PDCD1 and diffuse large B-cell lymphoma: This cluster also showed elevated expression of immune checkpoint genes, including CD274 (PD-L1), CTLA4, HAVCR2 (TIM-3), LGALS9 (Galectin-9), CSF1R, TGFB1, and CD244. PD-L1 overexpression induces T-cell exhaustion via PD-1/PD-L1 [26], while anti-PD-1/anti-CD20 therapy enhances T-cell activity in DLBCL models [27].