Valemetostat tosylate(Cat No.:I018290)is a potent, selective dual inhibitor of histone methyltransferases EZH1 and EZH2, key components of the polycomb repressive complex 2 (PRC2) involved in epigenetic gene silencing. Dysregulation of EZH1/2 contributes to oncogenesis by repressing tumor suppressor genes. By blocking their methyltransferase activity, valemetostat reactivates silenced genes, promoting cancer cell differentiation and apoptosis. It has shown clinical efficacy in treating adult T-cell leukemia/lymphoma (ATL) and other hematologic malignancies. As an approved targeted epigenetic therapy in Japan, it represents a major advance in precision oncology.