PDCD1 and glioblastoma: Due to the success of immunotherapy in melanoma and hematologic tumors, attempts have been made to understand GBM in terms of the immune microenvironment and immune response and to improve its prognosis (14).Unfortunately, CTLA-4 monoclonal antibody Ipilimumab, PD-1 monoclonal antibody Nivolumab and so on have shown in clinical trials limited efficacy against GBM (15).