A phase II study of neoadjuvant chemotherapy with docetaxel, cisplatin, and S-1 followed by gastrectomy for type 4 or large type 3 gastric cancer (OGSG 1402).

BACKGROUND

A multi-institutional phase II study (OGSG 1402) evaluated the efficacy and safety of neoadjuvant docetaxel, cisplatin, and S-1 (DCS) therapy for type 4 or large type 3 gastric cancers.

METHODS

Patients with macroscopic type 4 or large type 3 gastric cancer received two or three cycles of neoadjuvant DCS therapy (docetaxel 40 mg/m2 and cisplatin 60 mg/m2 intravenously on day 1, and S-1 80-120 mg/body orally for 14 days, every 4 weeks), followed by gastrectomy with D2 lymphadenectomy. After R0 resection, adjuvant S-1 chemotherapy was administered for 1 year. The primary endpoint was the R0 resection rate.

RESULTS

Between March 2015 and June 2018, 48 patients were enrolled, 47 of whom were eligible. The R0 resection rate was 68.1% (32/47, 95% confidence interval [CI] 52.9-80.9). Forty-two patients (89.4%) completed neoadjuvant chemotherapy (NAC). The most common grade 3 or 4 adverse event during NAC was neutropenia (23/47, 48.9%). Surgical morbidity of Clavien-Dindo grade IIIa or higher occurred in 8.5% (4/47) of patients. The pathological response rate, defined as grades 1b to 3, was 42.6% (20/47, 95% CI 28.3-57.8). The 5-year overall survival rate was 38.3% (95% CI 24.6-51.8) and the 5-year progression-free survival rate was 29.8% (95% CI 17.6-43.0).

CONCLUSIONS

In patients with type 4 or large type 3 gastric cancer, neoadjuvant DCS therapy did not meet the predefined threshold for the R0 resection rate. Despite its acceptable feasibility and manageable toxicity, the addition of docetaxel to the S-1 plus cisplatin regimen is unlikely to provide a survival benefit for this high-risk population.

TRIAL REGISTRATION: The study was registered with UMIN-CTR (number UMIN 000015631).