HDAC9 and plasma cell myeloma: To date, more than twenty HDAC inhibitors have been initiated in clinical trials, and four HDAC inhibitors vorinostat (SAHA),13 romidepsin (FK-228),14 belinostat (PXD-101),15,16 panobinostat (LBH-589),17 have been approved by FDA for the treatment of T-cell lymphoma, cutaneous T-cell lymphoma and multiple myeloma.