Subgroup analyses of the safety and efficacy of ramucirumab in Japanese and Western patients in RAINBOW: a randomized clinical trial in second-line treatment of gastric cancer

We evaluated the safety and efficacy of ramucirumab plus paclitaxel versus placebo plus paclitaxel in patients previously treated for advanced gastric or gastroesophageal junction adenocarcinoma in Japanese and Western subgroups from the RAINBOW trial. Patients received ramucirumab at 8 mg/kg or placebo (days 1 and 15) plus paclitaxel at 80 mg/m(2) (days 1, 8, and 15 of a 28-day cycle). End points were compared between treatment arms within Japanese (N = 140) and Western (N = 398) populations. The incidence of adverse events of grade 3 or higher was higher for ramucirumab plus paclitaxel in both populations (Japanese population, 83.8 % vs 52.1 %; Western population, 79.1 % vs 61.9 %). Neutropenia was the commonest adverse event of grade 3 or higher, with a higher incidence for ramucirumab plus paclitaxel (Japanese population, 66.2 % vs 25.4 %; Western population, 32.1 % vs 14.7 %). The incidence of febrile neutropenia was low and was similar between treatment arms in both populations. The overall survival hazard ratio was 0.88 (95 % confidence interval, 0.60-1.28) in the Japanese population and 0.73 (95 % confidence interval, 0.58-0.91) in the Western population. The progression-free survival hazard ratio was 0.50 (95 % confidence interval, 0.35-0.73) in the Japanese population and 0.63 (95 % confidence interval, 0.51-0.79) in the Western population. The objective response rate was higher for ramucirumab plus paclitaxel in both populations (Japanese population, 41.2 % vs 19.4 %; Western population, 26.8 % vs 13.0 %), as was the 6-month survival rate (Japanese population, 94.1 % vs 71.4 %; Western population, 66.0 % vs 49.0 %). Safety profiles of the ramucirumab plus paclitaxel arm were similar between populations, though there was a higher incidence of neutropenia in Japanese patients. Progression-free survival and objective response rate improvements were observed for ramucirumab plus paclitaxel in both populations. NCT01170663.