Phase I study of neoadjuvant chemotherapy with S-1 and oxaliplatin for locally advanced gastric cancer (Neo G-SOX PI)

BACKGROUND: The prognosis of locally advanced gastric cancer, such as clinical T4 disease, bulky nodal involvement, type 4 and large type 3 gastric cancer, remains unsatisfactory, even with D2 gastrectomy followed by adjuvant chemotherapy. One promising approach is neoadjuvant chemotherapy. Combination chemotherapy with S-1 and oxaliplatin (SOX) is recognised as a potentially promising regimen for gastric cancer. However, the use of neoadjuvant chemotherapy consisting of SOX for locally advanced gastric cancer has not been reported. The aim of this study was to determine the maximum tolerated dose (MTD) and recommended dose of preoperative chemotherapy combined with SOX for locally advanced gastric cancer. METHODS: Patients received two cycles of neoadjuvant chemotherapy with oxaliplatin on day 1, as well as S-1 (80 mg/m(2)/day, twice daily) for 14 days, repeated every 3 weeks. They then underwent gastrectomy with curative D2/3 lymph node dissection followed by adjuvant S-1 (80 mg/m(2)/day, twice daily) for 1 year. Escalation of oxaliplatin dose was planned (starting at level 0, oxaliplatin 100 mg/m(2); level 1, 130 mg/m(2)). RESULTS: Six patients were enrolled. MTD was not reached at level 1. Oxaliplatin 130 mg/m(2) in combination with S-1 80 mg/m(2)/day twice daily could be administered with acceptable toxicity. Peripheral neuropathy was observed in all patients but with no functional disorders. No treatment-related death was observed and the incidence of operative morbidity was tolerable. Resection with curative intent was undertaken in all patients with R0 resection performed in five (83%) and R1 in one. Two of the six patients had a pathological complete response (33%). CONCLUSION: Neoadjuvant chemotherapy with an SOX regimen was feasible in patients with locally advanced gastric cancer. The recommended phase II dose was determined to be oxaliplatin 130 mg/m(2) in combination with S-1 80 mg/m(2)/day, twice daily.