Pegylated interferons for the treatment of chronic hepatitis C infection

BACKGROUND: Interferon (IFN) alfa is a clinically effective therapy used in a wide range of viral infections and cell-proliferative disorders. Combination therapy with IFN alfa-2b and ribavirin is the current standard of care for the treatment of chronic hepatitis C (CHC) infection. However, standard IFN alfa has the drawbacks of a short serum half-life and rapid clearance. To overcome this problem, 2 pegylated forms of IFN have been developed and tested clinically. OBJECTIVE: This article reviews the development and properties of pegylated IFN alfa-2b and pegylated IFN alfa-2a, and presents safety and efficacy data from recent clinical trials. METHODS: Relevant clinical studies were identified through a MEDLINE search from 1966 through the present using the key words hepatitis C and interferon. Studies of the pegylated IFNs in humans were then selected. RESULTS: Pegylated IFN alfa-2b is formed by covalent conjugation of a 12-kd mono-methoxy polyethylene glycol (PEG) molecule to IFN alfa-2b, and pegylated IFN alfa-2a by covalent conjugation of a 40-kd branched mono-methoxy PEG molecule to IFN alfa-2a. The 2 pegylated IFNs differ in the mixture of pegylation isomers resulting from their conjugation chemistry. Pegylated IFN alfa-2b has a prolonged serum half-life (40 hours) relative to standard IFN alfa-2b (7-9 hours). The greater polymer size of pegylated IFN alfa-2a acts to reduce glomerular filtration, markedly prolonging its serum half-life (72-96 hours) compared with standard IFN alfa-2a (6-9 hours). In clinical studies, once-weekly dosing of the pegylated IFNs was associated with a sustained virologic response in patients infected with hepatitis C virus (HCV). Once-weekly dosing with either of the pegylated IFNs was more effective than the respective thrice-weekly regimen of IFN alfa, with a comparable safety profile. The combination of once-weekly pegylated IFN and ribavirin effectively reduced HCV viral load and sustained viral suppression. CONCLUSIONS: Once-weekly dosing with either pegylated IFN alfa-2b or pegylated IFN alfa-2a has been shown to produce significantly higher rates of viral eradication than standard thrice-weekly IFN alfa therapy without compromising safety. With respect to the treatment of CHC, the greatest anti-HCV efficacy has been achieved with the combination of once-weekly pegylated IFN and ribavirin.     

Genotype does not affect pattern of HCV RNA decrease among responders during interferon treatment of chronic hepatitis C. Consensus Interferon Study Group

We assessed differences in the pattern of HCV RNA decrease for HCV genotypes 1, 2, and 3 during interferon treatment to determine if the lower response rates observed among genotype 1 patients were related to a slower decrease in HCV clearance. Serum HCV RNA values of 472 chronic hepatitis C patients treated with either consensus interferon (CIFN) or interferon alfa-2b (IFN alfa-2b) were evaluated. Neither virological sustained responders nor relapsers differed in the pattern of serum HCV RNA decrease based on genotype. Virological sustained responders infected with genotype 1 cleared HCV RNA as rapidly as sustained responders who were infected with genotype 2 or 3. Relapsers had a slower rate of serum HCV RNA decrease than did virological sustained responders. Nonresponders differed in the pattern of serum HCV RNA decrease based on genotype: HCV genotype 3 patients had the greatest decrease in serum HCV RNA; genotype 2 patients had an intermediate decrease; and genotype 1 patients had the least serum HCV RNA decrease. HCV genotype 1 patients treated with CIFN had a greater decrease in serum HCV RNA during therapy than did patients treated with IFN alfa-2b. However, there was no difference in the magnitude of serum HCV RNA decrease between the two interferon treatments for patients infected with genotype 2 or 3. In summary, both genotype and ultimate response to treatment are determinants of the pattern and rate of serum HCV RNA change during interferon therapy of chronic hepatitis C.     

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.     

Utility of hepatitis C virus serotypes in predicting response to treatment of chronic hepatitis C. Consensus Interferon Study Group

Hepatitis C virus (HCV) genotyping has been shown to predict response to interferon, but is expensive. HCV serotyping is less expensive and simpler, and may be similarly useful. Using data from a large, randomized trial comparing consensus interferon (CIFN) and interferon alfa-2b (IFN alfa-2b) in patients with chronic HCV, we evaluated response rates based on HCV serotypes versus genotypes. Patients included in this analysis received subcutaneous injection of 9 microg CIFN (n = 232) or 3 MU IFN alfa-2b (n = 240) three times weekly for 24 weeks followed by 24 weeks of observation. Serum HCV RNA concentrations were measured regularly during treatment and at the end of both the treatment and post-treatment periods. Response to interferon was similar for HCV antibody types and their corresponding genotypes. The end-of-treatment HCV RNA rate of response (defined as undetectable serum on two consecutive assessments) was 29% for serotype 1 versus 24% for genotype 1 after CIFN; and 14% versus 15%, respectively, after IFN alfa-2b. Independently of treatment, patients infected with serotype or genotype 2 or 3 had a better therapeutic response than those infected with serotype or genotype 1. Similar results were obtained based on HCV antibody typing and genotyping, suggesting the potential of the former for predicting response to interferon.     

Viral interaction and responses in chronic hepatitis C and B coinfected patients with interferon-alpha plus ribavirin combination therapy

BACKGROUND/AIMS: We conducted a case-control study to investigate the efficacy of interferon-alpha (IFN-alpha) and ribavirin combination therapy for patients with chronic hepatitis C and B virus (HCV/HBV) coinfection and to elucidate the interaction of these two viruses. METHODS: Forty-two chronic HCV/HBV-coinfected patients (29 IFN-naive, 13 IFN-relapsed) and 84 HCV-monoinfected controls, matched for age, sex and previous history of IFN-alpha therapy, were enrolled. All patients were treated with IFN-alpha-2b 6 MU three-times weekly plus ribavirin 1000-1200 mg daily for 24 weeks. Serum HCV RNA and HBV DNA were determined every 24 weeks for 72 weeks. RESULTS: The rate of HCV sustained virological response (SVR) was comparable among IFN-naive and IFN-relapsed HCV/HBV-coinfected patients and IFN-naive and IFN-relapsed HCV-monoinfected patients (69.0%, 69.2%, 67.2% and 57.7%, respectively; intention-to-treat analysis). HCV genotype 1b, high pretreatment HCV RNA levels and liver fibrosis were significantly associated with a lower HCV SVR. Of 16 baseline HBV viraemic patients, five (31.3%) achieved HBV SVR, which correlated negatively to HCV genotype non-1b and HCV SVR. Only one (6.3%) had simultaneous seroclearance of HCV and HBV. Antibodies to HBV surface antigen seroconversion developed in five (11.9%) patients during long-term follow-up. HCV responders had significantly higher rates of HBV DNA resurgence than HCV non-responders during and after treatment. Reciprocal viral interference was noted between HCV and HBV after IFN-alpha/ribavirin therapy. CONCLUSIONS: IFN-alpha/ribavirin combination therapy is effective for HCV/HBV-coinfected patients in eradicating HCV infection and might promote HBV seroclearance, and there is a mutual viral response and reciprocal viral interaction between HBV and HCV.     

2'-,5'-Oligoadenylate synthetase response ratio predicting virological response to PEG-interferon-alpha2b plus ribavirin therapy in patients with chronic hepatitis C

OBJECTIVE: Although all the mechanisms of elimination of hepatitis C virus (HCV) by Interferon (IFN) have not been fully elucidated, the 2'-5'-oligoadenylate (2-5A) system is one of the mechanisms of the antiviral effect of IFN. Consequently, the measurement of 2'-5'-oligoadenylate synthetase (2-5AS) activity could be useful for the evaluation of IFN treatment. This retrospective study was aimed at assessing whether 2-5AS activity functions as a clinical marker of virological response to PEG-interferon-alpha2b (PEG-IFN) plus ribavirin therapy of chronic hepatitis C. METHODS: The 32 patients included in this study had high viral loads of serum HCV-RNA of genotype 1b with chronic hepatitis C. All the patients received a regimen of PEG-IFN plus ribavirin for 48 weeks, and were then divided into two groups: one group (effective group) with undetectable serum HCV-RNA levels at 24 weeks (n = 22) of therapy, the other group (ineffective group) with persistent presence of HCV-RNA in serum at 24 weeks (n = 10). The 2-5AS activity in serum was measured 2, 8 and 12 weeks before initial administration. RESULTS: The 2-5AS response ratio (measured value/measured value of baseline 2-5AS) at 2, 8 and 12 weeks after the administration in the effective group was significantly higher than that in the ineffective group. CONCLUSIONS: These results suggest that the ratio of 2-5AS is closely related to the antiviral effect, and that the measurement of 2-5AS response ratio may be a useful clinical parameter of virological response to PEG-IFN plus ribavirin therapy of chronic hepatitis C.     

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.     

Peginterferon alfa-2a: a review of approved and investigational uses

BACKGROUND: In October 2002, the US Food and Drug Administration approved peginterferon alfa-2a for the management of chronic hepatitis C virus (HCV) infection. The addition of polyethylene glycol (PEG) moiety to the interferon (IFN) molecule results in a product with altered pharmacokinetic properties. OBJECTIVE: The aim of this article is to review the pharmacology, medications interactions, adverse events (AEs), and approved or investigational uses of PEG-IFN alfa-2a for viral hepatitis and oncologic conditions. METHODS: Relevant articles were identified through searches of MEDLINE (1980-July 2003) and EMBASE (1980-July 2003). Search terms included, but were not limited to, peginterferon alfa-2a, pharmacokinetics, pharmacology, pharmacodynamics, and therapeutic use, as well as terms for specific disease states and AEs. Further publications were identified from citations of resulting papers. RESULTS: Pegylation of IFN alfa-2a results in major changes in the pharmacokinetics of the product. Absorption is prolonged and serum concentrations are sustained over the dosing regimen. PEG-IFN alfa-2a has been shown to be more effective with or without ribavirin (RBV), in the management of treatment-naive patients with chronic HCV infection, than unmodified IFN alfa-2a with or without RBV. Results in other disease states are still preliminary. AEs are similar, in incidence and severity, to those occurring with unmodified IFN. They include earlier hematologic symptoms and fewer influenza-like symptoms. Drug-drug interactions are the same as those occurring with the unmodified IFN product. CONCLUSIONS: The pharmacokinetic profile of IFN alfa-2a is improved by pegylation, which enables less frequent administration and results in improved efficacy with a similar side-effect profile. Combination of PEG-IFN alfa-2a with RBV is associated with a greater chance of achieving a sustained virologic response in treatment-naive patients with chronic HCV, compared with unmodified IFN alfa-2a/RBV combinations. Documentation of efficacy in other conditions awaits results of controlled clinical trials.     

Therapy for treatment-refractory chronic hepatitis C virus genotype 1b infection: A retrospective analysis

Background:

The most effective current therapy for hepatitis C virus (HCV) infection is the combination of pegylated interferon (peg-IFN) plus ribavirin (RBV).

Objective:

The aim of this retrospective analysis was to determine the rateof response to this therapy, and the factors affecting outcome, in patients with treatment-refractory chronic HCV genotype l b.

Methods:

The records of patients with chronic HCV infection and HCV geno-type1b who failed (nonresponse or relapse) previous treatment with standard interferon (IFN) + RSV were retrospectively analyzed for demographic data, virologic load, liver histology, biochemistry, treatment-related adverse effects (AEs), and the effects of dose reduction during treatment with peg-IFN + RBV for 48 weeks. Early virologic response (EVR) was defined as ≥2-log (copies/mL) decrease from baseline in serum HCV RNA concentration or the absence of detectable serum HCV RNA at treatment week 12. End-of-treatment response (ETR) was defined as the absence of detectable serum HCV RNA at treatment week 48. Sustained virologic response (SVR) was defined as the absence of detectable serum HCV RNA 24 weeks after treatment was discontinued. Factors affecting treatment outcome were determined using correlation analyses.

Results:

Data from the files of 17 patients (12 men, 5 women; mean [SD] age, 48 [2] years) were analyzed. EVR was achieved in 7 patients; however, viral breakthrough occurred in 2 of these patients during the treatment period, and 5 of these patients discontinued treatment because of severe treatment-related AEs (depression [1 patient] and neutropenia [4]). Seven patients achieved ETR, but HCV infection relapsed during the follow-up period. Three (18%) patients achieved SVR. Data concerning previous patterns of response to IFN + RBV therapy were available in 10 patients. Of these, 3 of 6 patients who had experienced relapse with the previous treatment achieved SVR with peg-IFN + RBV; neither of the 2 patients with nonresponse to the previous treatment achieved SVR. Major determinants of failure to reach SVR in these patients included previous nonresponder pattern, noncompliance with the therapy, and advanced-stage liver fibrosis. Tolerability was similar to that with the previous treatment.

Conclusions:

In this study in patients with chronic HCV genotype lb infectionand a history of relapse or nonresponse to standard IFN + RSV treatment, treatment with peg-IFN + RBV achieved an SVR rate of 18%. Further research is needed to determine the role of peg-IFN + RBV in the re-treatment of HCV infection.     

Treatment of chronic hepatitis C in southern Taiwan

Chronic hepatitis C virus (HCV) infection may lead to cirrhosis and hepatocellular carcinoma. Interferon (IFN)-alpha is effective in the treatment of chronic hepatitis C. The rate of response to IFN is enhanced by increasing the IFN dose. Extending the treatment duration can reduce the relapse rate. Addition of ribavirin to IFN increases the sustained virological response (SVR). Thus, combination therapy with IFN and ribavirin was adopted for the treatment of chronic hepatitis C in Kaohsiung Medical University Hospital in 1998. Approximately 60% of patients receiving IFN/ribavirin therapy gained SVR. IFN 6 million units three times per week combined with daily ribavirin for 6 months achieved SVR more frequently than combination therapy with 3 million units. Factors for SVR in these combination regimens were HCV genotype, viral load and early virological response. Long-term follow-up of patients treated with IFN has shown that SVR might reduce the risk of progression to cirrhosis and hepatocellular carcinoma. Pegylated (peg)-IFN has a longer half-life and better efficacy. Combination therapy with peg-IFN and ribavirin accomplished higher SVR than conventional IFN and ribavirin. A multicenter clinical trial was conducted in Taiwan to compare the efficacy of combination therapy between peg-IFN/ribavirin and conventional IFN/ribavirin for 6 months. SVR was higher in patients receiving peg-IFN and ribavirin, especially in those infected with HCV genotype 1b. Based on the results obtained, the national health insurance started to sponsor the combination therapy in October 2003, with a suggested duration for 6 months. Some small-scale studies in Taiwan have postulated higher SVR for treatment duration of 12 than of 6 months in patients with genotype 1b. Further investigation should be conducted in the near future.     

Efficacy and Tolerability of Combination Therapy with Interferon-Alfa Plus Ribavirin in Patients with Chronic Hepatitis C Virus Infection: A Single-Center Study in Relapsers and Nonresponders to Previous Treatment with High-Dose Interferon-Alfa Monotherapy

Background: In chronic hepatitis C virus (HCV) infection, interferon (IFN) monotherapy usually is carried out at doses of 3 to 6 million units (MU) 3 times per week, but treatment efficacy is low.Objective: The aim of our study was to assess the efficacy and tolerability of IFN-alfa_2b in combination with ribavirin in relapsers and nonresponders to high-dose IFN treatment (5 to 6 MU 3 times per week). We measured the biochemical and virologic responses to treatment and the risk for relapse during the 24 weeks following the end of treatment.Methods: Patients with chronic HCV infection (relapsers and nonresponders to a previous treatment with high-dose IFN) received IFN-alfa_2b, 3 MU 3 times per week, and ribavirin, 1000 or 1200 mg/d for 24 or 48 weeks. The patients were then followed up for an additional 24 weeks. Sustained response was defined as normal serum alanine aminotransferase (ALT) level and undetectable HCV RNA 24 weeks after treatment was stopped.Results: Forty-three patients (32 men, 11 women; mean [SD] age, 45 [2] years; 10 relapsers, 33 nonresponders) were included in the study. Four patients were withdrawn from the study at week 4 of treatment because of treatment-related adverse events, and 1 dropped out. At the end of the treatment period, normalization of serum ALT levels and undetectable HCV RNA levels were seen in 58.1% and 30.2% of patients, respectively. No significant difference in virologic response at the end of treatment was found between nonresponders (10/33 [30.3%]) to previous IFN therapy and relapsers (3/10 [30.0%]). At the end of follow-up, 3 (7.0%) treated patients had sustained response (2 nonresponders to the first IFN course and 1 relapser). All of the patients with sustained response were treated for 24 weeks.Conclusion: Based on the results of our study, combination therapy with IFN-alfa and ribavirin may be of value in a limited number of patients with chronic HCV infection who do not respond to, or relapse after, a first course of treatment with high-dose IFN monotherapy.     

HCV-HBV infection

Chronic infection of hepatitis C (HCV) and B virus (HBV) frequently causes viral hepatitis. Patients with chronic viral hepatitis are at risk for liver cirrhosis and even hepatocellular carcinoma. In patients with chronic hepatitis C, the most effective therapy is elimination of HCV with interferon (IFN). The most effective initial IFN therapy is the combination of pegylated IFN alpha-2b plus ribavirin. Forty-eight weeks of this combination therapy produces sustained viral response rates of approximately 50%. Moreover, several reports showed that long-term IFN therapy also reduced the risk of liver carcinogenesis. In patients with chronic hepatitis B, seroconversion from HBeAg to anti-HBe antibodies suppresses viral replication and attenuates the hepatitis. Twenty-four weeks of IFN therapy produces HBeAg seroconversion rates approximately 30%.     

Sustained suppression of hepatitis C virus by high doses of interferon and ribavirin in adult hemophilic patients

BACKGROUND: In a recent randomized controlled study, only a minority (15%) of adult hemophiliacs with chronic HCV achieved a sustained virologic response to treatment with interferon (IFN) and ribavirin given at standard doses. STUDY DESIGN AND METHODS: Whether the therapeutic response might be improved in these patients by increasing the doses of IFN was evaluated. Thirty-four previously untreated, adult hemophiliacs with chronic HCV but negative for HIV were investigated. There were 33 men and 1 woman, aged 21 to 60 years (mean, 36). Twenty-three patients (68%) had genotype 1, and median serum HCV-RNA was 473 x 10(3) IU per L (range, 3.6-2145). Patients were treated with IFN at 5 million units (MU) thrice weekly for 6 months, followed by 3 mol/L for 6 additional months in combination with daily oral doses of 1 or 1.2 g of ribavirin. RESULTS: A total of 33 patients (97%) completed the study; one patient withdrew because of treatment-related symptoms. Treatment dosage had to be reduced in 20 patients (59%). By intention-to-treat analysis, 14 patients (41%) had a sustained virologic response, particularly those infected by HCV genotype 2 or 3 (70% vs. 29% with genotype 1 or 4, p < 0.05). Sustained response rates were similar in the 13 compliant patients and the 20 patients who had to reduce IFN and/or ribavirin doses (54% vs. 35%). CONCLUSIONS: High-dose IFN therapy plus ribavirin provided high rates of sustained virologic responses in adult hemophiliacs with chronic HCV, even if side-effects led to dose reduction in half of these patients.     

Efficacy and Safety of Danoprevir-Ritonavir plus Peginterferon Alfa-2a–Ribavirin in Hepatitis C Virus Genotype 1 Prior Null Responders

Danoprevir (DNV) is a hepatitis C virus (HCV) protease inhibitor that achieves high sustained virologic response (SVR) rates in combination with peginterferon alfa-2a–ribavirin in treatment-naive HCV genotype 1 (G1)-infected patients. This study explored the efficacy and safety of ritonavir-boosted DNV (DNVr) plus peginterferon alfa-2a–ribavirin in G1-infected prior peginterferon-ribavirin null responders. Null responders (<2-log₁₀ reduction in HCV RNA level at week 12) were given an open-label combination of 100 mg of ritonavir and 100 mg of DNV (100/100 mg DNVr) every 12 h (q12h) plus peginterferon alfa-2a–ribavirin for 12 weeks. All patients achieving an early virologic response (EVR; ≥2-log₁₀ decrease in HCV RNA by week 12) continued treatment with peginterferon alfa-2a–ribavirin; those without an EVR discontinued all study drugs. Twenty-four prior null responders were enrolled; 16 patients (67%) were infected with HCV G1b, and 8 (33%) were infected with G1a. Ninety-six percent of patients had an IL28B non-CC genotype. A sustained virologic response at 24 weeks posttreatment (SVR24) was achieved in 67% of patients, with a higher rate in G1b-infected (88%) than G1a-infected (25%) patients. Resistance-related breakthrough occurred in 4/8 G1a and 1/16 G1b patients through the DNV resistance-associated variant (RAV) NS3 R155K. NS3 R155K was also detected in 2/2 G1a patients who relapsed. Treatment was well tolerated. Two patients withdrew prematurely from study medications due to adverse events. Two serious adverse events were reported; both occurred after completion of DNVr therapy and were considered unrelated to treatment. No grade 3 or 4 alanine aminotransferase (ALT) elevations were observed. DNVr plus peginterferon alfa-2a–ribavirin demonstrated high SVR24 rates in HCV G1b-infected prior null responders and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01185860","term_id":"NCT01185860"}}NCT01185860.)     

Predicting the therapeutic response in patients with chronic hepatitis C: the role of viral kinetic studies

A substantial proportion of patients infected with hepatitis C virus (HCV) genotype 1 still does not respond to pegylated interferon-alfa/ribavirin (IFN/RBV) therapy. Factors which identify potential non-responders are needed to limit exposure to drugs in patients unlikely to benefit from treatment and to save health care resources. Host predictive factors have a low negative predictive value. In contrast, viral factors have a high precision in predicting outcome of therapy. Viral kinetics are the basis for the study of response of therapy. The decrease in viral load within 24 h after administration of a single test dose of conventional IFN reflects the IFN-sensitivity of the virus strain and predicts the outcome of conventional IFN/RBV therapy even before treatment with a specificity of 100% and a sensitivity of 83%. In contrast to conventional IFN, the two available PEG-IFN preparations differ considerably in how they suppress viral replication, and cut-off values have to be prospectively established separately for each drug. Patients without an early virological response (HCV-RNA either undetectable or decrease by >or=2 log10 after 12 weeks) (EVR), do not achieve a sustained virological response (SVR; negative predictive value: 97-98%). Thus, in the absence of an EVR, treatment should be stopped. The outcome of PEG-IFN alfa-2a/RBV combination therapy is dependent on the rapidity of the virological response. Patients who become HCV-RNA negative after 4 weeks have the best chance of achieving an SVR. The rapidity of viral elimination may be a useful guide to tailoring the length of treatment in patients with an EVR.     

Sustained negativity for HCV-RNA over 24 or more months by long-term interferon therapy correlates with eradication of HCV in patients with hepatitis C virus genotype 1b and high viral load

OBJECTIVE: We assessed whether sustained negativity for HCV-RNA over 24 or more months by long-term interferon (IFN) therapy correlates with eradication of HCV in patients with hepatitis C virus genotype 1b and high viral load or not. METHODS: The number of patients with HCV-genotype 1b and high viral load exceeding 1 Meq/ml who received 6 MU of natural IFN-alpha daily for 2-8 weeks, followed by three times/week for 16-22 weeks and negativity for HCV-RNA during IFN administration was 403. Forty-one of 403 patients received 6 MU of natural IFN-alpha three times/week for more than 18 months after the initial IFN therapy (long-term-IFN-group). Three hundred and two patients did not receive any IFN treatment for 6 months after the termination of the 6-month course (6-month-IFN-group). Sustained virological response (SVR) was defined as negative HCV-RNA at both 3 and 6 months after the completion of IFN therapy. RESULTS: SVR was noted in 73.2% (30/41) of long-term-IFN-group and 18.2% (55/302) of 6-month-IFN-group. Multivariate analysis showed that long-term IFN therapy was the most significant contributor to SVR (p < 0.0001). CONCLUSION: Sustained negativity of HCV-RNA for 24 or more months by long-term IFN therapy correlated with SVR in patients with genotype 1b and high viral load.     

A comparison of the exponential decay slope between PEG-IFN alfa-2b/ribavirin and IFN alfa-2b/ribavirin combination therapy in patients with chronic hepatitis C genotype 1b infection and a high viral load

OBJECTIVES: A high virological response rate can often be shown to be obtained with PEG-IFN alpha-2b and ribavirin combination therapy in chronic hepatitis C patients. Viral dynamics have been utilized for the evaluation of antiviral effects, especially the exponential second decay slope, which represents the elimination of infected cells. METHODS: Forty-nine patients were randomly assigned to the IFN alpha-2b group (n = 26) or the PEG-IFN alpha-2b group (n = 23). Ribavirin was administered equally to both groups. Measuring the serum concentration of HCVRNA, the exponential viral decay during phase 1 and 2 was calculated. RESULTS: The exponential decay slope in phase 2 during the first 2 weeks was greater in the IFN alpha-2b group than in the PEG-IFN alpha-2b group; however, from weeks 3 to 4, it was greater in the PEG-IFN alpha-2b group than in the IFN alpha-2b group. Interestingly, in the PEG-IFN alpha-2b group, the exponential decay slope was greater from weeks 3 to 4 after initiating combination therapy than during the weeks 1-2 (p < 0.01), despite administration of the same PEG-IFN alpha-2b dose (1.5 microg/kg once weekly). CONCLUSIONS: In PEG-IFN alpha-2b and ribavirin combination therapy, elimination of infected cells may be pronounced following an increase in serum ribavirin concentration in chronic hepatitis C patients with genotype 1b infection and a high viral load.     

Peginterferon alfa-2a (40KD) (Pegasys) for the treatment of patients with chronic hepatitis C

Compared with conventional interferon alfa, peginterferon alfa-2a (40KD) has improved pharmacokinetics, provides sustained therapeutic plasma levels, and can be administered once weekly. In randomised, multinational trials, peginterferon alfa-2a (40KD) 180 microg once weekly was significantly more effective than three times weekly interferon alfa-2a in patients with chronic hepatitis C, including patients with cirrhosis. Peginterferon alfa-2a (40KD) and ribavirin 1000/1200 mg/day for 48 weeks produced significantly higher sustained responses than three times weekly interferon alfa-2b and ribavirin 1000/1200 mg/day in patients with chronic hepatitis C including those with HCV genotype 1, genotypes 2/3 and those with high or low viral loads at baseline. The drug is well tolerated when given alone or in combination with ribavirin. Health-related quality of life was significantly less impaired during treatment with peginterferon alfa-2a (40KD) than interferon alfa-2a in randomised trials. Peginterferon alfa-2a (40KD) is widely approved for use in patients with chronic hepatitis C.     

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.     

Prolonged negative HCV-RNA status led to a good outcome in chronic hepatitis C patients with genotype 1b and super-high viral load

OBJECTIVE: We examined whether a sustained negative HCV-RNA status for 48 weeks affects the outcome in patients with genotype 1b and super-high viral load, and also investigated whether the outcome is affected by the induction therapy of twice-daily pre-administrated interferon (IFN)-beta. METHODS: 78 eligible patients were divided into four groups. 40 were patients assigned to the short treatment protocol. 13 patients received 3 MU IFN-beta twice daily for 2 weeks followed by IFN-alpha2b+ribavirin for 22 weeks (beta-induction group: group 1). 27 patients received IFN-alpha2b+ribavirin for 24 weeks (standard combination group: group 2). 38 patients were assigned to the maintenance treatment protocol. All of the 13 in the beta-induction group (group 3) and 21 of 25 patients in the standard combination group (group 4) who were negative HCV-RNA PCR at week 24 had IFN monotherapy to maintain a negative HCV-RNA result for 48 weeks. RESULTS: An HCV-RNA-negative status at week 24 was observed in 96% (25/26) of groups 1 and 3 versus in 79% (41/52) of groups 2 and 4 (p<0.01). The sustained virological response (SVR) was 38% (5/13) in group 1 and 11% (3/27) in group 2 (p<0.05). In the maintenance treatment, SVR was observed in 46% (6/13) of group 3 and 32% (8/25) of group 4 (NS). CONCLUSIONS: A sustained negative HCV-RNA status for 48 weeks might be associated with viral elimination in patients with genotype 1 and super-high viral load.