PDCD1 and glioblastoma: In addition, the results of TUNEL assay suggested that the cell apoptosis rate of IR + PD-1 inhibitor + A2-CM-NP/siTREM2/spam1 group was more significant than other groups (Fig. 6E), which implied that TREM2 inhibition could further enhance the pro-apoptosis effect of radiotherapy and PD-1 inhibitor in GBM in vivo.