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.