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A Conformational Restriction Strategy for the Identification of a Highly Selective Pyrimido-pyrrolo-oxazine mTOR Inhibitor

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posted on 10.09.2019, 20:29 by Chiara Borsari, Denise Rageot, Alix Dall’Asen, Thomas Bohnacker, Anna Melone, Alexander M. Sele, Eileen Jackson, Jean-Baptiste Langlois, Florent Beaufils, Paul Hebeisen, Doriano Fabbro, Petra Hillmann, Matthias P. Wymann
The mechanistic target of rapamycin (mTOR) plays a pivotal role in growth and tumor progression and is an attractive target for cancer treatment. ATP-competitive mTOR kinase inhibitors (TORKi) have the potential to overcome limitations of rapamycin derivatives in a wide range of malignancies. Herein, we exploit a conformational restriction approach to explore a novel chemical space for the generation of TORKi. Structure–activity relationship (SAR) studies led to the identification of compound 12b with a ∼450-fold selectivity for mTOR over class I PI3K isoforms. Pharmacokinetic studies in male Sprague Dawley rats highlighted a good exposure after oral dosing and a minimum brain penetration. CYP450 reactive phenotyping pointed out the high metabolic stability of 12b. These results identify the tricyclic pyrimido-pyrrolo-oxazine moiety as a novel scaffold for the development of highly selective mTOR inhibitors for cancer treatment.