Efficacy and safety of anti-PD-1 antibody plus chemoradiotherapy in locally advanced esophageal squamous cancer

Objective To compare effects and adverse events of anti-programmed cell death protein 1 (anti-PD-1) antibody combined with chemoradiotherapy (CRT) and CRT alone as the initial treatment in locally advanced esophageal squamous cell carcinoma (ESCC). Methods We retrospectively reviewed locally advanced ESCC patients who received Anti-PD-1+CRT as initial treatment at 3 institutions. Primary outcomes of interest were progression-free survival (PFS) and overall survival (OS); secondary outcomes were objective response rate (ORR), disease control rate (DCR), duration of response (DoR), and treatment-related adverse events (AEs) including immune-related adverse events (irAEs). Results At data cutoff, 81 patients were included (30 Anti-PD-1+CRT, 51 CRT). Median follow-up was 31.4 months. Anti-PD-1+CRT resulted in significant improvements in PFS (median, 18.6 vs. 11.8 months, HR 0.48 [95% CI, 0.29–0.80], P = 0.008), and OS (median, 27.7 vs. 17.4 months, HR 0.37 [95% CI, 0.22–0.63], P = 0.002), compared with CRT in ESCC. The ORR and DCR of patients treated with Anti-PD-1+CRT were also significantly higher than those treated with CRT (80.0% vs. 56.9%, P = 0.034), (100% vs. 82.4%, P = 0.023), respectively. Anti-PD-1+CRT had better durable response compared with CRT, with DoR (median,17.3 vs. 11.1 months, P = 0.022). Treatment-related adverse event incidence was similar between the two groups (any Grade, 93.3% vs. 92.2%; ≥Grade 3, 50.0% vs. 33.3%). Conclusion Anti-PD-1 plus chemoradiotherapy demonstrated promising antitumor activity and was well tolerated in locally advanced ESCC.