SIAD onset in a patient affected by metastatic melanoma treated with immune checkpoint inhibitors: the role of nivolumab treatment.

Malignant melanoma is a broad and heterogeneous class of malignant tumors derived from melanocytes and classified as cutaneous (skin), uveal, and mucosal melanoma. The incidence of melanoma has increased worldwide in recent decades. Surgery remains the mainstay of treatment, but a dramatic change in systemic treatment occurred when immune checkpoint inhibitors (ICIs) entered the therapeutic armamentarium for metastatic melanoma. Pembrolizumab and nivolumab, both anti-programmed death antibodies, demonstrated superiority over standard therapies with a 5-year survival rate. Toxicities resulting from ICIs have an autoimmune etiology and can affect any organ system. We then present a case of a patient with metastatic melanoma treated with an ICI strategy who developed endocrine toxicity such as the syndrome of inappropriate antidiuresis (SIAD). A previous case report concerning an anti-programmed death ligand 1 antibody suggests that this pathway may be involved in the development of SIAD.