PDCD1 and glioblastoma: Previous studies have found that PD-1 and PD-L1 can inhibit T cell proliferation in glioma (Litak et al., 2019), and studies in GBM mice have confirmed the safety and effectiveness of monoclonal antibodies against PD-1 and PD-L1, indicating that they have a high anticancer potential (Huang et al., 2015).