Abstract Indoleamine 2,3-dioxygenase 1 (IDO1) is a heme-dependent enzyme that catalyzes the initial and rate-limiting step of tryptophan catabolism resulting in the local depletion of tryptophan and the concomitant production of kynurenine, both of which are immunosuppressive. Targeting IDO1 in combination with PD-1/PD-L1-targeted antibodies has shown promise in early phase clinical trials in several cancers and strongly suggests that, in some patients, IDO1 expression restrains PD-1/PD-L1-targeted checkpoint therapies. While some cancers extrinsically express IDO1 in response to IFN-γ produced from an ongoing, yet ineffective immune response, others select for the intrinsic expression of IDO1, independent of an immune response. We identified several cancer cell lines that intrinsically expressed either IDO1 or the related isozyme TDO2. Using these cell lines, we discovered LY3381916, a potent and selective inhibitor of cell-based IDO1 activity (IDO1 7 nM; TDO2 >20 µM). Using a variety of techniques, we demonstrated that LY3381916 binds to newly synthesized apo-IDO1 lacking heme, but does not inhibit mature heme-bound IDO1. Protein x-ray crystallography confirmed that LY3381916 binds to apo-IDO1 where it occupies the heme-binding pocket of IDO1. As a result of this novel mechanism of action, substantial inhibition of IDO1 in tumors requires the turn-over of mature heme-bound IDO1. Modeling of the pre-clinical PK/PD relationship suggests QD dosing of LY3381916 will maintain greater than 90% inhibition over 24 hours. In addition, due to the favorable properties of the drug, significant central nervous system (CNS) penetration has been measured for LY3381916 (rodent kp,uu 0.26). Kynurenine-mediated agonism of the aryl hydrocarbon receptor (AHR) is immunosuppressive in the tumor microenvironment. Inhibition of IDO1 and the subsequent reduction of kynurenine can relieve this immunosuppression. However, several heme-binding IDO1 inhibitors have been shown to replace kynurenine as an AHR agonist potentially limiting their ability to relieve this IDO1-dependent immunosuppressive mechanism. LY3381916 shows no confounding agonism of AHR up to 100 µM. Additionally, we characterized LY3381916 in pre-clinical tumor models and demonstrated that it was able to enhance LY3300054, anti-PD-L1 antibody (LY3300054) activity, which was associated with an enhanced T cell response. Based on these characteristics, LY3381916 is currently being investigated in a Phase I clinical trial. These data suggest further development of LY3381916 may be warranted. Citation Format: Frank C. Dorsey, Karim A. Benhadji, Lillian L. Sams, Debra A. Young, John F. Schindler, Karen L. Huss, Alexander Nikolayev, Carmine Carpenito, David Clawson, Bonita Jones, Andrew L. Faber, James E. Thomas, Steven A. Haney, Gaiying Zhao, William T. McMillen, Tod Smeal, Daniel J. Sall, Michael D. Kalos, Sandaruwan Geeganage, James R. Henry. Identification and characterization of the IDO1 inhibitor LY3381916 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5245.

ADVERTISEMENT RETURN TO ISSUEPerspectiveNEXTModern Phenotypic Drug Discovery Is a Viable, Neoclassic Pharma StrategyJonathan A. Lee*†, Mark T. Uhlik‡, Christopher M. Moxham⊥, Dirk Tomandl§, and Daniel J. Sall∥View Author Information∥ Departments of †Quantitative Biology, ‡Cancer-Angiogenesis, §Discovery Informatics, and ∥Discovery Chemistry Research and Technologies, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana⊥ ImClone Systems, a Wholly Owned Subsidiary of Eli Lilly and Company, New York, New York*Phone: 317-277-8123. Fax: 317-276-6009. E-mail: [email protected]Cite this: J. Med. Chem. 2012, 55, 10, 4527–4538Publication Date (Web):March 12, 2012Publication History Received6 December 2011Published online23 March 2012Published inissue 24 May 2012https://pubs.acs.org/doi/10.1021/jm201649shttps://doi.org/10.1021/jm201649sreview-articleACS PublicationsCopyright © 2012 American Chemical SocietyRequest reuse permissionsArticle Views6957Altmetric-Citations160LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Angiogenesis,Assays,Inhibition,Mathematical methods,Pharmaceuticals Get e-Alerts

The Hedgehog (Hh) pathway is a highly conserved signaling system that plays an important role in embryonic development and tissue homeostasis through regulation of cell differentiation and proliferation, and deregulated Hh signaling has been implicated in variety of cancers. Two distinct mechanisms are responsible for inappropriate and uncontrolled Hh pathway activation in human malignancies: ligand-dependent, due to over-expression of Hh ligand, and ligand-independent, resulting from genetic mutations in pathway components such as Patched (Ptch) and Smoothened (Smo). Smo, a member of the class F G-protein coupled receptor family, is a key regulator of Hh signaling pathway, and therefore is an attractive target for pathway modulation. We have identified a potent and selective small molecule antagonist of Smo. This novel molecule (LY2940680) binds to the Smo receptor and potently inhibits Hh signaling in Daoy, a human medulloblastoma tumor cell line, and C3H10T½, a mouse mesenchymal cell line. Importantly, LY2940680 binds to and inhibits the functional activity of resistant Smo mutant (D473H) produced by treatment with GDC-0449 (a Smo antagonist from Genentech). LY2940680 also has excellent pharmacokinetic properties in rodent and non-rodent species. Treatment of Ptch+/− p53−/− transgenic mice, which spontaneously develop medulloblastoma, with oral administration of LY2940680 produced remarkable efficacy and significantly improved their survival. Magnetic resonance imaging of these mice revealed rapid kinetics of anti-tumor activity. Immunohistochemistry analysis of medulloblastoma tumors showed that LY2940680 treatment induced Caspase-3 activity and reduced proliferation. LY2940680 inhibited Hh regulated gene expression in the subcutaneous xenograft tumor stroma and produced significant anti-tumor activity. In summary, we have characterized an orally bio-available small molecule Smo antagonist that may provide therapeutic benefit to cancer patients with deregulated Hh signaling. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2819. doi:10.1158/1538-7445.AM2011-2819

Analogs to a series of d-phenylglycinamide-derived factor Xa inhibitors were discovered. It was found that the S4 amide linkage can be replaced with an ether linkage to reduce the peptide character of the molecules and that this substitution leads to an increase in binding affinity that is not predicted based on modeling. Inhibitors which incorporate ether, amino, or alkyl S4 linkage motifs exhibit similar levels of binding affinity and also demonstrate potent in vitro functional activity, however, binding affinity in this series is strongly dependent on the nature of the S1 binding element.

The synthesis and biological evaluation of a series of oxindole β3 adrenergic receptor agonists is described. A modulation of rat atrial tachycardia was observed with substitution at the 3-position of the oxindole moiety.

The synthesis and biological evaluation of a series of benzimidazolone β3 adrenergic receptor agonists are described. A trend toward the reduction of rat atrial tachycardia upon increasing steric bulk at the 3-position of the benzimidazolone moiety was observed.