In vitro activity: AZD-2461 is a novel and potent PARP inhibitor, with IC50s of 5 nM, 2 nM and 200 nM for PARP1, PARP2 and PARP3, respectively. AZD-2461 (500 nM) shows inhibitory activity against DNA single-strand break repair in human A459 cells. AZD-2461 cuases resistance and high P-gp expression levels in BRCA2-deficient mouse breast cancer line KB2P3.4. AZD-2461 is cytotoxic to BT-20 cells (5-50 μM), increases the proportions of S- and G2-phase BT-20 cells (5-20 μM), and weakly affects the progression of cell cycle in SKBr-3 cells (5-20 μM).

Kinase Assay: AZD-2461 is a novel and potent PARP inhibitor, with IC50s of 5 nM, 2 nM and 200 nM for PARP1, PARP2 and PARP3, respectively.

Cell Assay: BT-20 and SKBr-3 human primary breast cancer cell lines are used in the assay. SKBr-3 cells are cultivated in DMEM medium with 10% FCS and BT-20 in RPMI medium under an atmosphere containing 5% CO2. Twenty four hours after plating (at 60-70% confluence), the cells are treated with the PARP-1 inhibitors NU1025, AZD-2461, iniparib, olaparib, and rucaparib at concentrations ranging from 50 to 200 μM, 5 to 50 μM, 5 to 50 μM, 1 to 10 μM, and 0.3 to 10 μM, respectively, for durations indicated in figures 1-7