A phase III trial comparing oral S-1/cisplatin and intravenous 5-fluorouracil/cisplatin in patients with untreated diffuse gastric cancer.

ABSTRACT

BACKGROUND: The effect of histology-based treatment regimen on diffuse gastric adenocarcinoma has not been evaluated in clinical trials. This international phase III trial evaluated the efficacy and safety of S-1 (a contemporary oral fluoropyrimidine)/cisplatin versus 5-fluorouracil (5-FU)/cisplatin in chemotherapy-naïve patients with diffuse-type adenocarcinoma involving the gastroesophageal junction or stomach. PATIENTS AND METHODS: Eligibility criteria included untreated, measurable, advanced diffuse adenocarcinoma confirmed by central pathology and performance status of 0-1. Patients were randomized (2  1) to receive S-1/cisplatin or 5-FU/cisplatin. Primary end point was overall survival (OS), and secondary end points were progression-free survival, time to treatment failure, overall response rate, and safety. A multivariable analysis was also carried out. RESULTS: Overall, 361 patients were randomized (S-1/cisplatin, n = 239; 5-FU/cisplatin, n = 122); half (51%) were men, and median age was 56.0 years. In each group, median number of treatment cycles per patient was 4 (range, S-1/cisplatin 1-20; 5-FU/cisplatin 1-30), and dose intensity was >95%. OS was not different in the two groups {median OS with S-1/cisplatin, 7.5 [95% confidence interval (CI) 6.7, 9.3]; 5-FU/cisplatin, 6.6 [95% CI 5.7, 8.1] months; hazard ratio, 0.99 [95% CI 0.76, 1.28]; P = 0.9312}. Overall response rate was significantly higher in the S-1/cisplatin than 5-FU/cisplatin group (34.7% versus 19.8%; P = 0.01), but progression-free survival and time to treatment failure were not different. Safety was similar between the 2 groups; however, fewer patients treated with S-1/cisplatin than 5-FU/cisplatin had ≥1 grade 3/4 treatment-emergent adverse event or ≥1 adverse event resulting in treatment discontinuation. One treatment-related death occurred in each group. Slow accrual led to early termination. CONCLUSIONS: These data suggest that S-1/cisplatin and 5-FU/cisplatin are similar in efficacy and safety in untreated patients with advanced diffuse adenocarcinoma of the gastroesophageal junction or stomach. The primary end point was not met. CLINICALTRIAL.GOV REGISTRATION NUMBER NCT01285557.