Design, Synthesis, and Evaluation of VHL-Based EZH2 Degraders to Enhance Therapeutic Activity against Lymphoma

Traditional EZH2 inhibitors are developed to suppress the enzymatic methylation activity, and they may have therapeutic limitations due to the nonenzymatic functions of EZH2 in cancer development. Here, we report proteolysis-target chimera (PROTAC)-based EZH2 degraders to target the whole EZH2 in lymphoma. Two series of EZH2 degraders were designed and synthesized to hijack E3 ligase systems containing either von Hippel-Lindau (VHL) or cereblon (CRBN), and some VHL-based compounds were able to mediate EZH2 degradation. Two best degraders, YM181 and YM281, induced robust cell viability inhibition in diffuse large B-cell lymphoma (DLBCL) and other subtypes of lymphomas, outperforming a clinically used EZH2 inhibitor EPZ6438 (tazemetostat) that was only effective against DLBCL. The EZH2 degraders displayed promising antitumor activities in lymphoma xenografts and patient-derived primary lymphoma cells. Our study demonstrates that EZH2 degraders have better therapeutic activity than EZH2 inhibitors, which may provide a potential anticancer strategy to treat lymphoma.