Danette Dudley

Discovery of 2-{3-[2-(1-Isopropyl-3-methyl-1H-1,2–4-triazol-5-yl)-5,6-dihydrobenzo[f]imidazo[1,2-d][1,4]oxazepin-9-yl]-1H-pyrazol-1-yl}-2-methylpropanamide (GDC-0032): A β-Sparing Phosphoinositide 3-Kinase Inhibitor with High Unbound Exposure and Robust in Vivo Antitumor Activity

Dysfunctional signaling through the phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway leads to uncontrolled tumor proliferation. In the course of the discovery of novel benzoxepin PI3K inhibitors, we observed a strong dependency of in vivo antitumor activity on the free-drug exposure. By lowering the intrinsic clearance, we derived a set of imidazobenzoxazepin compounds that showed improved unbound drug exposure and effectively suppressed growth of tumors in a mouse xenograft model at low drug dose levels. One of these compounds, GDC-0032 (11l), was progressed to clinical trials and is currently under phase I evaluation as a potential treatment for human malignancies.

Discovery of (S)-1-(1-(4-Chloro-3-fluorophenyl)-2-hydroxyethyl)-4-(2-((1-methyl-1H-pyrazol-5-yl)amino)pyrimidin-4-yl)pyridin-2(1H)-one (GDC-0994), an Extracellular Signal-Regulated Kinase 1/2 (ERK1/2) Inhibitor in Early Clinical Development.

The extracellular signal-regulated kinases ERK1/2 represent an essential node within the RAS/RAF/MEK/ERK signaling cascade that is commonly activated by oncogenic mutations in BRAF or RAS or by upstream oncogenic signaling. While targeting upstream nodes with RAF and MEK inhibitors has proven effective clinically, resistance frequently develops through reactivation of the pathway. Simultaneous targeting of multiple nodes in the pathway, such as MEK and ERK, offers the prospect of enhanced efficacy as well as reduced potential for acquired resistance. Described herein is the discovery and characterization of GDC-0994 (22), an orally bioavailable small molecule inhibitor selective for ERK kinase activity.

Discovery of 5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine inhibitors of Erk2.

The discovery and optimization of a series of tetrahydropyridopyrimidine based extracellular signal-regulated kinase (Erks) inhibitors discovered via HTS and structure based drug design is reported. The compounds demonstrate potent and selective inhibition of Erk2 and knockdown of phospho-RSK levels in HepG2 cells and tumor xenografts.

Discovery of thiazolobenzoxepin PI3-kinase inhibitors that spare the PI3-kinase β isoform.

A series of suitable five-membered heterocyclic alternatives to thiophenes within a thienobenzoxepin class of PI3-kinase (PI3K) inhibitors was discovered. Specific thiazolobenzoxepin 8-substitution was identified that increased selectivity over PI3Kβ. PI3Kβ-sparing compound 27 (PI3Kβ Ki,app/PI3Kα Ki,app=57) demonstrated dose-dependent knockdown of pAKT, pPRAS40 and pS6RP in vivo as well as differential effects in an in vitro proliferation cell line screen compared to pan PI3K inhibitor GDC-0941. A new structure-based hypothesis for reducing inhibition of the PI3K β isoform while maintaining activity against α, δ and γ isoforms is presented.

Structure-guided rescaffolding of selective antagonists of BCL-XL

Because of the promise of BCL-2 antagonists in combating chronic lymphocytic leukemia (CLL) and non-Hodgkins lymphoma (NHL), interest in additional selective antagonists of antiapoptotic proteins has grown. Beginning with a series of selective, potent BCL-XL antagonists containing an undesirable hydrazone functionality, in silico design and X-ray crystallography were utilized to develop alternative scaffolds that retained the selectivity and potency of the starting compounds.

Abstract DDT02-01: Discovery of GDC-0032: A beta-sparing PI3K inhibitor active against PIK3CA mutant tumors.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Modifications of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway are frequent in cancer due to multiple mechanisms, including activating mutations of the alpha isoform of PI3K. The dysregulation of this pathway has been implicated in many processes involved in oncogenesis. Thus, PI3K is a promising therapeutic target for cancer. Previously we have disclosed GDC-0941, a class 1 selective PI3K inhibitor and our class 1 PI3K/mTOR kinase inhibitor, GDC-0980. In this presentation we describe the design and discovery of a new class of PI3K inhibitors, which selectively inhibit the activated PI3Kα isoform relative to the PI3Kβ isoform. A lead was identified from a high throughput screen (HTS) that resulted in a novel chemical series of kinase inhibitors. Through a structure-based approach, this lead was optimized to provide very potent inhibitors of PI3K. In addition, this chemical series allowed for designing molecules that have different selectivity patterns with respect to the class 1 PI3K isoforms. In particular, a series of inhibitors were designed that could preferentially inhibit PI3Kα relative to PI3Kβ (“beta-sparing”). Further modification of the physicochemical properties led to the discovery of GDC-0032. GDC-0032 is a potent inhibitor of PI3Kα (PIK3CA) isoform with a Ki =0.2 nM, and with reduced inhibitory activity against PI3Kβ. This selectivity profile allowed for greater efficacy in vivo at the maximum tolerated dose relative to a pan inhibitor in representative PI3Kα (PIK3CA) mutant xenografts. It is notable that GDC-0032 preferentially inhibited PI3Kα (PIK3CA) mutant cells relative to cells with wild-type PI3K. Taken together, GDC-0032 is a potent and effective beta-sparing PI3K inhibitor, which currently is in clinical trials. Citation Format: Alan G. Olivero, Timothy P. Heffron, Matthew Baumgardner, Marcia Belvin, Leanne Berry Ross, Nicole Blaquiere, Erin Bradley, Georgette Castanedo, Mika Derynck, Steven Do, Jennafer Dotson, Danette Dudley, Kyle Edgar, Adrian Folkes, Ross Francis, Tony Gianetti, Richard Goldsmith, Paul Goldsmith, Jane Guan, Trevor Harrison, Robert Heald, Jerry Hsu, Phillip Jackson, Graham Jones, Amy Kim, Aleks Kolesnikov, Mark Lackner, Leslie Lee, John Lesnick, Cristina Lewis, Michael Mamounas, Neville McLean, Jeremy Murray, Chudi Ndubaku, Jim Nonomiya, Jodie Pang, Neil Pegg, Wei Wei Prior, Laurent Salphati, Deepack Sampath, Stephen Sideris, Michael Siu, Steven Staben, Daniel Sutherlin, Mark Ultsch, Jeff Wallin, Lan Wang, Christian Wiesmann, Xiaolin Zhang, Lori S. Friedman. Discovery of GDC-0032: A beta-sparing PI3K inhibitor active against PIK3CA mutant tumors. [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 DDT02-01. doi:10.1158/1538-7445.AM2013-DDT02-01