Immune checkpoint inhibitors (ICIs) for second-line retreatment in esophageal cancer progressing after first-line immunotherapy: a single-center retrospective cohort study.

Background: Controversy continues regarding whether immunosuppressive agents can be used across treatment lines after disease progression on first-line immunotherapy for advanced esophageal cancer. The aim of this study is to evaluate the efficacy and safety of immune checkpoint inhibitor (ICI) retreatment through real-world data. Methods: The clinical data of patients with esophageal cancer treated at The First Affiliated Hospital of Henan University of Science and Technology were retrospectively collected. All patients received first-line combination therapy with programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) inhibitors for more than 3 months, and following disease progression, received second-line therapy with PD-1/PD-L1 inhibitors for at least two cycles. Treatment efficacy and safety were evaluated. Results: In the overall population, the median overall survival (mOS) was 10.0 months [95% confidence interval (CI): 9.5-10.5] and the median progression-free survival (mPFS) was 4.4 months (95% CI: 4.1-4.5). The objective response rate (ORR) was 33.2%, and the disease control rate (DCR) was 65.9%. The Cox regression model analysis identified first-line PFS >6 months as an independent prognostic factor for both second-line PFS and OS. Safety was manageable, and no treatment-related deaths occurred. Conclusions: The results of this study suggest that ICI retreatment showed measurable activity in a selected real-world cohort and deserves further evaluation in comparative studies.