EPZ-005687 is a highly selective inhibitor of mutant EZH2, a histone methyltransferase (HMT) that exhibits point mutations at key residues Tyr641 and Ala677 in non-Hodgkin’s lymphoma and other cancers. EPZ-005687 displays anticancer chemotherapeutic activity through its inhibition of EZH2; this enzyme is responsible for methylation of lysine and arginine residues and controls gene transcription fidelity in cells. Inhibition of mutant EZH2 induces apoptosis.