Landmark analysis of overall survival (OS) by objective response (OR) in previously treated patients (pts) with advanced hepatocellular carcinoma (aHCC): Post-hoc analysis of the randomized, phase III KEYNOTE-240 study.

Abstract

318 Background: Studies have shown that OR is prognostic of OS in pts with HCC. KEYNOTE (KN)-224 (NCT02702414) evaluated pembrolizumab (pembro; anti-PD-1) in sorafenib (sora)-treated pts with aHCC and demonstrated an OR rate of 17% that was durable in responders receiving pembro, ultimately leading to its FDA approval. In KN-224, a landmark analysis showed that OR in pembro-treated pts was prognostic of longer OS. The KN-240 (NCT02702401) study evaluated pembro + best supportive care (BSC) vs placebo (pbo) + BSC in sora-treated pts with aHCC. Although clinical benefit was observed in KN-240 with pembro vs pbo, prespecified statistical significance criteria for OS and PFS were not met. This post hoc analysis of KN-240 was performed to determine whether OR at landmark is prognostic of longer survival after landmark time. Methods: Eligible pts were aged ≥18 y, had confirmed aHCC, and experienced progression during or after sora treatment or intolerance to sora. Landmark analyses of OS according to OR at 6, 12, and 18 wk after randomization were performed on the pembro arm to examine the association between survival after the landmark with response achieved prior to the landmark. OR was assessed by blinded independent central review per RECIST v1.1. Responders at each landmark were defined as pts with any response assessment of CR or PR before the landmark date; all other pts were defined as nonresponders. HRs and 95% CIs for survival after the landmark were calculated from the Cox proportional model with Efron’s method of tie handling with responder status as a single covariate. Analyses were performed in the ITT population. Results: As of Jan 2, 2019, the median time from randomization to data cutoff was 21.2 months (range 13.4-30.4) for pembro. There were 51 pts (18.3%) with a BOR of CR or PR in the pembro arm and 6 pts (4.4%) with a BOR of PR (no CR) in the pbo arm (excluded from landmark analyses). OS after landmark time was longer for responders compared with nonresponders at the wk 6, 12, and 18 time points (Table). The HR for OS after landmark time for responders versus nonresponders were 0.37 (95% CI 0.18-0.75), 0.39 (95% CI 0.23-0.66), and 0.37 (95% CI 0.21-0.63) at wk 6, 12, and 18, respectively. Conclusions: This post hoc analysis demonstrates that pts with sora-treated aHCC who achieve OR by landmark time with pembro have longer OS after the landmark time, confirming the prognostic association between OR with pembro and OS observed in KN-224. Clinical trial information: NCT02702401. [Table: see text]