Background:  To evaluate role of very early viral response in predicting sustained virological response rates to hepatitis C virus (HCV) therapy. Per protocol, 55 HIV/HCV-co-infected and 77 HCV-mono-infected patients completed HCV treatment.

Methods:  For all HIV/HCV-co-infected patients, mean CD4 count was 496 and they were treated for 24 to 48 weeks depending on genotype. Virological response was assessed at weeks 4 (very early viral response), 12 (early viral response), and 24, at end of treatment, and 24 weeks post-completion of treatment (sustained virological response). The primary endpoint was defined as undetectable HCV RNA at 24 weeks post-treatment completion.

Results:  Of the co-infected patients, 56% were on HAART. The majority were male; and 67% achieved sustained virological response (43% genotype 1/4; 82% genotype 2/3), whereas 84% in HCV-mono-infected patients achieved sustained virological response rates (67% genotype 1/4; 94% genotype 2/3). Of co-infected patients, 37 achieved a HCV RNA decline >2 log₁₀, or achieved undetectable levels compared with baseline by week 4. The positive predictive value of very early viral response (week 4) for HIV/HCV-co-infected patients was 92%, the negative predictive value was 88%. Within the mono-infected group, 61 patients achieved a very early viral response; with a positive predictive value of very early viral response of 94%, and a negative predictive value of 83%.

Conclusions:  Achievement of a significant decline in HCV RNA at week 4 is predictive of sustained virological response in this cohort of patients. This may be used to guide optimal treatment duration in patient groups. More significantly, the data serve to highlight the fact that the subgroup of patients who once achieve a very early viral response should be actively supported to complete HCV treatment with full-dose therapy, especially for those HCV/HIV patients infected with G2/3 disease for whom 6 months’ full-dose therapy may be sufficient to obtain a sustained virological response.