HDAC9 and plasma cell myeloma: The biological effects and potential therapeutic efficacy of HDAC inhibition has extensively been studied in hematopoietic differentiation and malignancies.49–52 HDACi, such as Romidepsin, Vorinostat, and Chidamide have been approved for clinical treatment of cutaneous T-cell lymphoma, peripheral T-cell lymphoma, and multiple myeloma.53–56 The current pilot study of Chidamide in NPC patient has extended the therapeutic potential of HDACi to solid tumors, advocating the further clinical studies of Romidepsin and the other HDACi approved by the US FDA or Conformit Europe (CE) in these patients.