Van Cutsem E, Muro K, Cunningham D, et al. - Given ramucirumab with paclitaxel as second-line treatment vs placebo plus paclitaxel afforded prolonged overall survival (OS) and progression-free survival (PFS) in patients with advanced gastric/gastroesophageal junction cancer who participated in the RAINBOW trial, and to explore predictive and prognostic biomarkers, plasma samples obtained from patients during the trial were used. Experts assayed circulating factors in plasma samples taken from mutually exclusive subsets of RAINBOW patients. A rise in plasma levels of vascular endothelial growth factor-D and placental growth factor was evident from baseline levels during therapy, and the levels reduced following the discontinuation of therapy. During treatment, a drop in angiopoietin-2 was seen, and the levels rose following treatment discontinuation. Experts reported C-reactive protein, hepatocyte growth factor, intercellular adhesion molecule-3, interleukin-8, serum amyloid A, and vascular cell adhesion molecule-1 as likely prognostic markers with low baseline concentrations corresponding to longer OS and PFS. Exploratory biomarker analyses in RAINBOW revealed pharmacodynamic as well as prognostic links; however, findings did not reveal any predictive markers for ramucirumab in gastric cancer.