D-2-HG produced by IDH mutant glioma cells is actively exported into the tumor microenvironment (Linninger et al., 2018) where it suppresses antitumor T-cell function (Bunse et al., 2018), thereby promoting intratumoral immunosuppression (Bunse et al., 2018; Notarangelo et al., 2022; Mellinghoff et al., 2023). The gene discussed is IDH2; the disease is glioma.