PDCD1 and cancer: Our study demonstrated that the RPM scores across 12 types of cancers were significantly associated with TMB, MSI, CD8+ T-cell infiltration, immune checkpoint molecules (PD-1/PD-L1, CTLA4), and cytokine (IFN-γ, TGF-β, and TNF-α) expression, which are key predictors of immunotherapy response.