EZH2 and breast cancer: The FDA has approved only nine epidrugs, many more are in clinical studies for solid and hematological tumours (NCT01928576, NCT03179943), including antagonists of DNA methyltransferases (DNMTs) (NCT03164057, NCT02717884), EZH2, IDH and HDAC.The phase II trials (NCT00676663 and NCT00828854) exploring the epidrugs’ effectiveness when used in conjunction with normal treatment in oestrogen receptor positive (ER+) breast cancer are significant, reflecting recent developments in the knowledge of the epigenetic process.