786P - Primary results of multicenter phase II study of neoadjuvant chemotherapy with S-1 and oxaliplatin for locally advanced gastric cancer (Neo G-SOX PII)

Abstract

BackgroundPrognosis for locally advanced gastric cancer (LAGC), such as clinical T4 disease, bulky nodal metastases, type 4 and large type 3 gastric cancer, was not satisfactory even by D2 gastrectomy followed by adjuvant chemotherapy. Neoadjuvant chemotherapy is another promising approach. We conducted a multi-institutional, single-arm, open label, phase II study (Clinical trial information: UMIN000018661). The aim of this study was to evaluate the efficacy and safety of the neoadjuvant chemotherapy of G-SOX followed by gastrectomy with D2/3 lymph node dissection for LAGC. MethodsEligibility criteria included histologically proven adenocarcinoma of the stomach; clinical T4; clinically resectable gastric cancer of type 4 or large type 3 (over 8cm); bulky nodal metastases around major branched arteries to the stomach; resectable peritoneal dissemination (pathological CY1 or P1, except for clinical CY1 or P1). Patients received two cycles of neoadjuvant chemotherapy with S-1 (80mg/m2, p.o., days 1-14 followed by 1 week rest) and oxaliplatin (130mg/m2 at day 1), followed by D2 or higher surgery with no residual disease. Patients with pathological R0/1 resection received S-1 (80mg/m2, p.o., days 1-28 followed by 2 week rest) for 1 year as adjuvant chemotherapy. Primary endpoint was curative resection rate. ResultsForty-one patients were enrolled from 11 institutions. Of the patients, 39 patients (95%) completed the two courses of neoadjuvant chemotherapy of G-SOX, 37 (90%) received gastrectomy, and 36 (87.8%) received curative resection (R0/1). Pathological response rate after neoadjuvant chemotherapy of G-SOX was 40.5%. Most frequent drug-related adverse events during neoadjuvant chemotherapy of G-SOX were anemia (76%), neutropenia (66%), anorexia (63%) and peripheral sensory neuropathy (63%). No treatment related deaths were observed. ConclusionsNeoadjuvant chemotherapy of G-SOX is a feasible and one of the promising strategies for patients with LAGC. Clinical trial identificationUMIN000018661. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureH. Satake: Honoraria (self): Taiho; Honoraria (self): Yakult. M. Kotaka: Honoraria (self): Taiho; Honoraria (self): Yakult. T. Kato: Honoraria (self): Taiho; Honoraria (self): Yakult. A. Tsuji: Honoraria (self): Taiho; Honoraria (self): Yakult. All other authors have declared no conflicts of interest.