Nivolumab versus chemotherapy in Japanese patients with advanced esophageal squamous cell carcinoma: a subgroup analysis of a multicenter, randomized, open-label, phase 3 trial (ATTRACTION-3)

Background: The efficacy and safety of nivolumab versus chemotherapy was evaluated in the Japanese subpopulation from the overall intent-to-treat (ITT) population of the ATTRACTION-3 trial conducted in patients with advanced esophageal squamous cell carcinoma (ESCC) as second-line treatment. Methods: Data from Japanese patients enrolled in the multicenter, randomized, open-label, phase 3 ATTRACTION-3 trial were analyzed. The primary endpoint was overall survival (OS). Secondary endpoints included duration of response (DOR), objective response rate (ORR), disease control rate (DCR), and safety. Exploratory subgroup analyses evaluated the association between OS and stratification factors/baseline variables. Results: Overall, 274 (nivolumab, 136; chemotherapy, 138) of the 419 patients in ATTRACTION-3 were enrolled from Japan: response-evaluable population (107; 108) and safety population (135; 138). OS tended to be longer in the nivolumab group versus the chemotherapy group (median: 13.4 months vs. 9.4 months; HR, 0.77; 95% CI 0.59–1.01). Median DOR was longer in the nivolumab group (7.6 months) versus the chemotherapy group (3.6 months). ORRs were similar between the nivolumab [22.4% of patients (24/107)] and chemotherapy groups [22.2% (24/108); odds ratio, 0.98; 95% CI 0.52–1.87]. DCR was lower in the nivolumab group [41.1% (44/107)] versus the chemotherapy group [66.7% (72/108)]. OS in the exploratory analysis consistently favored the nivolumab group versus the chemotherapy group. Overall, nivolumab demonstrated favorable efficacy and safety versus chemotherapy in the Japanese subpopulation, and the trend was similar to that observed in the overall ATTRACTION-3 ITT population. Conclusion: Nivolumab represents a new standard second-line treatment option for Japanese patients with advanced ESCC.