Knockdown of RRM2 suppressed tumor growth in xenograft tumor models, and RRM2 deficiency increased CD8 + T cells in tumor tissues and the spleen [30].Bufu Tang et al. found that the expression level of RRM2 was positively correlated with neutrophil and macrophage infiltration in LUAD tissue, suggesting that RRM2 promoted lung cancer progression and affected macrophage infiltration, stimulated M1 phenotype polarization, and inhibited the M2 phenotype [10]. The gene discussed is CD8A; the disease is lung cancer.