Impact of frontline doublet versus triplet therapy on clinical outcomes: Exploratory analysis from the RAINBOW study.

Abstract

4543 Background: Treatment (tx) of advanced gastric cancer (GC/GEJ) is highly heterogeneous, with substantial variability in tx patterns. Frontline tx choice may affect outcomes of subsequent tx, thereby influencing choice/efficacy of second-line (2L) tx. In RAINBOW, 2L ramucirumab(R) plus paclitaxel(P) significantly improved overall survival (OS) of patients (pts) with GC/GEJ. Here we explore efficacy, safety and quality of life (QoL) based on prior tx. Methods: Pts were grouped into doublet (DB) or triplet (TP) regimens based on prior cytotoxic tx received. OS and PFS were estimated using Kaplan-Meier method and tx effects on OS and PFS were evaluated by Cox PH model; safety and QoL were assessed descriptively for DB vs TP. Results: Use of DB and TP was similar between arms, with 23% in R+P and 26% in placebo (PB)+P arm receiving TP. Baseline characteristics were generally balanced between tx arms within DB and TP subgroups, with majority of TP administered in western regions (91%). Pts ≥65 years of age was 40% for DB and 28% for TP. DB pts (n = 498; 75%) received S1+cis (n = 97, 15%) and cape+ox (n = 71; 11%) as most common prior tx, while TP pts (n = 163; 25%) received epi+cape+ox (n = 74, 11%) and epi+cis+5FU (n = 53, 8%). Similar to ITT population, R+P improved OS and PFS in both DB and TP subgroups (Table). Patterns of overall and Grade ≥3 TEAEs between arms were similar regardless of prior tx. Higher rates of serious TEAEs were reported in TP pts (57%, 49%) than DB pts (44%, 40%) in R+P and PBO+P arms, respectively. Similar trend was observed for TEAEs leading to discontinuation for TP (40%, 30%) vs DB (29%, 22%) in respective tx arms. Baseline QoL scores were similar between tx arms within subgroups, but mean scores were > 5 points worse (range 0-100) for prior TP for role functioning, fatigue, pain, and appetite loss. Changes in mean scores were generally similar between arms and within subgroups. Conclusions: This exploratory analysis of RAINBOW suggests that although safety-related outcomes were less favorable in pts with prior TP, regardless of tx arm, similar improvements in efficacy were noted for R+P irrespective of prior DB or TP. Clinical trial information: NCT01170663 . [Table: see text]