HDAC3-IN-5 (9c) is a HDAC3 selective inhibitor, with IC 50 values of 4.2 nM, 1629 nM and 298.2 nM for HDAC3 , HDAC2 , HDAC1 , respectively.HDAC3-IN-5 (9c) can effectively induce apoptosis in MV4-11 cells in vitro and reduce the expression of anti-apoptotic proteins, the development of HDAC3 selective inhibitors may serve as a potential lead compound to reverse Venetoclax resistance.