Co-treatment with aurora kinase inhibitor MK-0457 and pan-histone deacetylase inhibitor vorinostat: A novel targeted treatment for AML and CML

Abstract

11054 Background: MK-0457 (M) is a pan-Aurora kinase inhibitor that also inhibits Bcr-Abl, including mutant Bcr-AblT315I. Aurora kinases are chaperoned by hsp90. Vorinostat (V) is a pan-histone deacetylase inhibitor that induces growth arrest, differentiation and apoptosis of acute leukemia cells. By inducing acetylation and inhibition of hsp90, V depletes the levels of hsp90 chaperoned proteins. Methods: Mouse BaF3 cells with ectopic expression of wild-type Bcr-Abl or mutant Bcr-AblE255K or Bcr-AblT315I, cultured human AML HL-60, OCI-AML3, and CML K562, as well as primary AML and imatinib-refractory CML cells were treated with M (50 to 250 nM) and/or V (0.5 to 2.0 μM) for 24 to 48 hours. Cell cycle status, DNA endoreduplication (PI staining) and apoptosis (Annexin/PI staining) were determined by flow cytometry. Intracellular levels of Aurora A and B, survivin, unmutated and mutant Bcr-Abl, p-STAT5, p-CrkL and Bim were determined by immunoblot analyses. Results: Treatment with M decreased phosphorylated (P)-serine 10 on histone H3 and p-survivin, as well as induced DNA endo-reduplication and apoptosis of the cultured AML cells. M induced more apoptosis of BaF3 cells with either the wild-type or mutant Bcr-AblE255K or Bcr-AblT315I, versus the control BaF3 cells. Co-treatment with M and V versus either agent alone resulted in more attenuation of the levels and activity of Aurora kinases and synergistically induced apoptosis of the cultured AML cells. Co-treatment with V and M markedly attenuated the levels of p-Bcr-Abl, p-STAT5, p-CrkL and Aurora kinases, as well as increased Bim and synergistically induced apoptosis of K562 cells. Co-treatment with M and V also induced synergistic apoptosis of BaF3/Bcr-Abl, BaF3/Bcr-AblE255K and BaF3/Bcr- AblT315I cells. M and V versus either agent alone, caused more loss of cell viability of primary AML and imatinib-refractory CML cells. The combination was also less toxic to normal CD34+ progenitor cells. Finally, co-treatment with M and V also inhibited leukemia growth and prolonged survival of NOD-SCID mice engrafted with OCI-AML3 cells. Conclusions: Combined treatment with M and V is highly active and should be tested in patients with AML or resistant CML, especially with Bcr-AblT315I. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Merck & Co. Novartis Institute for Biomedical Research Inc. Merck & Co., Novartis, Novartis Institute for Biomedical Research Inc.