Three-Year Outcomes of a Phase II Study of Perioperative Capecitabine Plus Oxaliplatin Therapy for Clinical SS/SE N1-3 M0 Gastric Cancer (OGSG 1601)

BACKGROUND: We previously reported the good feasibility and favorable efficacy of perioperative capecitabine plus oxaliplatin (CapeOx) in patients (pts) with clinical T3(SS)/T4a(SE) N1-3 M0 gastric cancer (GC) in a phase II study in which the pathological response rate, the primary endpoint, of 54.1% was demonstrated. Here, we report 3-year follow-up data. METHODS: The eligibility criteria included clinical T3(SS)/T4a(SE) N1-3 M0 GC according to the Japanese Classification of Gastric Carcinoma-3rd English Edition (JCGC). Three cycles of neoadjuvant CapeOx (capecitabine, 2000mg/m(2) for 14 days; oxaliplatin, 130mg/m(2) on day 1, every 3 weeks) were administered, followed by 5 cycles of adjuvant CapeOx after D2 gastrectomy. Three-year overall survival and relapse-free survival are presented here, and analyzed by cohorts based on pathologic response rate (pRR). RESULTS: Thirty-seven pts were enrolled from July 2016 to May 2017, and fully evaluated for efficacy and toxicity. Thirty-three pts (89.2%) completed the planned three cycles of neoadjuvant CapeOx and underwent gastrectomy, with an R0 resection rate of 78.4% (n = 29). 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. Further, the 3-year OS rate in pts with pathological response of grade 1a (n = 13) and grade 1b or higher (n = 20) was 69.2% (95% CI: 48.2-99.5%) and 100.0%, respectively, based on JCGC. Pathological response rate was classified according to JCGC as follows: grade 0, the tumor was not affected; grade 1a, less than one-third of the tumor was affected; grade 1b, one to two thirds of the tumor was affected; grade 2, greater than or equal to two thirds was affected; and grade 3, no residual tumor. A pathological response was defined as grade 1b or greater. CONCLUSION: Perioperative CapeOx showed good feasibility and favorable prognosis, especially in pts with pathological response of grade 1b or higher and was found to be useful in predicting prognosis. The data obtained using this novel approach warrant further investigation (Trial ID: UMIN000021641, jRCTs051180109).