The Discovery and Optimization of Hexahydro-2H-pyrano[3,2-c]quinolines (HHPQs) As Potent and Selective Inhibitors of the Mitotic Kinesin-5

Here we describe the discovery and optimization of hexahydro-2H-pyrano[3,2-c]quinolines (HHPQs) as potent and selective inhibitors of the mitotic kinesin-5 originally found during a high-throughput screening (HTS) campaign sampling our in-house compound collection. The compounds optimized subsequently and characterized herein were potently inhibiting the ATPase activity of Kinesin-5 and also exhibited consistent cellular activity, in that cells arrested in mitosis and apoptosis induction could be observed. X-ray crystallographic data demonstrated that these inhibitors bind in an allosteric pocket of Kinesin-5 distant from the nucleotide and microtubule binding sites. The selected clinical candidate EMD 534085 caused strong growth inhibition in human tumor xenograft models using Colo 205 colon carcinoma cells at doses below 30mg/kg administered twice weekly without showing severe toxicity as determined by loss of body weight.