Structural characteristics and SARs of EZH2 inhibitors

Enhancer of zeste homolog 2 (EZH2), the catalytic subunit of the polycomb repressive complex 2 (PRC2), plays a central role in the post-translational methylation of histone H3 lysine 27 (H3K27me3), thereby regulating gene silencing. Extensive studies have demonstrated that EZH2 is frequently overexpressed in a broad range of malignancies, where it promotes tumorigenesis and progression. Elevated EZH2 expression is strongly associated with increased tumor cell proliferation, invasion, metastasis, therapeutic resistance, higher tumor grade, and poor clinical outcomes. Currently, two EZH2 inhibitors have received regulatory approval for the treatment of cancers such as lymphoma, and both have shown clinical benefit in patients with relapsed or refractory disease. In this review, we provided a systematic analysis of recent advances in EZH2 inhibitor development, with a particular emphasis on classification based on core structural scaffolds. We highlighted the structure-activity relationships (SARs), pharmacological profiles, and the respective advantages and limitations of representative compounds in preclinical development. These insights were intended to offer the design of next-generation EZH2 inhibitors with improved selectivity, safety, and translational potential for targeted cancer therapy.