PDCD1 and metastatic melanoma: First, a 77-year-old male kidney transplant recipient maintained his graft function after three doses of anti-CTLA-4 antibodies of ipilimumab at a dose of 3 mg/kg every 3 weeks followed by the anti-PD-1 antibody of nivolumab at a dose of 3 mg/kg every 2 weeks for metastatic melanoma.