Immunotherapy combined with definitive chemoradiotherapy for locally advanced unresectable esophageal squamous cell carcinoma

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.