Therapeutic Response to Peg IFN-alpha-2b and Ribavirin in HIV/HCV Co-infected African American and Caucasian Patients as a function of HCV Viral Kinetics and Interferon Pharmacodynamics

摘要

In this study we sought to characterize the relationship between several pharmacokinetic (PK) and pharmacodynamic (PD) parameters and virologic responses among HIV/HCV genotype-1 co-infected patients receiving pegylated interferon-alpha-2b (peg-IFN2b) and ribavirin. We also tried to establish the underlying mechanisms that lead to poor SVR rates observed with African Americans (AA) against Caucasians and compared their results with those observed in a cohort of HCV mono-infected patients.Among our studied population, a viral decline of more than 1.0 log at day 3 combined with viral load of less than 5.0 log IU/ml at day 28 predicted SVR with NPV=100% and PPV=100%. AA had significantly (P<0.01) slower HCV VK as compared to Caucasians. However, peg-IFN2b concentrations and PK parameters, peg-IFN2b max and peg-IFN2b half-life, were similar in both groups and did not predict SVR. Nevertheless, the PD parameter Ec50, estimated from non-linear fitting of the viral kinetics together with peg-IFN2b concentration data, showed that HIV/HCV co-infected AA have lower sensitivity to interferon-alpha thus giving rise to slower viral decline. The combined PK/PD parameter IFNmax/Ec90 was excellent predictor of SVR, thus showing the importance to maintain peg-IFN2b levels above Ec90 to achieve successful treatment. Further studies are needed to evaluate whether these pharmacodynamical predictions are a result of differential host response to peg-IFN2b or other viral factors conferring relative resistance to peg-IFN2b.