Impact of low serum iron on treatment outcome of PD-1 inhibitors in advanced gastric cancer

Background: The aim of this study was toinvestigate the influence of serum iron levels in advanced gastric cancer (GC) patients treated with programmed cell death protein-1 (PD-1) inhibitors. Methods: : We retrospectively reviewed 179 GC patients who were treated with PD-1 inhibitors at our center. Clinicopathological characteristics, laboratory data, and clinical outcomes were analyzed. Results: ： Multivariate analysis showed that Eastern Cooperative Oncology Group performance status (ECOG PS), histological subtype, baseline serum iron levels and surgery were independent prognostic factors for overall survival (OS), while ECOG PS, metastatic sites, and treatment lines were independent prognostic factors for progression-free survival (PFS). Patients with baseline low serum iron levels (LSI) had a significantly shorter median OS and PFS compared to patients with normal serum iron levels (NSI)(OS: 8 vs 15 months, p = 0.001; PFS: 4 vs 5 months, p = 0.009). Patients with baseline LSI had a disease control rate (DCR) of 61.2% at 2 months after PD-1inhibitor initiation (M2), compared to 77.8% in patients with NSI ( p = 0.024). Patients with baseline LSI had a DCR of 43.2% at 4 months, compared to 60.7% in patients with NSI ( p = 0.029). Conclusions: : LSI was associated with worse OS, PFS, and DCR in GC patients treated with PD-1 inhibitors and might be a quick and efficient biomarker to predict the efficacy of PD-1 inhibitors.