Approved agents for relapsed/refractory PTCL include HDAC inhibitors romidepsin and belinostat (Beleodaq), folate analog pralatrexate (Folotyn), and CD30-directed antibody-drug brentuximab vedotin (Adcetris, for ALCL; Celgene Corporation, 2013; Spectrum Pharmaceuticals, Inc., 2014; Allos Therapeutics, Inc., 2012; Seattle Genetics, Inc., 2013). Here, HDAC9 is linked to mature T-cell and NK-cell non-Hodgkin lymphoma.