HDAC9 and hematopoietic and lymphoid cell neoplasm: The frequent upregulation of KDACs in NSTs (the most aggressive and challenging subtypes of TGCTs), especially of those that are dependent on Zn2+ (HDACs), also indicates a potential benefit from HDAC inhibitors (HDACi), such as hydroxamic acid inhibitors (one of which—suberanilohydroxamic acid—is already approved again for the treatment of hematological cancers) [92,93].