CD8A and neoplasm: Notably, the recently discovered hypothalamic–pituitary–bone marrow (BM) axis demonstrates how TME‐activated paraventricular nucleus (PVN) neurons stimulate pituitary α‐melanocyte‐stimulating hormone release, which binds melanocortin 5 receptor on hematopoietic progenitors to promote myeloid‐derived suppressor cell (MDSC) and tumor‐associated macrophage (TAM) differentiation, ultimately suppressing CD8+ T cell antitumor activity [39].