CD4 and cancer: Preclinical and clinical studies have reported that certain intratumoral CD4+ T cells possess cytotoxic activity to directly mediate cancer cell death.[37] In order to accurately develop RNase1 as a serum biomarker or therapeutic target in clinical practice to determine and boost T‐cell activity in tumors, further careful investigations are necessary to elucidate the complex role of RNase1 in the differentiation and activation of CD4+ T cells.