From a biology-driven standpoint, 5-azacitidine—alone or combined with romidepsin—has shown activity in TFH-derived nodal PTCL (AITL and PTCL-NOS with a TFH phenotype), in which epigenetic lesions involving DNMT3A and TET2 are frequent [9,28,29]. This evidence concerns the gene TET2 and mature T-cell and NK-cell non-Hodgkin lymphoma.