CD274 and neoplasm: Among the many factors involved in the development of resistance, epigenetic inhibitors have recently attracted increased attention, demonstrating a direct impact on the activity of tumor infiltrating immune cells via mechanisms such as i) induction of the activity of antigen-presenting cells and human leukocyte antigen expression, ii) reinvigoration of exhausted T cells, iii) upregulation of the expression of programmed death-ligand 1 (PD-L1) in cancer cells, and iv) modulating Treg cell activity in the tumor microenvironment (20).