valemetostat tosylate + pembrolizumab

**Valemetostat tosylate + pembrolizumab** is an investigational combination therapy consisting of valemetostat tosylate, a selective dual inhibitor of enhancer of zeste homolog 1 and 2 (EZH1/EZH2), and pembrolizumab, a humanized monoclonal antibody that blocks programmed death receptor-1 (PD-1). Valemetostat tosylate targets epigenetic regulation by inhibiting both EZH1 and EZH2, which are involved in oncogenic histone methylation. Pembrolizumab acts as an immune checkpoint inhibitor, restoring antitumor immune responses by blocking PD-1-mediated T-cell inhibition. This combination is under clinical investigation for the treatment of advanced cancers, particularly lymphomas and solid tumors where both epigenetic dysregulation and immune escape play key pathogenic roles. Pembrolizumab (marketed as Keytruda) is developed and manufactured by Merck and is approved for multiple cancer indications, while valemetostat tosylate is developed by Daiichi Sankyo.