Histone deacetylase (HDAC) inhibitors show efficacy in treatment of T cell lymphoma. two HDAC inhibitors, vorinostat and romidepsin, have been approved by the Food and Drug Administration.[126][127] However, since these HDAC inhibitors alter the acetylation state of many proteins in addition to the histone of interest, knowledge of the underlying mechanism at the molecular level of patient response is required to enhance the efficiency of using such inhibitors as treatment.[17] Treatment with HDAC inhibitors has been found to promote gene reactivation after DNA methyl-transferases inhibitors have repressed transcription.[128] Panobinostat is approved for certain situations in myeloma.[129]