Abstract 193: Inhibitors of MPS1: Discovery of CCT289346, a highly potent, selective and orally available preclinical candidate

MPS1 (also known as TTK), is a dual-specificity protein kinase and one of the main components of the spindle assembly checkpoint. Cancer cells heavily rely on MPS1 to cope with aneuploidy resulting from aberrant numbers of chromosomes and MPS1 has been found to be upregulated in a large number of tumor types. Extensive work by us and other groups has shown that MPS1 inhibitors are effective against a variety of cancers, particularly when used in combination with other drugs, for example, tubulin-targeting agents. We recently reported the structure-based design and discovery of a series of pyrido[3,4-d]pyrimidines inhibitors of MPS1 (1). Advanced compounds showed very potent inhibition of MPS1 in biochemical and cellular assays. However, these compounds suffered from high lipophilicity and pronounced metabolism in human liver microsomes preventing progression into preclinical development. Here we report the optimisation of this series ultimately yielding CCT289346, our preclinical candidate. CCT289346 shows excellent potency, kinase selectivity, and ADME properties including stability in human liver microsomes. The compound has been produced on a kilogram scale and is currently undergoing preclinical development. We will discuss our design approach and hypotheses leading to the discovery of CCT289346 and disclose in vivo efficacy data. References 1. Innocenti P et al. Rapid Discovery of Pyrido[3,4-d]pyrimidine Inhibitors of Monopolar Spindle Kinase 1 (MPS1) Using a Structure-Based Hybridization Approach. Journal of Medicinal Chemistry. 2016; 59(8):3671-88. Citation Format: Hannah L. Woodward, Paolo Innocenti, Kwai-Ming J. Cheung, Sebastien Naud, Angela Hayes, Alan T. Henley, Amir Faisal, Grace Mak, Gary Box, Isaac M. Westwood, Michael Carter, Melanie Valenti, Alexis De Haven Brandon, Lisa O’Fee, Harry Saville, Rosemary Burke, Rob van Montfort, Florence Raynaud, Suzanne A. Eccles, Spiros Linardopoulos, Julian Blagg, Swen Hoelder. Inhibitors of MPS1: Discovery of CCT289346, a highly potent, selective and orally available preclinical candidate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 193. doi:10.1158/1538-7445.AM2017-193