Subgroup analysis of East Asians in RAINBOW: A phase 3 trial of ramucirumab plus paclitaxel for advanced gastric cancer

Background and Aim: East Asia has higher gastric cancer incidence and mortality rates than other regions. We present a subgroup analysis of East Asians in the positive study RAINBOW. Methods: Patients with advanced gastric or gastroesophageal junction adenocarcinoma previously treated with platinum and fluoropyrimidine received ramucirumab 8mg/kg or placebo on days 1 and 15 plus paclitaxel 80mg/m² on days 1, 8, and 15 of a 28-day cycle. Results: Of 665 intention-to-treat patients, 223 were East Asian. Median overall survival was 12.1months for ramucirumab plus paclitaxel and 10.5months for placebo plus paclitaxel (hazard ratio: 0.986, 95% confidence interval: 0.727-1.337, P=0.929). Median progression-free survival was 5.5months for ramucirumab plus paclitaxel and 2.8months for placebo plus paclitaxel (hazard ratio: 0.628, 95% confidence interval: 0.473-0.834, P=0.001). Objective response rates were 34% for ramucirumab plus paclitaxel and 20% for placebo plus paclitaxel. Grade ≥3 neutropenia (60% vs 28%) and leukopenia (34% vs 13%) were higher for ramucirumab plus paclitaxel. The rate of febrile neutropenia was low (4% vs 4%). Special interest adverse events included any grade bleeding/hemorrhage (55% vs 25%), proteinuria (27% vs 7%), and hypertension (22% vs 2%). Conclusions: Ramucirumab plus paclitaxel significantly improves progression-free survival and response rate, with prolonged median overall survival and an acceptable safety profile in East Asians with advanced gastric cancer.