Long-term response to interferon alpha is unrelated to "interferon sensitivity determining region" variability in patients with chronic hepatitis C virus-1b infection.

BACKGROUND/AIMS: Contradictory data have been reported about the predictive value of the variability in interferon sensitivity determining region (ISDR) of hepatitis C virus (HCV) genotype-1b on response to interferon-alpha (IFN-alpha) therapy. The aim of this study was to examine this issue in a series of patients with long-term response to IFN treatment. METHODS: We retrospectively analyzed 24 patients with chronic HCV genotype-1b infection treated with IFN-alpha (total dose median 677, range 216-1350 MU) selected in 6 Italian Liver Units. These patients were defined as true long-term responders (LTR) since they showed persisting biochemical and virological responses to IFN treatment (mean follow-up 38 months). HCV genomes from pretreatment serum samples were amplified and directly sequenced. The ISDR amino-acid sequences obtained were aligned and compared with the published sequence of HCV-J. RESULTS: Amino-acid substitutions were found in 23 of the 24 patients, and 22 of them showed an H to R amino-acid change at codon 2218. Fourteen patients showed only one mutation (at codon 2218), two had 2, five had 3, one had 4 and one had 5 mutations. When we compared the ISDR sequences from the 24 LTR with those of non-responders (NR), we found no significant correlation between the number of mutations and the response to therapy. CONCLUSIONS: Our results demonstrate that the persisting efficacy of IFN treatment in patients with chronic HCV is not related to the number of ISDR amino acid substitutions of the infecting viruses. Further studies are needed to verify whether other NS5A sequences outside the ISDR might be involved in the mechanisms of IFN resistance.     

聚乙二醇干扰素α-2a联合利巴韦林治疗自身免疫抗体阳性慢性丙型肝炎的临床疗效

目的 观察聚乙二醇干扰素α-2a (Peg-IFN α-2a)联合利巴韦林(RBV)治疗自身免疫抗体阳性慢性丙型肝炎患者的疗效,并与自身免疫抗体阴性的患者比较,探讨自身免疫抗体是否影响慢性丙型肝炎疗效. 方法 86例慢性丙型肝炎患者完善自身免疫抗体等检测后,按体质量给予Peg-IFN α-2a 135 μg或180 μg,每周1次,皮下注射;联合按体质量分配的利巴韦林800～ 1200mg/d,分次口服,共治疗48周.分别检测治疗前,治疗后4、12、24、36、48周以及治疗终止后24周的HCV RNA载量.数据比较用单因素方差分析或x2检验.结果 24例患者检出至少1种自身免疫抗体,其中抗线粒体抗体(ANA)阳性14例,抗平滑肌抗体阳性5例,抗1型肝肾微粒抗体阳性3例,ANA合并抗SSB抗体阳性1例,ANA合并抗肝细胞胞浆抗原1型抗体阳性1例.24例自身免疫抗体阳性患者中,17例(70.8％)获得了快速病毒学应答(RVR),19例(79.2％)获得了持续病毒学应答(SVR);62例自身免疫抗体阴性的患者中,45例(72.5％)获得了RVR,51例(82.2％)获得了SVR,两组患者的RVR及SVR率差异均无统计学意义(x2值分别为0.026和0.001,P值均＞ 0.05).结论 Peg-IFN α-2a联合RBV治疗自身免疫抗体阳性的慢性丙型肝炎患者仍然有显著疗效;自身免疫抗体的检出可能不是慢性丙型肝炎患者疗效的独立预测因素.     

Changes in haemoglobin during interferon alpha-2b plus ribavirin combination therapy for chronic hepatitis C virus infection

Interferon alpha and ribavirin (RBV) combination therapy is associated with decreases in haemoglobin (Hb) concentrations and anaemia. The aim of this analysis was to better characterize the magnitude and frequency of Hb changes and risk factors. This retrospective analysis evaluated treatment‐related changes in Hb in 677 patients who participated in either of two interferon alpha‐2b plus RBV studies for chronic hepatitis C virus (HCV) infection. Study 1 included 192 interferon alpha‐naïve patients randomized to receive RBV 1000–1200 mg/day plus interferon alpha‐2b 3 million IU daily or three times weekly for 48 weeks. Study 2 included 485 interferon alpha‐experienced patients randomized to receive RBV 1000‐1200 mg daily plus interferon alpha‐2b 3 million IU daily or three times weekly for 4 weeks, followed by three times weekly dosing for 44 weeks. More than 50% of all patients experienced a decrease in Hb ≥30 g/L. Women were 4.4 times as likely as men to experience a Hb level of <100 g/L; however, men were at a 40% higher risk to experience a Hb decline of >30 g/L from baseline. Daily use of interferon alpha‐2b did not impact the magnitude of Hb decrease. In this pooled analysis, RBV dose reduction resulted in increases in Hb concentration of approximately 10 g/L. Lower baseline creatinine clearance, higher baseline Hb levels and increased age were independently associated with increased risk of Hb decreases of >27.7%. Lower baseline weight was not associated with increased risk of Hb decrease. Substantial Hb decreases occur frequently with interferon alpha/RBV combination therapy. Sex, the magnitude of the Hb decline and renal function are potentially important factors to consider in patients receiving RBV. Further research is needed to determine the impact on virological response and to develop strategies to manage the medical consequences.     

Rapid virological response in peripheral blood mononuclear cells with an increase of hepatitis C virus-specific interferon-gamma production predisposes to sustained virological response in patients with chronic hepatitis C genotype 1 undergoing treatment with pegylated-interferon alpha 2a plus ribavirin

Abstract

Objective. Viral load evaluation in plasma, after 1 month of treatment, represents one of the most important parameters to predict treatment response during interferon (IFN) treatment in chronic hepatitis C (CHC). It has been proven that hepatitis C virus (HCV) RNA may be present in peripheral blood mononuclear cells (PBMCs) but few studies have investigated the viral load in PBMCs during treatment. The aim of this study was to evaluate HCV RNA in PBMCs during therapy with pegylated-IFN-α2a plus ribavirin and whether its clearance in PBMCs may induce a treatment response. Furthermore, we also analyzed the IFN-γ and interleukin (IL)-4 responses of PBMCs during therapy. Material and methods. We studied 35 patients with CHC genotype 1 undergoing antiviral treatment with pegylated IFN-α2a 180 μg weekly plus ribavirin 1000 mg/daily. In these patients we evaluated HCV-RNA in plasma and PBMCs, IFN-γ and IL-4 before treatment, after 1, 3 and 12 months of treatment and 6 months after the end of treatment. Results. We found that rapid virological clearance of HCV-RNA in PBMCs with a restored and improved HCV-specific IFN-γ response was statistically significantly higher in those with a sustained virological response (SVR). Conclusion. Patients having a rapid virological response in PBMCs with an improved Th1 network achieve a complete SVR, whereas those having viral clearance only in plasma without a restored Th1 network have a relapse.     

Rapid and early virological response to chronic hepatitis C treatment with IFN alpha2b or PEG-IFN alpha2b plus ribavirin in HIV/HCV co-infected patients

BACKGROUND AND AIMS: An algorithm based on a 2 log(10) decline in hepatitis C virus (HCV) RNA at week (W) 12 has been proposed in US and European recommendations for the management of patients with chronic hepatitis C treated with pegylated-interferon and ribavirin. METHODS: We examined rapid virological response (RVR; at W2 and W4 after the initiation of therapy) in HIV/HCV co-infected patients. Using HCV RNA measurements (Versant HCV RNA 3.0, Cobas Amplicor HCV 2.0), RVR was studied in 323 patients from the ANRS HC02 RIBAVIC trial, comparing interferon alpha2b 3 MU x3/week with pegylated interferon alpha2b 1.5 microg/kg/week, each combined with ribavirin 800 mg/day over 48 weeks. RESULTS: The best positive and negative predictive values of sustained virological response (SVR) were obtained with an undetectable HCV RNA at W4 (97%) and with more than a 2 log(10) decrease at W12 (99%), respectively. Prediction of non-SVR was obtained in all patients by using HCV RNA cut-off levels above 460,000 IU/ml at W4 and above 39,000 UI/ml at W12 irrespective of the HCV genotype and arm of treatment. CONCLUSION: We propose a new algorithm based on RVR thresholds using HCV RNA that allows for excellent prediction of non-SVR as early as W4.     

Pegylated interferon alpha2b plus ribavirin for the treatment of chronic hepatitis C in HIV-infected patients

BACKGROUND: Hepatitis C virus (HCV) and HIV coinfection constitutes an important epidemiological and clinical problem. We evaluated the safety and efficacy of Pegylated interferon alpha2b (Peg-IFN) and a fixed dose of ribavirin in the treatment of chronic hepatitis C in HIV coinfection. METHODS: Open, prospective study in HCV-HIV coinfected patients with persistently elevated alanine aminotransferase (ALT) levels and a liver biopsy showing either portal or bridging fibrosis. Therapy included Peg-IFN (50 micro g weekly) with ribavirin 800 mg for 48 weeks. The primary end point was sustained virological response (SVR). Univariate and multivariate analyses were performed to determine factors associated with response. RESULTS: By intent-to-treat analysis, 11 of 35 patients (31%) reached SVR. SVR was significantly better for genotypes 2/3 than for genotype 1 (54% versus 21%; P < 0.05). By multivariate logistic regression analysis, only a non-1 genotype was an independent factor for SVR [odds ratio (OR), 6; 95% confidence interval (CI), 1.1-31.7; P < 0.005]. A decrease of at least 1.5 log10 HCV RNA at week 12 of therapy was highly predictive of SVR (OR, 49.9; 95% CI, 4.9-508.2; P < 0.001). Most patients developed adverse events, although only six patients (17%) discontinued treatment due to toxicity. CONCLUSIONS: The combination of low doses of Peg-IFN plus a fixed dose of ribavirin resulted in a rate of SVR similar to that obtained with higher doses of the drugs in HIV-infected patients and lower than those obtained in non-HIV patients. Response at week 12 may be useful to help guide therapy in HCV-HIV co-infected patients.     

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.     

Optimal follow-up time to determine the sustained virological response in patients with chronic hepatitis C receiving pegylated-interferon and ribavirin

Background and Aim: This study evaluated whether the assessment of hepatitis C virus (HCV)‐RNA at 12 weeks (FW+12) post‐treatment follow‐up was as applicable as FW+24 to evaluate sustained virological response (SVR) using the highly sensitive real‐time polymerase chain reaction (PCR) HCV assay. Methods and Results: Two hundred and twenty‐two patients with chronic hepatitis C were included in this study. Pegylated interferon (Peg‐IFN) and ribavirin were administered for 24–72 weeks based on the genotype and viral load. Serum HCV‐RNA was measured using real‐time PCR at pretreatment, the end of treatment, FW+4, FW+8, FW+12, FW+16, FW+20 and FW+24. Two hundred patients had a virological response at the end of treatment. One hundred and forty‐eight of 200 (74.0%) patients with a virological response at the end of treatment had an SVR at the FW+24. The positive predictive value (PPV) to identify patients with SVR at FW+4, FW+8, FW+12 was 87.1, 96.1, 98.0%, respectively. The viral load showed a reversion to the basal level as early as 8 weeks in relapse patients. There were only three patients who relapsed after FW+12 and all three of these patients were females with genotype Ib and a high viral load. Conclusion: The assessment of serum HCV‐RNA FW+12, using the highly sensitive real‐time PCR assay, is almost as effective as FW+24 to predict SVR. However, there are false negatives in female patients with a high viral load of genotype Ib when the SVR is predicted by FW+12. The current standard with FW+24 is reasonable, but the assessment of serum HCV‐RNA FW+12 may be effective in most patients.     

Peginterferon alpha-2b plus ribavirin vs interferon alpha-2b plus ribavirin for chronic hepatitis C in HIV-coinfected patients

Treatment of chronic hepatitis C in human immunodeficiency virus (HIV)-infected patients is associated with low response rates and high incidence of side effects. One hundred twenty-one hepatitis C virus (HCV)-HIV-coinfected patients were randomized to receive interferon alpha-2b (3 MU thrice weekly; n = 61) or peginterferon alpha-2b (1.5 microg/kg/week; n = 60), plus ribavirin (800 mg daily), for 24 (genotype 2 or 3) or 48 weeks (genotype 1 or 4). We assessed early virological response at 4, 8 and 12 weeks to predict sustained virological response (SVR). Safety assessment included frequent blood lactate measurement and relative quantitation of mitochondrial DNA (mtDNA) content in peripheral blood mononuclear cells. In intention-to-treat analysis, the SVR rate was higher in the peginterferon group (55%vs 26%; P = 0.002). The difference for HCV genotypes 1 and 4 was 45%vs 14% (P = 0.009) and 50%vs 27% (P = 0.387), respectively, and for genotype 2 or 3, 71%vs 43% (P = 0.12) Viral response at 4, 8 and 12 weeks of treatment was highly predictive of SVR. Among genotype 3 patients, 17 of 20 (85%) whose HCV RNA was already undetectable at 4 weeks had an SVR after 24 weeks of treatment. Hyperlactataemia occurred in 22 patients and was clinically significant in six, two of whom died. mtDNA decreased significantly 4-12 weeks after the start of treatment in patients developing clinically significant hyperlactataemia. Peginterferon alpha-2b plus ribavirin was more effective than interferon alpha-2b plus ribavirin in HIV-coinfected patients. Frequent monitoring of virological response may be very helpful to optimize treatment compliance, to tailor treatment duration and to minimize side effects.     

Long-term response to interferon plus ribavirin in patients with chronic hepatitis C refractory to interferon.

OBJECTIVE: A sustained response (SR) to interferon (IFN) is only observed in 15-20% of patients with chronic hepatitis C (CHC). The aim of this study was to determine the long-term effectiveness and safety of the treatment with IFN plus ribavirin (RIB) over two years in CHC patients without SR to IFN. DESIGN: A prospective and open longitudinal follow-up study was conducted over 3 years. PATIENTS AND METHODS: A total of 77 CHC patients were included: 63 non-responders (NR) and 14 relapsers (R) to IFN. Patients were treated with IFN (3 MU s.c. three times a week) and RIB (1,000-1,200 mg p.o. daily) for 12 months. Treatment tolerance and viral response (HCV-RNA in serum < 1,000 copies/ml) were assessed after 1, 3, 6 and 12 months of treatment. SR and relapsing rates were subsequently evaluated 6, 12 and 24 months after the end of the treatment, together with those variables capable of predicting SR. RESULTS: At the end of the treatment, 19/77 patients responded (24.7%), 9/63 (14.3%) were non-responders and 10/14 (71.4%) relapsers, and these same patients exhibited SR after 6 months. The SR rate two years after treatment was 22.1% [8/63 (12.7%) NR and 9/14 (64.3%) R]. The relapse rate after 6 months and two years was respectively 0 and 10.5% (2/77). Independent variables capable of predicting SR were negative viremia conversion within the first month of treatment, maintenance of such negative viremia after 6 months, and R status to IFN. Side effects were recorded in 90.9% of cases (70/77), the most frequent being pseudoinfluenza syndrome. Treatment had to be discontinued in 33.8% of patients (26/77). CONCLUSIONS: Combined IFN-RIB therapy for 12 months in CHC patients without SR to IFN obtains a long-term SR of 22.1%, this rate being higher in relapsers to prior IFN therapy (64.3% in R versus 12.7% in NR).     

Investigation of hyperuricemia during pegylated-interferon-alpha2b plus ribavirin combination therapy in patients with chronic hepatitis C

OBJECTIVE: Hyperuricemia has been reported as being an adverse effect of pegylated-interferon-alpha2b (Peg-IFNalpha2b) and ribavirin combination therapy for chronic hepatitis C and hyperuricemic changes occur in some patients during the therapy. However, detailed investigation of the elevation of uric acid has not been carried out previously. The incidence and mechanism of hyperuricemia were investigated in this study. METHODS: The data of 50 patients with chronic hepatitis C who had been treated with Peg-IFNalpha2b and ribavirin combination therapy or pegylated-interferon-alpha2a monotherapy for more than 24 weeks were analyzed. The effects of these treatments were evaluated clinically by the serum uric acid level and its urinary excretion rates. RESULTS: In patients with pegylated-interferon-alpha2a monotherapy, no significant elevation was shown either in serum uric acid concentrations or excretion rates. On the other hand, serum uric acid concentrations were significantly elevated during the combination therapy, reaching > or =7.0 mg/L in men and > or =6.5 mg/L in women in 15% of patients. The urinary uric acid excretion rate was also elevated significantly. CONCLUSION: Peg-IFNalpha2b plus ribavirin combination therapy induced an elevation of uric acid concentration, although the elevated levels were still within normal limit in many cases. It may be that ribavirin plays a leading role in its elevation and other factors may also be involved.     

Impact of early viral kinetics on pegylated interferon alpha 2b plus ribavirin therapy in Japanese patients with genotype 2 chronic hepatitis C

Summary. The recommended therapy for genotype‐2 chronic hepatitis C is a regimen of pegylated interferon alpha (peginterferon) plus ribavirin. This study was conducted to determine the value of early viral kinetics as a predictive factor for sustained virologic responder (SVR). Peginterferon alpha 2b (1.5 μg/kg/week) plus weight‐based ribavirin (600–1000 mg/day) was administered to 51 patients with chronic HCV genotype 2 for 24 weeks. The HCV‐RNA loads were measured at the baseline, hour 24, and week 1. The rebound index (RI, an index obtained from the viral load of week 1 divided by that of hour 24) was calculated. Compared with the baseline, the viral load at hour 24 for SVR was reduced by more than 1‐log: it continued to decline thereafter, and at week 1 it was significantly lower than at hour 24 (P < 0.05). The viral load for non‐SVR increased again between hour 24 and week 1. The SVR of patients with RI ≤1.0 was 100% (39/39). The SVR conversion for rapid virologic responders was 92% (35/38). The RI (≤1.0) was the only significant independent factor for SVR by multiple logistic regression analysis and is the first predictive factor in 24‐week peginterferon plus ribavirin therapy for patients infected with genotype 2.     

Pegylated interferon plus ribavirin combination therapy for chronic hepatitis C in patients with congenital coagulation disorders

Chronic hepatitis C (CHC) and end-stage liver disease are becoming an increasingly common cause of mortality in patients with congenital bleeding disorders, especially in the HIV-coinfected group. Combination of pegylated interferon (Peg-IFN) and ribavirin has recently become the treatment of choice for CHC. In this study, we evaluated the safety and efficacy of combination therapy with Peg-IFN plus ribavirin for the treatment of CHC in human immunodeficiency virus (HIV)- and HIV+ patients with congenital bleeding disorders. Between 2000 and 2004, 50 (18-68 years old) patients with CHC (19 HIV+) from two hemophilia centers were included in the study. They were treated with weekly subcutaneous administration of Peg-INF-alpha combined with 800-1,200 mg ribavirin daily, for 24-48 weeks depending on viral genotype. Response was evaluated at weeks 12, 24, 48 (end of treatment response) and 72 had sustained virological response). Overall, 22/50 patients (43.8%) had end of treatment response and 20/50 (40%) sustained virological response. HIV- patients responded similarly to the general population (58.1%), while HIV+ patients had very low response rates (10.5%). The high rate of discontinuation (36.9%) as a result of side effects contributed to the observed low response rate in the HIV+ group. The only factor strongly associated with sustained virological response in the HIV- patients was the reduction of HCV RNA at 12 weeks (p = 0.001). Patients with viral genotypes other than 1 had higher SVR rates, but this was not found to be statistically significant. Peg-INF plus ribavirin is safe for the treatment of CHC monoinfected patients with inherited bleeding disorders, with similar response rates to nonhemophiliacs. On the contrary, in HIV coinfected hemophilic patients under highly active antiretroviral therapy it is associated with severe toxicity and very poor sustained virological response rates. Careful evaluation and several considerations are needed before starting treatment in this population.     

Homocysteine levels and sustained virological response to pegylated‐interferon α2b plus ribavirin therapy for chronic hepatitis C: a prospective study

Background: Chronic hepatitis C affects about 3% of the world's population. Pegylated interferon (IFN) α plus ribavirin is the gold standard treatment. Methylenetetrahydrofolate reductase(MTHFR) is a key enzyme in the metabolism of homocysteine. MTHFR gene polymorphisms and high levels of homocysteine are associated with a high degree of steatosis and fibrosis, conditions associated with a low sustained virological response (SVR) rate. Aims: To evaluate whether MTHFR polymorphisms and homocysteine levels are predictors of the outcome of treatment in 102 prospectively enrolled patients with chronic hepatitis C naive to treatment. Methods: Patients were treated with pegylated interferon α‐2b plus ribavirin. All patients underwent blood tests, assessment of homocysteine, vitamin B₁₂, folate, hepatitis C virus (HCV)‐RNA levels, screening for MTHFR gene polymorphisms and liver ultrasound examination. Results: Homocysteine levels were deranged (>16 μmol/L) in 10.5% of MTHFR wild‐type patients vs 40.3% of non‐wild‐type patients (P=0.015). Homocysteine levels were 14.4 μmol/L in SVR patients and 15.5 μmol/L in non‐SVR patients (P=0.049). The SVR rate was 40.0% in MTHFR wild‐type patients, 52.0% in heterozygote mutants and 39.3% in homozygote mutants (P=0.467). At logistic regression analysis, genotypes 2 and 3 (odds ratio: 12.328, 95% confidence interval: 3.390–44.837, P=0.0001), homocysteine <16 μmol/L (odds ratio: 3.397, 95% confidence interval: 1.033–11.177, P=0.044) and aspartate aminotransferase (AST) levels <48 U/L (odds ratio: 3.262, 95% confidence interval: 1.125–9.458, P=0.029) were independent predictors of SVR. Conclusions: In patients with chronic hepatitis C, homocysteine levels are associated with the outcome of pegylated‐IFNα plus ribavirin treatment, while polymorphisms of MTHFR are not.     

Mutations in the NS5A and E2-PePHD region of hepatitis C virus type 1b and correlation with the response to combination therapy with interferon and ribavirin

Nonstructural 5A (NS5A) and the second envelope (E2) proteins of hepatitis C virus (HCV) have the potential to block interferon (IFN)-induced RNA-dependent protein kinase (PKR) and may therefore interfere with the response to IFN therapy, but controversy still exists regarding the relevance of this. This study aimed to assess whether mutations in these regions correlated with the response to combination therapy, IFN and ribavirin. Pretreatment parameters were analysed in 57 HCV-1b patients who had received IFN-alpha2b (3 or 5 MU three times weekly) and ribavirin (800-1200 mg per day) for 24 weeks. The amino acid sequences of the NS5A and PKR-eIF2alpha phosphorylation homology domain (E2-PePHD) were deduced from the corresponding coding sequence, which were determinated by direct sequencing of the HCV genome amplified by the polymerase chain reaction. Twenty (36%) patients achieved a sustained virological response (SVR). The mean number of amino acid substitutions in the NS5A-PKR binding domain (2209-2274), interferon sensitivity-determining region (ISDR) (2209-2248), and E2-PePHD sequence (659-670) in patients with and without SVR were 4.53 +/- 3.31 vs 2.83 +/- 1.78 (P = 0.094), 2.45 +/- 2.74 vs 1.03 +/- 1.32 (P = 0.042) and 0.25 +/- 0.70 vs 0.03 +/- 0.17 (P = 0.109), respectively. Patients with a mutant-type (>/= 4) NS5A-ISDR had a higher rate of SVR (six of nine, 67%) than those with wild-type (five of 22, 23%) (P = 0.038). Stepwise multiple logistic regression analysis of the factors (age, gender, viral load, cirrhosis rate, IFN dosage and amino acid substitutions) revealed that the mutation in NS5A-ISDR (>/= 4 vs < 4) was the only independent variable of treatment outcome. Our study showed that NS5A-ISDR mutations were correlated with the SVR to combination therapy in chronic HCV-1b patients in Taiwan.