Nivolumab for patients with metastatic uveal melanoma previously untreated with ipilimumab: a single-institution retrospective study.

We evaluated the efficacy of nivolumab in patients with metastatic uveal melanoma previously untreated with ipilimumab. We performed a retrospective study at the National Cancer Center Hospital in Tokyo, Japan, where nivolumab was approved 1 year earlier than ipilimumab. Clinical efficacy outcomes were determined by assessing best overall response according to the Response Evaluation Criteria in Solid Tumors (version 1.1), progression-free survival and overall survival. Fourteen patients were analyzed; none had received any prior systemic therapies although eight had undergone transarterial chemoembolization. The median follow-up period was 15 months. The objective response and disease control rates were 7.1% and 42.9%, respectively (one partial response and five stable diseases). The median progression-free survival and overall survival were 10 (range, 4-105) and 60 (range, 5-105) weeks, respectively. Liver metastases in three patients were all programmed cell death-1 ligand negative. Lower lactate dehydrogenase, development of vitiligo, and a neutrophil-to-lymphocyte ratio less than 5 at week 6 were associated with favorable progression-free survival and overall survival; of these, only a neutrophil-to-lymphocyte ratio less than 5 at week 6 was statistically significant. Even with the use of nivolumab before ipilimumab, metastatic uveal melanoma appears to remain refractory to nivolumab monotherapy. However, because one patient in our cohort achieved an objective response, and the median overall survival exceeded 1 year, treatment strategies that incorporate anti-PD1 antibody should be further investigated. Whether a neutrophil-to-lymphocyte ratio less than 5 at week 6 is a favorable early on-treatment marker should be validated in larger cohorts.