PDCD1 and neoplasm: In 2010, T.K. Choueiri and G.G. Malouf found that most patients with Xp11.2 tRCC exhibited an immune escape microenvironment characterized by low PD-L1 levels and CD8+ T-cell infiltration in the tumor stroma and that single-agent PD-1/PD-L1 blockers could not sufficiently improve the prognosis of these patients (24, 31).