Effect of First-line S-1 Plus Oxaliplatin With or Without Ramucirumab Followed by Paclitaxel Plus Ramucirumab on Advanced Gastric Cancer in East Asia: The Phase 2 RAINSTORM Randomized Clinical Trial.

IMPORTANCE Ramucirumab, a human IgG 1 antibody against vascular endothelial growth factor receptor 2, has been shown to improve progression-free survival and overall survival in patients with advanced gastric cancer in the second-line setting. OBJECTIVE To compare progression-free survival for S-1 and oxaliplatin plus ramucirumab with that for S-1 and oxaliplatin plus placebo in patients with advanced gastric cancer. DESIGN, SETTING, AND PARTICIPANTS This phase 2, double-blind randomized clinical trial (RAINSTORM [First-line S-1 Plus Oxaliplatin With or Without Ramucirumab Followed by Paclitaxel Plus Ramucirumab in Patients With Advanced Gastric Cancer]) was conducted from October 12, 2015, to April 11, 2018, at 36 sites in Japan, South Korea, and Taiwan. Participants were chemotherapy-naive patients (n = 189) with metastatic gastric or gastroesophageal adenocarcinoma. Analyses of the full analysis set and safety population were conducted between November 27, 2017, and June 4, 2018. INTERVENTIONS Patients randomized to the ramucirumab plus S-1 and oxaliplatin arm received S-1, 80 to 120 mg/d twice daily, on days 1 to 14 and oxaliplatin, 100 mg/m2, on day 1 with ramucirumab, 8 mg/kg, on days 1 and 8 in part A (21-day cycle). Patients randomized to the placebo plus S-1 and oxaliplatin arm received the same S-1 and oxaliplatin dosage as well as placebo on days 1 and 8 in part A. Eligible patients received second-line paclitaxel, 80 mg/m2, on days 1, 8, and 15 and ramucirumab, 8 mg/kg, on days 1 and 15 in part B (28-day cycle). MAIN OUTCOMES AND MEASURES The primary end point was progression-free survival, analyzed using the stratified log-rank test; the hazard ratio (HR) was estimated using the stratified Cox proportional hazards regression model. Secondary end points included overall survival and adverse events. RESULTS In total, 189 patients were randomized and received treatment: 96 to the ramucirumab plus S-1 and oxaliplatin arm and 93 to the placebo plus S-1 and oxaliplatin arm. Among the 189 patients, 121 (64.0%) were male, and the median (range) age was 62.0 (26-84) years. Median progression-free survival was not prolonged in the ramucirumab plus S-1 and oxaliplatin arm compared with the placebo plus S-1 and oxaliplatin arm (6.34 [80% CI, 5.65-6.93] vs 6.74 [80% CI, 5.75-7.13] months; HR, 1.07; 80% CI, 0.86-1.33; P = .70). Median overall survival was 14.65 (80% CI, 12.39-15.67) months in the ramucirumab plus S-1 and oxaliplatin arm and 14.26 (80% CI, 13.83-17.31) months in the placebo plus S-1 and oxaliplatin arm (HR, 1.11; 80% CI, 0.89-1.40; P = .55). The most commonly reported grade 3 or higher treatment-emergent adverse events in the ramucirumab plus S-1 and oxaliplatin arm in part A were decreased neutrophil count (14 patients [14.6%]), hypertension (10 patients [10.4%]), and anemia (10 patients [10.4%]). CONCLUSIONS AND RELEVANCE In this randomized clinical trial, the addition of ramucirumab to first-line S-1 and oxaliplatin treatment did not prolong progression-free survival or overall survival compared with S-1 and oxaliplatin alone among East Asian patients with advanced gastric cancer; no new safety signals for ramucirumab were identified. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT02539225.