High-Dose Pegylated Interferon-α and Ribavirin in Nonresponder Hepatitis C Patients and Relationship With IL-28B Genotype (SYREN Trial)
Download the PDF here
"High-dose pegylated IFN-α and ribavirin, therefore, appears to be a viable option to optimize HCV clearance rates in patients who failed on standard therapy and are retreated with a triple combination of pegylated IFN-α, ribavirin, and a protease inhibitor. This option, along with the ideal treatment schedule (our results suggest that high-dose pegylated IFN-α2a should be administered once weekly, but the question remains open for pegylated IFN-α2b, which bears different pharmacokinetic properties), should now be studied in prospective clinical trials according to the IL-28B genotype........Overall, our data suggest that high-dose pegylated IFN-α, in combination with a standard or a high dose of ribavirin, is an interesting option for combination with telaprevir or boceprevir in order to minimize the risk of resistance selection and increase the SVR rates in nonresponders to earlier standard therapy. This is reinforced by the fact that these treatments would be given for 24 to 48 weeks, and the antiviral effect was sustained over this duration in our study in patients who responded. The minimal antiviral effect of pegylated IFN-α and ribavirin to achieve a high cure rate is still unknown. Phase II and III trials with pegylated IFN-α2b, ribavirin, and boceprevir, which included a lead-in phase with pegylated IFN-α2b and ribavirin alone, suggested that it could be of the order of 1.0-1.5 Log10 IU/mL at week 4.10, 15, 16 Results from the REALIZE Trial with pegylated IFN-α2a, ribavirin, and telaprevir, which included a lead-in phase with pegylated IFN-α2a and ribavirin alone, also suggest a threshold at 1.0 Log10 IU/mL at week 4."
Background & Aims
In patients with chronic hepatitis C who failed to respond to standard therapy, high-dose pegylated interferon (IFN)-α and/or ribavirin could induce a stronger antiviral response and prevent treatment failure and HCV resistance when combined with direct-acting antivirals. The influence of genetic determinants in this context remains unknown.
Eighty-three patients infected with HCV genotype 1 who were nonresponsive to standard therapy received pegylated IFN-α2a (360 μg once per week or 180 μg twice per week) with ribavirin (1.0-1.2 or 1.2-1.6 g/d) for up to 72 weeks. Virological responses were assessed at different time points, and the influence of the IL-28B genotype was studied.
At weeks 12 and 24, respectively, 47 (56.6%) and 50 (60.2%) patients achieved a ≥2-Log10 decrease of HCV RNA levels; 8 (9.6%) and 21 (25.3%) patients had undetectable HCV RNA after 12 and 24 weeks of treatment, respectively. Patients with a CT IL-28B genotype responded significantly better and earlier than those with a TT genotype. In multivariate analysis, the IL-28B genotype was an independent predictor of the virological responses at weeks 4, 12, and 24.
High-dose pegylated IFN-α with standard or high doses of ribavirin induces a potent antiviral response in a substantial number of patients who did not respond to standard therapy. The IL-28B genotype is an independent predictor of the antiviral response. High-dose pegylated IFN-α in combination with ribavirin and protease inhibitors appears as an attractive option for future study in this population.
Hepatitis C virus (HCV) chronically infects approximately 120-130 million individuals worldwide.1 Chronic HCV infection is a major cause of life-threatening liver disease, and approximately 20% of HCV-infected patients develop cirrhosis.2 Indeed, HCV infection is the main indication for liver transplantation and is becoming the leading cause of hepatocellular carcinoma in industrialized areas.2 Mortality related to HCV infection has been estimated at approximately 300,000 deaths per year.
HCV infection is curable by therapy. Current treatment is based on a combination of pegylated interferon (IFN)-α and ribavirin. In patients infected with HCV genotype 1, by far the most frequent HCV genotype worldwide, only 40% to 50% of such treatment led to a cure of infection.3, 4, 5 Failure of IFN-α-based treatments to eradicate HCV infection has been recently shown, at least partly, to be genetically determined. Single nucleotide polymorphisms (SNPs) in the region upstream of the IL-28B (IFN-λ3) gene in chromosome 19 have been identified to be strongly associated with the ability of pegylated IFN-α and ribavirin to cure HCV infection.6, 7, 8 The underlying mechanisms remain obscure.
In 2011, new treatments will be available for chronic HCV genotype 1 infection. They will be based on a combination of pegylated IFN-α, ribavirin, and a specific HCV protease inhibitor, telaprevir or boceprevir. Phase II and III clinical trials have shown that approximately 25%-35% of treatment-naïve patients, and 50%-60% of those who have previously failed on pegylated IFN-α and ribavirin alone, fail to eradicate HCV on such triple combination.9, 10, 11, 12, 13, 14, 15, 16, 17 Treatment failure is principally due to an insufficient antiviral response to pegylated IFN-α and ribavirin, favoring the outgrowth of protease inhibitor resistant viruses selected by the direct acting antiviral agent.10, 12, 13, 18 Therefore, a sufficient antiviral response to pegylated IFN-α and ribavirin is an absolute prerequisite to achieve cure of infection with new triple combination therapies without selecting for resistant viruses.
Because recent reports indicated that the outcomes of triple combinations with pegylated IFN-α, ribavirin, and an HCV protease inhibitor strongly depend on the ability of IFN-α and ribavirin to substantially reduce HCV replication,10, 12, 13, 18 which has recently been shown to be strongly associated with IL-28B polymorphisms,6, 7, 8, 19, 20 we decided to assess the ability of high doses of pegylated IFN-α with standard or high doses of ribavirin to induce a significant antiviral response in genotype 1 patients who failed to respond to a first course of therapy at standard doses and whether responsiveness to high-dose pegylated IFN-α and ribavirin is genetically driven in this population.
The SYREN trial (ClinicalTrials.gov number NCT00412334) is a phase II randomized, open-labeled clinical trial that included 104 patients infected with HCV genotype 1. These patients were previously treated with the standard combination of pegylated IFN-α2a (180 μg per week) and ribavirin (1.0-1.2 g/d according to body weight), received at least 80% of the treatment dose during the first 12 weeks of therapy, and did not achieve a ≥2-Log10 decrease of HCV RNA levels between baseline and week 12 of treatment (the same HCV RNA assay was used at both time points).
Inclusion criteria were male or female patient 18 years of age or older; evidence of chronic HCV infection (positive anti-HCV antibody and detectable HCV RNA); HCV genotype 1; normal or elevated serum alanine aminotransferase level; compensated liver disease; liver fibrosis assessment by means of a noninvasive serological or elastographic test within 12 months before inclusion; negative pregnancy test for women of childbearing age at inclusion; efficacious double contraception (patient and partner) on treatment and 6 months thereafter; health insurance coverage; and written informed consent. At least 4 weeks without treatment were required before inclusion.
Exclusion criteria included current pregnancy or breastfeeding; male partner of a pregnant women; decompensated liver disease; hepatocellular carcinoma; human immunodeficiency virus, hepatitis A virus or hepatitis B virus co-infection; any other cause of liver disease; previous history of autoimmune disease, chronic lung disease, severe heart disease, organ transplantation, cancer; hemoglobin level <12 g/dL (women) or <13 g/dL (men); patient at increased risk of anemia or for whom anemia could be a vital risk; neutropenia <1500 cells/mm3; thrombocytopenia <75,000/mm3; creatininemia >1.5 times the upper limit of normal values; patient who withdrew from earlier pegylated IFN-α2a and ribavirin treatment for hematological adverse events; previous history of allergy to experimental drugs or to one of their components; any antiviral, antineoplastic or immunomodulatory treatment within 6 months before inclusion, except pegylated IFN-α2a and ribavirin; active drug abuse or current chronic alcoholism; previous history of severe psychiatric disease; current treatment with anticonvulsants; thyroid disorder not controlled by medication; severe retinopathy or eye disorder related to diabetes or hypertension; poorly controlled high blood pressure; and previous history or risk of vein thrombosis.
The goal of the SYREN trial was to evaluate the efficacy and safety of 4 intensified regimens of pegylated IFN-α2a and ribavirin in this population. The patients were randomized to receive pegylated IFN-α2a, either 360 μg once per week or 180 μg twice per week, in combination with ribavirin, either 1.0-1.2 g/d or 1.2-1.6 g/d according to body weight, for the full duration of therapy. As per the protocol stopping rules, treatment was halted at weeks 12 or 24 in patients with a <0.5- or <2.0-Log10 drop of HCV RNA levels, respectively, or if HCV RNA was still detectable at week 48. The planned treatment duration in the remaining patients was initially 48 weeks. An amendment was passed to prolong therapy for a total of 72 weeks at the same doses of pegylated IFN-α and ribavirin in patients who had undetectable HCV RNA at week 48 of therapy. The study was approved by an Institutional Review Board (Comite de Protection des Personnes, Hopital Henri Mondor, Creteil, France).
All of the analyses have been performed on the intent-to-treat population, which included 98 nonresponder patients who received at least 1 dose of study drug and had at least 1 HCV RNA measurement under treatment. After the report of a relationship between IL-28B genotype and the response to IFN-α-based therapy, another amendment was passed in order to allow us to test the patients for IL-28B genotype. Eighty-three of the 98 patients gave their informed consent to the genetic testing and constitute the study population of this article. The baseline characteristics of the patients who did not give their informed consent did not differ from those in the study patients. As no significant differences in virological response rates were observed between the treatment groups at different time points, the patients from the 4 groups were considered together in this study.
HCV RNA Level Monitoring
HCV RNA levels were measured at baseline and at weeks 1, 2, 4, 12, 24, 48, and 72 hours of therapy. In the patients receiving 72 weeks of therapy, HCV RNA levels were also measured at week 96, ie, 24 weeks after the end of treatment. The COBAS AmpliPrep/COBAS TaqMan automated real-time polymerase chain reaction (PCR) platform (Roche Molecular Systems, Pleasanton, CA) was used. This assay has a lower limit of detection of 15 IU/mL and a lower limit of quantification of 43 IU/mL.21 The sustained virological response (SVR) was defined as an undetectable HCV RNA 24 weeks after the end of therapy; the SVR corresponds to a cure of infection in >99% of cases.22
IL-28B Polymorphism (rs12979860) Determination
IL-28B genotype at SNP position rs12979860 was determined by means of an original real-time PCR method using genomic DNA extracted from frozen serum samples in conjunction with minor groove binder probes. Briefly, free circulating nucleic acids were extracted from 400 μL serum by means of the QIAsymphony DNA Midi kit (Qiagen GmbH, Hilden, Germany) on the QIAsymphony SP automated extractor. rs12979860 genotyping was performed by means of real-time PCR in the TaqMan Gene Expression Master Mix on the ABI 7300 Real-Time PCR system (Applied Biosystems, Foster City, CA), with the following primers and probes: reverse primer: 5'-GAGCGCGGAGTGCAATTC-3'; forward primer: 5'-TGCCTGTGCTGTACTGAA-3'; VIC-probe: 5'-TCCCCGAAGGCGTGA-3'; FAM-probe: 5'-AAGGCGCGAACCA-3'. Automated allele calling was performed by means of Sequence Detection System software version 1.4 (Applied Biosystems).
Statistical analysis was performed with SAS 9.1 software (SAS Institute Inc, Cary, NC). Tests were 2-sided and a type I error was set at .05. Missing data were not replaced. The week 1 virological response was calculated between treatment start and day 7 of therapy. The second-phase slope was computed by linear regression using HCV RNA levels at days 8 and 28 of therapy. Comparisons between IL-28B genotypes (CT vs TT) were performed using χ2 test or Fisher exact test for qualitative variables, and Student t test or Wilcoxon test for continuous variables.
The relationship between the virological responses at different time points and explanatory variables was analyzed by logistic regression. The variables were selected by univariate logistic regression among age, sex, IL-28B polymorphisms, body mass index (BMI), duration of HCV infection, source of HCV infection, cirrhosis, subtype of HCV genotype, HCV RNA level changes during the first course of treatment, duration of the first course of treatment, baseline HCV RNA level, alanine aminotransferase level and γ-glutamyl transferase activity, number of pegylated IFN-α injections per week, and daily ribavirin dose. Significant variables after univariate regression analysis were entered into a stepwise multivariate model. Results are expressed as odds ratios with 95% confidence intervals.
The positive and negative predictive values, sensitivities, and specificities of the IL-28B genotypes for the virological responses at different time points were calculated.
Role of the Funding Source
This study is investigator-initiated. It has been sponsored by Roche (Neuilly-sur-Seine, France). Roche also provided medication and support for statistical analysis.
Characteristics of the Study Patients
Table 1 shows the characteristics of the 83 patients who gave their consent for the IL-28B analysis. All of them had undergone a first course of therapy with standard doses of pegylated IFN-α2a and ribavirin, had received >80% of the pegylated IFN-α2a and ribavirin dose, and had stopped therapy at week 12 because they failed to achieve a >2 Log10 HCV RNA level drop. They were retreated with high-dose pegylated IFN-α combined with standard- or high-dose ribavirin. No significant differences (and no trend toward differences) in virological responses were observed between the 4 treatment groups (either 360 μg once per week or 180 μg twice per week of pegylated IFN-α, combined with a standard or a high dose of ribavirin) at different time points. In particular, there was no influence of a standard or high dose of ribavirin on virological outcomes (data not shown). Thus, the patients from the 4 groups were pooled together for analysis to assess the virological response to retreatment with a high dose of pegylated IFN-α (with a standard or high dosee of ribavirin) and the influence of the IL-28B genotype on this response. Figure 1 shows a flow chart of patient disposition in the trial. The following results are based on intent-to-treat analysis.
Only 3 patients had a CC genotype at IL-28B SNP position rs12979860. Their characteristics at baseline did not differ from those in the remaining patients. Two of them did not achieve a 2-Log10 HCV RNA decline and stopped therapy at week 24 as per the protocol stopping rule; the third one responded but failed to achieve an SVR. The CC patients were thus removed from the analysis to allow for comparison of the 55 (66.3%) CT and the 25 (30.1%) TT patients. The characteristics of the patients did not differ between these 2 groups. In particular, there was no significant difference in the mean HCV RNA levels at baseline (P = .76) (Table 1).
Virological Response to High-Dose Pegylated IFN-α With Ribavirin
At week 12, 48 of the 83 patients (57.8%) who had not responded to a standard treatment dose (<2-Log10 HCV RNA level drop) achieved a ≥2-Log10 HCV RNA level drop and 8 (9.6%) had undetectable HCV RNA (<15 IU/mL). At week 24, 51 patients (61.4%) achieved a ≥2-Log10 HCV RNA level drop and 21 (25.3%) had undetectable HCV RNA.
Due to a high incidence of post-treatment relapses, only 5 patients (6.0%) achieved an SVR. HCV RNA was undetectable at week 12 of therapy in all of them, and already at week 4 in 1 of them. Only 1 of the 5 patients who achieved an SVR had received the full 72 weeks of therapy, the remaining 4 having discontinued earlier due to adverse events or patient or investigator decision.
Week 12 Virological Response to Retreatment With High-Dose Pegylated IFN-α With Ribavirin According to the IL-28B Genotype
At week 12 of retreatment with high-dose pegylated IFN-α with standard- or high-dose ribavirin, the mean ± standard deviation Log10 HCV RNA level decrease was significantly greater than during the first course of therapy with a standard dose of pegylated IFN-α and ribavirin in both patients with a CC and a TT IL-28B genotype: -2.78 ± 1.59 vs -1.04 ± 0.55 (P < .0001), and -1.72 ± 0.90 vs -0.86 ± 0.65 (P = .0015), respectively.
Kinetics of Virological Response to High-Dose Pegylated IFN-α With Ribavirin According to the IL-28B Genotype
As shown in Figure 2 and in Table 2, patients with a CT genotype responded significantly better (and earlier) to high-dose pegylated IFN-α and ribavirin than those with a TT genotype. Indeed, the proportions of CT patients with a >0.5, 1.0, or 2.0 Log10 HCV RNA decrease were significantly higher than those in TT patients at weeks 2, 4, and 12-24, respectively. At weeks 24, 48, and at week 72 (end of treatment in patients who had undetectable HCV RNA at week 48), the proportion of patients with an undetectable HCV RNA was significantly higher in the CT patients than in the TT patients. The 5 patients who achieved an SVR were all in the CT group (9.1% vs 0%, not significant).
Mean ± standard deviation (SD) HCV RNA level reductions from baseline in patients with a CT genotype (black circles) or a TT genotype (black squares). As a comparator, mean ± SD HCV RNA level reductions at week 12 of an earlier course of therapy with standard doses of pegylated IFN-α and ribavirin in the same patients are shown as dotted lines. P values are for CT vs TT patients.
As shown in Figure 2, the average HCV RNA decline during the first 7 days of therapy, which combines both first- and second-phase HCV RNA declines, was slightly but not significantly greater in CT than in TT patients (-0.35 ± 0.49 vs -0.24 ± 0.34 Log10 IU/mL, respectively; P = .33). In contrast, the average weekly HCV RNA decline between days 8 and 28 of therapy, which accurately measures the second-phase decline, was significantly greater in CT than in TT patients (-0.28 ± 0.17 vs -0.18 ± 0.12 Log10 IU/mL/week, respectively; P = .004).
Predictors of Virological Responses to High-Dose Pegylated IFN-α and Ribavirin
As shown in Table 3, the IL-28B genotype was an independent predictor of the virological response at all tested time points, with CT patients being significantly more likely to respond than TT patients. Other predictors of response included female sex, BMI (paradoxically, bigger patients responded better to high-dose therapy), absence of cirrhosis, a >0.5 Log10 HCV RNA decrease during the first course of therapy with standard doses of pegylated IFN-α and ribavirin, and a low HCV RNA level at baseline (Table 3).
Predictive Value of the IL-28B Genotype on Virological Responses to High-Dose Pegylated IFN-α and Ribavirin
Table 4 shows the positive and negative predictive values, sensitivities, and specificities of the IL-28B genotype for the virological responses to high-dose pegylated IFN-α and ribavirin at weeks 4, 12, and 24.
Every patient experienced at least one adverse event during the study period; 23 of them (27.7%) experienced at least 1 severe adverse event. Treatment discontinuation due to an adverse event or to a severe adverse event has been observed in 11 (13.3%) and 6 (7.2%) patients, respectively. Table 5 shows the most frequent (≥10%) adverse events observed in the 83 patients during the trial. In contrast with a recent observation in patients receiving a standard dose of pegylated IFN-α and ribavirin,23 no significant difference was observed between CT and TT patients (data not shown).
In this study, patients chronically infected with HCV genotype 1 who failed to respond to a standard dose of pegylated IFN-α and ribavirin by a >2-Log10 HCV RNA level drop were retreated with a high dose of pegylated IFN-α2a and a standard or high dose of ribavirin. High-dose pegylated IFN-α2a was administered for the full duration of therapy, which was extended to 72 weeks if HCV RNA was undetectable at week 48. In this respect, the design of the trial was original, as formerly published retreatment trials used either standard doses of pegylated IFN-α and ribavirin for the full treatment course or short-term induction with high-dose pegylated IFN-α at the beginning of therapy.24, 25, 26, 27 These studies generally also included patients who responded by a >2-Log10 HCV RNA level drop at week 12, but subsequently failed to achieve an SVR during the first course of therapy. Despite these differences, only 5 patients in this trial (6%) achieved an SVR, all of them belonging to the CT group.
An important finding in this study was that in patients who were not able to achieve a 2.0 Log10 drop of HCV RNA levels at week 12 of treatment with standard doses of pegylated IFN-α and ribavirin, the use of a high dose of pegylated IFN-α2a induced a substantial antiviral response at weeks 12 and 24 (≥2.0 Log10 HCV RNA level reduction) in more than half of cases, with approximately one-quarter of the patients achieving undetectable HCV RNA at week 24. Although our study was not powered to assess this hypothesis, the lack of any trend toward a difference between the 4 treatment arms, and between the patients who received a standard and a high dose of ribavirin, suggests that the high dose of pegylated IFN-α2a used was responsible for the significantly greater antiviral efficacy observed, regardless of pegylated IFN-α frequency of administration (once or twice a week) and of the ribavirin dose administered. However, a marginal role for the latter could not be ruled out by our analysis and would require further analyses in larger groups of patients.
The present study also demonstrates that the ability of high-dose pegylated IFN-α with a standard or high dose of ribavirin to induce a significant antiviral response in earlier nonresponders to standard doses is under the influence of genetic determinants. Indeed, both patients with a CT and a TT genotype at SNP position rs12979860 responded significantly better to retreatment with high-dose pegylated IFN-α than to the first course of therapy with standard-dose pegylated IFN-α. Nevertheless, patients with a CT genotype responded significantly better, and earlier, to high-dose retreatment than patients with a TT genotype (Figure 2). These findings are in keeping with recent reports showing that, in treatment-naïve patients infected with HCV genotype 1, CT patients respond better than TT patients to standard doses of pegylated IFN-α and ribavirin.6, 7, 8, 19, 20 Interestingly, CT patients had less favorable baseline parameters, such as a higher BMI and a higher proportion of males (not significant), than TT patients, further emphasizing the importance of the genetic background of the host in the response to IFN-α.
A recent study assessing frequent viral kinetics in treatment-naïve patients receiving standard doses of pegylated IFN-α and ribavirin has shown nearly identical early viral kinetics among CT and TT patients.28 CC patients, who achieve the highest rates of viral clearance, had a significantly steeper first-phase HCV RNA level decline than both CT and TT patients, while their second-phase slopes were not different.28 This suggested that the IL-28B genotype essentially influences the ability of the patients to mount a potent direct antiviral response against HCV in response to IFN-α. Our data suggest that, when higher doses of pegylated IFN-α are used, CT patients respond significantly better than TT patients. In addition, the maximum effect of the IL-28B genotype in our study was on the second-phase decline, which measures the progressive clearance of infected cells. High doses of pegylated IFN-α could trigger antiviral mechanisms that are not involved when standard doses are used, and/or the lower level of "resistance" of cells from CT patients to the action of IFN could allow them to respond when exposure is increased.
Our sampling schedule did not allow us to study the first-phase decline in our patients. We cannot rule out a role for a difference between CT and TT patients in the first-phase decline that would ultimately influence the second-phase decline. Indeed, in patients who are naturally poorly responsive to IFN-α and ribavirin, a modest reduction of HCV RNA levels below a threshold that triggers infected cell clearance (or cure?) could have visible consequences on the second-phase decline only. These hypotheses will be difficult to verify unless appropriate experimental models are available and the molecular mechanisms underlying the relationship between IL-28B polymorphisms and HCV response to IFN-α-based therapy are unraveled.
Overall, our data suggest that high-dose pegylated IFN-α, in combination with a standard or a high dose of ribavirin, is an interesting option for combination with telaprevir or boceprevir in order to minimize the risk of resistance selection and increase the SVR rates in nonresponders to earlier standard therapy. This is reinforced by the fact that these treatments would be given for 24 to 48 weeks, and the antiviral effect was sustained over this duration in our study in patients who responded. The minimal antiviral effect of pegylated IFN-α and ribavirin to achieve a high cure rate is still unknown. Phase II and III trials with pegylated IFN-α2b, ribavirin, and boceprevir, which included a lead-in phase with pegylated IFN-α2b and ribavirin alone, suggested that it could be of the order of 1.0-1.5 Log10 IU/mL at week 4.10, 15, 16 Results from the REALIZE Trial with pegylated IFN-α2a, ribavirin, and telaprevir, which included a lead-in phase with pegylated IFN-α2a and ribavirin alone, also suggest a threshold at 1.0 Log10 IU/mL at week 4.
Although the IL-28B genotype is a strong, independent predictor of the ability of high-dose pegylated IFN-α and ribavirin to induce an antiviral response in nonresponders, the individual predictive value of this marker was not very high in our study. Specifically, a substantial number of TT patients were able to achieve a significant antiviral response on treatment. Therefore IL-28B genotyping should not be recommended as a tool to deny high-dose pegylated IFN-α and ribavirin therapy in nonresponders retreated with a triple combination. Nevertheless, nonresponder CT patients represent an ideal population for this strategy. Stratification on the IL-28B genotype should therefore be recommended in future trials assessing strategies based on high-dose pegylated IFN-α and ribavirin.
Other predictors of response at different time points included female sex, absence of cirrhosis, a >0.5 Log10 HCV RNA decline during the first course of therapy at standard doses and a low baseline HCV RNA level, parameters known to be associated with better SVR rates in HCV-infected patients.3, 4, 5 The noted effects of increased BMI appeared paradoxical, as bigger patients had a better response at weeks 12 and 24. This could be explained by the fact that higher doses work particularly well in patients in whom the principal cause of failure was a high BMI, responsible for insufficient IFN-α exposure during the first treatment course.
In conclusion, this study shows that high-dose pegylated IFN-α with standard or high doses of ribavirin is able to induce a potent antiviral response in a substantial number of patients who did not respond or responded poorly to a standard dose regimen. Patients with a CT IL-28B genotype respond significantly better and earlier to high-dose pegylated IFN-α and ribavirin than those with a TT genotype. High-dose pegylated IFN-α and ribavirin, therefore, appears to be a viable option to optimize HCV clearance rates in patients who failed on standard therapy and are retreated with a triple combination of pegylated IFN-α, ribavirin, and a protease inhibitor. This option, along with the ideal treatment schedule (our results suggest that high-dose pegylated IFN-α2a should be administered once weekly, but the question remains open for pegylated IFN-α2b, which bears different pharmacokinetic properties), should now be studied in prospective clinical trials according to the IL-28B genotype.