Phase II feasibility study of adjuvant S-1 plus CPT-11 for stage III gastric cancer patients after curative D2 gastrectomy (OGSG 0801).

Abstract

142 Background: An adjuvant chemotherapy with S-1 has become the standard treatment for patients (pts) with stage II/III gastric cancer (GC) in Japan. But, it is assumed that the survival benefit for stage III pts who received S-1 is modest. S-1 plus CPT-11 has not shown the superiority in median overall survival (OS), but shown the well response rate (56%) and tolerability in Phase III trial (TOP-002 study). The aims of this phase II study were to evaluate the feasibility and safety of adjuvant S-1 plus CPT-11 in pts with stage III GC who underwent D2 surgery. Methods: Pts with pathological stage IIIA and IIIB GC who underwent gastrectomy D2 dissection, age 20-75 years, performance status < 1, and informed consent received oral S-1 (80 mg/m2/day) administration for consecutive 3 weeks and intravenous CPT-11 (80 mg/m2) on day 1, 15, repeated every 5 weeks (1 cycle). The treatment was repeated for 4 cycles, followed by S-1 administration until 1 year after surgery. The primary endpoint was feasibility of the 4 cycles administration of S-1 plus CPT-11. Results: We enrolled forty-five pts, 22 males and 23 females with a median age of 61 years, between December 2008 and April 2010. Pathological stages included IIIA in 25 pts and IIIB in 20 pts. The feasibility of planned 4 cycles of treatment was 62.2% (95% CI 46.5-76.2%, p=0.068) with 28 pts out of 45 pts. Non-hematological toxicities of grade 3 or more involved diarrhea in 13%, anorexia in 16%, nausea in 7% and vomiting in 4%. No Grade 4 toxicities were observed. Conclusions: Adjuvant S-1 plus CPT-11 therapy had moderate hematological toxicities, but observed several severe non-hematological toxicities. Therefore, predicted feasibility was not achieved. Although the follow-up period is too short to evaluate OS and feasibility of S-1 administration, it is hoped that this regimen will be a candidate for future phase III trial seeking for the optimal adjuvant chemotherapy for stage III GC pts after D2 dissection if OS will be improved.