CD8A and cancer: In addition, dysregulation of circRNAs may serve as tumor antigen owing to their evolutionarily conserved, stable and specific properties (5), and play significant roles in the initiation, progression and metastasis of numerous cancers by tuning abundance in immune cells (i.e., Treg cells, CD8+ T-cell, plasma cells, M2 macrophages, cancer-related fibroblast, etc), pathological angiogenesis and antitumor Immunity (14, 24–27).