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Background & Aims: Triple therapy with peginterferon/ribavirin (PR) plus an NS3 protease inhibitor has emerged as the standard-of-care for patients with chronic hepatitis C genotype-1. We provide a detailed safety analysis comparing PR to boceprevir plus PR (BOC/PR) across three phase 2/3 studies., Methods: SPRINT-1 was an open-label phase 2 study in 595 treatment-naive patients. In the two phase 3 studies, 1500 patients (1097 treatment-naive, SPRINT-2; 403 treatment-failure, RESPOND-2) were randomized to receive PR alone, or one of two regimens where BOC was added to PR after a 4-wk PR lead-in. In this analysis, the respective BOC/PR and PR arms were combined for all three trials. The benefit of shortened duration of treatment using response-guided therapy (RGT) was also explored in the SPRINT-2 trial., Results: Only two adverse events, anaemia and dysgeusia, occurred 20% more often with the BOC-containing regimens compared with PR. Nausea, diarrhoea and neutropenia were the only other common events with an incidence of at least 5% greater when BOC was added to the PR backbone. The proportions of patients reporting serious adverse events (AE), life-threatening AEs, and study drug discontinuation because of an AE were similar in the PR and BOC/PR arms. In treatment-naive patients, RGT generally did not result in a lower frequency of common AEs; however, RGT led to decreased exposure to all 3 study drugs and to a decrease in the mean duration of several clinically relevant AEs such as anaemia, neutropenia, fatigue and depression, as well as earlier normalization of haemoglobin and neutrophil counts., Conclusions: The safety profile of BOC combination therapy largely reflects the known profile of peginterferon and ribavirin, with incremental haematolgical effects and dysgeusia. Shorter treatment duration with RGT significantly reduced the duration of AEs., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background & Aims: Boceprevir with peginterferon/ribavirin (BOC/PR) leads to significantly higher sustained virological response (SVR) rates in patients with chronic hepatitis C and partial response or relapse after prior treatment with peginterferon/ribavirin. We studied the efficacy of BOC/PR in patients with prior treatment failure, including those with a null response (<2-log10 decline in HCV RNA), to peginterferon/ribavirin., Methods: Patients in the control arms of boceprevir Phase 2/3 studies who did not achieve SVR were re-treated with BOC/PR for up to 44 weeks. Patients enrolling >2 weeks after end-of-treatment in the prior study received PR for 4 weeks before adding boceprevir., Results: Of 168 patients enrolled, four discontinued from the PR lead-in and 164 received BOC/PR. Baseline viral load was >800,000 IU/ml in 77% of patients; 62% had HCV genotype 1a, and 10% were cirrhotic. In the ITT analysis (all 168 patients), SVR was achieved in 20 (38%) of 52 patients with prior null response, 57 (67%) of 85 with prior partial response, and 27 (93%) of 29 with prior relapse. In the mITT analysis (164 BOC/PR-treated patients), SVR rates were 41% (20/49), 67% (57/85), and 96% (27/28), respectively. SVR was achieved by 48% of patients with <1-log10 decline in HCV-RNA after lead-in and 76% of those with ⩾ 1-log10 decline or undetectable HCV-RNA after lead-in. The most common adverse events were anemia (49%), fatigue (48%), and dysgeusia (35%); 8% of patients discontinued due to adverse events., Conclusions: Re-treatment with BOC/PR improved SVR rates in all patient subgroups, including those with prior null response., (Copyright © 2014 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background: Resistance to direct-acting antivirals represents a new challenge in the treatment of chronic hepatitis C., Methods: SPRINT-1 was a randomized study of treatment-naive patients with genotype (G) 1 hepatitis C infection (n=595) that evaluated the safety and efficacy of boceprevir (BOC) when added to pegylated interferon-α2b plus ribavirin (PR). Plasma samples collected at protocol-specified visits were analysed by population sequencing for detection of BOC-associated resistance-associated variants (RAVs)., Results: A total of 17/24 (71%) patients randomized to BOC with baseline RAVs achieved sustained virological response (SVR). V55A/I (n=14), Q41H (n=11) and T54S (n=9) were the most frequently detected polymorphisms at baseline. Seven non-SVR patients with baseline RAVs had V55A (relapse, n=3; breakthrough, n=1; and non-response, n=1) and/or R155K (non-response, n=2). In total, 63/144 (44%) patients with sequenced post-baseline samples (2 SVR, 61 non-SVR) had detectable RAVs after BOC treatment (G1a: R155K [39/49; 80%], V36M [37/49; 76%] and T54S [24/49; 49%]; G1b: T54S [3/11; 27%], T54A [4/11; 35%], A156S [2/11; 18%] and V170A [2/11; 18%]). RAV frequency varied according to the virological response: 90%, 67%, 27% and 37% of breakthrough, incomplete virological response, relapse and non-responder patients, respectively, had post-baseline RAVs present. Similar RAVs were identified in both the PR lead-in and no-lead-in arms and the frequency of post-baseline RAVs was highest in the low-dose ribavirin arm., Conclusions: SVR rates were not compromised among patients with RAVs at baseline; however, a lower starting mg/kg dose of ribavirin was associated with a higher frequency of post-baseline RAVs.

Background & Aims: Interferon-alfa (IFN)-related cytopenias are common and may be dose-limiting. We performed a genome wide association study on a well-characterized genotype 1 HCV cohort to identify genetic determinants of peginterferon-α (pegIFN)-related thrombocytopenia, neutropenia, and leukopenia., Methods: 1604/3070 patients in the IDEAL study consented to genetic testing. Trial inclusion criteria included a platelet (Pl) count ≥80×10(9)/L and an absolute neutrophil count (ANC) ≥1500/mm(3). Samples were genotyped using the Illumina Human610-quad BeadChip. The primary analyses focused on the genetic determinants of quantitative change in cell counts (Pl, ANC, lymphocytes, monocytes, eosinophils, and basophils) at week 4 in patients >80% adherent to therapy (n=1294)., Results: 6 SNPs on chromosome 20 were positively associated with Pl reduction (top SNP rs965469, p=10(-10)). These tag SNPs are in high linkage disequilibrium with 2 functional variants in the ITPA gene, rs1127354 and rs7270101, that cause ITPase deficiency and protect against ribavirin (RBV)-induced hemolytic anemia (HA). rs1127354 and rs7270101 showed strong independent associations with Pl reduction (p=10(-12), p=10(-7)) and entirely explained the genome-wide significant associations. We believe this is an example of an indirect genetic association due to a reactive thrombocytosis to RBV-induced anemia: Hb decline was inversely correlated with Pl reduction (r=-0.28, p=10(-17)) and Hb change largely attenuated the association between the ITPA variants and Pl reduction in regression models. No common genetic variants were associated with pegIFN-induced neutropenia or leucopenia., Conclusions: Two ITPA variants were associated with thrombocytopenia; this was largely explained by a thrombocytotic response to RBV-induced HA attenuating IFN-related thrombocytopenia. No genetic determinants of pegIFN-induced neutropenia were identified., (Copyright © 2011 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Unlabelled: Black Americans are disproportionally infected with hepatitis C virus (HCV) and are less likely than whites to respond to treatment with peginterferon (PEG-IFN) plus ribavirin (RBV). The impact of race on HCV treatment eligibility is unknown. We therefore performed a retrospective analysis of a phase 3B multicenter clinical trial conducted at 118 United States community and academic medical centers to evaluate the rates of and reasons for HCV treatment ineligibility according to self-reported race. In all, 4,469 patients were screened, of whom 1,038 (23.2%) were treatment ineligible. Although blacks represented 19% of treated patients, they were more likely not to be treated due to ineligibility and/or failure to complete required evaluations (40.2%) than were nonblack patients (28.5%; P < 0.001). After the exclusion of persons not treated due to undetectable HCV RNA or nongenotype 1 infection, blacks were 65% less likely than nonblacks to be eligible for treatment (28.1% > 17.0%; relative risk, 1.65; 95% confidence interval, 1.46-1.87; P < 0.001). Blacks were more likely to be ineligible due to neutropenia (14% versus 3%, P < 0.001), anemia (7% versus 4%, P = 0.02), elevated glucose (8% versus 3%, P < 0.001), and elevated creatinine (5% versus 1%, P < 0.001)., Conclusion: Largely due to a higher prevalence of neutropenia and uncontrolled medical conditions, blacks were significantly less likely to be eligible for HCV treatment. Increased access to treatment may be facilitated by less conservative neutrophil requirements and more effective care for chronic diseases, namely, diabetes and renal insufficiency., (Copyright © 2011 American Association for the Study of Liver Diseases.)

Previous studies of chronic hepatitis C virus (HCV) treatment have demonstrated variations in response among racial and ethnic groups including poorer efficacy rates among African American and Hispanic patients. The individualized dosing efficacy vs flat dosing to assess optimaL pegylated interferon therapy (IDEAL) trial enrolled 3070 patients from 118 United States centres to compare treatment with peginterferon (PEG-IFN) alfa-2a and ribavirin (RBV) and two doses of PEG-IFN alfa-2b and RBV. This analysis examines treatment response among the major racial and ethnic groups in the trial. Overall, sustained virologic response (SVR) rates were 44% for white, 22% for African American, 38% for Hispanic and 59% for Asian American patients. For patients with undetectable HCV RNA at treatment week 4, the positive predictive value of SVR was 86% for white, 92% for African American, 83% for Hispanic and 89% for Asian American patients. The positive predictive values of SVR in those with undetectable HCV RNA at treatment week 12 ranged from 72% to 81%. Multivariate regression analysis using baseline characteristics demonstrated that treatment regimen was not a predictor of SVR. Despite wide-ranging SVR rates among the different racial and ethnic groups, white and Hispanic patients had similar SVR rates. In all groups, treatment response was largely determined by antiviral activity in the first 12 weeks of treatment. Therefore, decisions regarding HCV treatment should consider the predictive value of the early on-treatment response, not just baseline characteristics, such as race and ethnicity., (© 2010 Blackwell Publishing Ltd.)

Background: Peginterferon-ribavirin therapy is the current standard of care for chronic infection with hepatitis C virus (HCV). The rate of sustained virologic response has been below 50% in cases of HCV genotype 1 infection. Boceprevir, a potent oral HCV-protease inhibitor, has been evaluated as an additional treatment in phase 1 and phase 2 studies., Methods: We conducted a double-blind study in which previously untreated adults with HCV genotype 1 infection were randomly assigned to one of three groups. In all three groups, peginterferon alfa-2b and ribavirin were administered for 4 weeks (the lead-in period). Subsequently, group 1 (the control group) received placebo plus peginterferon-ribavirin for 44 weeks; group 2 received boceprevir plus peginterferon-ribavirin for 24 weeks, and those with a detectable HCV RNA level between weeks 8 and 24 received placebo plus peginterferon-ribavirin for an additional 20 weeks; and group 3 received boceprevir plus peginterferon-ribavirin for 44 weeks. Nonblack patients and black patients were enrolled and analyzed separately., Results: A total of 938 nonblack and 159 black patients were treated. In the nonblack cohort, a sustained virologic response was achieved in 125 of the 311 patients (40%) in group 1, in 211 of the 316 patients (67%) in group 2 (P<0.001), and in 213 of the 311 patients (68%) in group 3 (P<0.001). In the black cohort, a sustained virologic response was achieved in 12 of the 52 patients (23%) in group 1, in 22 of the 52 patients (42%) in group 2 (P=0.04), and in 29 of the 55 patients (53%) in group 3 (P=0.004). In group 2, a total of 44% of patients received peginterferon-ribavirin for 28 weeks. Anemia led to dose reductions in 13% of controls and 21% of boceprevir recipients, with discontinuations in 1% and 2%, respectively., Conclusions: The addition of boceprevir to standard therapy with peginterferon-ribavirin, as compared with standard therapy alone, significantly increased the rates of sustained virologic response in previously untreated adults with chronic HCV genotype 1 infection. The rates were similar with 24 weeks and 44 weeks of boceprevir. (Funded by Schering-Plough [now Merck]; SPRINT-2 ClinicalTrials.gov number, NCT00705432.).

Background & Aims: Hepatitis C virus (HCV) treatment is frequently complicated by anemia from ribavirin (RBV)-related hemolysis and peginterferon-alfa (PEG-IFN)-related bone marrow suppression. We investigated the relationships among treatment outcomes, anemia, and their management with RBV dose reduction and/or erythropoiesis-stimulating agents (ESAs)., Methods: We analyzed data from a trial conducted at 118 United States academic and community centers in treatment-naïve patients with HCV genotype 1. Patients were treated for as many as 48 weeks with 1 of 3 PEG-IFN/RBV regimens. ESAs were permitted for anemic patients (hemoglobin [Hb] <10 g/dL) after RBV dose reduction. Sustained virologic responses (SVR) were assessed based on decreases in Hb, anemia, and ESA use., Results: While patients received treatment, 3023 had their Hb levels measured at least once. An SVR was associated with the magnitude of Hb decrease: >3 g/dL, 43.7%; ≤3 g/dL, 29.9% (P < .001). Anemia occurred in 865 patients (28.6%); 449 of these (51.9%) used ESAs. In patients with early-onset anemia (≤ 8 weeks of treatment), ESAs were associated with higher SVR rate (45.0% vs 25.9%; P < .001) and reduced discontinuation of treatment because of adverse events (12.6% vs 30.1%, P < .001). ESAs did not affect SVR or discontinuation rates among patients with late-stage anemia., Conclusions: Among HCV genotype 1-infected patients treated with PEG-IFN/RBV, anemia was associated with higher rates of SVR. The effect of ESAs varied by time to anemia; patients with early-onset anemia had higher rates of SVR with ESA use, whereas no effect was observed in those with late-onset anemia. Prospective trials are needed to assess the role of ESAs in HCV treatment., (Copyright © 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Peginterferon plus ribavirin achieves sustained virological response (SVR) in fewer than half of patients with genotype 1 chronic hepatitis C virus infection treated for 48 weeks. We tested the efficacy of boceprevir, an NS3 hepatitis C virus oral protease inhibitor, when added to peginterferon alfa-2b and ribavirin., Methods: In part 1 of this trial, undertaken in 67 sites in the USA, Canada, and Europe, 520 treatment-naive patients with genotype 1 hepatitis C virus infection were randomly assigned to receive peginterferon alfa-2b 1.5 mug/kg plus ribavirin 800-1400 mg daily for 48 weeks (PR48; n=104); peginterferon alfa-2b and ribavirin daily for 4 weeks, followed by peginterferon alfa-2b, ribavirin, and boceprevir 800 mg three times a day for 24 weeks (PR4/PRB24; n=103) or 44 weeks (PR4/PRB44; n=103); or peginterferon alfa-2b, ribavirin, and boceprevir three times a day for 28 weeks (PRB28; n=107) or 48 weeks (PRB48; n=103). In part 2, 75 patients were randomly assigned to receive either PRB48 (n=16) or low-dose ribavirin (400-1000 mg) plus peginterferon alfa-2b and boceprevir three times a day for 48 weeks (low-dose PRB48; n=59). Randomisation was by computer-generated code, and study personnel and patients were not masked to group assignment. The primary endpoint was SVR 24 weeks after treatment. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00423670., Findings: Patients in all four boceprevir groups had higher rates of SVR than did the control group (58/107 [54%, 95% CI 44-64], p=0.013 for PRB28; 58/103 [56%, 44-66], p=0.005 for PR4/PRB24; 69/103 [67%, 57-76], p<0.0001 for PRB48; and 77/103 [75%, 65-83], p<0.0001 for PR4/PRB44; vs 39/104 [38%, 28-48] for PR48 control). Low-dose ribavirin was associated with a high rate of viral breakthrough (16/59 [27%]), and a rate of relapse (six of 27 [22%]) similar to control (12/51 [24%]). Boceprevir-based groups had higher rates of anaemia (227/416 [55%] vs 35/104 [34%]) and dysgeusia (111/416 [27%] vs nine of 104 [9%]) than did the control group., Interpretation: In patients with untreated genotype 1 chronic hepatitis C infection, the addition of the direct-acting antiviral agent boceprevir to standard treatment with peginterferon and ribavirin after a 4-week lead-in seems to have the potential to double the sustained response rate compared with that recorded with standard treatment alone., Funding: Merck., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Background & Aims: We recently identified a polymorphism upstream of interleukin (IL)-28B to be associated with a 2-fold difference in sustained virologic response (SVR) rates to pegylated interferon-alfa and ribavirin therapy in a large cohort of treatment-naive, adherent patients with chronic hepatitis C virus genotype 1 (HCV-1) infection. We sought to confirm the polymorphism's clinical relevance by intention-to-treat analysis evaluating on-treatment virologic response and SVR., Methods: HCV-1 patients were genotyped as CC, CT, or TT at the polymorphic site, rs12979860. Viral kinetics and rates of rapid virologic response (RVR, week 4), complete early virologic response (week 12), and SVR were compared by IL-28B type in 3 self-reported ethnic groups: Caucasians (n = 1171), African Americans (n = 300), and Hispanics (n = 116)., Results: In Caucasians, the CC IL-28B type was associated with improved early viral kinetics and greater likelihood of RVR (28% vs 5% and 5%; P < .0001), complete early virologic response (87% vs 38% and 28%; P < .0001), and SVR (69% vs 33% and 27%; P < .0001) compared with CT and TT. A similar association occurred within African Americans and Hispanics. In a multivariable regression model, CC IL-28B type was the strongest pretreatment predictor of SVR (odds ratio, 5.2; 95% confidence interval, 4.1-6.7). RVR was a strong predictor of SVR regardless of IL-28B type. In non-RVR patients, the CC IL-28B type was associated with a higher rate of SVR (Caucasians, 66% vs 31% and 24%; P < .0001)., Conclusions: In treatment-naive HCV-1 patients treated with pegylated interferon and ribavirin, a polymorphism upstream of IL-28B is associated with increased on-treatment and sustained virologic response and effectively predicts treatment outcome., (Copyright 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Treatment guidelines recommend the use of peginterferon alfa-2b or peginterferon alfa-2a in combination with ribavirin for chronic hepatitis C virus (HCV) infection. However, these regimens have not been adequately compared., Methods: At 118 sites, patients who had HCV genotype 1 infection and who had not previously been treated were randomly assigned to undergo 48 weeks of treatment with one of three regimens: peginterferon alfa-2b at a standard dose of 1.5 microg per kilogram of body weight per week or a low dose of 1.0 microg per kilogram per week, plus ribavirin at a dose of 800 to 1400 mg per day, or peginterferon alfa-2a at a dose of 180 microg per week plus ribavirin at a dose of 1000 to 1200 mg per day. We compared the rate of sustained virologic response and the safety and adverse-event profiles between the peginterferon alfa-2b regimens and between the standard-dose peginterferon alfa-2b regimen and the peginterferon alfa-2a regimen., Results: Among 3070 patients, rates of sustained virologic response were similar among the regimens: 39.8% with standard-dose peginterferon alfa-2b, 38.0% with low-dose peginterferon alfa-2b, and 40.9% with peginterferon alfa-2a (P=0.20 for standard-dose vs. low-dose peginterferon alfa-2b; P=0.57 for standard-dose peginterferon alfa-2b vs. peginterferon alfa-2a). Estimated differences in response rates were 1.8% (95% confidence interval [CI], -2.3 to 6.0) between standard-dose and low-dose peginterferon alfa-2b and -1.1% (95% CI, -5.3 to 3.0) between standard-dose peginterferon alfa-2b and peginterferon alfa-2a. Relapse rates were 23.5% (95% CI, 19.9 to 27.2) for standard-dose peginterferon alfa-2b, 20.0% (95% CI, 16.4 to 23.6) for low-dose peginterferon alfa-2b, and 31.5% (95% CI, 27.9 to 35.2) for peginterferon alfa-2a. The safety profile was similar among the three groups; serious adverse events were observed in 8.6 to 11.7% of patients. Among the patients with undetectable HCV RNA levels at treatment weeks 4 and 12, a sustained virologic response was achieved in 86.2% and 78.7%, respectively., Conclusions: In patients infected with HCV genotype 1, the rates of sustained virologic response and tolerability did not differ significantly between the two available peginterferon-ribavirin regimens or between the two doses of peginterferon alfa-2b. (ClinicalTrials.gov number, NCT00081770.), (2009 Massachusetts Medical Society)

Unlabelled: WIN-R (Weight-based dosing of pegINterferon alfa-2b and Ribavirin) was a multicenter, randomized, open-label, investigator-initiated trial involving 236 community and academic sites in the United States, comparing response to pegylated interferon (PEG-IFN) alfa-2b plus a flat or weight-based dose of ribavirin (RBV) in treatment-naive patients with chronic hepatitis C and compensated liver disease. Patients were randomized to receive PEG-IFN alfa-2b at 1.5 microg/kg/week plus flat-dose (800 mg/day) or weight-based-dose RBV (800 mg/day for weight <65 kg, 1000 mg/day for 65-85 kg, 1200 mg/day for >85-105 kg, or 1400 mg/day for >105-<125 kg). Sustained virologic response (SVR; undetectable [<125 IU/mL] hepatitis C virus [HCV] RNA at end of follow-up) in patients > or =65 kg was the primary end point. Low SVR rates have been reported among African American individuals, in whom there is a preponderance of HCV genotype 1. This subanalysis of WIN-R was conducted to evaluate the efficacy of weight-based dosing among African American individuals with genotype 1 infection enrolled in the trial. Of 362 African American patients in the primary efficacy analysis, 188 received RBV flat dosing and 174 received weight-based dosing. SVR rates were higher (21% versus 10%; P = 0.0006) and relapse rates were lower (22% versus 30%) in the weight-based-dose group than in the flat-dose group. Safety and rates of drug discontinuation were similar between the 2 groups., Conclusion: Weight-based dosing of RBV is more effective than flat dosing in combination with PEG-IFN alfa-2b in African American individuals with HCV genotype 1. Even with weight-based dosing, response rates in African American individuals are lower than reported in other ethnic groups.

Hepatitis C virus (HCV) infection is resistant to interferon-alpha (IFN-alpha) in some patients. The mechanism of this resistance is unknown. Interleukin-1 receptor antagonist (IL-1Ra) is induced by IFN-alpha and is a good indicator of IFN activity. In the current study, we compared IL-1Ra levels in rapid virologic responders and flat responders who showed resistance to IFN. Three groups of patients were examined, including those who received a single dose of consensus IFN (IFN-con1), patients who received daily IFN-con1 for 1 week, and patients who received IFN-con1 daily for 24 weeks. Serum IL-1Ra, IL-6, and HCV RNA were measured serially in all groups. Serum IL-1Ra levels increased rapidly in all patients with hepatitis C after IFN-alpha administration, irrespective of their virologic response. IL-1Ra levels remained elevated at 1 week but were similar to baseline by week 2 of treatment in patients receiving continuous therapy. IL-6 levels also increased acutely but rose more slowly than IL-1Ra levels. The increase in IL-1Ra and IL-6 observed in both flat and rapid virologic responders indicates that IFN receptors are functioning in patients with IFN-resistant hepatitis C and that the lack of response is related to other virologic or immunologic factors.

Cytokine production has been implicated in the antiviral response to interferon-alpha (IFN-alpha) in hepatitis C and in the development of IFN-alpha-related side effects. We characterized acute changes in serum cytokine levels following administration of a single dose of consensus IFN (IFN-con1) and during continuous treatment of chronic hepatitis C patients. Serum samples were collected at baseline, at multiple times early after IFN administration, and weekly thereafter. Viral RNA titers were assessed by RT-PCR, and viral kinetics were followed. ELISA assays were used to measure IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2), IL-4, IL-6, and IL-16. Serum cytokine levels were low at baseline. IL-6 was detected in patients with hepatitis C but not in healthy control subjects by either ELISA or RT-PCR, indicating that low levels of circulating IL-6 were associated with hepatitis C infection. None of the cytokines measured increased significantly after IFN administration except for IL-6. IL-6 levels rose rapidly, peaked at 6-15 h in a dose-dependent manner, and returned to baseline by 48 h in both patients receiving a single dose of IFN and those receiving continuous treatment. This was confirmed by RT-PCR. Pretreatment IL-6 levels were directly correlated with area under the curve (AUC) for IL-6 during the 24 h after IFN dosing (r = 0.611, p = 0.007). Viral titers decreased within 24-48 h after a single dose of IFN-con1. Changes in hepatitis C RNA titers were not significantly associated with pretreatment IL-6 levels or with changes in IL-6 levels. In conclusion, (1) baseline serum cytokine levels, except for IL-6, were low or within the normal range in patients with hepatitis C, (2) IL-6 levels were detected in some patients with hepatitis C before treatment but not in healthy controls, (3) IL-6 levels increased acutely after a single dose of IFN-alpha, and IL-6 induction was related to baseline IL-6 level, and (4) changes in IL-6 levels did not correlate with the early virologic response to IFN.