Abstract 477P
Background
Immune checkpoint inhibitors (ICIs) have been approved for the treatment of unresectable advanced gastric cancer (AGC). GC develops from chronic gastritis, including those caused by Helicobacter pylori infection. Although studies have reported that H. pylori infection reduces the efficacy of cancer immunotherapy, it remains unclear whether the degree of gastritis affects ICI treatment. We thus investigated the association between endoscopic findings of the gastric background mucosa and ICI efficacy.
Methods
This retrospective study included patients (pts) with unresectable AGC treated with nivolumab monotherapy after at least two chemotherapy regimens and who underwent gastrointestinal endoscopy in our hospital between November 2017 and December 2023. The status of each gastric background mucosa was evaluated by two expert endoscopists using the Kyoto classification, which scores the degree of gastritis based on endoscopic findings of atrophy, intestinal metaplasia, enlarged folds, nodularity, and diffuse erythema. Pts were divided into two groups based on median Kyoto classification scores. Progression-free survival (PFS), overall survival (OS), and objective response rate (ORR) to nivolumab between the two groups were compared.
Results
A total of 49 pts were included in this study. The median age was 72 years (range, 38-86) and male was 31 (63%). As the median Kyoto classification score was 2 (range, 0-6), pts were divided into two groups: those with scores ≤2 (Group A, N = 32) and ≥3 (Group B, N = 17). There were no significant differences between the two groups in terms of age (p = 0.15), sex (p = 0.88), PS (p = 0.79), or histological subtype (p = 0.23). The PFS and OS were non-significantly slightly better in Group A than in Group B. The median PFS and OS in Group A/Group B were 3.2/2.1 months (mo) (p = 0.17) and 8.3/6.1 mo (p = 0.82), respectively. Notably, the PFS at 12 mo was 13% in Group A and 0% in Group B. The ORR was 11% with one complete response in Group A and 0% in Group B.
Conclusions
Longer PFS, durable effects, and higher response rates to nivolumab were observed in pts with less gastritis. Endoscopic findings of the background gastric mucosal status may be useful predictors of ICIs.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.