Schering-Plough Reports Top-Line Results Of IDEAL Study
Schering-Plough Corporation reported top- line results of the IDEAL study, the first large, randomized, clinical study comparing the leading therapies for chronic hepatitis C: PEGINTRON (peginterferon alfa-2b) and REBETOL (ribavirin, USP) combination therapy vs.
Pegasys (peginterferon alfa-2a) and Copegus (ribavirin, USP) combination therapy,(1) as well as a lower dose of PEGINTRON in an investigational combination regimen. The results showed that sustained virologic response (SVR),(2) the primary endpoint of the study, was similar for the two leading combination therapies for hepatitis C; and that using a lower dose of PEGINTRON with REBETOL also resulted in a similar SVR. The study also showed that fewer patients treated with both PEGINTRON regimens relapsed after the end of treatment compared to those receiving Pegasys and Copegus.
In the IDEAL (Individualized Dosing Efficacy vs. Flat Dosing to Assess optimaL pegylated interferon therapy) study, both PEGINTRON regimens utilized investigational weight-based ribavirin dosing. The three treatment regimens studied were:
(1) PEGINTRON 1.5 mcg/kg/week and REBETOL 800-1,400 mg/day;
(2) PEGINTRON 1.0 mcg/kg/week and REBETOL 800-1,400 mg/day; and
(3) Pegasys 180 mcg/week and Copegus 1,000-1,200 mg/day
In the study, 3,070 previously untreated U.S. patients with HCV genotype 1, the most common form of the virus worldwide and most difficult to treat, were randomized to one of the three treatment regimens and received up to 48 weeks of combination therapy with 24 weeks of follow-up. SVR, the primary endpoint of the study, was similar for the three treatment regimens (40 vs. 38 vs. 41 percent, respectively).
Importantly, while end of treatment response was higher in the Pegasys combination therapy arm, IDEAL showed that fewer patients receiving PEGINTRON combination therapy relapsed after the end of treatment (24 vs. 20 vs. 32 percent, respectively).
Overall adverse events reported for the three treatment regimens were similar and, as seen in other studies with these treatments, a range of "flu- like symptoms" were the most commonly reported adverse events for all three treatment regimens. Discontinuation rates due to adverse events also were similar (13 vs. 10 vs. 13 percent, respectively).
"While the sustained response rates were similar in the IDEAL study, we were pleased to see that fewer patients relapsed following PEGINTRON combination therapy," said Robert J. Spiegel, M.D., chief medical officer and senior vice president, Schering-Plough Research Institute. "With these results, we now have, for the first time, a large body of well-controlled clinical data demonstrating how the similarities and differences of the two leading combination therapies for hepatitis C affect outcomes for patients. These findings provide important clinical-based evidence that will help physicians in making treatment decisions and in guiding their patients through what is a long and challenging course of therapy. We look forward to further analyses of this large data set to gain additional clinical insights into the management of this serious disease."
In IDEAL, the combination regimen of Pegasys and Copegus used the recommended doses in accordance with their approved U.S. labeling, which includes a flat dose of Pegasys (180 mcg/week) for all patients regardless of body weight, and 1,000 or 1,200 mg/day of Copegus, adjusted for two weight categories. PEGINTRON was dosed either at 1.5 mcg/kg/week or an investigational combination dose of 1.0 mcg/kg/week with REBETOL at an investigational dose of 800-1,400 mg/day, adjusted by four weight categories. As a result, the majority of patients (1598/3070, 52 percent) were assigned the same dose of ribavirin (either REBETOL or Copegus) based on their weight groups. In the study, 39 percent of patients in the Pegasys arm were assigned a higher dose of ribavirin, while 9 percent of patients in the PEGINTRON arms were assigned a higher dose of ribavirin. Among those who were assigned equivalent doses of ribavirin based on their weight group, SVR also was similar (40 vs. 38 vs. 38 percent, respectively). Also, fewer of these patients treated with PEGINTRON and REBETOL relapsed after the end of therapy compared with those treated with Pegasys and Copegus (22 vs. 20 vs. 35 percent, respectively).