TP53 and glioblastoma: We further classified 78 patients with wild-type IDH GBM who had complete p53 and PD-L1 expression data into four subgroups based on their p53 and PD-L1 immunostaining status: p53 + /PD-L1 + , p53 + /PD-L1 − , p53 − /PD-L1 + , and p53 − /PD-L1 − .