Since current HDAC inhibitors are more effective against certain hematological malignancies such as cutaneous T-cell lymphoma (CTCL) [24], but not B-cell lymphoma, we further investigated the antitumor effect and detail mechanisms of MPT0E028 in B-cell lymphomas in vitro and in vivo. This evidence concerns the gene HDAC9 and primary cutaneous T-cell non-Hodgkin lymphoma.