EPZ005687 is a selective small-molecule inhibitor primarily used in epigenetic research. It targets the enhancer of zeste homolog 2 (EZH2), which is a catalytic subunit of the polycomb repressive complex 2 (PRC2) responsible for histone H3 lysine 27 trimethylation (H3K27me3). By inhibiting EZH2 activity, EPZ005687 modulates gene expression patterns associated with cell proliferation and differentiation. This compound is widely applied in cancer research, particularly in studies involving tumors with gain-of-function EZH2 mutations, such as certain lymphomas and solid tumors. It helps in evaluating the therapeutic potential of suppressing aberrant epigenetic silencing of tumor suppressor genes. EPZ005687 is also used as a tool compound to study PRC2-dependent cellular processes, including stem cell maintenance, development, and chromatin remodeling. Due to its specificity, it supports the development of targeted therapies and provides insights into resistance mechanisms in epigenetic drug treatments. Its use remains primarily confined to preclinical research, aiding in the validation of EZH2 as a druggable target in oncology.