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Serine/threonine protein kinases Aurora A, B, and C play essential roles in cell mitosis and cytokinesis. Currently a number of Aurora kinase inhibitors with different isoform selectivities are being evaluated in the clinic. Herein we report the discovery and characterization of 21c (AC014) and 21i (AC081), two structurally novel, potent, kinome-selective pan-Aurora inhibitors. In the human colon cancer cell line HCT-116, both compounds potently inhibit histone H3 phosphorylation and cell proliferation while inducing 8N polyploidy. Both compounds administered intravenously on intermittent schedules displayed potent and durable antitumor activity in a nude rat HCT-116 tumor xenograft model and exhibited good in vivo tolerability. Taken together, these data support further development of both 21c and 21i as potential therapeutic agents for the treatment of solid tumors and hematological malignancies.

A series of potent, selective platelet-derived growth factor receptor-family kinase inhibitors was optimized starting from a globally selective lead molecule 4 through structural modifications aimed at improving the physiochemical and pharmacokinetic properties, as exemplified by 18b. Further clearance reduction via per-methylation of the α-carbons of a solubilizing piperidine nitrogen resulted in advanced leads 22a and 22b. Results from a mouse tumor xenograft, a collagen-induced arthritis model, and a 7 day rat in vivo tolerability study culminated in the selection of compound 22b (AC710) as a preclinical development candidate.