There is growing evidence that the IDH mutation might play important roles in altering the tumour immunological microenvironment, as indicated by a suppression of tumour-infiltrating lymphocytes, natural killer cells and cytotoxic T cells.93,94 An initial investigation on glioma data sets showed that the presence of IDH mutation correlates with a decrease in the expression of programmed death-ligand 1 (PD-L1)95 when compared with IDH wild-type gliomas. This evidence concerns the gene IDH2 and central nervous system cancer.