Pegylated interferon fractal pharmacokinetics: individualized dosing for hepatitis C virus infection.

Despite recent advances in hepatitis C virus (HCV) therapeutics, the combination of pegylated interferon and ribavirin (PEGIFN/RBV) remains the cornerstone of treatment. Optimization and individualization of PEGIFN dosing could improve outcomes. Week one PEGIFN serum concentrations in 42 HCV genotype 1-infected patients treated with conventional PEGIFN/RBV were analyzed using multicompartmental pharmacokinetic models. For each patient, pharmacokinetic parameter estimates, weight, age, interleukin-28B (IL-28B) single-nucleotide polymorphism, CD4 count, baseline HCV RNA, gender, race, and HIV status were examined using classification and regression tree analysis to identify factors predictive of sustained viral response (SVR). Survival analysis was performed to compare the time to undetectable viral load in patients with and without the highest scoring predictor. PEGIFN concentrations varied at least 87-fold. Pharmacokinetics were best described by a two-compartment model with an 8.4-h absorption lag. Patient weight correlated with PEGIFN systemic clearance based on fractal geometry relationships. SVR was achieved in 36% of patients; a PEGIFN cumulative 1-week area under the curve (AUC) of ≤0.79 mg · h/liter scored highest in predicting poor response, followed by a weight of ≥93.7 kg. Patients with a PEGIFN AUC of >0.79 mg · h/liter achieved undetectable viral load more rapidly than those with a lower AUC (hazard ratio, 1.63; 95% confidence interval, 1.21 to 2.04). PEGIFN exhibits wide pharmacokinetic variability, mainly driven by patient weight, so that the standard dose may not reach levels needed to achieve SVR. Optimizing dose to patient weight and PEGIFN AUC in the first week offers a solution to improve SVR and to potentially shorten duration of therapy.

A single nucleotide polymorphism in IL28B affects viral evolution of hepatitis C quasispecies after pegylated interferon and ribavirin therapy.

Interleukin-28B (IL28B) polymorphisms are associated with viral response to peginterferon and ribavirin (RBV) in chronic hepatitis C (HCV). Their recognition represents a breakthrough in the understanding of the role of the host in viral eradication. How these polymorphisms determine viral eradication is unknown. The IL-28B variants are hypothesized to have a differential impact on HCV quasispecies evolution during treatment with pegylated interferon (PEG-IFN) and RBV. In this study, HCV RNA levels were measured at early time points in 33 naïve genotype 1 hepatitis C patients and clonal analysis of the entire NS5A region was performed on sera from baseline and Day 7. Site rs12979860 polymorphisms were determined by direct sequencing of PCR products and classified into CC, CT, and TT and were identified in 13, 11, and 9 patients, respectively. The CC polymorphism more commonly was seen in Whites versus Blacks [12/21 (57%) vs. 1/12 (8%), P = 0.009] and HIV-infected versus mono-infected [13/25 (52%) vs. 0/8 (0%), P = 0.009]. Patients with CC and non-CC had similar baseline viral loads. More patients with the CC polymorphism had amino acid substitutions in NS5A compared to non-CC patients. Despite similar baseline viral diversity, by Day 7, significantly more patients with CC had higher non-synonymous substitution values compared to non-CC (P = 0.02). Chronic hepatitis C patients with the CC IL28B polymorphism have a higher number of amino acid substitutions in the NS5A region and early viral evolution due to greater interferon induced selective pressure during this critical period of treatment.

Faldaprevir and pegylated interferon α-2a/ribavirin in individuals co-infected with hepatitis C virus genotype-1 and HIV.

OBJECTIVE: Faldaprevir is a potent, once-daily hepatitis C virus (HCV) NS3/4A protease inhibitor. STARTVerso4 assessed the efficacy and safety of faldaprevir and response-guided pegylated interferon α-2a/ribavirin (PegIFN/RBV) in individuals with HCV/HIV co-infection. DESIGN: A phase 3 open-label study (NCT01399619). METHODS: Individuals (N = 308) co-infected with HCV genotype 1 (treatment-naive or prior interferon relapsers) and HIV [96% on antiretroviral therapy (ART)] received faldaprevir 120 mg (N = 123) or 240 mg (N = 185) and PegIFN/RBV. Those receiving a protease inhibitor or efavirenz ART were assigned to faldaprevir 120 or 240 mg, respectively. Individuals achieving early treatment success (ETS; HCV RNA <25 IU/ml at week 4 and undetectable at week 8) were randomized to 24 or 48 weeks of PegIFN/RBV. The primary endpoint was sustained virologic response 12 weeks after treatment (SVR12). RESULTS: SVR12 was achieved in 221 (72%) individuals, and the rates were comparable across faldaprevir doses. ETS was achieved in 80%, and of these 86% achieved SVR12, with comparable rates with 24 and 48 weeks of PegIFN/RBV (87 and 94%, respectively). In multivariate analysis, age below 40 years, IL28B CC genotype, and baseline HCV RNA below 800 000 IU/ml were associated with SVR12 (P = 0.027, P < 0.0001, and P = 0.0002, respectively), whereas treatment (ART regimen and faldaprevir dose), liver cirrhosis, and genotype 1 subtype were not. The safety profile was comparable to that of faldaprevir in HCV-monoinfected individuals. CONCLUSIONS: High SVR12 rates were achieved with faldaprevir and PegIFN/RBV in HIV/HCV co-infected individuals, regardless of faldaprevir dose and background ART, HCV genotype 1 subtype, or cirrhosis status. SVR rates mirrored those obtained with similar regimens in HCV monoinfected individuals.

Role of ribavirin in HCV treatment response: now and in the future.

IMPORTANCE OF THE FIELD: Ribavirin is a broad spectrum antiviral agent that is used with pegylated IFN (Peg-IFN) for HCV treatment. Ribavirin does not significantly reduce HCV viral load when used alone but increases rates of sustained virologic response (SVR) when combined with Peg-IFN. HCV genotype 1 infected patients require higher doses of ribavirin administered for a longer duration of time versus HCV genotypes 2 and 3 patients who respond effectively to Peg-IFN with lower doses of ribavirin and shorter duration of therapy. Higher serum concentrations of ribavirin are associated with higher response rates but also higher rates of hemolytic anemia which is a dose limiting side effect. Alternatives to current therapy are under clinical evaluation. AREAS COVERED IN THIS REVIEW: Systematic literature review of ribavirin use in HCV patients from 1995 to 2009 was conducted. WHAT THE READER WILL GAIN: To review the efficacy and safety of ribavirin in current HCV treatment and in new therapies in Phase III clinical trials. TAKE HOME MESSAGE: Ribavirin is a drug which is essential to produce higher SVR rates both with Peg-IFN and HCV protease inhibitors currently in Phase III clinical trials. Thus, ribavirin is and will remain an important drug to achieving higher SVR rates in HCV infected persons.

Pegylated interferon and ribavirin promote early evolution of nonstructural 5A protein in individuals with hepatitis C who demonstrate a response to treatment.

BACKGROUND: Hepatitis C virus (HCV) quasispecies diversity is more likely to affect early viral decline during treatment of hepatitis C than is having human immunodeficiency virus (HIV) infection. We evaluated the influence of HCV therapy on changes in the nonstructural 5A (NS5A) protein. METHODS: Fifteen patients with HCV genotype 1 infection with or without HIV infection were recruited for the present study, and the decrease in the HCV RNA level was measured at early time points. The evolution of HCV NS5A quasispecies within the first week was analyzed by comparing the clones observed at later times in the study with the baseline consensus sequence of individual patients. The response to therapy was defined as an early response (ER; ie, an HCV RNA level <615 IU/mL at week 4) or a slow response (SR; ie, a detectable HCV RNA level at week 4). RESULTS: HIV infection did not affect early viral kinetics. At baseline, lower diversity was seen in NS5A and in the amino and carboxyl termini of patients with an ER, compared with those with an SR. Rapid evolution of the NS5A genetic region occurred in patients with an ER (P = .01) but not in those with an SR (P = .73). The evolution was the result of an increase in the number of amino acid substitutions in the carboxyl region (P = .02) in patients with an ER. CONCLUSIONS: Selective pressure appears to result in more-marked changes in individuals with an ER than in those with an SR. The carboxyl terminus was subject to the most change and may be an important determinant of phenotypic resistance to interferon-based therapy.

Gamma/Delta T cell mRNA levels decrease at mucosal sites and increase at lymphoid sites following an oral SIV infection of macaques.

The oral and esophageal mucosa have been identified as possible sites of HIV/SIV entry following oral infection. Here, gamma/delta (gammadelta) T cells, a multi-functional T cell subset, were assessed at oral/esophageal mucosa and lymphoid sites at the earliest times (1-14 days) post-oral SIV inoculation utilizing quantitative RT-PCR. During these earliest times post-infection, decreased gammadelta TCR mRNA levels were observed at the oral gingiva and esophageal mucosa, while increased levels were observed within regional lymph nodes (cervical and retropharyngeal). Higher lymph node gammadelta TCR levels were associated with increased mRNA expression of the lymphoid homing chemokine/receptor (CCL21/CCR7) pair in these lymph nodes. In contrast to gammadelta TCR levels, CD4 mRNA expression remained relatively stable through 4 days post-infection, and depletion of CD4 T cells was only evident after 7 or 14 days post-infection. The decrease of gammadelta T cell mRNA from mucosal sites and the corresponding increase at lymphoid sites suggest a rapid redistribution of these immune cells at these earliest times post-SIV infection.