While HDAC inhibitors are among the anticancer agents that exert the best synergistic anticancer effects with BET bromodomain inhibitors, through synergistically reducing oncogene expression29, we have confirmed that combination therapy with THZ1 and the HDAC inhibitor panobinostat synergistically reduces JMJD6, N-Myc, c-Myc, and E2F2 expression and neuroblastoma cell proliferation, and synergistically induces neuroblastoma cell death, which can be partly blocked by JMJD6 overexpression. This evidence concerns the gene HDAC9 and neuroblastoma.