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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%DpR ≤ 0%; 0%DpR ≤ 30%; 30%DpR ≤ 50%; 50%DpR) according to tumor shrinkage, clinically meaningful differences in PFS, and OS were noted. Patients with DpR of ≥30% had favorable survival time in nivolumab monotherapy as a later-line treatment. Conclusion The final analysis confirmed the efficacy of nivolumab monotherapy for patients with advanced GC in routine clinical practice. The exploratory analysis indicated that increasing DpR was associated with longer median PFS and OS in nivolumab treatment at a later-line setting.
Sunakawa et al. (Sat,) studied this question.