CP-466722

CP-466722 is a selective inhibitor of ATM kinase with IC50 value of 0.41 μM [1].

ATM (ataxia-telangiectasia, mutated) is a serine/threonine protein kinase and plays an important role in the cellular responses to DNA double-strand breaks (DSBs) [2] [3].

CP-466722 is a potent ATM inhibitor and is regareded as a promising drug to increase tumor cells sensitivity to IR. When tested with MCF7 cells, CP-466722 (10 μM) showed inhibition on the pATM and pKAP1 signals which induced by etoposide pre-treatment (25 μM) [1]. In GBM 12 cells, CP-466722 treatment significantly increased the cell sensitivity to TMZ and increased the cell apoptosis which had no effect on the TMZ-resistant GBM12 TMZ cells which indicated that CP-466722 (as an ATM inhibitor) may enhance the efficacy of TMZ in tumors that were inherently sensitive to TMZ [2]. When tested with Hela, MCF-7 and mouse cells pre-treated with IR which induced the increase in ATM-dependent phosphorylation events and then CP-466722 treatment resulted in the disruption of ATM-dependent phosphorylation events and inhibiton of ATM-dependent p53 inducetion at the minimal dose of 6 μM. Further, it was shown that CP-466722 treatment disrupted ATM-dependent cell cycle in increasing the percent in G2/M phase while decreasing the proportion in G1-phase without adverse effects [3].

References:
[1].  Guo, K., et al., Development of a cell-based, high-throughput screening assay for ATM kinase inhibitors. J Biomol Screen, 2014. 19(4): p. 538-46.
[2].  Nadkarni, A., et al., ATM inhibitor KU-55933 increases the TMZ responsiveness of only inherently TMZ sensitive GBM cells. J Neurooncol, 2012. 110(3): p. 349-57.
[3].   Rainey, M.D., et al., Transient inhibition of ATM kinase is sufficient to enhance cellular sensitivity to ionizing radiation. Cancer Res, 2008. 68(18): p. 7466-74.