PDCD1 and neoplasm: The immune correlation analysis using the TISIDB database revealed that the upregulation of PTTG genes is linked to immune evasion mechanisms, including increased expression of immune inhibitors (e.g., PDCD1, TIGIT, CTLA4) and reduced expression of immune stimulators (e.g., CD27, ICOS, CD40LG), suggesting that PTTG genes may play a role in modulating the tumor microenvironment by promoting immune suppression and facilitating immune escape in LUAD.