2 g/dl at the end of therapy) than those in group 2 (11.5 ± 0.8 g/dl). Sustained virological response was 59.7% in group 1 compared with 34.4% in group 2 (p<0.01).

CONCLUSIONS

In patients with 1b HCV-related chronic hepatitis who develop anemia during antiviral treatment, administration of epoetin alpha increases hemoglobin levels and the end-of-treatment rate and sustains virological response by improving treatment adherence.

Efficacy and tolerability of peginterferon alfa-2a or alfa-2b plus ribavirin in the daily routine treatment of patients with chronic hepatitis C in Germany: the PRACTICE study

In randomized clinical trials, treatment with peginterferon plus ribavirin (RBV) results in a sustained virological response (SVR) in around half of hepatitis C virus genotype 1-infected and 80% of genotype 2/3-infected individuals. This study aimed to evaluate efficacy and tolerability of peginterferon alfa-2a plus RBV compared with peginterferon alfa-2b plus RBV for the treatment of chronic hepatitis C in routine clinical practice. The intent-to-treat cohort consisted of 3414 patients treated with either peginterferon alfa-2a plus RBV (Group A) or peginterferon alfa-2b plus RBV (Group B) in 23 centres participating in the large, multicentre, observational PRACTICE study. Collected data included baseline characteristics, treatment regimen, RBV dose and outcome. Rates of early virological response, end of treatment response and SVR were 76.6%, 75.7% and 52.9% in Group A, and 70.2%, 65.6% and 50.5% in Group B, respectively. In patients matched by baseline parameters, 59.9% of patients in Group A and 55.9% in Group B achieved an SVR (P < or = 0.051). In genotype 1-infected patients matched by baseline parameters and cumulative RBV dose, SVR rates were 49.6% and 43.7% for Group A and Group B, respectively (P < or = 0.047); when matched by baseline parameters and RBV starting dose, SVR rates were 49.9% and 44.6%, respectively (P = 0.068). Overall, 21.8% of group A and 29.6% of group B patients discontinued treatment (P < or = 0.0001). The efficacy and tolerability of peginterferon plus RBV in this large cohort of patients treated in routine daily practice was similar to that in randomized clinical trials. In matched pairs analyses, more patients achieved an SVR with peginterferon alfa-2a compared with peginterferon alfa-2b.

Identifying HCV genotype 1 patients at risk of relapse

OBJECTIVE

The objective of this analysis was to identify predictors of relapse in genotype 1 patients after 48 weeks of treatment with peginterferon plus ribavirin.

METHODS

Retrospective analysis of data from treatment-naive genotype 1 patients with an end-of-treatment response after 48 weeks of treatment with peginterferon alpha-2a plus ribavirin 1000/1200 mg/day in the Canadian Pegasys Expanded Access Program.

RESULTS

Among treatment-naive genotype 1 patients with an end-of-treatment response (n = 432), the sustained virological response status was known for 405 individuals (sustained virological response n = 328, 81%; relapse n = 77, 19%). Early virological response rates at week 12 were similar in relapsers (98.7%) and sustained responders (98.5%). More relapsers (12 of 77, 15.6%) than sustained responders (15 of 328, 4.6%) had quantifiable hepatitis C virus (HCV) RNA (>or=600 IU/ml) at week 12 and, among these patients, mean and maximum HCV RNA levels were higher in relapsers, although the median values were similar. Factors significantly associated with relapse in the multiple logistic regression analysis include older age (odds ratio: 1.48 per decade, 95% confidence interval: 1.06-2.07; P = 0.023), Caucasian ethnicity (odds ratio: 3.23, confidence interval: 1.25-8.33; P = 0.016), higher baseline serum HCV RNA level (P = 0.005), the drop in HCV RNA between baseline and week 12 (P = 0.026), and the interaction between baseline HCV RNA level and the decrease in HCV RNA between baseline and week 12 (P = 0.032).

CONCLUSION

Older age, Caucasian ethnicity, and high baseline HCV RNA level, and a smaller decrease in HCV RNA between baseline and week 12 predict a relapse in genotype 1 patients.

Feasibility of individualized treatment for hepatitis C patients in the real world

BACKGROUND AND AIM

Individualized treatment with a combination of peg-interferon and ribavirin for patients with hepatitis C virus (HCV) infection has been validated in randomized controlled clinical trials, but its usefulness in the real world is unknown. The aim of the present study was to assess the feasibility of individualized treatment for HCV patients compared with standard therapy in a real-life clinical setting.

METHODS

A total of 253 naïve patients with HCV infection who received peg-interferon and ribavirin combination treatment were analyzed and grouped into one of three clinical settings: (i) infection with genotype non-1 (HCV non-1) and treatment for standard 24 weeks (n = 105; none received an abbreviated therapy); (ii) genotype 1 (HCV-1) and standard therapy for either 24 weeks (n = 71) or 48 weeks (n = 21); and (iii) HCV-1 and individualized treatment (n = 56). The individualized therapy used was an abbreviated 24-week treatment for HCV-1 patients who achieved a rapid virological response, otherwise patients received a 48-week course of treatment. Early termination of treatment at week 16 was recommended for non-responders.

RESULTS

A sustained virological response (SVR) was achieved in 83.8% of patients with HCV non-1 infection. Among the HCV-1-infected patients, 53.5% of patients who underwent standard 24-week treatment, 66.7% of patients who underwent standard 48-week treatment, and 64.3% of patients treated by individualized therapy achieved SVR. Patients infected with HCV-1 and treated by individualized therapy had a similar efficacy response compared with the standard 48-week therapy (adjusted odds ratio [OR] 0.765, 95% confidence interval [CI], 0.220-2.659, P = 0.673). Both individualized therapy (adjusted OR 2.855, 95% CI 1.189-6.855, P = 0.019) or standard 48-week treatment (adjusted OR 3.733, 95% CI 1.073-12.986, P = 0.038) had significantly higher odds of SVR compared with HCV-1 patients treated by standard 24-week course.

CONCLUSION

Individualized therapy is feasible in the real world, especially for patients with HCV-1 infection.

Optimizing the treatment of chronic viral hepatitis C

Chronic hepatitis C is a major health concern. The current standard therapy is based on a combination of pegylated (PEG)-IFN-alpha and ribavirin (RBV). This treatment produces a sustained virological response (SVR) in approximately 55% of chronically infected patients. A number of virological factors (e.g., the hepatitis C virus [HCV] genotype and baseline titer of HCV RNA) may influence the treatment response. Indeed, the SVR rate is approximately 80% for patients infected with HCV genotypes 2 or 3, and approximately 45% for genotype 1 or 4 patients. Furthermore, the treatment duration can be modified as a function of the genotype. New drugs are being developed for the treatment of chronic hepatitis C but will probably be used in combination with the current standard therapy. This means that improvements in therapy based on a PEG-IFN-RBV combination will remain a true challenge in the coming years. Recent clinical trial results have demonstrated that the current therapy can be optimized. Modulation of the treatment duration and/or the RBV dose may increase the SVR rate. The present article reviews the current approaches to optimizing the treatment of chronic hepatitis C.

Efficacy of chronic hepatitis C therapy in community-based trials

Prospective, randomized, controlled, phase 3 clinical trials establish pegylated interferon (PEG-IFN) alfa plus ribavirin as the standard of care for patients with chronic hepatitis C. Such clinical trials are conducted in a highly regimented manner; patients must meet strict inclusion/exclusion criteria, and treatment is administered under rigid protocols with close monitoring by study personnel. Whether the results of phase 3 trials can be generalized or achieved in everyday clinical practice is questioned in several therapeutic areas. The efficacy of PEG-IFN alfa plus ribavirin therapy observed in pivotal phase 3 trials has been confirmed in several community-based trials conducted in North America and Europe, demonstrating consistent overall rates of sustained virologic response across a wide range of patient populations. Sustained virologic response rates stratified by genotype, viral load, fibrosis score, age, and ethnicity, factors known to impact treatment outcome, are consistent between these trials and comparable to those reported in clinical trials. The United States-based WIN-R trial confirmed the value of combining weight-based ribavirin dosing with weight-based PEG-IFN alfa-2b dosing across a spectrum of patient body weights. Large Canadian trials (POWeR and EAP), a German trial (AWB), a French study (Hepatys), and an Italian study demonstrated that PEG-IFN alfa plus ribavirin produces excellent efficacy in difficult-to-treat patient populations. Collectively, these results confirm the efficacy of current standard treatment regimens in a wide range of community-based settings, affording clinicians confidence that they can attain results similar to those of rigidly controlled randomized trials.

Spotlight on peginterferon-alpha-2a (40 kD) plus ribavirin in the management of chronic hepatitis C mono-infection

Peginterferon-alpha-2a (40 kD) [Pegasys(R)] is a conjugate of recombinant interferon-alpha-2a and a 40 kD branched polyethylene glycol (PEG) moiety that is highly active against hepatitis C virus (HCV). Ribavirin (Copegus) is a synthetic nucleoside analog that acts in synergy with the antiviral activity of peginterferon-alpha-2a (40 kD). The combination of subcutaneous peginterferon-alpha-2a (40 kD) once weekly plus oral ribavirin twice daily is widely approved for use in adult patients with chronic hepatitis C, including those with persistently 'normal' ALT activity or HIV-HCV co-infection, and is recommended as a first-line treatment option for patients with chronic hepatitis C and compensated liver disease. In randomized, phase III trials, the combination has consistently demonstrated good therapeutic efficacy (i.e. high sustained virologic response [SVR] rates) and has been generally well tolerated in both treatment-naïve and treatment-experienced patients with chronic hepatitis C, including those with compensated, advanced liver disease. Several baseline and dynamic (on-treatment) predictors of an SVR that can be used to guide and optimize therapy were also determined in these trials and in subsequent analyses. By utilizing these predictors, therapy with peginterferon-alpha-2a (40 kD) plus ribavirin can be individualized to achieve the optimal balance between efficacy and tolerability, further increasing the usefulness of this drug combination. Thus, peginterferon-alpha-2a (40 kD) plus ribavirin remains a valuable therapy in patients with chronic hepatitis C, as a first-line option in those with compensated liver disease and as a second-line therapy in those with advanced liver disease.

Reduced ribavirin antiviral efficacy via nucleoside transporter-mediated drug resistance. J Virol. 2009;83:4538-4547. [PMID: 19244331 DOI: 10.1128/jvi.02280-08]

Treatment for hepatitis C virus infection currently consists of pegylated interferon and ribavirin (RBV), a nucleoside analog. Although RBV clearly plays a role in aiding the treatment response, its antiviral mechanism is unclear. Regardless of the specific mechanism of RBV, we hypothesize that differences in levels of cellular uptake of RBV may affect antiviral efficacy and treatment success and that cells may become RBV resistant through reduced uptake. We monitored RBV uptake in various cell lines and determined the effect of uptake capacity on viral replication. RBV-resistant cells demonstrated reduced RBV uptake and increased growth of a model RNA virus, poliovirus, in the presence of RBV. Overexpression of equilibrative nucleoside transporter 1 (ENT1) or concentrative nucleoside transporter 3 (CNT3) increased RBV uptake in RBV-sensitive cell lines and restored the uptake defect in most RBV-resistant cell lines. However, CNT3 is not expressed in Huh-7 liver cells, and inhibition of concentrative transport did not affect RBV uptake. Blocking equilibrative transport using the inhibitor nitrobenzylmercaptopurine riboside recapitulated the RBV-resistant phenotype in RBV-sensitive cell lines, with a reduction in RBV uptake and increased poliovirus growth. Taken together, these results indicate that RBV uptake is restricted primarily to ENT1 in the cell lines examined. Interestingly, some RBV-resistant cell lines may compensate for reduced ENT1-mediated nucleoside uptake by increasing the activity of an alternative nucleoside transporter, ENT2. It is possible that RBV uptake affects the antiviral treatment response, either through natural differences in patients or through acquired resistance.