Preliminary Results of International Trial
Speaking at the satellite symposium (see p 1), Dr. Stephanos Hadziyannis (Hippokration Hospital, Athens, Greece) presented preliminary data from an ongoing multicenter, international, open-label clinical trial designed to evaluate the efficacy of daily induction dosing with IFN alfa-2b in previously untreated (naive) patients infected with HCV. The aim of the study is to evaluate the effect of daily IFN alfa-2b induction therapy versus standard three-times-weekly (TIW) therapy on viral clearance and load and to identify whether a dose response occurs with IFN alfa-2b using these regimens. This study also will evaluate the efficacy of IFN alfa-2b/ribavirin combination therapy; these results are not yet available.
Patients enrolled in this trial received IFN alfa-2b (3-, 5-, or 10-MU doses) given either in the standard TIW regimen or daily for 2-4 weeks. A central virology laboratory (National Genetics Institute, California, USA) was used to quantitate viral load in all patients enrolled in the study; the technique used to determine viral load has a level of quantitiation of 100 viral copies/mL. Viral titers were obtained frequently in each patient during the first week (baseline and at 12, 24, 48, 72, 120, and 168 hours) and twice weekly during the remaining 3 weeks of the induction period. Preliminary data were available on 62 patients. Although there was some genotype imbalance because of the limited enrollment to date across the multiple arms of the study, baseline viral loads were similar among the treatment groups.
Overall, daily IFN dosing resulted in better viral suppression compared with TIW dosing. Although patients receiving TIW dosing with either 3, 5, or 10 MU demonstrated a moderate decline in viral load, virus remained detectable at the end of week 4 in the majority of these patients. Daily dosing resulted in much greater declines in HCV RNA; by week 2, patients receiving daily doses demonstrated a 2- to 3-log decline in viral load and virus was not detectable in some patients. At week 4, similar declines were observed. These preliminary findings seem to demonstrate that daily IFN alfa-2b dosing produces an earlier and more pronounced reduction in viral load (Figure 1). Further, higher doses seem to result in better viral suppression. When comparing HCV RNA reduction for similar total doses administered over 4 weeks, it was apparent that daily dosing was more effective than higher TIW dosing in decreasing viral load (Table 1), suggesting that the dose effect was related to the administration schedule.
No patient required dose interruption or reduction. The most frequent adverse event reported was low-grade fever (grade 1: 30/62 patients; grade 2: 13/62). Grade 1/2 myalgia and depression each were reported infrequently (8/62 and 4/62, respectively). While there were no toxicity differences between the daily and TIW treatment arms, Dr. Hadziyannis commented that patients receiving daily therapy seemed to tolerate IFN better and that patients going to TIW therapy after daily dosing preferred daily dosing. It is hypothesized that this might be due to achievement of steady-state IFN levels rather than constantly fluctuating levels.
These preliminary results demonstrate that daily dosing produces an earlier and more pronounced decrease in viral load compared with TIW dosing. There appeared to be a trend for improved response with higher daily doses. In patients infected with HCV genotype 1b, there was a significant reduction in viral load only when doses of 5 or 10 MU daily were used. Daily IFN alfa-2b dosing also was effective in patients infected with HCV genotype 1b. Of the 6 patients infected with HCV genotype 1 b who received IFN alfa-2b 5 or 10 MU daily, 4 had undetectable HCV RNA levels at the end of the induction period; another patient experienced a 3- to 4-log decline in viral load during this time period. Accrual to the study is continuing, and additional data will be subsequently reported.
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