Improving anti-hepatitis C virus therapy

The estimated prevalence of hepatitis C virus (HCV) infection is 2%, representing 123 million infected individuals worldwide. HCV infection burdens public health in relation to hepatic (cirrhosis and its complications in 20% of patients) and extrahepatic (vasculitis) complications, and lessens quality of life. Major progress has been made in the last two decades for the diagnosis and treatment of HCV, including more appropriate screening strategies for HCV infection (improved sensitivity of serological and virological tests); a better evaluation of the impact of chronic HCV infection on the liver (semi-quantitative scoring systems of necro-inflammation and fibrosis on liver biopsy, non-invasive evaluation of fibrosis with biochemical markers and elastometry); and improved therapeutic regimens. This progress provides a better definition of who to treat (clinical impact or significant fibrosis); how to treat; tailoring therapies for doses and durations of the pegylated interferon plus ribavirin combination according to virological (mainly genotype and early viral kinetics, but also baseline viral load) and hosts factors (fibrosis, immune status, weight); and how to monitor efficacy and tolerance of therapy. The progress has now resulted in a 50% rate of complete HCV eradication, ranging 45 – 90% according to the genotype and especially in those patients with early viral response. New therapies, specifically HCV protease or polymerase inhibitors, in combination with pegylated interferon, or more potent and less toxic new formulations of interferons or ribavirin, will increase these encouraging results in the future.     

Retreatment of patients who do not respond to initial therapy for chronic hepatitis C

Despite improvements in the treatment of chronic hepatitis C virus (HCV) infection, nearly half of all patients do not respond to initial therapy. Retreatment of these patients with pegylated interferon and ribavirin has been successful in only a limited percentage of cases. Factors associated with sustained virologic response (SVR) following retreatment include prior treatment with interferon monotherapy, HCV genotype 2 or 3, a low serum HCV RNA level, and the absence of cirrhosis. Fewer than 6% of nonresponders who were previously treated with interferon and ribavirin and who have cirrhosis, genotype 1, and a high viral load achieve SVR following retreatment with pegylated interferon and ribavirin. No therapy has been shown to yield SVR in patients who do not respond to pegylated interferon and ribavirin. Long-term maintenance therapy with pegylated interferon is currently being evaluated in nonresponders with advanced fibrosis and cirrhosis. Its use should be considered investigational at this time.     

Antiviral treatment of hepatitis C: present status and future prospects

Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis. A substantial proportion of patients with chronic hepatitis C eventually develop hepatocellular carcinoma (HCC), which is one of the leading causes of death worldwide. Therefore, efficient antiviral treatments for HCV have long been needed. A recently developed combination therapy of pegylated interferon and ribavirin has dramatically improved the outcome of antiviral therapy for HCV infection. In genotype 1b HCV infection, 48 weeks of the combination therapy achieved eradication of the virus in 50% of patients, and in genotype 2 HCV infection, 24 weeks of the therapy resulted in viral eradication in 80%–90% of patients. By this eradication, an improvement in the hepatic fibrosis, an inhibition of HCC development, and an improvement in life expectancy were attained. Patients who did not respond to the combination therapy may be treated with long-term interferon monotherapy, which is not intended to eradicate HCV, but will lower the serum alanine aminotransferase (ALT) level. Thus, the treatment for HCV infection has progressed significantly, but therapies with new modalities, such as inhibitors of viral protease or RNA polymerase, are still being awaited.     

Early on-treatment viral load and baseline METAVIR score: improved prediction of sustained virological response in HCV genotype 1 patients

BACKGROUND: On-treatment HCV viral load during early therapy with pegylated interferon (PEG-IFN) and ribavirin is highly predictive of sustained virological response (SVR). We sought to provide further refinement of this prediction through an extensive evaluation of the effect of HCV viral loads at weeks 4, 8 and 12 on SVR, including analysis by liver disease stage grouping. METHODS: A total of 309 patients with genotype 1 chronic HCV and recent liver biopsy enrolled in the CHARIOT study received 180 μg of PEG-IFN-α2a weekly with 1,000/1,200 mg of ribavirin daily. The probability of an SVR was estimated using baseline METAVIR fibrosis stage and HCV viral loads at weeks 4, 8 and 12. RESULTS: HCV RNA was undetectable in 27.5%, 50.3% and 62.6% of patients at weeks 4, 8 and 12, respectively. SVR was 80.0%, 76.8% and 72.4% among patients with undetectable HCV RNA at weeks 4, 8 and 12, respectively. SVR decreased in a progressive fashion with increasing HCV viral loads at each early time point, but was similar for patients with HCV viral load <15 IU/ml, 15-100 IU/ml and 100-1,000 IU/ml. The effect of fibrosis stage on SVR was modest for patients with HCV viral load <1,000 IU/ml at week 4, but more marked for those with week 4 HCV viral load >1,000 IU/ml, and all HCV viral load categories at weeks 8 and 12. CONCLUSIONS: A combination of baseline fibrosis stage and on-treatment HCV viral load at early time points provides improved estimates for treatment response in patients with chronic HCV genotype 1.     

Impaired response to interferon-alpha2b plus ribavirin in cirrhotic patients with genotype 3a hepatitis C virus infection

Patients with chronic infection with the 3a genotype of hepatitis C virus (HCV) are considered as 'easy-to-treat' with interferon/ribavirin (IFN/RBV), independent of liver disease severity. However, patients with extensive fibrosis or cirrhosis were under-represented in all the registration Phase III trials performed so far. To assess the influence of liver fibrosis on the outcome of anti-HCV therapy, all patients with genotype 3a hepatitis C who were naive to IFN-based therapies, and received RBV combined with standard IFN or pegylated IFN-(alpha2b (peg-IFN-alpha2b) as standard of care for their disease, were investigated at our centre. A sustained virological response (SVR) was achieved in 68 of 91 patients (75%) independent of IFN type, pretreatment viraemia, clearance of HCV RNA at week 4 and relevant co-morbidities. A SVR was less common in cirrhotics (6 of 17) than in non-cirrhotics (62 of 74; 35% vs 84%; P<0.0005). Compared to non-cirrhotics, the age and sex adjusted odds ratio (OR) of treatment failure for cirrhotics was 10.1 (95% confidence interval: 2.4-41.7). By multivariate analysis, cirrhosis was the only predictor of non-SVR. In conclusion, cirrhosis is an independent predictor of IFN/RBV treatment failure in patients chronically infected with HCV 3a and is associated with an increased risk of post-treatment hepatitis relapse. Evaluation of liver fibrosis is important in the management of patients with genotype 3a hepatitis C, since it helps to predict response to IFN/RBV therapy.     

Serine protease inhibitors as anti-hepatitis C virus agents

Approximately 3% of the worldwide population (i.e., more than 170 million people) are chronically infected with the hepatitis C virus (HCV). An estimated 20% of these patients will develop liver cirrhosis within a mean of 20 years, and 2–5% of cirrhotic patients will die of end-stage liver disease or hepatocellular carcinoma. The currently approved antiviral therapy with pegylated interferon (pegIFN) and ribavirin induces a sustained virological response (SVR) in 40–50% of patients infected with genotype 1, the most prevalent HCV type. In this review, we focus on the development and clinical application of serine protease inhibitors as anti-HCV agents. Although highly active in inducing a significant decline of serum HCV RNA, the rapid development of resistance must be counteracted in combination with other antiviral agents, currently pegIFN-α and ribavirin. Two serine protease inhibitors have reached clinical Phase III trials, increasing SVR rates and shortening treatment duration when combined with pegIFN and ribavirin. Trials of interferon-free targeted combination therapies are currently underway.     

Hepatitis C

Hepatitis C virus (HCV) infection is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. Here, we briefly review the virology, diagnosis and therapy of hepatitis C. Standard therapy with pegylated interferon-alpha and ribavirin results in a sustained virological response in 40-50% of genotype 1- and in about 80% of genotype 2- or 3-infected patients. Recent progress has allowed the identification of novel antiviral targets and therapeutic strategies. These will likely complement existing therapeutic modalities in the near future.     

Chronic hepatitis C in patients with HIV/AIDS: a new challenge in antiviral therapy

HIV-infected patients are living longer since the introduction of highly active antiretroviral therapy. However, coinfection with the hepatitis C virus (HCV) leads to increased morbidity from liver disease and higher overall mortality. The prevalence of chronic hepatitis C among patients with HIV/AIDS ranges from 7% (sexual transmission of HIV) to >90% (injection drug use). Uncontrolled HIV infection seems to accelerate the progression of HCV-induced liver fibrosis. Forty-eight weeks of combination therapy with pegylated interferon alpha (2a or 2b) plus ribavirin achieves a sustained viral response in coinfected individuals in up to 38% with HCV genotype 1 and up to 73% with genotypes 2 or 3. The safety profile of this treatment is similar to therapy in HCV-monoinfected patients with influenza-like symptoms, cytopenia and neuropsychiatric symptoms dominating. However, HIV/HCV-coinfected patients who also take zidovudine develop more profound anaemia than those on other HIV nucleoside analogue therapy. Didanosine and stavudine are associated with rare but serious mitochondrial toxicity, such as pancreatitis or lactic acidosis. It does not appear that the addition of ribavirin increases that risk. There is currently no evidence that in HIV/HCV coinfection one pegylated interferon product is superior to the other. Contrary to common perception, it is also unproven that HIV/HCV-coinfected patients respond less well to therapy with peginterferon alpha plus ribavirin than HCV-monoinfected patients. Given the safety and efficacy of combination therapy with peginterferon plus ribavirin and the deleterious effects of chronic hepatitis C, all HIV/HCV-coinfected patients should be evaluated for therapy.     

Lack of rapid virological response predicts interferon-alpha2b/ribavirin therapy failure in HCV genotype 2 patients: a single-centre study

BACKGROUND: A minority of patients with HCV-2 chronic hepatitis does not attain a sustained virological response to interferon-based therapies. Registration trials have failed to identify the real proportion of HCV-2 non-responders, and predictors of non-response. The analysis of 'real-life' HCV-2 patients might help define the effectiveness of anti-HCV therapy and the role of response moderators. METHODS: A re-analysis of all treatment-naive HCV-2 patients who consecutively received weight-dosed ribavirin with either 3 MU three times a week standard interferon-alpha2b or 1.5 microg/kg/week pegylated interferon-alpha2b. RESULTS: The 94 interferon-treated patients and the 136 pegylated-interferon-treated patients were comparable for demography, prevalence of cirrhosis (25%) and adherence to therapy (74%). By intention-to-treat analysis, the overall sustained virological response rate was 80% (82% interferon versus 78% pegylated interferon). Overall, sustained virological rates were 83% for the 182 patients who cleared HCV RNA at week 4 (rapid virological response) and 52% for the 48 who did not (P < 0.001). The corresponding week 12 figures of HCV RNA clearance were 90% and 32%, respectively (P < 0.001). Sustained response was independent of gender, age, body mass index, modality of infection, duration and severity of liver disease, adherence to therapy and interferon type. After stratification for interferon type, the only treatment failure predictor was persistence of HCV RNA at week 4 and 12. CONCLUSIONS: Despite the prevalence of moderators of treatment outcome, HCV-2 patients showed as high sustained virological response rates as those reported in registration trials for HCV-2 and HCV-3 pooled patients; pegylated interferon therapy failure was predicted by lack of rapid virological response.     

Practical Management of Boceprevir and Immunosuppressive Therapy in Liver Transplant Recipients with Hepatitis C Virus Recurrence

Hepatitis C virus (HCV) recurrence is the most important complication in HCV liver transplant patients. Boceprevir with pegylated interferon and ribavirin (PegIFN/RBV) enabled improvement in sustained virological response rates of patients with genotype 1 HCV. Boceprevir interacts with immunosuppressive therapy (IT) by inhibiting the cytochrome P450 3A enzyme. Our aim was to study interactions and assess the safety of boceprevir in the context of HCV recurrence. Boceprevir (800 mg three times a day) initiated after a 4-week lead-in phase was associated with cyclosporine (three patients), tacrolimus (two patients), and everolimus (one patient) in five liver transplant patients with genotype 1 HCV infection who experienced HCV recurrence. The mean follow-up period after HCV therapy was 14.8 ± 3.1 weeks. Estimated oral clearances of IT decreased on average by 50%, requiring reduced dosing regimens. Anemia occurred in all patients, with a mean fall in hemoglobin levels between baseline and week 12 of 3.12 ± 2.27 g/dl. All patients required administration of β-erythropoietin (n = 5), three needed ribavirin dose reduction, and one needed a blood transfusion. A virological response was observed in all patients (mean HCV viral load [HVL] decrease at week 12, 6.64 ± 0.35 log₁₀ IU/ml). These preliminary results in liver transplant patients with HCV recurrence demonstrate the feasibility and safety of coadministration of boceprevir and IT.     

Simultaneous occurrence of pleural effusion and interstitial pneumonitis after treatment with pegylated interferon for hepatitis C virus infection

Combination of pegylated interferon and ribavirin has been the standard program for hepatitis C virus (HCV) infection. Pulmonary complications, although uncommon, have been reported in association with the use of interferon, and pleural effusion is rare. We report the second case of pleural effusion and interstitial pneumonitis in a patient treated with pegylated interferon and ribavirin for chronic HCV infection. The respiratory symptoms of our patient continued to progress even though the treatment with pegylated interferon had been withdrawn, but the symptoms improved dramatically following treatment with steroids.     

Response to combined interferon and ribavirin is better in patients infected with hepatitis C virus genotype 6 than genotype 1 in Hong Kong

Data on the treatment efficacy of interferon (IFN)-alpha and ribavirin in patients with chronic hepatitis infected with hepatitis C virus (HCV) of genotype 6 are lacking. A study has been reported from Hong Kong which compared the treatment efficacy of IFN-alpha and ribavirin in the treatment of chronic HCV infection with genotypes 1 and 6. Twenty-four patients with HCV genotype 1 and 16 patients with HCV genotype 6 were studied. The baseline demographic data including median age, gender ratio, alanine aminotransferase levels, bilirubin levels, HCV RNA levels and histological scores were comparable between the two groups of patients. All patients received IFN-alpha 5 million units three times per week and ribavirin (1,000 mg for those weighing 75 kg) for 1 year. Patients infected with HCV genotype 6 achieved virological response significantly higher than those with HCV genotype 1 (67 vs. 33% at week 24, p = 0.02; 75 vs. 42% at the end of treatment, p = 0.05; 63 vs. 29% at 6 months after completion of treatment, p = 0.04). Histological improvement in inflammatory activity and fibrosis in the liver were observed in 25% and 25% of patients infected with HCV genotype 6 in contrast to only 13 and 8% in patients infected with HCV genotype 1; however, the differences were not statistically significant. In conclusion, patients with HCV genotype 6 gain a better response to combined treatment with IFN-alpha and ribavirin than those with HCV genotype 1 and achieve a significantly higher rate of sustained virological response.     

Role of viral kinetics under HCV therapy in HIV/HCV-coinfected patients

Patients coinfected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) are less responsive to anti-HCV therapies and are at a higher risk of toxicity than HCV monoinfected patients. HCV viral kinetics is the basis for the study of response to interferon-based therapy and for predicting sustained virological response (SVR). A lack of early virological response (EVR; undetectable HCV RNA or a decrease of >/=2 log(10) from baseline) after 12 weeks of pegylated interferon (peg-IFN) plus ribavirin (RBV) is an equally reliable predictor of lack of SVR in HIV/HCV-coinfected patients and in the monoinfected HCV population. Early stopping rules are particularly important in coinfected HIV/HCV patients, considering their low chances of response in the more difficult-to-treat HCV genotypes 1 and 4 (<30%). Several factors have been involved in this low efficacy, including higher baseline HCV viraemia, slower viral kinetics decay under interferon pressure and a defective immune substratum. A better understanding of HCV viral kinetics under HCV therapy may be the basis for assaying different peg-IFN plus RBV schedules, such as induction or extending strategies, and may help physicians to make tailored decisions for the management of their patients.     

Boceprevir: an oral protease inhibitor for the treatment of chronic HCV infection

Chronic hepatitis C (CHC) virus infection affects more than 170 million people globally. The aim of treatment of CHC is to affect sustained elimination of the virus (a sustained virological response [SVR]). The success and duration of therapy with interferon is dependent on HCV genotype. The current standard of care comprises combined treatment with pegylated interferon and ribavirin. Rates of SVR in patients with genotype 1 infection, the least responsive group, are less than 50%. Boceprevir is a ketoamide protease inhibitor that binds reversibly to the HCV nonstructural NS3 protease active site inhibiting intracellular viral replication. Phase III clinical studies have demonstrated that, in combination with the current standard of care, boceprevir significantly increases the SVR rate in both treatment-naive and previously treated patients with genotype 1 CHC. Both the US FDA and EMA have approved boceprevir for the treatment of genotype 1 CHC: the first directly-acting antiviral drug to be licensed for this indication. This article will review the pharmacology and pharmacodynamics of boceprevir, the efficacy and safety of the drug, and explore possible future developments in the management of CHC.     

Prediction of sustained virological response by ribavirin plasma concentration at week 4 of therapy in hepatitis C virus genotype 1 patients

BACKGROUND: Pegylated interferon/ribavirin combination is currently the standard treatment for chronic hepatitis C virus (HCV) infection. Body weight adjustment of ribavirin is crucial for response. However, previous studies found no relation between ingested dose and plasma concentration. The aim of this study was to define the ribavirin trough plasma concentration at week 4 (W4) associated with sustained virological response (SVR). METHODS: Thirty-one HCV genotype 1 patients (8 naive and 23 non-responders to a previous pegylated interferon/ribavirin therapy) were treated with pegylated interferon/ribavirin and assessed by HPLC for ribavirin plasma concentration at W4. RESULTS: Eleven patients (35%) achieved SVR, whereas 20 (65%) were non-responders. The median ribavirin plasma concentration at W4 (1.90 mg/l) varied from 1.62 mg/l in patients with subsequent non-response to 2.28 mg/l in sustained responders (P=0.007). Receiver operating characteristic curve analysis indicated that the 2.01 mg/l threshold gave the best sensitivity and specificity (73% and 80%, respectively, area under the curve =0.80; P=0.007). Sixty-seven percent of patients with median ribavirin plasma concentration >2 mg/l achieved SVR versus only 16% below this level (P=0.007). Multivariate regression analysis indicated that a ribavirin plasma concentration >2 mg/l at W4 was associated with SVR independent of gender, age, weight, baseline viral load and response to previous therapy. CONCLUSION: These results, which remain to be confirmed in large clinical trials, highlight the potential relevance of ribavirin plasma level monitoring at an early stage of treatment. This monitoring could be of help in guiding antiviral therapy by offering dose adjustment in patients with ribavirin plasma level below the 2 mg/l threshold.     

Treatment options for nonresponders and relapsers to initial therapy for hepatitis C

As treatment for chronic hepatitis C virus (HCV) infection has advanced over the past decade, efforts have evolved to retreat patients who did not achieve a sustained virologic response to previous antiviral regimens. Retreating nonresponders to interferon alfa monotherapy with a combination of interferon and ribavirin yields a sustained virologic response in 9% to 32% of patients, whereas retreatment with peginterferon alfa plus ribavirin yields a sustained virologic response in up to 30% to 40% of patients. Sustained virologic response is more likely in retreated patients with HCV genotype 2 or 3, low serum HCV RNA levels, and lack of response to prior interferon monotherapy. Retreatment of nonresponders to interferon-ribavirin combination therapy is associated with lower response rates (< or = 20%). Despite treatment advances, the efficacy of current antiviral regimens for nonresponders remains inadequate. The next few years will see more-targeted antiviral regimens for these patients and therapies focused on slowing the progression of liver disease rather than viral eradication.     

Pegylated interferon-alpha2b plus ribavirin: an efficacious and well-tolerated treatment regimen for patients with hepatitis C virus related histologically proven cirrhosis

BACKGROUND: Little is known about the efficacy, safety and tolerability of pegylated interferon plus ribavirin treatment in patients with chronic hepatitis Cvirus (HCV) infection and histologically proven fully established cirrhosis. We aimed here to evaluate the safety of this regimen in such patients and to identify baseline and on-treatment predictors of a sustained virological response (SVR). METHODS: Patients with histologically proven, HCV-induced cirrhosis were randomized to receive pegylated interferon-alpha2b (PEG-IFN-alpha2b; 1.0 microg/kg/week, n=56; group A) or recombinant interferon-alpha2b (IFN-alpha2b; 3 million IU three times/week, n=36; group B), each in combination with a weight-based dose of ribavirin (800-1,200 mg/day) for up to 48 weeks. The primary endpoint of the study was the assessment of SVR, defined as undetectable HCV RNA 24 weeks after treatment cessation. RESULTS: Overall, 40% (37/93) of patients attained SVR: 44% (25/57) in group A and 33% (12/36) in group B (P=0.31). SVR rates were significantly higher in genotype 2/3 patients than in genotype 1 patients (69% versus 25%; P<0.0001). Platelet count at baseline, rapid virological response, and early virological response were predictors of SVR. Twelve patients discontinued treatment because of an adverse event and 20 patients required ribavirin dose reduction for the management of anaemia. CONCLUSIONS: PEG-IFN-alpha2b plus ribavirin for 48 weeks is an efficacious and well-tolerated treatment regimen for patients with HCV-induced cirrhosis. Although SVR rates were more satisfactory in genotype 2/3 than in genotype 1 patients, our study identified additional predictors of response that could allow physicians to better manage treatment in this 'difficult-to-cure' subset of patients.     

Long-term follow-up of HIV-infected patients with chronic hepatitis C virus infection treated with interferon-based therapies

BACKGROUND: Chronic hepatitis C virus (HCV) infection is frequent among HIV-infected patients. Clearance of serum HCV RNA 6 months after discontinuing HCV therapy is generally interpreted as a cure of HCV infection in HIV-negative subjects. However, the occurrence of liver complications (including hepatocellular carcinoma) and/or HCV relapses in coinfected patients when followed for long periods of time after HCV therapy is not well known. METHODS: All HIV-infected patients who had been treated for chronic hepatitis C at our institution and had a minimum follow-up of 6 months after discontinuing therapy were retrospectively analysed. They had received one of three HCV treatment modalities: IFN monotherapy, IFN plus ribavirin (RBV) or pegylated interferon (PEG-IFN) plus RBV. RESULTS: A total of 351 patients were retrospectively analysed. Sustained virological response (SVR) to HCV therapy had been reached by 77 (22%) of them: 22/119 (18.5%) with IFN monotherapy, 17/106 (16%) with IFN plus RBV and 38/126 (30.2%) with PEG-IFN plus RBV. Considering the HCV genotypes, SVR had been reached by 19/184 (10.3%) of patients with genotype 1, 54/138 (39.1%) with genotypes 2 or 3, and 4/29 (13.8%) of those with genotype 4. Within a total of 4466 patient-months follow-up (mean of 58 months), none of the 77 patients with SVR showed HCV-RNA rebounds, elevations in liver enzymes potentially linked to HCV, development of hepatocellular carcinoma or episodes of decompensated cirrhosis. In contrast, all 274 patients who did not reach SVR with HCV therapy showed evidence of persistent serum HCV RNA and 90% of them showed liver enzyme elevations during a total of 15344 patient-months follow-up (mean of 56 months). Moreover, 11 (4%) developed clinical complications of liver cirrhosis and two of them died of end-stage liver disease. CONCLUSIONS: HCV replication and HCV-related liver disease seem to be permanently halted in HIV/HCV-coinfected patients showing HCV-RNA clearance 6 months after completing any kind of IFN-based therapy. In contrast, complications of liver disease due to persistent HCV infection continue to occur in non-responders. The role of maintenance HCV therapy should be explored in HIV/HCV-coinfected patients.     

Initial treatment for chronic hepatitis C: current therapies and their optimal dosing and duration

The main treatment goal in patients with chronic hepatitis C virus (HCV) infection is the prevention of progressive hepatic fibrosis by eradicating serum and intrahepatic virus. The current standard of care in previously untreated patients with chronic hepatitis C is combination therapy with pegylated interferon alfa and ribavirin. The duration of therapy and the dose of ribavirin should be determined according to the patient's HCV genotype. Adherence to the full dose of therapy for the prescribed treatment duration enhances the likelihood of sustained virologic response. Early virologic response is a good predictor of eventual sustained response for patients with HCV genotype 1 infection. Despite important gains in treating chronic hepatitis C, many treatment challenges remain.     

Chronic hepatitis C virus management: 2000-2005 update

OBJECTIVE: To review recent advances that have significantly changed the management of chronic hepatitis C virus (HCV) infection. DATA SOURCES: A MEDLINE search (2000-July 2005) was conducted using key words such as hepatitis C, interferon, pegylated interferon, and therapy. STUDY SELECTION AND DATA EXTRACTION: All articles pertaining to treatment of chronic HCV infection were identified. Studies evaluating HCV treatment in treatment-naive patients were considered for this review. DATA SYNTHESIS: Over the past several years, response to treatment for chronic HCV infection has significantly improved with the use of pegylated interferon and ribavirin therapy. Treatment response is influenced by HCV genotype and viral load, as well as patient-related factors, including adherence. CONCLUSIONS: Treatment of chronic HCV infection has improved, with overall response rates of approximately 55%. Identification and management of common adverse effects is important in maximizing adherence and response to therapy. Studies are needed to further delineate the optimum treatment of chronic HCV infection in specific patient populations.