KU-0060648

IC50: KU-0060648 inhibited cellular DNA-PK autophosphorylation with IC50 values of 0.17 μmol/L (SW620 cells) and 0.019 μmol/L (MCF7 cells), and PI-3K–mediated AKT phosphorylation with IC50 values of 0.039 μmol/L (MCF7 cells) and more than 10 μmol/L (SW620 cells).
DNA double-strand breaks (DSB) are the most cytotoxic lesions induced by topoisomerase II poisons. Nonhomologous end joining (NHEJ) is a major pathway for DSB repair and requires DNA-dependent protein kinase (DNA-PK) activity. DNA-PK catalytic subunit (DNA-PKcs), which promotes cell survival and proliferation and is upregulated in many cancers, is structurally similar to PI-3K,. KU-0060648 is a dual inhibitor of DNA-PKand PI-3K in vitro.
In vitro: KU-0060648 was investigated in a panel ofhumanbreast and colon cancer cells. Five-day exposure to 1 μM KU-0060648 was found to inhibite cell proliferation by more than 95% in MCF7 cells but only by 55% in SW620 cells. KU-0060648 increased the etoposide and doxorubicin cytotoxicity across the DNA-PKcs–proficient cell panel rather than in DNA-PKcs–deficient cells, therefore confirming the enhanced cytotoxicity was due to the inhibition of DNA-PK [1].
In vivo: In mice bearing SW620 and MCF7 xenografts, KU-0060648 concentrations that were sufficient for in vitro growth inhibition and chemosensitization were maintained within the tumor at nontoxic doses for at least 4 hours. KU-0060648 alone delayed the MCF7 xenografts growth and increased etoposide-induced tumor growth delay in both in MCF7 and SW620 xenografts by up to 4.5 folds, without causing etoposide toxicity to unacceptable levels [1].
Clinical trial: KU-0060648 is still in pre-clinical development stage and no clinicl trial is ongoing currently.
Reference:
[1] Munck JM, Batey MA, Zhao Y, Jenkins H, Richardson CJ, Cano C, Tavecchio M, Barbeau J, Bardos J, Cornell L, Griffin RJ, Menear K, Slade A, Thommes P, Martin NM, Newell DR, Smith GC, Curtin NJ. Chemosensitization of cancer cells by KU-0060648, a dual inhibitor of DNA-PK and PI-3K. Mol Cancer Ther. 2012;11(8):1789-98.