CD8A and breast cancer: Targeting specific cells within the TME, such as eosinophils, tumour-associated macrophages, cancer-associated fibroblasts, tumour-infiltrating lymphocytes, and regulatory CD4+/CD8+ T cells, can enhance anti-tumour immunity in breast cancer (Li Y. et al., 2020; Li D. et al., 2020; Wu et al., 2020; Grisaru-Tal et al., 2021; Soongsathitanon et al., 2021; Sun et al., 2021).