Abstract
BACKGROUND: Claudin18.2 (CLDN18.2)-specific chimeric antigen receptor (CAR)-T cell treatment holds promise for advanced gastric cancer (GC) but has variable efficacy. This study investigates the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) in CAR-T cell treatment and elucidates the molecular mechanisms of treatment resistance. METHODS: GC patients treated with CLDN18.2-specific CAR-T cell treatment were analyzed. Outcomes included objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). Survival analyses utilized Kaplan-Meier methods, log-rank tests, and Cox regression. Single-cell RNA sequencing was performed on peripheral blood samples to investigate the mechanisms of pro-tumor circulating neutrophils. RESULTS: Elevated NLR was significantly associated with lower ORR (34.2% vs. 55.9%, P < 0.001), shorter median PFS (3.6 vs. 8.0 months, P < 0.001), and OS (5.6 vs. 13.8 months, P < 0.001). Single-cell sequencing identified a circulating neutrophil subcluster (NE-3) linked to disease progression. NE-3 expressed pro-tumoral factors (MMP-9), and was enriched in the IL-17 signaling pathway. The cellular interactions between neutrophils and T cells were more prominent in progression disease (PD) group than in partial response (PR) group. CONCLUSIONS: This study highlights NLR as a significant prognostic factor in advanced GC patients receiving CLDN18.2-specific CAR-T cell treatment and provides insights into neutrophil-mediated treatment resistance. Further validation and exploration of strategies to mitigate neutrophil-induced immunosuppression are needed. TRIAL REGISTRATION: NCT03874897.