Abstract
BACKGROUND: This prospective observational study evaluated the real-world effectiveness of nivolumab monotherapy in previously treated advanced gastric cancer (GC). A preplanned 2-year final analysis was performed to confirm survival and tumor behavior with nivolumab monotherapy. PATIENTS AND METHODS: The primary endpoint was overall survival (OS). The data regarding tumor size were prospectively collected and evaluated using the RECIST criteria. Exploratory analyses were performed for survival according to the tumor response and depth of response (DpR) in patients with measurable lesions who were receiving nivolumab monotherapy as third- or later-line therapy. RESULTS: In 487 patients, the median OS and progression-free survival (PFS) were 5.8 (95% CI 5.3-6.9) months and 1.8 (95% CI 1.7-2.0) months, respectively. The response rate (RR) was 14.5% in 282 patients with measurable lesions. In 234 patients treated with third- or later-line, the DpR was found to be associated with PFS and OS in the Spearman analysis (r = 0.55 and 0.44, respectively) as well as using a discrete variable. When the DpR was divided into 5 groups (-20%≥DpR; -20%