CTLA4 and renal cell carcinoma: Recent work using single-cell RNA sequencing (scRNA-seq) has further shown that more advanced stages of RCC are more highly enriched with exhausted CD8+ T cell populations, characterized by high expression of multiple immune co-inhibitory molecules, including PD-1, CTLA-4, LAG3, TIM-3, and TIGIT, as well as other markers of terminal T cell exhaustion, as part of a dysfunctional immune circuit that develops as RCC progresses to more advanced stages (12).