AZD2461 is a novel PARP inhibitor.

PARP3:200 nM, PARP2:2 nM, PARP1:5 nM

AZD2461 had a lower affinity for Pgp than olaparib.

AZD2461 had a lower affinity for Pgp than olaparib.

ELISA-Based ERBB Kinase Assay: The ERBB1, ERBB 2, and ERBB4 cytoplasmic fusion proteins are made by cloning the ERBB1 sequence (Met-668 to Ala-1211), ERBB2 (Ile-675 to Val-1256), and ERBB4 sequence (Gly-259 to Gly-690) into the baculoviral vector pFastBac using PCR. Proteins are expressed in baculovirusinfected Sf9 insect cells as GST fusion proteins. The proteins are purified by affinity chromatography using glutathione sepharose beads. Inhibition of ERBB tyrosine kinase activity is assessed using an ELISA-based receptor tyrosine kinase assay. Kinase reactions (50 mM HEPES, pH 7.4, 125 mM NaCl, 10 mM MgCl2, 100 μM sodium orthovanadate, 2 mM dithiothreitol, 20 μM ATP, PF299804 or vehicle control, and 1-5 nM GST-erbB per 50 μL of reaction mixture) are run in 96-well plates coated with 0.25 mg/mL poly-Glu-Tyr. The reactions are incubated for 6 minutes at room temperature while being shaken. Kinase reactions are stopped by removal of the reaction mixture, and then the wells are washed with wash buffer (0.1% Tween 20 in PBS). Phosphorylated tyrosine residues are detected by adding 0.2 μg/mL antiphosphotyrosine antibody (Oncogene Ab-4; 50 μL/well) coupled to horseradish peroxidase (HRP) diluted in PBS containing 3% BSA and 0.05% Tween 20 for 25 minutes while being shaken at room temperature. The antibody is removed, and plates are washed in wash buffer. HRP substrate (SureBlue3,3?,5,5?-tetramethyl benzidine or TMB) is added (50 μL per well) and incubated for 10-20 minutes while it is shaken at room temperature. The TMB reaction is stopped with the addition of 50 μL of stop solution (0.09 N H2SO4). The signal is quantified by measuring absorbance at 450 nm. IC50 values are determined for PF299804 using the median effect method.