EZH2 is targeted for the treatment of certain non-Hodgkin's lymphomas and breast cancer subtypes. EZH2 targets the catalytic center of a multiprotein complex known as polycomb repressive complex 2 (PRC2). The PRC2 complex is responsible for placing three methyl groups on a specific histone lysine known as H3K27. In many human cancers, elevated levels of PRC2 enzyme activity cause hyper-trimethylation of H3K27, resulting in the silencing of genes that otherwise control cell proliferation. In the absence of these control mechanisms, cancer cells are free to proliferate rapidly. Recently, Epizyme scientists discovered that specific mutations in the EZH2 enzyme are responsible for driving hyper-trimethylation of H3K27, hence malignancy, in certain forms of non-Hodgkin's lymphomas. Our EZH2 inhibitors selectively kill these mutant-bearing lymphoma cells. The optimization of these inhibitors will lead to selective treatments for patients carrying the EZH2 mutant forms of lymphoma. This program is partnered with Eisai with Epizyme retaining the right to co-commercialize the product in the US.