Taken together, although we could not find synergistic or suppressive effects of HDAC- and DOT1L-inhibitors in CTCL during short term in vitro cell culture, the crosstalk between HDAC and DOT1L still warrants further investigation, especially in the context of in vivo immune responses. This evidence concerns the gene HDAC9 and primary cutaneous T-cell non-Hodgkin lymphoma.