Sam Butterworth

Discovery of a Potent and Selective EGFR Inhibitor (AZD9291) of Both Sensitizing and T790M Resistance Mutations That Spares the Wild Type Form of the Receptor

Epidermal growth factor receptor (EGFR) inhibitors have been used clinically in the treatment of non-small-cell lung cancer (NSCLC) patients harboring sensitizing (or activating) mutations for a number of years. Despite encouraging clinical efficacy with these agents, in many patients resistance develops leading to disease progression. In most cases, this resistance is in the form of the T790M mutation. In addition, EGFR wild type receptor inhibition inherent with these agents can lead to dose limiting toxicities of rash and diarrhea. We describe herein the evolution of an early, mutant selective lead to the clinical candidate AZD9291, an irreversible inhibitor of both EGFR sensitizing (EGFRm+) and T790M resistance mutations with selectivity over the wild type form of the receptor. Following observations of significant tumor inhibition in preclinical models, the clinical candidate was administered clinically to patients with T790M positive EGFR-TKI resistant NSCLC and early efficacy has been observed, accompanied by an encouraging safety profile.

Structure- and Reactivity-Based Development of Covalent Inhibitors of the Activating and Gatekeeper Mutant Forms of the Epidermal Growth Factor Receptor (EGFR)

A novel series of small-molecule inhibitors has been developed to target the double mutant form of the epidermal growth factor receptor (EGFR) tyrosine kinase, which is resistant to treatment with gefitinib and erlotinib. Our reported compounds also show selectivity over wild-type EGFR. Guided by molecular modeling, this series was evolved to target a cysteine residue in the ATP binding site via covalent bond formation and demonstrates high levels of activity in cellular models of the double mutant form of EGFR. In addition, these compounds show significant activity against the activating mutations, which gefitinib and erlotinib target and inhibition of which gives rise to their observed clinical efficacy. A glutathione (GSH)-based assay was used to measure thiol reactivity toward the electrophilic functionality of the inhibitor series, enabling both the identification of a suitable reactivity window for their potency and the development of a reactivity quantitative structure-property relationship (QSPR) to support design.

Osmium-mediated oxidative cyclizations: a study into the range of initiators that facilitate cyclization.

A general route to prepare substituted, saturated five-membered heterocycles has been developed. The application of a wide range of starting materials to the osmium-catalyzed oxidative cyclization reaction is described. Diols, hydroxy-amides, hydroxy-sulfonamides, and carbamates all cyclize in moderate to excellent yields to give cis-tetrahydrofurans and pyrrolidines, depending upon the position of the heteroatoms in the starting materials. These cyclizations all proceed with near total selectivity for the cis-heterocycles, and with stereospecific introduction of a hydroxy group adjacent to the ring. Moreover, routes to enantiopure starting materials are described, which give enantiopure products upon cyclization. Catalyst loadings of as low as one mol percent have been successfully employed for this transformation.

Abstract B94: Discovery of and first disclosure of the clinical candidate AZD9291, a potent and selective third-generation EGFR inhibitor of both activating and T790M resistant mutations that spares the wild type form of the receptor.

Abstracts: AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics--Oct 19-23, 2013; Boston, MA Small molecule inhibitors of the epidermal growth factor receptor (EGFR) tyrosine kinase such as gefitinib and erlotinib have been employed successfully in the treatment of non-small cell lung cancer (NSCLC) patients harboring an activating mutation (EGFRm+). However, resistance to these inhibitors in the form of additional mutations in the kinase domain such as T790M is emerging as a growing clinical issue. This presentation will describe the discovery of AZD9291, an orally bioavailable, irreversible EGFR inhibitor of both the resistance (NCI-H1975, cell phosphorylation IC50 0.5 μM). Wild type EGFR inhibition is believed to drive the observed dose limiting toxicities (such as skin rash and diarrhea) for these first generation therapies in the clinic. New data will be discussed for the first time including the medicinal chemistry program that led to the identification of AZD9291, details of significant in vivo oral activity in pre-clinical xenograft models (including tumor regression in the L858R/T790M double mutant setting at a dose of 5 mpk) and the first disclosure of the candidate drug structure. The pre-clinical findings from this work strongly supported selection of AZD9291 as a clinical candidate, and first dose in man was achieved with AZD9291 in March 2013. View this table: Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B94. Citation Format: M. Raymond V. Finlay, Mark Anderton, Susan Ashton, Peter G. Ballard, Rob H. Bradbury, Sam Butterworth, Nicola Colclough, Darren A. E. Cross, Heather L. McFarland, Martine J. Mellor, Richard A. Ward, Mike J. Waring. Discovery of and first disclosure of the clinical candidate AZD9291, a potent and selective third-generation EGFR inhibitor of both activating and T790M resistant mutations that spares the wild type form of the receptor. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B94.

Abstract 4744: Structure-based development of covalent inhibitors of the activating and T790M gatekeeper mutant forms of the epidermal growth factor receptor (EGFR) leading to the discovery of AZD9291

Small molecule inhibitors of the Epidermal Growth Factor Receptor (EGFR) tyrosine kinase such as gefitinib and erlotinib have been employed successfully in the treatment of non-small cell lung cancer (NSCLC) patients harboring an activating mutation (EGFRm+). However, resistance to these inhibitors in the form of additional mutations such as T790M, (mutation of the gatekeeper residue), is recognized as a clinical issue. This presentation will describe the discovery and evolution of one of our novel chemical series, leading ultimately to the identification of AZD9291, an orally bioavailable, covalent EGFR inhibitor of both the resistance (NCI-H1975, cell phosphorylation IC50 0.5 uM). Wild type EGFR inhibition is believed to drive the observed dose limiting toxicities (such as skin rash and diarrhea) for these first generation therapies in the clinic. New data will be presented for the first time including a broader description of the medicinal chemistry program that led to the identification of AZD9291. We shall also present previously undisclosed work on the identification of additional distinct chemical series and an update of recent data from ongoing AZD9291 Phase I clinical studies in NSCLC patients. Citation Format: Richard A. Ward, Susan Ashton, Mark Anderton, Pete G. Ballard, Rob H. Bradbury, Sam Butterworth, Nicola Colclough, Darren A E Cross, M Ray V. Finlay, Heather L. McFarland, Martine Mellor, Mike J. Waring. Structure-based development of covalent inhibitors of the activating and T790M gatekeeper mutant forms of the epidermal growth factor receptor (EGFR) leading to the discovery of AZD9291. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4744. doi:10.1158/1538-7445.AM2014-4744