Efficacy and Safety of Salvage-line Nivolumab Monotherapy for Advanced Esophageal Squamous Cell Carcinoma: Comparison of 240 mg Versus 480 mg Doses.

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: In the second-line group, patient characteristics for the 240 mg and 480 mg groups were as follows (240 mg vs. 480 mg): performance status (PS) 0/1/2 was 34/61/5% vs. 54/42/4%, and prior fluoropyrimidine plus platinum therapy (FP) was 81.3% vs. 42.3%. In the later-line group, the characteristics were: PS 0/1/2 was 28/60/12% vs. 14/86/0%, and prior FP was 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.