Abstract
We report the 5-year follow-up results from a single-arm, open-label, multicenter phase II study (ONO-4538-08) conducted in Japan. Twenty-four patients with treatment-naïve, recurrent, or unresectable stage III/IV malignant melanoma received 3 mg/kg nivolumab every 2 weeks until progressive disease or unacceptable toxicity occurred. The 5-year overall survival (OS) rate was 26.1%. Five years after the start of nivolumab treatment, there were six survivors. The 5-year OS rate was 66.7% for patients with a superficial spreading type, 14.3% for acral lentiginous type, and 16.7% for mucosal type. The 5-year progression-free survival rate was 17.2%. No new cases of partial response or complete response were observed after 3 years, and overall response and disease control rates were similar to those reported at 3 years. The treatment-related adverse events reported between the 3- and 5-year follow-up periods were anemia (grade 2), white blood cell count decrease (grade 2), and psoriasiform dermatitis (grade 2) in one patient each. No new grade 3 or higher treatment-related adverse events occurred in this period. In conclusion, first-line treatment with nivolumab in Japanese patients with unresectable or metastatic melanoma resulted in confirmed long-term survival. No new safety signals were reported in the studied population.