Abstract 3242: CCT271850, a novel, selective, highly potent and orally bioavailable Mps1 kinase inhibitor.

Abstract

Abstract The main role of the cell cycle is to enable error-free DNA replication, chromosome segregation and cytokinesis. Surveillance mechanisms, the so-called checkpoint pathways, monitor passage through mitosis at several stages. One of the best characterised is the spindle assembly checkpoint that prevents anaphase onset until the appropriate tension and attachment across kinetochores is achieved. One of the first components of the spindle assembly checkpoint signal, identified by a genetic screen in budding yeast, was MPS1 (monopolar spindle 1; also known as TTK). MPS1 gene was shown to encode an essential dual-specificity kinase conserved from yeast to humans. MPS1 activity peaks at the G2/M transition and is enhanced upon activation of the spindle assembly checkpoint with nocodazole. We and others, have identified the autophosphorylation of T676 in the activation loop of MPS1 and shown that this is essential for MPS1 function. MPS1 has been found aberrantly overexpressed in a wide range of human tumours including breast, lung, oesophagus, and prostate. MPS1 is required for the establishment and maintenance of the spindle assembly checkpoint during mitosis. Aneuploid tumour cells possess a compromised spindle checkpoint to allow onset of anaphase and cell division. We have shown that depletion of MPS1 by siRNA induces cell death selectively in PTEN-deficient breast cancer cell lines. We have developed biochemical and cellular assays for MPS1 activity and a high throughput screening of our compound library delivered multiple hit series. We have previously reported the discovery of CCT251455 as a selective and orally bioavailable MPS1 inhibitor that inhibits the growth of a panel of human tumour cell lines, abrogates nocodazole-induced mitotic arrest and reduces the time spent in mitosis. Medicinal chemistry in combination with X-ray crystallography led to the discovery of CCT271850, a novel inhibitor of MPS1 kinase activity. CCT271850 selectively inhibits MPS1 kinase activity with an IC50 of 0.004 μM, inhibits autophosphorylation of MPS1 in cells with an IC50 of 0.07 μM and reduces the growth of a panel of human tumour cell lines, particularly PTEN-deficient cell lines. Tumour cells treated with CCT271850 contain aberrant numbers of chromosomes and the majority of cells divide their chromosomes without proper alignment. CCT271850 is orally bioavailable (F = 68%) and shows modulation of biomarkers in vivo. Citation Format: Amir Faisal, Paolo Innocenti, Isaac Westwood, Sebastan Naud, Jessica Schmitt, Angela Hayes, Grace Mak, Mark Gurden, Vassilios Bavetsias, Jack Cheung, Hannah Woodward, Peter Sheldrake, Butrus Atrash, Rosemary Burke, Ross Baker, Craig McAndrew, Martin Rowlands, Melanie Valenti, Paul Workman, Suzanne Eccles, Florence Raynaud, Rob vanMontfort, Swen Hoelder, Julian Blagg, Spiros Linardopoulos. CCT271850, a novel, selective, highly potent and orally bioavailable Mps1 kinase inhibitor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3242. doi:10.1158/1538-7445.AM2013-3242