Irinotecan plus S-1 (IRIS) versus S-1 alone as first line treatment for advanced gastric cancer: Preliminary results of a randomized phase III study (GC0301/TOP-002)

Abstract

4525 Background: Irinotecan has single agent activity and combination activity with S-1 reportedly in phase I/II studies with advanced gastric cancer patients (pts). S-1, oral fluoropyrimidine, also has activity on gastric cancer. A multicenter, randomized phase III trial comparing IRIS to S-1 alone in advanced gastric cancer was conducted. Methods: Pts with previously untreated gastric cancer were randomized to Arm A (oral S-1 80 mg/m 2 /day from day 1 to 28 followed by a 14-day rest period), or Arm B (oral S-1 80 mg/m 2 /day from day 1 to 21 and intravenous irinotecan 80 mg/m 2 on days 1 and 15 followed by a 14-day rest). Treatment was continued unless disease progression was observed. Inclusion criteria: PS (ECOG) of 0 to 2; adequate major organ functions. Primary endpoint was overall survival. Results: From June 2004 to November 2005, 326 pts were randomized to arm A (162 pts) and arm B (164 pts). Pts characteristics (arm A vs. arm B) were as follows: median age: 63 vs. 63 years, PS 0–1: 97% vs. 97%, and distribution of subtype of intestinal/diffuse/others: 44%/55%/1% vs. 41%/58%/1%. Among 187 RECIST-evaluable pts (93 vs 94) reviewed by independent review panel, best response rates were 26.9% for arm A and 41.5% for arm B(p=0.035). Among 319 toxicity-evaluable patients (161 vs 158), grade 3 or 4 toxicities for arm A vs arm B (% of pts) were as follows: neutropenia 9.3% vs 26.6%, diarrhea 5.6% vs 15.8%, anorexia 9.9% vs 15.8%, nausea 3.7% vs 7.0%, vomiting 0.6% vs 2.5%. Conclusions: IRIS is effective, and well tolerated in pts with advanced gastric cancer. Survival analysis is underway. No significant financial relationships to disclose.