Abexinostat (PCI-24781)

HDAC8, HDAC3, HDAC2, HDAC1

397, 42

Female BALB/c nu/nu mice implanted s.c. with HCT116 and DLD-1 tumor cells

A Phase I study of PCI-24781 in subjects with lymphoma is currently ongoing.

ca.200 mg/kg

7 nM (Ki), 7 nM (Ki), 7 nM (Ki), 7 nM (Ki), 7 nM (Ki), 7 nM (Ki)

Administration of PCI-24781 at 200 mg/kg once daily every other day (q.o.d.) significantly inhibits the growth of HCT116 and DLD-1 xenografts in mice by 69% and 59%, respectively. Administration of PCI-24781 at 20 mg/kg, 40 mg/kg, 80 mg/kg, or 160 mg/kg once daily for 4 consecutive days followed by 3 days without treatment each week (q.d., 4 per week) in the HCT116 model causes inhibition of tumor growth by 48%, 57%, 82.2%, or 80.0%, respectively. [1]

HDAC Activity, HDAC activity is measured using a continuous trypsin-coupled assay. For inhibitor characterization, measurements are done in a reaction volume of 100 uL using 96-well assay plates. For each isozyme, the HDAC protein in reaction buffer [50 mM HEPES, 100 mM KCl, 0.001% Tween 20, 5% DMSO (pH 7.4), supplemented with bovine serum albumin at concentrations of 0% (HDAC1), 0.01% (HDAC2, 3, 8, and 10), or 0.05% (HDAC6)] is mixed with PCI-24781 at various concentrations and allowed to incubate for 15 minutes. Trypsin is added to a final concentration of 50 nM, and acetyl-Gly-Ala-(N-acetyl-Lys)-AMC is added to a final concentration of 25 uM (HDAC1, 3, and 6), 50 uM (HDAC2 and 10), or 100 uM (HDAC8) to initiate the reaction. Negative control reactions are done in the absence of PCI-24781 in replicates of eight. Reactions are monitored in a fluorescence plate reader. After a 30-minute lag time, the fluorescence is measured over a 30-minute time frame using an excitation wavelength of 355 nm and a detection wavelength of 460 nm. The increase in fluorescence with time is used as the measure of the reaction rate. Inhibition constants Ki(app) are obtained using the program BatchKi.

DMSO 80 mg/mL, Water <1 mg/mL, Ethanol <1 mg/mL

3-((dimethylamino)methyl)-N-(2-(4-(hydroxycarbamoyl)phenoxy)ethyl)benzofuran-2-carboxamide