Multicenter phase 2 trial of atezolizumab after definitive chemoradiotherapy for unresectable locally advanced esophageal squamous cell carcinoma

Platinum-based definitive chemoradiotherapy (dCRT) is the standard treatment for patients with unresectable locally advanced esophageal squamous cell carcinoma (LA ESCC) that invades the aorta, vertebral body, or trachea. Complete respons rates remain low. The phase 2 EPOC1802 trial, at 7 centers in Japan, evaluated addition of 17 cycles (one year) of atezolizumab monotherapy after dCRT. The confirmed complete response rate among the first consecutive 38 patients was 42.1% (90% CI 28.5-56.7). The median progression-free survival was 3.2 months with a 12-month PFS rate of 20.6%; the median overall survival was 31.0 months with a 12-month OS rate of 65.8%. No treatment-related death occurred during the study. The author conclude that atezolizumab monotherapy after dCRT for unresectable LA ESCC resulted in a promising confirmed complete response rate.