Checkpoint inhibition for advanced mucosal melanoma.

Background: Whereas anti-PD-1 therapy has demonstrated a significant and durable response against advanced cutaneous melanoma, conventional chemotherapies have shown only minor benefit against advanced mucosal melanoma.
Objectives: To investigate the efficacy of anti-PD-1 therapy in a small cohort of patients with mucosal melanoma of the head and neck.
Materials & Methods: We analysed five patients with mucosal melanoma of the head and neck who received nivolumab or pembrolizumab, at an advanced stage. Expression of PD-L1 and PD-1 in all tumour samples was evaluated immunohistochemically.
Results: All patients received at least two cycles of nivolumab or pembrolizumab. The most severe adverse events were categorised as CTCAE (common terminology criteria for adverse events) Grade 2. All patients showed progressive disease after restaging at three and six months, and no partial or complete response was observed. Immunohistochemical staining demonstrated PD-L1 expression in less than 5% of tumour cells.
Conclusion: Systemic therapy with either nivolumab or pembrolizumab showed no clinical response, however, tumour progression was identified in all patients using Response Evaluation Criteria In Solid Tumors (RECIST) v1.1 and immune-related response criteria (irRC) to evaluate tumour response.