IDH1 and glioma: Immune functions are related to tumor cell metabolism; for example, gain-of-function mutations in isocitrate dehydrogenase (IDH) resulted in the production of D-2-hydroxyglutarate, an oncometabolite that altered T-cell metabolism to impair CD8+ T cytotoxicity and interferon-gamma signaling in patients with IDH1 mutant gliomas (128).