Introduction
Gastric cancer, death, gastric/GEJ cancer, cancer, adenocarcinoma, tumors, advanced/metastatic gastric/GEJ cancer
GASTRIC CANCER, DISEASE PROGRESSION, CANCER, ADENOCARCINOMA, CPS, TUMORS
Gastric cancer (GC) is the fifth most common cancer worldwide, and the geographic distribution of GC incidence and mortality is disproportionate, with the highest rates observed in east Asian countries, such as South Korea, Mongolia, and Japan [In Japan, the current standard of care for unresectable advanced, recurrent, or metastatic GC in the first-line setting is systemic chemotherapy with a fluoropyrimidine plus platinum-based agent with or without nivolumab for human epidermal growth factor receptor 2 (HER2)–negative tumors or a trastuzumab-containing regimen for HER2-positive tumors [The PD-1 inhibitor pembrolizumab was approved by the US Food and Drug Administration—based on the KEYNOTE-059 study—for recurrent locally advanced or metastatic programmed death ligand 1 (PD-L1)–positive (combined positive score (CPS) ≥ 1) gastric/gastroesophageal junction (GEJ) adenocarcinoma with disease progression on or after ≥ 2 previous lines of therapy, including fluoropyrimidine- and platinum-containing chemotherapy, and, if appropriate, HER2/neu-targeted therapy [In the single-arm, multicohort, phase 2 KEYNOTE-059 study, patients with advanced gastric/GEJ cancer in cohort 1 received pembrolizumab in the third-line or later setting [KEYNOTE-061 was a randomized, phase 3 study of second-line therapy with pembrolizumab versus paclitaxel in advanced gastric/GEJ cancer [First-line therapy with pembrolizumab with or without chemotherapy (cisplatin plus 5-fluorouracil or capecitabine) versus chemotherapy was assessed in the randomized, phase 3 KEYNOTE-062 study in patients with advanced/metastatic gastric/GEJ cancer [We retrospectively evaluated Japanese patients with gastric/GEJ cancer enrolled in KEYNOTE-059, KEYNOTE-061, and KEYNOTE-062 to characterize treatment response with pembrolizumab monotherapy across several lines of therapies.