Pembrolizumab (pembro) versus standard of care chemotherapy (chemo) in patients with advanced gastric or gastroesophageal junction adenocarcinoma: Asian subgroup analysis of KEYNOTE-062.

Abstract

4523 Background: First-line treatment with pembro or pembro + chemo vs chemo alone was evaluated in patients with PD-L1 combined positive score (CPS) ≥1, HER2-negative advanced gastric cancer in the randomized, active-controlled, phase 3 KEYNOTE-062 study (NCT02494583). We present results from the Asian subpopulation receiving pembro monotherapy or chemo. Methods: Eligible patients were randomly assigned 1:1:1 to pembro 200 mg, pembro + chemo (cisplatin + 5-FU or capecitabine), or placebo + chemo every 3 weeks for ≤35 cycles (~2 years). Randomization was stratified by region, disease status, and fluoropyrimidine treatment. Primary end points for this analysis were overall survival (OS) in patients with CPS ≥1 and patients with CPS ≥10; progression-free survival (PFS) and objective response rate (ORR) were exploratory end points. Data cutoff was March 26, 2019. Results: Globally, 256 patients received pembro monotherapy and 250 received chemo. Pembro was noninferior to chemo for OS in CPS ≥1 per prespecified margins (median OS, 10.6 vs 11.1 months, respectively; HR [99.2% CI], 0.91 [0.69-1.18]). In the Asian population 62 patients received pembro and 61 received chemo; 26 and 22 had CPS ≥10 (Table). Compared with the global population, Asian patients had a higher proportion of ECOG performance status 0, more diagnoses of stomach cancer, and a greater proportion with 0-2 metastatic sites. Median OS was longer with pembro than chemo using both CPS cutoffs (HR [95% CI]: CPS ≥1, 0.54 [0.35-0.82]; CPS ≥10, 0.43 [0.21-0.89]); 12- and 24-month OS rates were higher for pembro using both CPS cutoffs (12-month OS: CPS ≥1, 69% vs 54%; CPS ≥10, 81% vs 68%; 24-month OS: CPS ≥1, 45% vs 23%; CPS ≥10, 54% vs 27%). The HR (95% CI) for PFS was 1.11 (0.76-1.64) for CPS ≥1 and 0.71 (0.36-1.39) for CPS ≥10. Conclusions: In Asian patients with advanced gastric cancer, OS favored pembro in patients with CPS ≥1 and CPS ≥10. Clinical trial information: NCT02494583 . [Table: see text]