Checkpoint inhibitors in metastatic gastric and GEJ cancer: a multi-institutional retrospective analysis of real-world data in a Western cohort.

BACKGROUND: Safety and efficacy of immune checkpoint inhibitors in advanced gastric or gastroesophageal junction (GEJ) cancer could be demonstrated in predominantly Asian cohorts, whereas data in Western patients outside of clinical trials are vastly missing. METHODS: In this multi-institutional retrospective analysis conducted at nine oncologic centers in Austria, we tried to assess feasibility of checkpoint inhibitors in advanced gastric/GEJ cancer in a real-world Western cohort. RESULTS: In total, data from 50 patients with metastatic gastric/GEJ cancer who received nivolumab or pembrolizumab in a palliative setting between November 2015 and April 2020 have been evaluated. The median number of previous palliative therapy lines was two. The median progression-free survival (PFS) and overall survival (OS) were 2.1 (95% CI: 1.4-2.8) and 6.3 (95% CI: 3.3-9.3) months, respectively. There was no statistically significant difference in median OS according to microsatellite or PD-L1 status. However, a trend towards prolonged PFS and OS for the microsatellite instability high subgroup could be observed. Patients with an ECOG Performance Status (PS) ≥ 2 displayed a significantly worse outcome than those with an ECOG PS ≤ 1 (p = .03). Only one patient discontinued immunotherapy due to treatment-related toxicity. CONCLUSIONS: Our results support feasibility of nivolumab and pembrolizumab in pre-treated patients with metastatic gastric and GEJ cancer in a Western real-world cohort. Further phase II/III studies are needed to confirm clinical efficacy.