HDAC9 and mature T-cell and NK-cell non-Hodgkin lymphoma: In addition to pralatrexate and romidepsin, the HDAC inhibitor belinostat and the anti‐CD30 antibody‐drug conjugate brentuximab vedotin have been approved by the US FDA to treat patients with relapsed/refractory PTCL 12, 26, 27, 28.