A report of patients with IDH-Mut oligodendroglioma under therapy with the mutant-IDH inhibitor ivosidenib (n = 7 untreated, 3 treated including 1 matched-pair) revealed a shift towards differentiated AC-like states and away from undifferentiated and proliferating cells through scRNA-seq profiling.66 Given the current clinical trials inhibiting other epigenetic regulators such as EZH2 and HDAC in gliomas,63 single-cell characterization of subsequent studies would greatly improve our understanding of epigenetic dysregulation and glioma cell differentiation. Here, HDAC9 is linked to glioma.