Chung HC, et al. - In a phase 1b expansion cohort including 150 patients without or with disease progression following first-line chemotherapy for advanced gastric/gastroesophageal cancer (GC/GEJC), researchers tested avelumab, a human anti–PD-L1 IgG1 antibody, as first-line switch-maintenance (1 L-mn) or second-line (2 L) treatment, focusing on its antitumor activity and safety. Every 2 weeks, patients were administered avelumab 10 mg/kg intravenously. They followed-up 1 L-mn and 2 L subgroups for median 36.0 and 33.7 months, respectively. In the 1 L-mn and 2 L subgroups, the median progression-free survival (PFS) was 2.8 months and 1.4 months, with 6-month PFS rates of 23.0% and 7.9%, and median overall survival (OS) was 11.1 months and 6.6 months, respectively. An infusion-related reaction of any grade was seen in 20.7% across both subgroups. Fatigue (10.0%) and nausea (6.7%) were commonly experienced treatment-related adverse events (TRAEs). Overall, findings revealed clinical activity and an acceptable safety profile of avelumab in patients with GC/GEJC.