Interestingly, Tang et al. 2022 demonstrated a positive correlation between the expression of PD-1—but not CTLA4, TIM3 nor LAG3—on EGFRvIII-targeting CD4+ CAR-T cells, with the area under the curve of log10 CAR copies/mg genomic DNA in peripheral blood post-infusion, and the PFS in patients with EGFRvIII-expressing recurrent GBM [97]. Here, PDCD1 is linked to glioblastoma.