The histone lysine methyltransferase EZH2 has been implicated as a key component in cancer aggressiveness, metastasis and poor prognosis. This study discovered a new class of hexahydroisoquinolin derivatives as EZH2 inhibitors. A structure–activity relationship study showed that the steric hindrance was important to the activity for EZH2. A preliminary optimization study led to the discovery of several potent compounds with low nanomolar to sub-nanomolar potency for EZH2. Biological evaluation indicated that SKLB1049 was a highly potent with improved solubility compared to EPZ6438, SAM-competitive, and cell-active EZH2 inhibitor that decreased global H3K27me3 in SU-DHL-6 and Pfeiffer lymphoma cells in a concentration- and time-dependent manner. Further study indicated that SKLB1049 caused cell arrest in G0/G1 phase. These compounds would be useful as chemical tools to further explore the biology of EZH2 and provided us with a start point to develop new EZH2 inhibitors.
