The treatment response of chronically hepatitis C virus-infected patients depends on interferon concentration but not on interferon gene expression in peripheral blood mononuclear cells.

The current treatment of chronic hepatitis C is based on pegylated alpha interferon (PEG-IFN-α) and ribavirin. The aim of this study was to identify biological and clinical variables related to IFN therapy that could predict patient outcome. The study enrolled 47 patients treated with PEG-IFN and ribavirin combined therapy. The interferon concentration was measured in serum by a bioassay. The expression of 93 interferon-regulated genes in peripheral blood mononuclear cells was quantified by real-time quantitative reverse transcription-PCR (RT-PCR) before and after 1 month of treatment. The interferon concentration in the serum was significantly lower in nonresponders than in sustained virological responders. Moreover, a significant correlation was identified between interferon concentration and interferon exposition as well as body weight. The analysis of interferon-inducible genes in peripheral blood mononuclear cells among the genes tested did not permit the prediction of treatment outcome. In conclusion, the better option seems to be to treat patients with weight-adjusted PEG-IFN doses, particularly for patients with high weight who are treated with PEG-IFN-α2a. Although the peripheral blood mononuclear cell samples are the easiest to obtain, the measurement of interferon-inducible genes seems not be the best strategy to predict treatment outcome.

A new tool to study ribavirin-induced haemolysis.

BACKGROUND: Today, treatment of chronic hepatitis C is based on a synergistic combination of pegylated interferon and ribavirin with antiprotease inhibitors. Haemolytic anaemia, which is the major side effect of ribavirin treatment, disrupts ribavirin treatment compliance and varies significantly from one patient to another. There is an individual susceptibility to ribavirin haemolysis. With a view to studying haemolysis, and thus optimizing the treatment response, we have developed a new in vitro tool for analysing the ribavirin-induced lysis of red blood cells. METHODS: Resuspended red blood cells were incubated with isotonic buffer and a range of concentrations of ribavirin. Haemolysis was quantified by spectrophotometric measurement of the supernatant at 540 nm. The assay was used to test the effects of various compounds and to investigate the susceptibility of patients to haemolytic anaemia. RESULTS: In our assay, the degree of haemolysis is dependent on the ribavirin concentration used and can be inhibited by the addition of dipyridamole (50% inhibitory concentration [IC(50)] 30 µM), ATP or glutathione (IC(50) 1.63 mM and 767 µM, respectively). We observed a strong decrease in red blood cell haemolysis in the presence of the ribavirin prodrug viramidine (Taribavirin(®)). When testing the performance of this assay with blood from 24 patients before treatment, we observed a strong correlation between in vitro haemolysis before treatment and the decrease in haemoglobin levels seen in vivo during subsequent treatment (P<0.001). CONCLUSIONS: With this new tool it is possible to better evaluate individual susceptibility to ribavirin-induced haemolysis before the start of treatment. In addition, this model will enable the mechanism of ribavirin-induced anaemia to be further explored and allow molecules that could reduce ribavirin haemolysis to be screened and tested in vitro. This approach could help optimize current and future therapeutic strategies involving ribavirin in the treatment of chronic hepatitis C.