UNC1999 is a potent, orally bioavailable and selective inhibitor of EZH2 and EZH1 with IC50 of 2 nM and 45 nM in cell-free assays, respectively, showing >1000-fold selectivity over a broad range of epigenetic and non-epigenetic targets. UNC1999 is a potent autophagy inducer. UNC1999 specifically suppresses H3K27me3/2 and induces a range of anti-leukemia effects including anti-proliferation, differentiation, and apoptosis.