Long-term follow up of nivolumab in previously untreated Japanese patients with advanced or recurrent malignant melanoma.

The immune checkpoint inhibitor nivolumab inhibits the programmed death 1 receptor and suppresses the immune resistance of cancer cells. This is a long-term follow up of a single-arm, open-label, multicenter, phase II study of nivolumab in untreated Japanese patients with stage III/IV or recurrent melanoma. In addition, a post-hoc subgroup analysis stratified by melanoma types was performed. Nivolumab was administered intravenously at a dose of 3 mg/kg every 2 weeks. The primary endpoint was the overall response rate (ORR), and secondary endpoints included overall survival (OS), progression-free survival (PFS), best overall response, the disease control rate and change in tumor diameter. Safety was assessed by recording treatment-related adverse events (TRAE), including select immune-related adverse events. Of the 24 patients initially included in the primary phase II study, 10 survived for over 3 years (41.7%). The ORR was 34.8% (90% confidence interval [CI]: 20.8, 51.9) for all patients. When analyzing by melanoma type, the ORR was 66.7% (90% CI: 34.7, 88.3) for superficial spreading, 33.3% (90% CI: 11.7, 65.3) for mucosal, and 28.6% (90% CI: 10.0, 59.1) for acral lentiginous tumors. The median OS was 32.9 months, the 3-year OS rate was 43.5%, and the 3-year PFS rate was 17.2%. A long-term response was observed in all the tumor types. The most common TRAE included skin toxicity (45.8%) and endocrine disorders (29.2%). This study demonstrated the long-term efficacy and tolerability of nivolumab in patients with advanced or recurrent melanoma, irrespective of melanoma type.