Kawabata, Ryohei

203 Background: D2 gastrectomy followed by adjuvant S-1 is one of the standard therapy for the patients (pts) with stage III gastric cancer (GC) in Japan; however, the outcome is not satisfactory. We examined the efficacy of perioperative capecitabine and oxaliplatin (CapeOx) in pts with clinical SS/SE N1-3 M0 GC. Methods: The eligibility criteria included histopathologically confirmed clinical T3(SS)/T4a(SE) N1-3 M0 GC according to the Japanese Classification of GC (JCGC; 3rd English Edition). Three cycles of neoadjuvant CapeOx (NAC; capecitabine, 2,000 mg/m2 for 14 days; oxaliplatin, 130 mg/m2 on day 1, every 3 weeks) were administered, followed by five cycles of adjuvant CapeOx after D2 gastrectomy. The primary endpoint was the pathological response rate (pRR) according to JCGC ( ≥Grade 1b). Results: Thirty-seven pts were enrolled from April 2016 to May 2017, and fully evaluated for efficacy and toxicity. Thirty-three pts (89.2%) completed the planned three cycles of NAC and underwent gastrectomy, with an R0 resection rate of 78.4% (n = 29) and a pRR of 54.1% (n = 20, p = .058; 90% confidence interval [CI], 39.4–68.2) were demonstrated. The relative dose intensity (RDI) of capecitabine and oxaliplatin were 90.5% and 91.9%, respectively. Among 27 pts who initiated AC, 21 (63.6%) completed the treatment, and the RDI of capecitabine and oxaliplatin were 80.9% and 65.1%, respectively. Grade 3–4 toxicities during NAC included neutropenia (8%), thrombocytopenia (8%), and anorexia (8%) and during AC included neutropenia (37%), diarrhea (4%), and anorexia (4%), but no treatment-related death was reported. The overall survival (OS) rate and relapse free survival (RFS) rate at 3 years was 83.8% (95% CI, 72.7-96.5%) and 73.0% (95% CI, 60.0-88.8%), respectively. Subgroup analyses according to residual tumor after surgery (R status) showed a 3-year OS and RFS rate of 86.2% (95% CI, 74.5-99.7%) and 75.7% (95% CI, 63.0-90.8%) for R0. Conclusions: Perioperative CapeOx showed good feasibility and favorable prognosis with sufficient pathological response, although statistical significance at .058 did not reach the commonly accepted cutoff of .05. The data obtained using this novel approach warrant further investigations. Clinical trial information: 000021641.

102 Background: This phase II study aimed to investigate the safety and efficacy of XP compared to SP in the first-line treatment of HER2 negative AGC. Methods: Patients were randomly assigned to receive either SP (S-1 at 40–60 mg twice daily for 21 days plus cisplatin at 60 mg/ m2 on day 8, every 5 weeks) or XP (capecitabine 1,000 mg/m2 twice daily for 14 days plus cisplatin 80 mg/m2 on day 1, every 3 weeks). Primary endpoint was response rate (RR), and secondary endpoints were progression-free survival (PFS), overall survival (OS), time to treatment failure (TTF), and adverse events. Results: 84 eligible patients were randomly assigned to receive SP ( N = 41) or XP ( N = 43). No statistical difference was observed in overall RR between the SP and XP groups [51.2% (95% CI, 35.1% to 67.1%) vs. 53.5% (95% CI, 37.7% to 68.8%), P = 1.000]. Despite not significant, however, SP vs. XP showed a trend toward better PFS [median, 5.9 months vs. 4.1 months; hazard ratio (HR), 0.763; 95% CI, 0.462 to 1.259; P = .284] and OS (median, 13.5 months vs. 10.0 months; HR, 0.776; 95% CI, 0.485 to 1.244; P = .290). This trend in the SP vs. XP comparison was more pronounced in TTF (median, 4.5 months vs. 3.1 months; HR, 0.651; 95% CI, 0.421 to 1.006; P = .052). Common grade 3 to 4 hematological toxicities were neutropenia and anemia (SP group, 23% and 23%; XP group, 35% and 28%). Grade 3-4 anorexia and hyponatremia were more frequently seen in the XP group (31% and 16%) compared to the SP group (13% and 5%). Treatment-related deaths occurred in one patient (2.3%) in the XP group. Conclusions: XP failed to demonstrate the superior efficacy over SP. Higher incidence of severe toxicities by XP suggests SP as the standard 1st line chemotherapy for HER2 negative AGC in Japan. Clinical trial information: UMIN000006755.