Efficacy and safety of salvage-line nivolumab monotherapy for advanced esophageal squamous cell carcinoma: Comparison of 240 mg versus 480 mg doses

Abstract Background Nivolumab monotherapy is the standard second-line treatment for advanced esophageal squamous cell carcinoma (ESCC) after failure of platinum-based chemotherapy without anti-PD-1 antibody. Fixed dosing with 240 mg every 2 weeks was approved initially, followed by fixed dosing with 480 mg every 4 weeks based on pharmacokinetics data. However, information on the comparative efficacy and safety of the two doses remains limited. Methods We compared progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and the incidence of adverse events (AEs) between the two doses in 117 patients who received second-line(n=85) or later-line(n=32) nivolumab monotherapy at our institution between January 2016 and December 2021. Results Patient characteristics in the second-line group were as follows (240 mg vs. 480 mg): performance status (PS) 0/1/2, 34/61/5% vs 54/42/4%; prior FP, 81.3 vs. 42.3%. Those in the later-line group were as follows: PS 0/1/2, 28/60/12% vs. 14/86/0%; prior FP, 60.0 vs. 42.8%. ORR was 11.9 vs. 24.0% in the second-line group (p=0.19) and 0 vs. 14.3% in the later-line group (p=0.22). Median PFS was 1.7 vs. 4.1 months on second-line (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.35-1.01, p=0.056) and 1.4 vs. 1.8 months on later-line (HR 0.58, 95% CI 0.23-1.46, p=0.25); AEs of any grade were observed in 58.3 vs. 69.7%, respectively. Conclusions The efficacy and safety of the two doses of nivolumab monotherapy were comparable in patients with advanced ESCC.