Prolonged treatment with pegylated interferon alpha 2b plus ribavirin improves sustained virological response in chronic hepatitis C genotype 1 patients with late response in a clinical real-life setting in Japan

Long-term pegylated interferon monotherapy following 72 weeks of pegylated interferon and ribavirin in hepatitis C virus genotype-1-infected slow responders

OBJECTIVE

Slow responders to pegylated interferon (Peg-IFN) and ribavirin (RBV) among patients infected with hepatitis C virus (HCV) genotype 1 may benefit from an extended treatment course. The aim of this study was to determine the efficacy of persistent negative serum HCV RNA over 96 weeks during long-term Peg-IFN monotherapy following 72 weeks of combination therapy.

METHODS

A total of 46 HCV genotype 1-infected slow responders were treated for 72 weeks with Peg-IFN and RBV combination therapy alone (n=25) or additional long-term biweekly treatment with 90 μg of Peg-IFN-α2a (n=21). The criterion for the completion of long-term Peg-IFN monotherapy was defined as the attainment of constantly negative HCV RNA in the serum over 96 weeks during IFN treatment.

RESULTS

The patients with sustained negative serum HCV RNA during 96 weeks of IFN treatment had a higher rate of sustained virological response (SVR) than those without (81 vs. 40%, p=0.012). A multivariate analysis identified sustained negativity of serum HCV RNA over 96 weeks of IFN treatment to be a predictive factor for SVR.

CONCLUSION

In the present study, sustained negative serum HCV RNA over 96 weeks during long-term Peg-IFN monotherapy following 72 weeks of combination therapy of Peg-IFN and RBV resulted in beneficial virological outcomes among HCV genotype 1-infected slow responders.

Relationship between HCV dynamics and sustained virological responses in chronic hepatitis C genotype 1b patients treated with telaprevir-based triple therapy

OBJECTIVES

This study investigated the relationship between hepatitis C virus (HCV) dynamics and sustained virological response (SVR), as well as the efficacy of an extended treatment with telaprevir-based triple therapy among patients with chronic hepatitis C genotype 1b.

METHODS

Among 220 patients receiving triple therapy for 24 weeks, the SVR rate was analyzed at each time point at which HCV RNA became undetectable. The SVR rates in the patients who did not achieve a rapid virological response (RVR) were compared with those in 27 patients who received triple therapy for 48 weeks.

RESULTS

The SVR rates of interleukin 28B (IL28B) TT and non-TT patients were 100 versus 66.7% after 1 week, 97.6 versus 72.2% after 2 weeks, 95.2 versus 84.2% after 3 weeks, 93.1 versus 72.2% after 4 weeks, 76.9% versus 11.1% after 6 weeks, and 88.9 versus 14.3% after 8 weeks, respectively. All of the IL28B TT patients who showed undetectable HCV RNA levels until week 8 achieved an SVR. In contrast, the SVR rates in the IL28B non-TT patients who did not achieve RVR with 24 and 48 weeks of treatment were 11.8 and 62.5%, respectively (P=0.017).

CONCLUSION

These results suggest that an SVR can frequently be achieved by IL28B TT patients, even with 24 weeks of treatment, when HCV RNA remains undetectable until week 8, and also that IL28B non-TT patients should have RVR values to achieve an SVR with 24 weeks of treatment. The SVR rate was low in IL28B non-TT patients treated for 24 weeks who did not achieve an RVR; however, it could increase when the treatment duration was extended to 48 weeks.

Association of IL28B polymorphisms with virological response to peginterferon and ribavirin therapy in children and adolescents with chronic hepatitis C

AIM

The objective of the current study was to find baseline predictive factors of response to therapy with pegylated interferon and ribavirin (PEG-IFN/RBV therapy) in children and adolescents with chronic hepatitis C.

METHODS

IL28B genotype and mutations in the core of hepatitis C virus (HCV) were analyzed in 30 patients treated with PEG-IFN/RBV for HCV infection. The initial rate of decrease in the viral load was assessed during the first 2 weeks of treatment.

RESULTS

IL28B major allele was seen more frequently in patients with sustained virologic response (SVR) than in non-SVR patients (P < 0.001). There was no difference between these two groups in frequency of Core 70 mutation. Among patients with genotype-1, SVR was achieved in more patients (P = 0.007) in the IL28B major allele group than in those in the minor allele group. The early decrements in the viral load (log/2 weeks) were 3.80 ± 0.86 in the genotype-2 major allele group, 1.82 ± 0.84 in the genotype-1 major allele group, and 0.41 ± 0.33 in the genotype-1 minor allele group.

CONCLUSIONS

Among pediatric patients with HCV infection the effectiveness of PEG-IFN/RBV therapy may be lower in the group with genotype-1 IL28B minor alleles than in other groups with IL28B major allele. Treatment strategy should be carefully implemented in patients with IL28B unfavorable type.

Indices of initial hepatitis C virus RNA reduction rate to predict efficacy of interferon-beta followed by peginterferon plus ribavirin for genotype 1b high viral load

AIM

Initial hepatitis C virus (HCV) RNA reduction was investigated as a potential index for sustained virological response (SVR) in the treatment of interferon (IFN)-β followed by peginterferon plus ribavirin (PEG IFN/RBV).

METHODS

The treatment course was retrospectively analyzed in 64 genotype 1b patients with a HCV RNA level of 5.0 logIU/mL or higher. IFN-β was administrated twice a day for 2 weeks followed by 24 or 48 weeks of PEG IFN/RBV. The serum HCV RNA level was measured by real-time polymerase chain reaction before administration and at 1, 2 and 4 weeks of therapy.

RESULTS

By the duration of PEG IFN administration, the SVR rates were 11% (2/18, <19 weeks), 64% (23/36, 20-24 weeks) and 40% (4/10, 25-72 weeks) (P = 0.0011, χ(2) -test). The SVR rate was high in patients in whom the HCV RNA level had decreased by 2.5 logIU/mL or greater at 1 week of IFN-β (29/55 [53%] vs 0/9 [0%], P = 0.0029, χ(2) -test). Among these patients, the SVR rate was even higher in those with continuous reduction in the first 2 weeks after the switch to PEG IFN/RBV (27/45 [60%] vs 2/10 [20%], P = 0.0048). Age below 65 years, no previous IFN course and good initial HCV RNA reduction were significantly associated with SVR on multivariate analysis, and the SVR rate was 95% (18/19) among these patients.

CONCLUSION

The 2.5 logIU/mL reduction in HCV RNA at 1 week of IFN-β and the continuous reduction just after the switch to PEG IFN/RBV are important SVR-predictive indices.

Low-dose pegylated interferon-α2a plus ribavirin therapy for elderly and/or cirrhotic patients with HCV genotype-1b and high viral load

BACKGROUND

Pegylated interferon (PEG-IFN) plus ribavirin therapy is still recommended for elderly and/or cirrhotic patients. This study examined whether sustained virological response (SVR) to low-dose PEG-IFN-α2a plus ribavirin therapy for elderly and/or cirrhotic patients could be predicted based on viral reduction within 2 weeks after therapy initiation or interleukin IL-(28B) polymorphism and viral mutations.

METHODS

Participants comprised 115 elderly (≥65 years) and/or cirrhotic patients with genotype-1b and high viral load. Reduced doses of PEG-IFN-α2a (90 μg/kg/week) and ribavirin (400-800 mg/day) were administered for 48-72 weeks based on virological response of each patient.

RESULTS

SVR was achieved in 34% (39/115), and treatment was discontinued in 15% (17/115). Univariate analysis identified age, α-fetoprotein, fibrosis marker, interferon sensitivity-determining region (ISDR), IL-28B polymorphism and level of viral reduction within 2 weeks as factors contributing significantly to SVR. However, no significant differences were noted in core amino acid substitutions. Multivariate analysis identified age, hyaluronic acid, ISDR and viral reduction as factors independently associated with SVR. Positive predictive value (PPV) and negative predictive value (NPV) of SVR based on the level of viral reduction at 2 weeks (cutoff level, 1.7 log IU/ml) were 83% and 84%, respectively. The PPV of SVR based on IL-28B major and ISDR mutant was 70%, and the NPV of SVR based on IL-28B minor and wild-type ISDR was 89%.

CONCLUSIONS

Evaluations of viral reduction at 2 weeks or both IL-28B and ISDR are useful to predict SVR to low-dose PEG-IFN-α2a plus ribavirin therapy for elderly and/or cirrhotic patients.

Predictors of psychopathological outcome during peg-interferon and ribavirin therapy in patients with chronic HCV-correlated hepatitis

Peg-interferon (Peg-IFN) and ribavirin (RBV) therapy is reported to induce psychiatric symptoms and syndromes in 20% of patients treated for Hepatitis C Virus (HCV) infection. Present study was aimed to quantify the phenomenon and assess the influence of psychiatric counseling over antiviral completion rate and the use of psychometric tools, in terms of prediction of psychopathological outcome. Ninety-six HCV patients were assessed, before antiviral treatment, by means of the Sheehan Disability Scale (SDS), Mood Disorder Questionnaire (MDQ), Symptom Checklist-90, and Internal State Scale (ISS). Sociodemographic and clinical variables and completion rate were collected. Binary logistic regression was performed to evaluate whether scores were predictive of psychiatric visit, development of psychiatric disorders, and need for treatment. Ninety-five patients (99%) completed antiviral treatment; 27 subjects (29%) needed psychiatric visit: among them, mood disorder was diagnosed in 15 (16%) and were pharmacologically treated. Baseline SDS and MDQ higher scores were found to be predictive of psychiatric visit [odds ratio (OR)=1.258, P<0.001 and OR=1.425, P=0.05, respectively]. Furthermore, higher MDQ score (P=0.017) and ISS hostility scores (OR=1.048, P=0.014) at baseline predicted the subsequent development of mood episodes, while ISS activation correlated negatively (OR=0.948, P=0.009). Finally, the need for treatment was predicted by higher scores at the MDQ and ISS activation items (OR=2.467, P=0.030; OR=0.970, P=0.038). Present findings suggest that psychiatric counseling may be needed in almost 30% of HCV patients on antiviral treatment, with positive influence over the completion rate. Baseline higher scores at psychometric questionnaires-MDQ-in particular, predictors of psychopathological outcome during Peg-IFN and RBV therapy in patients with chronic HCV-correlated hepatitis reflecting individual functioning before starting antiviral therapy and positive history for mood disorders, seem to predict psychiatric visit, onset of mood episodes, and need for psychopharmacological treatment. Further investigation is warranted to confirm results.

Response-guided therapy for patients with chronic hepatitis who have high viral loads of hepatitis C virus genotype 2

AIM

  We evaluated the efficacy of response-guided therapy in patients with hepatitis C virus (HCV) genotype 2.

METHODS

  We studied 105 patients with an HCV genotype 2 load of higher than 5.0 Log IU/mL who received more than 75% of the target dose of pegylated interferon plus ribavirin. Among patients with rapid viral response (RVR; no HCV RNA detected at week 4), 14 selected 16 weeks of therapy (group A), and 28 selected 24 weeks of therapy (group B). Among non-RVR patients, 40 selected 24 weeks of therapy (group C), and 19 selected 48 weeks of therapy (group D).

RESULTS

  All patients in group A and B achieved a sustained viral response (SVR). Clinical characteristics did not differ significantly between groups C and D. However, the proportion of patients in whom HCV RNA disappeared at a later week after starting treatment was higher in group D (P = 0.0578). SVR rate was 73% in C, and 79% in D. Among patients in whom HCV RNA disappeared between weeks 5 and 8, SVR was achieved in 28 (82%) of 34 patients in C and 10 (91%) of 11 patients in D. Among patients whose HCV RNA disappeared between weeks 9 and 12, SVR was achieved in one (20%) of five patients in C and five (63%) of eight patients in D (not statistically significant).

CONCLUSIONS

  16 weeks of combination therapy could achieve an adequate antiviral effect for RVR patients. Extending therapy could not significantly improve SVR rate in non-RVR patients.

Toward the establishment of a prediction system for the personalized treatment of chronic hepatitis C

BACKGROUND

Although several direct-acting antivirals (DAAs) are now available, the therapy regimen for chronic hepatitis C will continue to include pegylated interferon and ribavirin for the foreseeable future. Despite their improved rate of sustained virological response (SVR), DAAs pose increased risks of side effects and selection for antiviral resistance. Not all patients require DAA to achieve SVR, whereas others are unlikely to respond even to triple therapy. Therefore, a personalized approach to candidate selection is necessary.

METHODS

In this retrospective study, data from 640 Japanese patients who were treated for chronic hepatitis C genotype 1, 2, or 3 with pegylated interferon plus ribavirin combination therapy was compiled to identify robust pretreatment predictive factors for SVR.

RESULTS

A logistic regression model for personalized therapy was developed based on age, viral genotype, initial viral load, aspartate aminotransferase/alanine aminotransferase ratio, α-fetoprotein levels, and IL28B single-nucleotide polymorphism genotype. The area under the receiver-operating characteristic curve (AUC) was 0.85. The mean AUC following 10 rounds of 10-fold cross validation was 0.82, with a true positive rate of 78.2%.

CONCLUSIONS

A personalized approach to therapy may better inform treatment decisions and reduce incidence of side effects and antiviral resistance.

Favorable factors for re-treatment with pegylated interferon α2a plus ribavirin in patients with high viral loads of genotype 1 hepatitis C virus

AIM

  Effect of re-treatment for pegylated interferon (PEG-IFN) plus ribavirin was not fully evaluated. We examined the effects of re-treatment with PEG-IFN plus ribavirin in patients with high viral loads of genotype 1 hepatitis C virus who failed to achieve a sustained virological response (SVR) with combination therapy.

METHODS

  We examined 38 patients who were re-treated with PEG-IFN α2a plus ribavirin for more than 60 weeks, among whom 14 were non-responders and 24 were relapsers after previous treatment with PEG-IFN α2b plus ribavirin. IL28B genotyping was done in 21 patients.

RESULTS

  The overall SVR rate was 34%. Analysis of baseline characteristics showed that the relapsers had a significantly higher SVR rate than the non-responders (50.0%, 12/24 vs. 7.1%, 1/14, respectively, P = 0.012) The SVR rates of re-treated patients who had turned hepatitis C virus (HCV) RNA-negative at weeks 8, 12, 24, and 48 of the previous therapy were 67% (4/6), 67% (4/6), 29% (2/7), and 25% (1/4), respectively. Re-treatment achieved an SVR in five of 12 patients with IL28B major alleles and three of nine patients with IL28B minor alleles. During the re-treatment, patients with complete viral suppression at week-12 achieved a significantly higher SVR rate (P = 0.001).

CONCLUSIONS

  Re-treatment with PEG-IFN α2a plus ribavirin therapy is effective in patients who relapse after a course of PEG-IFN α2b plus ribavirin therapy. Re-treatment is a particularly useful option for patients who achieve early viral clearance during previous therapy.

Cancer preventive effect of pegylated interferon α-2b plus ribavirin in a real-life clinical setting in Japan: PERFECT interim analysis

AIM

  This study was conducted to clarify the incidence of hepatocellular carcinoma (HCC) and the factors contributing to its occurrence by following chronic hepatitis C patients who received pegylated interferon (PEG-IFN) α-2b plus ribavirin (RBV) combination therapy.

METHODS

  Patients who received PEG-IFN α-2b and RBV combination therapy with no history of HCC or HCC within 3 months after the start of treatment were observed for the onset of HCC at 67 centers.

RESULTS

  Sustained virological response (SVR) was observed in 999 (53.5%) of 1865 patients eligible for analysis. During the observation period (median duration: 4 years and 3 months), HCC developed in 59 patients (3.1%). A significant difference was observed in the 5-year cumulative incidence of HCC between SVR and non-SVR patients (1.1% vs. 7.1%). Factors contributing to HCC selected in multivariate analysis were therapeutic efficacy, sex, age, alanine aminotransferase (ALT) level at 24 weeks after the end of treatment, and platelet count. Non-SVR patients with ALT improvement after the end of treatment had a significantly lower 5-year cumulative incidence of HCC than those without (3.4% vs. 11.0%). HCC developed in 10 patients who achieved SVR, and multivariate analysis indicated that ALT level at 24 weeks after the end of treatment was the only significant factor contributing to HCC.

CONCLUSION

  Several known risk factors for HCC contributed to HCC in patients who received PEG-IFN α-2b and RBV combination therapy, and ALT abnormality after the end of treatment contributes to the onset of HCC in both non-SVR and SVR patients.

Factors predictive of sustained virological response following 72 weeks of combination therapy for genotype 1b hepatitis C

BACKGROUND

Treatment of genotype 1b chronic hepatitis C virus (HCV) infection has been improved by extending peg-interferon plus ribavirin combination therapy to 72 weeks, but predictive factors are needed to identify those patients who are likely to respond to long-term therapy.

METHODS

We analyzed amino acid (aa) substitutions in the core protein and the interferon sensitivity determining region (ISDR) of nonstructural protein (NS) 5A in 840 genotype 1b chronic hepatitis C patients with high viral load. We used logistic regression and classification and regression tree (CART) analysis to identify predictive factors for sustained virological response (SVR) for patients undergoing 72 weeks of treatment.

RESULTS

When patients were separately analyzed by treatment duration using multivariate logistic regression, several factors, including sex, age, viral load, and core aa70 and ISDR substitutions (P = 0.0003, P = 0.02, P = 0.01, P = 0.0001, and P = 0.0004, respectively) were significant predictive factors for SVR with 48 weeks of treatment, whereas age, previous interferon treatment history, and ISDR substitutions (P = 0.03, P = 0.01, and P = 0.02, respectively) were the only significant predictive factors with 72 weeks of treatment. Using CART analysis, a decision tree was generated that identified age, cholesterol, sex, treatment length, and aa70 and ISDR substitutions as the most important predictive factors. The CART model had a sensitivity of 69.2% and specificity of 60%, with a positive predictive value of 68.4%.

CONCLUSIONS

Complementary statistical and data mining approaches were used to identify a subgroup of patients likely to benefit from 72 weeks of therapy.

Extended treatment duration for treatment naïve chronic hepatitis C genotype 1 late viral responders: a meta-analysis comparing 48 weeks vs 72 weeks of pegylated interferon and ribavirin

Patients with genotype I chronic hepatitis C virus (HCV) infection with late virological response to therapy have low sustained viral response (SVR) with standard 48 weeks of therapy and may benefit from extended therapy. We performed a systematic review and meta-analysis of five studies to compare the outcome of 48 weeks vs 72 weeks treatment in treatment naïve chronic hepatitis C genotype I patients with late virological response. The end of treatment response with extended 72 weeks of treatment compared to standard 48 weeks of treatment was similar 48% and 56%, respectively, with pooled odds ratio (OR) (0.85; 95% CI 0.52-1.37). However, the SVR rates were higher with 72 weeks of treatment compared to 48 weeks treatment 32%vs 25% with pooled OR of 1.67 in favour of extended duration therapy (95% CI 1.16-2.40). This was because of lower relapse rates with extended duration therapy (35%vs 55%) with OR of 0.39 in favour of 72 weeks therapy (95% CI 0.25-0.61). There was no heterogeneity. No publication bias was noted as assessed by Egger's test. Extending the treatment duration from 48 to 72 weeks in genotype 1 infected patients with late virological response improves SVR. Thus, therapy extension in genotype 1 late viral responders (LVR) may be a consideration to improve treatment response; however, the proportion of patients with LVR that might benefit from 72-week therapy appears to be small.

Accumulation of refractory factors for pegylated interferon plus ribavirin therapy in older female patients with chronic hepatitis C

AIM

  Several host and viral factors have been reported to influence the effectiveness of pegylated interferon plus ribavirin combination therapy for chronic hepatitis C. In Japan, where the age of treated patients is comparatively high, recent studies have reported poor response to treatment in older female patients, but little is known about the relationship between advanced age in women and previously reported factors.

METHODS

  Using a database of 1167 patients chronically infected with hepatitis C virus (HCV) genotype 1b, we analyzed the amino acid sequences of the HCV core protein and interferon sensitivity determining region (ISDR) and examined the relationships among predictive factors.

RESULTS

  The proportion of patients with substitutions at core 70, which is associated with poor response to pegylated interferon plus ribavirin therapy, increased with age only in female patients. A similar trend was observed for ISDR wild type (wt). We also found that core 70 wt is associated with core 91 wt (P = 5.4 × 10(-9) ) as well as ISDR wt (P = 0.025). HCV RNA levels were higher in patients with core and ISDR wt (P < 0.001). Furthermore, core amino acid mutations were associated with advanced fibrosis and higher inflammatory activity (P = 0.028 and 0.048, respectively) as well as higher gamma-glutamyltranspeptidase, alanine aminotransferase and low-density lipoprotein cholesterol levels (P < 0.001, 0.006 and 0.001, respectively).

CONCLUSION

  A combination of factors account for poor response rate in older female patients in Japan. Elucidating the relationship between amino acid substitutions and metabolic alteration is an important step in understanding the mechanism of HCV interferon resistance.

Inhibition of hepatitis C virus replication by IFN-mediated ISGylation of HCV-NS5A

ISG15 is a ubiquitin-like molecule whose expression is induced by type I IFN (IFN-α/β) or in response to virus or bacterial infection. ISG15 or conjugation of ISG15 to target proteins was reported to play critical roles in the regulation of antiviral responses. IFN restricts replication of hepatitis C virus (HCV). However, molecular mechanism of IFN-α/β that inhibits HCV replication is not clear yet. In the current study, we demonstrated that replication of HCV was inhibited by overexpression of ISG15 and ISG15-conjugation enzymes in the HCV subgenomic replicon cells. Among various nonstructural proteins of HCV, NS5A was identified as the substrate for ISGylation. Furthermore, protein stability of NS5A was decreased by overexpression of ISG15 or ISG15-conjugating enzymes. The inhibitory effect of ISG15 or ISGylation on NS5A was efficiently blocked by substitution of lysine at 379 residue to arginine within the C-terminal region, suggesting that ISGylation directly controls protein stability of NS5A. Finally, the inhibitory effect of IFN-α/β on HCV replication was further enhanced by ISGylation, suggesting ISG15 as a therapeutic tool for combined therapy with IFN against HCV.

Differential impact of adherence to pegylated interferon and ribavirin in the treatment of genotype 1 high viral titer chronic hepatitis C

To clarify the impact of adherence, we treated 122 genotype 1 high viral titer chronic hepatitis C patients with pegylated interferon (peg-IFN) and ribavirin for 48 weeks at nine referral hospitals, and evaluated the prognostic factors with a focus on the adherence to the treatment. This study included 68 (55.7%) treatment-naïve patients and 54 (44.3%) patients who did not respond to the previous treatment. Multivariate analysis revealed adherence to peg-IFN and ribavirin as the only significant predictor. Sustained virological response (SVR) rate was 72.2%, 19.0%, and 27.3% in patients given ≥80%, 60%–80%, and <60% dose peg-IFN, respectively, and was 68.6%, 41.2%, and 5.3% in those given ≥80%, 60%–80%, and <60% dose ribavirin, respectively. SVR rate sharply fell when exposure to peg-IFN was below 80% whereas it decreased in a stepwise manner as for ribavirin. Therefore, ≥80% of peg-IFN and as much as possible dose of ribavirin are desired to achieve SVR in the treatment of genotype 1 high viral titer chronic hepatitis C.

Mutations in the interferon sensitivity determining region and virological response to combination therapy with pegylated-interferon alpha 2b plus ribavirin in patients with chronic hepatitis C-1b infection

BACKGROUND

Pegylated-interferon-alpha 2b (PEG-IFN) plus ribavirin (RBV) therapy is currently the de-facto standard treatment for hepatitis C virus (HCV) infection. The aims of this study were to analyze the clinical and virological factors associated with a higher rate of response in patients with HCV genotype 1b infection treated with combination therapy.

METHODS

We analyzed, retrospectively, 239 patients with chronic hepatitis C-1b infection who received 48 weeks of combination therapy. We assessed clinical and laboratory parameters, including age, gender, pretreatment hemoglobin, platelet counts, HCV RNA titer, liver histology, the number of interferon sensitivity determining region (ISDR) mutations and substitutions of the core amino acids 70 and 91. Drug adherence was monitored in each patient. We carried out univariate and multivariate statistical analyses of these parameters and clinical responses.

RESULTS

On an intention-to-treat (ITT) analysis, 98 of the 239 patients (41%) had sustained virological responses (SVRs). Patients with more than two mutations in the ISDR had significantly higher SVR rates (P<0.01). Univariate analyses showed that stage of fibrosis, hemoglobin, platelet counts, ISDR mutations, serum HCV RNA level, and adherence to PEG-IFN plus RBV were significantly correlated with SVR rates. Multivariate analysis in subjects with good drug adherence extracted the number of ISDR mutations (two or more: odds ratio [OR] 5.181).

CONCLUSIONS

The number of mutations in the ISDR sequence of HCV-1b (>or=2) is the most effective parameter predicting a favorable clinical outcome of 48-week PEG-IFN plus RBV therapy in patients with HCV genotype 1b infection.