Rocilinostat, also known as ACY-1215, is a selective HDAC6 inhibitor with IC50 of 5 nM. It is over 10-fold more selective for HDAC6 than HDAC1, 2, 3 (class I HDACs) with slight activity against HDAC8, and minimal activity against HDAC4, 5, 7, 9, 11, SIRT1, and SIRT2.