Among four different checkpoint combinations, PD-1/TIM-3, PD-1/LAG-3, PD-1/CTLA-4, and PD-1/TIGIT, Lee et al. discovered that CAR-T cells with downregulated PD-1 and TIGIT displayed strong anti-tumor activity and significantly improved the prognosis of diffuse large B-cell lymphoma patients [114]. This evidence concerns the gene PDCD1 and diffuse large B-cell lymphoma.