Henry Masur

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

Method: In this study we sought to characterize the relationship between several pharmacokinetic and pharmacodynamic parameters and virologic responses among HIV/hepatitis C virus 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 sustained virologic responder rates observed with African-Americans against Caucasians and compared their results with those observed in a cohort of hepatitis C virus mono-infected patients. Results: 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 sustained virologic responders with negative predictive value 100% and positive predictive value 100%. African-Americans had significantly (P < 0.01) slower hepatitis C virus viral kinetics as compared to Caucasians. However, peg-IFN2b concentrations and pharmacokinetic parameters, peg-IFN2bmax and peg-IFN2b half-life, were similar in both groups and did not predict sustained virologic responders. Nevertheless, the pharmacodynamic parameter EC50, estimated from nonlinear fitting of the viral kinetics together with peg-IFN2b concentration data, showed that HIV/ hepatitis C virus co-infected African-Americans have lower sensitivity to interferon-alpha thus giving rise to slower viral decline. The combined pharmacokinetic/pharmacodynamic parameter IFNmax/EC90 was an excellent predictor of sustained virologic responders, thus showing the importance of maintaining peg-IFN2b levels above EC90 to achieve successful treatment. Conclusion: Further studies are needed to evaluate whether these pharmacodynamic predictions are a result of differential host response to peg-IFN2b or other viral factors conferring relative resistance to peg-IFN2b.

Rapid changes in peripheral lymphocyte concentrations during interferon-free treatment of chronic hepatitis C virus infection

Treatment of chronic hepatitis C virus (HCV) infection with direct‐acting antivirals results in a rapid decline in viral load and markers of hepatic inflammation, including serum chemokine (C‐X‐C motif) ligand 10 (CXCL10) concentration, which is followed in most cases by a sustained virologic response. Whether parallel changes of significance occur in the cellular composition of peripheral blood is relatively unknown. We hypothesized that longitudinal characterization of peripheral blood during treatment would provide insight into cellular migration and immune activation, which would have implications for understanding host immunity both before and after HCV treatment and may relate to HCV clearance. We analyzed longitudinal peripheral innate and adaptive immune cell populations by flow cytometry from 95 subjects enrolled in two direct‐acting antiviral clinical trials and examined chemokine receptor expression on T lymphocytes in 43 patients. Within 1‐2 weeks of initiating treatment, significant increases were observed in the concentration of peripheral cluster of differentiation 4–positive (CD4+) and CD8+ T lymphocytes but not monocyte or natural killer cells. In tandem with these changes, the percent of both CD4+ and CD8+ T lymphocytes with an activated phenotype (human leukocyte antigen [HLA] DR+ and CD38+) decreased, and T‐lymphocyte surface expression of chemokine (C‐X‐C motif) receptor 3, the chemokine receptor for CXCL10, increased. Conclusion: Rapid changes in peripheral cellular populations occur during direct‐acting antiviral treatment of HCV infection, which could potentially relate to hepatic efflux of tissue lymphocytes due to altered inflammation and chemokine receptor signaling, providing critical insight into the relationship between host immunity and viral clearance during HCV infection. (Hepatology Communications 2017;1:586–594)