Douglas S. Werner

Imidazo[1,5-a]pyrazines: orally efficacious inhibitors of mTORC1 and mTORC2.

The discovery and optimization of a series of imidazo[1,5-a]pyrazine inhibitors of mTOR is described. HTS hits were optimized for potency, selectivity and metabolic stability to provide the orally bioavailable proof of concept compound 4c that demonstrated target inhibition in vivo and concomitant inhibition of tumor growth in an MDA-MB-231 xenograft model.

Discovery of an Orally Efficacious Imidazo[5,1-f][1,2,4]triazine Dual Inhibitor of IGF-1R and IR.

This report describes the investigation of a series of 5,7-disubstituted imidazo[5,1-f][1,2,4]triazine inhibitors of insulin-like growth factor-1 receptor (IGF-1R) and insulin receptor (IR). Structure-activity relationship exploration and optimization leading to the identification, characterization, and pharmacological activity of compound 9b, a potent, selective, well-tolerated, and orally bioavailable dual inhibitor of IGF-1R and IR with in vivo efficacy in tumor xenograft models, is discussed.

A Novel, Nonpeptidic, Orally Active Bivalent Inhibitor of Human β-Tryptase

β-Tryptase is released from mast cells upon degranulation in response to allergic and inflammatory stimuli. Human tryptase is a homotetrameric serine protease with 4 identical active sites directed toward a central pore. These active sites present an optimized scenario for the rational design of bivalent inhibitors, which bridge 2 adjacent active sites. Using (3-[1-acylpiperidin-4-yl]phenyl)methanamine as the pharmacophoric core and a disiloxane linker to span 2 active sites we have successfully produced a novel bivalent tryptase inhibitor, compound 1a, with a comparable profile to previously described inhibitors. Pharmacological properties of compound 1a were studied in a range of in vitro enzymic and cellular screening assays, and in vivo xenograft models. This non-peptide inhibitor of tryptase demonstrated superior activity (IC50 at 100 pmol/L tryptase = 1.82 nmol/L) compared to monomeric modes of inhibition. X-ray crystallography validated the dimeric mechanism of inhibition, and 1a demonstrated good oral bioavailability and efficacy in HMC-1 xenograft models. Furthermore, compound 1a demonstrated extremely slow off rates and high selectivity against-related proteases. This highly potent, orally bioavailable and selective inhibitor of human tryptase will be an invaluable tool in future studies to explore the therapeutic potential of attenuating the activity of this elusive target.

Abstract 3900: Discovery of FQIT: An imidazo[5,1-f][1,2,4]triazine derived dual IGF-1R/IR inhibitor

Insulin-like growth factor-1 receptor (IGF-1R) has been recognized as a major target in cancer drug discovery due to its strong implications in various stages of tumorigenesis based on accumulated preclinical data over the years. Recent research on compensatory crosstalk between IGF-1R and insulin receptor (IR) signaling pathways suggests that targeting both receptors is critical to fully blocking the IGF signaling axis. Therefore, inhibition of both receptors is anticipated to result in a more therapeutically beneficial response than targeting IGF-1R alone (e.g. IGF-1R specific antibodies). These findings provided the biological rationale as well as set the foundation for the pursuit and ultimate discovery of OSI-906 (linsitinib), a small molecule dual IGF-1R/IR inhibitor currently in clinical development. As part of OSI9s ongoing investment in a small molecule drug discovery platform targeting IGF-1R and IR, a new series of potent and selective imidazo[5,1-f][1,2,4]triazine derived inhibitors of IGF-1R and IR have been identified. Structure-activity relationships and optimization driven by structure-based drug design (SBDD) leading to the discovery of FQIT, a potent, highly selective, well-tolerated and orally bioavailable dual inhibitor of IGF-1R and IR with in vivo efficacy in multiple tumor xenograft models will be discussed. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3900. doi:1538-7445.AM2012-3900