Identification of a high-response patient population to S-1 via predictive enrichment strategy analysis of the S-CUBE phase III trial.

229 Background: S-CUBE was a randomized, double-blind, phase III trial evaluating the efficacy and safety of S-1 in patients with sorafenib-refractory advanced hepatocellular carcinoma (HCC). The study’s primary outcome was presented at the 2015 ASCO Annual Meeting. Although S-1 did not significantly improve overall survival (OS) in all cohort (hazard ratio [HR] = 0.86; confidence interval [CI] = 0.67–1.10; P = 0.2201), we conducted predictive enrichment strategy analysis (PESA) to identify a patient population with a better response to S-1. Methods: Predictive enrichment strategy is a newly introduced concept proposed by the United States Food and Drug Administration, “to select a study population in which detection of a drug effect (if one is in fact present) is more likely than it would be in an unselected population. (Temple R. [2012] )” Therefore, in our study, PESA provides robust results and identifies advanced HCC patients who are more likely to respond to S-1. Clinically meaningful baseline chara...