PDCD1 and neoplasm: In TME, lncRNAs can directly or indirectly affect the growth of tumor cells, and play a nonnegligible role in the regulatory recircuit of the immune cells, promoting recruitment of immunosuppressive cells such as Tregs, M2-type macrophages and myeloid-derived suppressor cells (MDSCs), down-regulating the expression of adhesion molecules on endothelial cells, as well as up-regulating of immune checkpoints (PD-1/PD-L1 and CTLA4), which could contribute to tumor development and resistance to drugs or radiotherapy (Fu et al., 2021; Taheri et al., 2021).