CX-6258 hydrochloride hydrate is a potent, orally efficacious Pim 1/2/3 kinase(IC50=5 nM/25 nM/16 nM) inhibitor with excellent biochemical potency and kinase selectivity.IC50 Value: 5 nM/25 nM/16 nM (Pim 1/2/3) [1]Target: pan-Pimin vitro: CX-6258 inhibited Flt-3 and Pim-3 (IC50=0.134 and 0.016 uM). At 0.5 uM of CX-6258, only Pim-1, Pim-2, Pim-3, and Flt-3 of the 107 kinases tested were inhibited by more than 80%, showing excellent selectivity. CX-6258 was also shown to be a reversible inhibitor of Pim-1 (Ki=0.005 uM). CX-6258 showed robust antiproliferative potencies against all cell lines tested derived from human solid tumors and hematological malignancies. In mechanistic cellular assays with MV-4-11 human AML cells, (13) caused dose-dependent inhibition of the phosphorylation of 2 pro-survival proteins, Bad and 4E-BP1, at the Pim kinase specific sites S112 and S65 and T37/46, respectively[1]. Pim-1 inhibition using the small molecule inhibitor CX-6258 (12 mM, 3 h) diminishes endogenous NKX3.1 steady state levels in 22RV1 and LNCaP cells. CX-6258 treatment (12 mM, 3 h) treatment diminished steady-state levels of ectopic NKX3.1 in PC3 cells. CX-6258 treatment resulted in a significant reduction in NKX3.1 half-life. While ectopically expressed NKX3.1 in control cells had a half-life of _90 min, Pim-1 inhibition reduced the half-life to _52 min [2].in vivo: CX-6258 showed dose-dependent efficacy in mice bearing MV-4-11 xenografts, with 45% and 75% TGI at 50 and 100 mg/kg/day, respectively. Treatment of mice bearing PC3 xenografts with CX-6258 p.o. 50 mg/kg was also well tolerated and produced 51% TGI.
[1]. Mustapha Haddach, Jerome Michaux, Michael K, Discovery of CX-6258. A Potent, Selective, and Orally Efficacious pan-Pim Kinases Inhibitor. ACS Med. Chem. Lett., 2012, 3 (2), pp 135-139 [2]. Padmanabhan A, Gosc EB, Bieberich CJ. Stabilization of the prostate-specific tumor suppressor NKX3.1 by the oncogenic protein kinase Pim-1 in prostate cancer cells. J Cell Biochem. 2013 May;114(5):1050-7.