778P - Subgroup analyses of a randomized two-by-two factorial phase II trial comparing neoadjuvant chemotherapy with 2 and 4 courses of cisplatin/S-1 (CS) and docetaxel/cisplatin/S-1 (DCS) as neoadjuvant chemotherapy for locally advanced gastric cancer

Abstract

BackgroundNeoadjuvant chemotherapy is promising to improve the survival of locally advanced gastric cancer. However, optimal regimen and duration of treatment have not been established. We previously reported the primary results of COMPASS-D trial (ASCO-GI 2019). Herein, we report the results of subgroup analyses of efficacy by baseline disease characteristics and demographics. MethodsPatients with M0 and either T4 or T3 in case of junctional cancer or schirrhous type received 2 or 4 courses of cisplatin (60mg/m2 at day 8) / S-1 (80mg/m2 for 21 days with 1 week rest) or docetaxel (40mg/m2 at day 1) / cisplatin (60mg/m2 at day 1) / S-1 (80mg/m2 for 14 days with 2 weeks rest) as neoadjuvant chemotherapy. Then, patients underwent D2 gastrectomy and adjuvant S-1 chemotherapy for 1 year. The primary endpoint was 3-year overall survival. Subgroup analysis was performed in each regimen (CS vs DCS) and duration (2 vs 4 courses), stratified by age, gender, esophageal invasion, macroscopic type, histological type, cT, and cN. ResultsBetween Oct 2011 and Sep 2014, 132 patients were assigned to CS (n=66; 33 in 2-courses and 33 in 4-courses) and DCS (n=66; 33 in 2-courses and 33 in 4-courses). The 3-year OS was 58.1% in 2-courses CS, 58.1% in 4-courses CS, 48.5% in 2-courses DCS, and 71.9% in 4-courses DCS. Subgroup analyses were summarized in the table.Table778PTableSubgroupHR of 4-sourses (95%CI)HR of DCS (95%CI)Overall0.77 (0.43-1.22)0.80 (0.48-1.34)Age < 70 y.o.0.82 (0.45-1.52)0.88 (0.48-1.62)Age=> 70 y.o.0.49 (0.17-1.39)0.68 (0.26-1.76)Male0.53 (0.27-1.05)0.81 (0.42-1.54)Female1.22 (0.51-2.90)0.79 (0.33-1.87)Esophageal invasion-0.72 (0.40-1.31)0.71 (0.39-1.27)Esophageal invasion+0.73 (0.24-2.17)1.06 (0.36-3.16)Schirrhous or large Type30.47 (0.22-1.00)0.82 (0.41-1.63)Non schirrous or large Type30.74 (0.23-2.41)0.50 (0.13-1.87)Differentiated0.37 (0.08-1.66)0.38 (0.09-1.71)Undiffirentiated0.66 (0.32-1.36)1.24 (0.63-2.43)cT3 or T4a0.66 (0.38-1.17)0.76 (0.44-1.32)cT4bN/A2.33 (0.26-21.4)cN00.77 (0.32-1.86)0.74 (0.31-1.80)cN+0.66 (0.34-1.27)0.87 (0.46-1.66) ConclusionsThe DCS regimen and duration 4-courses showed a beneficial tendency as a neoadjuvant setting regardless of disease characteristics and demographics. The 4-courses DCS is widely applicable to future phase III study to confirm of neoadjuvant chemotherapy for locally advanced gastric cancer. Clinical trial identificationUMIN000006378. Legal entity responsible for the studyThe authors. FundingThe Nongovermental Organization, Kanagawa Standard Anti-cancer Therapy Support System. DisclosureAll authors have declared no conflicts of interest.