AbstractBackgroundThis study aimed to determine whether the immune prognostic index (ECIPI), based on hemoglobin (Hb) and neutrophil‐to‐lymphocyte ratio (NLR), could predict the prognosis in patients with advanced esophageal squamous cell carcinoma (ESCC) receiving programmed cell death‐1 (PD‐1) inhibitor treatment.MethodsAdvanced ESCC patients who had been treated with PD‐1 inhibitors from Jan 2016 to Oct 2021 were included. Kaplan–Meier method and Cox proportional hazards regression were used to analyze progression‐free survival (PFS) and overall survival (OS). The overall response rate (ORR) was the percentage of complete and partial responses. Univariate and multivariate analyses were used for estimating hazard ratio (HR) and 95% confidence interval (CI). Patients were grouped by ECIPI (good: Hb > 105 g/L and NLR ≤ 4.3; intermediate: Hb ≤ 105 g/L and NLR ≤ 4.3, or Hb > 105 g/L and NLR < 4.3; poor: Hb ≤ 105 g/L and NLR > 4.3). Variables for the multivariate model were selected if thep‐value was below 0.05 in the univariate analysis. All statistical comparisons were two‐way, and ap‐value below 0.05 was set as statistical significance.ResultsTotally, of 123 ESCC patients with stage III or IV were included in the study. Efficacy evaluation showed that patients with pretreatment ECIPI good had the best ORR compared with those with ECIPI intermediate and ECIPI poor (53% vs. 22% vs. 8%,p< 0.01). Multivariate analysis showed that ECIPI was an independent influential factor for PFS (p= 0.004) and OS (p< 0.001). Kaplan–Meier curves demonstrated that patients with ECIPI good had the longest PFS (median: 11.6 vs. 3.5 vs. 1.7 months,p< 0.0001) and OS (median: 23.6 vs. 16.7 vs. 4.0 months,p< 0.0001) compared with those with ECIPI intermediate and ECIPI poor. Subgroup analysis indicated that ECIPI good was associated with improved PFS and OS in patients with ECOG 0–1, PD‐1 inhibitor plus chemotherapy, first‐line treatment, and smoke (allp< 0.05).ConclusionsPretreatment ECIPI was associated with the prognosis in advanced ESCC patients with anti‐PD‐1 therapy, suggesting that ECIPI may be a useful tool to identify patients likely sensitive to PD‐1 inhibitors.