CD4 and renal cell carcinoma: Recent studies by Julià and colleagues have explored the changes in blood immune cell subsets after anti-PD-1 therapy and found that an increased frequency of central memory CD4+ T cells and leukocyte count was associated with response, whereas increases in PD-L1+ NK cells and naïve CD4+ T cells were associated with a lack of response,40 fueling the need for improved biomarker studies that provide further insight to the circulating lymphocytes in RCC.