It catalyzes the degradation of tryptophan (Trp) into kynurenine (Kyn), which increases the numbers of regulatory T cells (Tregs), myeloid‐derived suppressor cells (MDSCs), and M2‐type tumor‐associated macrophages (M2‐TAMs) in tumor microenvironment (TME).[9] These together suppress the activation and infiltration of effector T (CD8+ T) cells, natural killer (NK) cells, and M1‐TAMs, creating a favorable microenvironment for tumor growth.[10]. The gene discussed is CD8A; the disease is neoplasm.