PDCD1 and neoplasm: Finally, the expression of lncRNA microRNA 155 host gene (MIR-155HG) in a variety of tumor types, including skin cutaneous melanoma, cholangiocarcinoma, lung adenocarcinoma, glioblastoma multiform, kidney renal clear cell carcinoma, glioma and head and neck squamous cell carcinoma appears to significantly interfere with immune cell infiltration within TME and expression of immune breaks, such as PD-1, PD-L1, CTLA-4, LAG3 and TIM-3, hence affecting tumor responsiveness to immune checkpoint inhibitors [129].