PIK3CA and neoplasm: Oncogenic signalling pathways such as PI3K/AKT, MAPK, and MYC affect constitutive PD-L1 expression [50,51], while pro-inflammatory cytokines, particularly interferon-gamma (IFN-γ) produced by tumour-infiltrating lymphocytes (TILs), induce adaptive PD-L1 expression [52].