CD8A and breast cancer: Currently, many clinical studies related to immune checkpoint inhibitors (ICIs) mainly focus on the regulation of CD8+ cytotoxic T cells (CTLs) on the tumor immune microenvironment (TIME) and the possible mechanism of immune-related targets, for example, IMpassion 130 (3), KEYNOTE-119 (4), and the FUTURE trial (5) for advanced breast cancer and KEYNOTE-173 (6) and IMpassion 031 (7) for early breast cancer.