HDAC9 and hematopoietic and lymphoid cell neoplasm: To date, several HDAC inhibitors are approved for the treatment of hematological cancers (e.g., vorinostat for cutaneous T-cell lymphoma and Panobinostat for multiple myeloma) and several clinical trials are investigating HDAC inhibitors as both single agents and in combination with chemotherapeutics, for additional tumor entities [34,35,36].