Pembrolizumab versus paclitaxel for previously treated patients with PD-L1–positive advanced gastric or gastroesophageal junction cancer (GC): Update from the phase III KEYNOTE-061 trial.

Abstract

4503 Background: KEYNOTE-061 ( NCT02370498) is a global phase 3 study of pembrolizumab vs paclitaxel as second-line therapy for GC. At the time of primary analysis (data cutoff: Oct 26, 2017), in patients with PD-L1–positive status (combined positive score [CPS] ≥1), pembrolizumab did not significantly prolong overall survival (OS) vs paclitaxel (9.1 months vs 8.3 months) but did elicit a longer duration of response (DOR) and a favorable safety profile vs paclitaxel. We present results of KEYNOTE-061 in patients with CPS ≥1, ≥5, and ≥10 after 2 additional years of follow-up (cutoff: Oct 7, 2019). Methods: Adult patients with GC that progressed after platinum + fluoropyrimidine chemotherapy were randomly assigned 1:1 to pembrolizumab 200 mg Q3W for up to 35 cycles (~2 y) or standard-dose paclitaxel. OS and progression-free survival (PFS) in the CPS ≥1 population were the primary end points. Comparisons were made using stratified log-rank tests. Results: At the time of this analysis, 366/395 patients with CPS ≥1 had died (92.6%). Pembrolizumab prolonged OS vs paclitaxel in PD-L1–positive patients (Table). No significant differences appeared between groups in PFS (Table). Objective response rate (ORR) was higher for pembrolizumab in the CPS ≥10 group, and DOR was longer with pembrolizumab using all CPS cutoffs (Table). There were fewer drug-related adverse events (AEs) with pembrolizumab than paclitaxel in the overall population (53% vs 84%). Conclusions: This long-term analysis found that second-line pembrolizumab prolonged OS among patients with PD-L1–positive GC and led to fewer drug-related AEs vs paclitaxel. Clinical trial information: NCT02370498 . [Table: see text]