GNA002 is a highly potent, specific and covalent EZH2 (Enhancer of zeste homolog 2) inhibitor with an IC50 of 1.1 μM. GNA002 can specifically and covalently bind to Cys668 within the EZH2-SET domain, triggering EZH2 degradation through COOH terminus of Hsp70-interacting protein (CHIP)-mediated ubiquitination. GNA002 efficiently reduces EZH2-mediated H3K27 trimethylation, reactivates polycomb repressor complex 2 (PRC2)-silenced tumor suppressor genes.