Is ramucirumab and paclitaxel therapy beneficial for second-line treatment of metastatic gastric or junctional adenocarcinoma for patients with ascites? Analysis of RAINBOW phase 3 trial data

Abstract

Purpose: Second-line treatment with ramucirumab-paclitaxel has demonstrated statistically significant and clinically meaningful survival outcomes compared to paclitaxel-alone in patients with advanced gastric cancer (HR=0.807, 95% CI 0.678-0.962; P=0.017). Post hoc, exploratory analyses of RAINBOW patient data were performed to examine whether ascites impacted the efficacy and safety of ramucirumab-paclitaxel. Patients and methods: Patients were placed in with- or without-ascites subgroups based on baseline information collected on case report forms. The Kaplan-Meier method was used to estimate median progression-free survival (PFS) and overall survival (OS) of the ascites subgroups. HR and 95% CI were calculated using the Cox proportional hazards model. Survival distributions within the two arms in each ascites subgroup were compared using the log-rank test. Results: There were 36% of RAINBOW trial patients (237/665) that had ascites at baseline (with-ascites subgroup); 64% of patients (428/665) had no baseline ascites (without-ascites subgroup). Most baseline characteristics were balanced. The with-ascites subgroup had a higher percentage of patients with peritoneal metastases (91% vs 23%) as expected. Overall survival for the with-ascites subgroup was worse than for the without-ascites subgroup (median OS for placebo-treated patients: 5.2 vs 8.5 months, respectively). However, OS treatment effects did not seem to differ significantly among patients with ascites (OS stratified HR=0.864, 95% CI=0.644-1.161; P=0.3362) vs those without ascites (OS stratified HR=0.745, 95% CI=0.593-0.936; P=0.0115). Similar results were observed for PFS. Ramucirumab treatment was associated with a greater incidence of all-grade vomiting for the with-ascites subgroup vs the without-ascites subgroup (ramucirumab arm: 39.2% vs 18.8%; placebo arm: 23.3% vs 19.5%, respectively). The incidence of adverse events of special interest was not elevated among the ramucirumab-treated ascites subgroup over the without-ascites subgroup. Conclusion: The benefit/risk profile of ramucirumab-paclitaxel remains favorable in patients with ascites and is consistent with the findings of the RAINBOW trial.