CTLA4 and renal cell carcinoma: Introduction of immune checkpoint inhibitors (ICIs)—monoclonal antibodies that bind and block the immune checkpoint pathway proteins PD-1, PDL-1 or CTLA-4—has resulted in significant improvements in the survival of patients with UC and RCC, either alone or in combination with other agents such as antibody-drug conjugates or VEGF tyrosine kinase inhibitors [4,5,6,7,8,9,10,11].