Abstract
BACKGROUND: The clinical value of immune checkpoint inhibitors (ICIs) in the treatment of unresectable locally advanced esophageal squamous cell carcinoma (LA-ESCC) remains under investigation in large-scale randomized clinical trials. In this study, we aimed to assess the efficacy and safety of concurrent ICIs in combination with definitive chemoradiotherapy (dCRT) in a relatively large cohort of patients with unresectable LA-ESCC. METHODS: Between January 2019 and December 2023, this retrospective study included patients with LA-ESCC who received ICIs concurrently with dCRT at Jiangsu Cancer Hospital. The primary endpoints were overall survival (OS) and progression-free survival (PFS), while secondary endpoints included clinical response and safety. RESULTS: A total of 165 patients with LA-ESCC were included in this study, with a median age of 66 years (IQR 60-70 years), and 163 (98.8%) had stage III or IVA disease. After a median follow-up of 24 months (IQR 16-33 months), the 2-year OS was 64.3% (95%CI 57.2%-72.3%), and the 2-year PFS was 50.2% (95%CI 42.9%-58.8%). It is noteworthy that induction therapy before dCRT did not improve OS (HR = 1.09, 95% CI: 0.61-1.93, P = 0.770) or PFS (HR = 1.00, 95% CI: 0.59-1.72, P = 1.000). The objective response rate (ORR) was 70.9% and disease control rate (DCR) was 86.7%. The most common adverse event was grade 3 or worse lymphopenia, observed in 60.0% of the patients (90/165). CONCLUSION: ICIs combined with concurrent dCRT demonstrated promising efficacy and manageable safety in patients with unresectable LA-ESCC.