HDAC9 and mature T-cell and NK-cell non-Hodgkin lymphoma: Vorinostat, depsipeptide, panobinostat, and belinostat are the FDA-approved HDAC inhibitors for cancer therapy; these drugs are used specifically for the treatment of refractory cutaneous T-cell lymphoma (CTCL), peripheral T-cell lymphoma (PTCL), and multiple myeloma [8].