Zabadinostat (CXD101) is a potent, selective and orally active class I HDAC inhibitor with IC 50 s of 63 nM, 570 nM and 550 nM for HDAC1 , HDAC2 and HDAC3 , respectively. Zabadinostat has no activity against HDAC class II. Zabadinostat has antitumor activity In Vitro Zabadinostat has been tested in vitro in colon, lung, non-Hodgkin lymphoma, and myeloma cell lines with IC 50 s ranged from 0.2 to 15 μM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Zabadinostat substantially reduces tumor size in murine xenograft lung (A549a) and colon (HT29) models at a dose of 50 mg/kg. Tumor reductions are found to be associated with increased histone acetylation and decreased HDAC enzyme activity. For Zabadinostat, after oral dosing in murine and canine models, peak plasma concentrations (C max ) are reached 1 to 2 hours after the dose and terminal half‐lives are 6 hours and 8 hours, respectively. After murine oral [ 14 C]-Zabadinostat at a dose of 1.6 mg/kg (4 μmol/kg), tissue radioactivity peaked 3 to 6 hours after the dose and declined slowly thereafter with Zabadinostat‐related material still present in tissue 21 days after the dose. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:HDAC1 63 nM (IC 50 ) HDAC3 550 nM (IC 50 ) HDAC2 570 nM (IC 50 )