V‐domain immunoglobulin suppressor of T‐cell activation and programmed death receptor 1 dual checkpoint blockade enhances antitumour immunity and survival in glioblastoma

Abstract Background and Purpose The current therapy cannot meet the needs of glioblastoma (GBM). V‐domain immunoglobulin suppressor of T‐cell activation (VISTA) is significantly up‐regulated in GBM patients; however, its therapeutic potential in GBM is still unclear. Experimental Approach Flow cytometry was used to detect the expression of VISTA and the co‐expression pattern of VISTA and programmed death receptor 1 (PD‐1) on brain infiltrating lymphocytes of GBM mice. Monoclonal antibody therapy was used to evaluate the therapeutic effect of α ‐VISTA monotherapy and α ‐VISTA combined with α ‐PD‐1 on GBM mice. Transcriptome analysis, flow cytometry, and immunofluorescence were used to detect changes of immune microenvironment in mouse brain tumours. Immunofluorescence and TCGA data analysis were used to further validate the combined treatment strategy on patient data. Key Results Compared with normal mice, the frequency of VISTA expression and co‐expression of VISTA and PD‐1 on tumour‐infiltrating lymphocytes (TILs) in tumour‐bearing mice was increased. Anti‐VISTA monotherapy significantly up‐regulated multiple immune stimulation‐related pathways and moderately prolonged mouse survival time. Blocking the immune checkpoint VISTA and PD‐1 significantly prolonged the survival time of mice and cured about 80% of the mice; CD8 + T cells played an important role in this process. In addition, we found that the expression of VISTA and PD‐1 was significantly up‐regulated in GBM patients by immunofluorescence, and patients with high expression of VISTA and PD‐1 were associated with poor overall survival. This combination of blocking the immune checkpoint VISTA and PD‐1 may achieve clinical transformation in GBM.