IDH1 and glioma: D-2-HG also suppresses signal transducer and activator of transcription 1, leading to decreased CD8+ T cell recruitment in the tumour region.99 Combining a pan-IDH1-mutant inhibitor BAY1436032 improves the efficacy of anti-PD-1-derived immunotherapy, causing enhanced intratumoural CD4+ T-cell proliferation, a reduction in tumour volume and prolonged overall survival.94 Additional immune checkpoint inhibitors are currently under investigation for IDH1-mutated glioma.