HDAC9 and glioblastoma: Although we did not test the BET-HDAC combination strategy in MB orthotopic models, it is evident from preclinical animal studies that BET-HDAC inhibitors including OTX015 and panobinostat, as single agents, can cross the blood–brain-barrier and target brain tumors such as MB and glioblastoma [16, 27, 33, 34].