Potential conflict of interest: Nothing to report.
A sustained virologic response (SVR) in patients with chronic hepatitis C receiving pegylated interferon (PEG-IFN) plus ribavirin is defined as undetectable serum HCV-RNA at 24 weeks (W+24) posttreatment follow-up. Viral load outcome in patients with virological relapse (VR) has not been explored. This study evaluated whether the assessment of serum HCV-RNA 12 weeks (W+12) after the end of treatment was as relevant as W+24 to evaluate SVR in 573 patients who received combination PEG-IFN and ribavirin and had a virological response at the end of treatment. Serum HCV-RNA was measured, using a new assay based on transcription-mediated amplification (TMA) with a lowest detection limit of 5-10 IU/mL, at W+12 and W+24 after the end of treatment. VR was defined as reappearance of detectable HCV-RNA at W+24 posttreatment follow-up. The positive predictive value (PPV) of undetectable serum HCV-RNA at W+12 was evaluated to identify patients with SVR, and the viral load outcome was measured in relapse patients. At the W+24 posttreatment follow-up, 408 (71%) patients had an SVR, 181 (71.2%) were treated with PEG-IFNα-2a and ribavirin, and 227 (71.1%) were treated with PEG-IFNα-2b and ribavirin. At W+12, serum HCV-RNA was undetectable in 409 patients, and 408 patients were SVR (PPV 99.7%, 95% confidence interval 99.1-100). In relapse patients, serum HCV-RNA levels were 5.623 ± 0.748, 4.979 ± 0.870, and 5.216 ± 0.758 log10 IU/mL at baseline, W+12, and W+24, respectively. Conclusion: Our results show that the assessment of serum HCV-RNA 12 weeks after the end of treatment, using the highly sensitive TMA assay (PPV 99.7%), is as relevant as after 24 weeks to predict SVR and make decisions on the management of treated patients, suggesting a new definition for SVR. (HEPATOLOGY 2010.)
The goal of treating patients with chronic hepatitis C virus (HCV) is to obtain a sustained virological response (SVR), signaling eradication of HCV infection.1–4 Major improvements in antiviral therapy for chronic HCV infection have been made in the past decade.5–12 The addition of ribavirin to interferon α therapy and the introduction of pegylated interferon (PEG-IFN) have substantially improved SVR rates.10–12 The current standard for the determination of SVR is undetectable serum HCV-RNA 24 weeks (W+24) after the end of treatment13 and the continued durability of viral response beyond W+24 posttreatment follow-up has been clearly established.1–4 This standard is based on the results of many previous reports that late relapse, defined as reappearance of serum HCV-RNA, is rarely observed.1–4, 14–16 However, this definition of SVR is rather arbitrary, because the timing of relapse within W+24 posttreatment follow-up has not been evaluated.
Until now, investigators in clinical trials have used qualitative HCV-RNA assays (based on polymerase chain reaction) with the lowest limits of detection of 50-100 IU/mL, to establish undetectable serum HCV-RNA at the end of therapy and after treatment. Recently, a new assay based on transcription-mediated amplification (TMA) became available with a lowest detection limit of 5-10 IU/mL. Studies have recently reported that the highly sensitive TMA detected residual serum HCV-RNA in a high proportion (up to 12%) of patients, who had been classified as having a virological end-of-treatment response with a less sensitive assay and were, consequently early relapsers.17–19 Despite improved evaluation of end-of-treatment virological response, there are still 15%-20% of patients who experience a relapse at W+24 posttreatment follow-up. The early phase of viral load outcome has never been explored in these patients.
The aim of this study was to (1) evaluate if measurement of serum HCV-RNA at 12 weeks (W+12) posttreatment to assess SVR was as relevant as at 24 weeks posttreatment in patients with a virological end of treatment response, assessed with a highly sensitive assay (TMA), and (2) to measure early viral load outcome in patients with relapse after treatment cessation.
Seven hundred eighty-one patients with chronic hepatitis C treated with combination PEG-IFN and ribavirin therapy from January 2002 to June 2007 were prospectively included in this community-based study. Patients were excluded if they had neutropenia (<750 neutrophils/mL3), thrombocytopenia (<50,000 platelets/mL3), anemia (<100 g/L hemoglobin), coinfection with human immunodeficiency virus, or hepatitis B virus.
Four hundred thirty-nine patients received PEG-IFNα-2b (PegIntron, Schering Plough Corporation, Kenilworth, NJ) at a dose of 1.5 μg/kg/week and ribavirin (Rebetol, Schering Plough Corporation Kenilworth, NJ) at a dose of 800-1,200 mg/kg/day in genotypes 1 and 4 and 800 mg/kg/day in genotypes 2 and 3. Three hundred forty-two patients received PEG-IFNα-2a at a dose of 180 μg/week (Pegasys, Roche Corporation, Kenilworth, NJ) and weight-based ribavirin 1,000-1,200 mg/kg/day (Copegus, Roche). Naïve patients infected with genotypes 1, 4, and 5 and all previously treated patients were treated for 48 weeks; naïve patients infected with genotypes 2 and 3 were treated for 24 weeks.
Patients were included if they completed a full course of therapy. All patients with a virological end-of-treatment response defined as undetectable serum and who complied with the W+12 and W+24 posttreatment follow-up schedule for serum HCV-RNA determination were eligible for inclusion. Assessment at the 4-week posttreatment follow-up was optional.
Definition of the Virological Responses.
End-of-treatment virological response was defined as undetectable serum HCV-RNA at the end of therapy. A nonresponse was defined as detectable serum HCV-RNA at the end of treatment. Virological relapse (VR) was defined as undetectable serum HCV-RNA at the end of treatment and detectable serum HCV-RNA at the W+24 posttreatment follow-up. SVR was defined as undetectable serum HCV-RNA at the W+24 posttreatment follow-up.
Serum samples were prospectively evaluated by the VERSANT HCV-RNA Qualitative Assay (HCV Qual [TMA], Siemens Healthcare Diagnostics, Saint Denis, France) with a detection limit of 9.6 IU/mL.20 Serum HCV-RNA was retrospectively quantified by the VERSANT HCV-RNA 3.0 (bDNA) Assay (Siemens Healthcare Diagnostics, Saint Denis, France) (quantification range, 615-7,690,000 IU/mL).21 All serum samples were stored at −80°C within 90 minutes after collection.
Patients' descriptive statistics were reported. Continuous variables are summarized as the mean ± standard deviation, categorical variables as frequency and percentage. Results are expressed as odds ratios with 95% confidence intervals (CIs). Serum samples were tested for the presence or absence of HCV-RNA. The positive predictive value (PPV) was defined as the probability that the outcome of interest (i.e., undetectable serum HCV-RNA) occurs in patients fulfilling the criteria at 12 weeks and 24 weeks after treatment cessation. The comparison of continuous variables at different time points (outcome of posttreatment viral load) was performed using the Wilcoxon signed-rank test.
Of 781 patients, 573 (73%) had an end-of-treatment virological response and were included in the study. At the end of the W+24 posttreatment follow-up, 408 (71%) patients were SVR and 165 (29%) patients had a virological relapse. Response rates and baseline patient characteristics according to treatment schedule are shown in Table 1. Among this cohort, fibrosis stages were: F1, 33%; F2, 33%; F3, 19%; and F4, 15% (Table 1). At the end of therapy, serum alanine aminotransferase levels were 43± 42 IU/mL (range, 8-325) and 45 ± 43 IU/mL (range, 4-337) in SVR and VR patients, respectively (not significant), and 44 ± 44 IU/mL (range, 5-337) and 43 ± 42 IU/mL (range, 8-287) in patients treated with PEG-IFNα-2a and PEG-IFNα-2b, respectively (not significant).
Table 1. Baseline Characteristics of the Patients with an End of Treatment Virological Response
Of the 573 patients with end-of-treatment virological response, 337 (59%) underwent a follow-up visit 4 weeks after treatment cessation. Serum HCV-RNA was undetectable in 252 (74.8%) patients, and 242 of these demonstrated an SVR (PPV 96.0%, 95% CI 93.9-98.1) (Table 2). The PPVs were 95.4% (95% CI 92.0-98.80) and 96.4% (95% CI 93.7-99.0) in patients treated with PEG-IFNα-2a and PEG-IFNα-2b, respectively. A subset of 50 patients had a frozen serum sample available for measurement of both baseline and 4 weeks posttreatment. Serum HCV-RNA levels were: 5.622±0.767 log10 IU/mL (range, 3.062-6.606) and 4.408±1.293 log10 IU/mL (range, 2.585-6.874) at baseline and 4 weeks posttreatment, respectively (P < 0.0001).
Week 12 Posttreatment.
All patients underwent a follow-up visit at week 12 after treatment. Serum HCV-RNA was undetectable in 409 of 573 (71.38%) patients, and 408 of these had an SVR. The PPV for SVR was 99.7% (95% CI 99.1-100) at that time (Table 2). The PPVs were 99.5% (95% CI 98.5-100) and 100% in patients treated with PEG-IFNα-2a and PEG-IFNα-2b, respectively. A subset of 81 patients had a frozen serum sample available for measurement of both baseline and 12 weeks posttreatment. Serum HCV-RNA levels were 5.674 ± 0.706 log10 IU/mL (range, 3.062-6.697) and 5.078 ± 0.744 log10 IU/mL (range, 2.921-6.319) at baseline and12 weeks posttreatment, respectively (P < 0.02).
Week 24 Posttreatment.
All patients underwent a follow-up visit at 24 weeks posttreatment. Serum HCV-RNA was undetectable in 408 of 573 (71.20%) patients, and an SVR was found in all patients (100%) (Table 2). The patient demonstrating a relapse at W+24 (undetectable at W+12) was a 55-year-old genotype 2–naïve patient treated for 24 weeks of the combination therapy PEG-IFNα-2a plus ribavirin. At inclusion serum alanine aminotransferase level was subnormal (1.1 N), serum HCV-RNA load was 5.124 log IU/mL, liver histology showed a moderate liver disease (A2/F2; Metavir scoring system). Serum HCV-RNA was undetectable 12 weeks after treatment initiation. Interestingly, this patient was a sustained responder to a second course of 48 weeks of the combination therapy PEG-IFNα-2a plus ribavirin. A subset of 89 patients had frozen serum samples available for measurement of both baseline and 24 weeks posttreatment. Serum HCV-RNA levels were 5.617 ± 0.752 (range, 3.062-6.606) log10 IU/mL and 5.205 ± 0.744 (range, 2.921-6.319) log10 IU/mL at baseline and 24 weeks posttreatment, respectively (P = 0.001). Serum HCV-RNA level outcome in one typical relapse patient during 36 weeks posttreatment follow-up as shown in Fig. 1.
Serum HCV-RNA Outcome in Relapse Patients.
A subset of 58 patients had frozen serum samples available at baseline, W+12, and W+24 after the end of treatment. Serum HCV-RNA levels were: 5.623 ± 0.748 log10 IU/mL (range, 3.062-6.606), 4.979 ± 0.870 log10 IU/mL (range, 2.585-6.129), and 5.216 ± 0.758 log10 IU/mL (range, 2.921-6.319) at baseline, W+12, and W+24, respectively (P < 0.001) (Fig. 2). These results show that the viral load increases rapidly in relapse patients to nearly reach baseline levels as early as 24 weeks posttreatment.
In this community-based study performed in a large cohort (n = 573) of patients with an end-of-treatment virological response assessed with a sensitive assay (TMA), 408 of 409 patients with undetectable serum HCV-RNA 12 weeks after the end of treatment had an SVR (PPV 99.4%). It is noteworthy that 34% of the patients had advanced fibrosis (19% had bridging fibrosis [stage F3]; 15% had cirrhosis [stage F4]). Viral load showed a trend reverting to basal level as early as 24 weeks after the end of treatment in patients with a relapse.
HCV-RNA testing 24 weeks after the completion of therapy13 is currently the gold standard to assess the success of antiviral therapy in chronic hepatitis C. Patients with undetectable serum HCV-RNA at 24 weeks are considered to have an SVR, which has been associated with persistent eradication of infection.1–4, 15–16 Our results show that testing patients for serum HCV-RNA 12 weeks after completion of therapy (PPV 99.7%) is as informative as testing at 24 weeks to identify an SVR (PPV 100%). These results are similar in patients treated with PEG-IFNα-2a and ribavirin and in patients treated with PEG-IFNα-2b and ribavirin. Identical results were reported in patients treated with standard interferon α-2a or PEG-IFNα-2a.22 These results suggest that the addition of RVB to PEG-IFN enhances the SVR rates but does not affect the timing of relapse. The finding in our study that the PPV of undetectable HCV-RNA reaches 96% as early as 4 weeks after completing therapy, reinforces the observation that VR occurs within the W+12 posttreatment follow-up. Determining serum HCV-RNA 12 weeks after the end of treatment might, therefore, be considered an appropriate time point for the identification of sustained virological response and relapse.
Early determination of posttreatment response status in patients can help make decisions and might allow relapse patients to begin alternative therapy earlier. Our results showing that the viral load increases rapidly after relapse, nearly reaching basal levels within 24 weeks posttreatment, confirm the importance of identifying relapse patients early. Indeed, it is now well established that low baseline viral load is associated with higher SVR rates.23–27 When viral load is still low, patients might benefit from early retreatment with different regimens or from inclusion in controlled trials evaluating new molecules.
In conclusion, testing for HCV-RNA, using the highly sensitive TMA assay, 12 weeks after the end of treatment is as effective as testing at 24 weeks to assess persistent virological response in patients receiving combination PEG-IFN and ribavirin therapy, indicating that posttreatment follow-up to identify patients with SVR or VR could be shortened to 12 weeks posttreatment, providing a new definition of SVR. Reducing the posttreatment follow-up period to 12 weeks from the current standard of 24 weeks could improve patient care and reduce costs associated with the response monitoring. A shorter duration of posttreatment follow-up might accelerate the assessment of the efficacy of new compounds and/or new treatment schedules such as triple therapy and reduce the costs for both patients and society.