Discovery of a Novel Oral Glucocorticoid Receptor Modulator

Drug Annotation Cite This: J. Med. Chem. 2018, 61, 1785−1799

pubs.acs.org/jmc

Discovery of a Novel Oral Glucocorticoid Receptor Modulator (AZD9567) with Improved Side Effect Profile Lena Ripa,*,† Karl Edman,‡ Matthew Dearman,† Goran Edenro,† Ramon Hendrickx,† Victoria Ullah,† Hui-Fang Chang,† Matti Lepistö,† Dave Chapman,† Stefan Geschwindner,‡ Lisa Wissler,‡ Petter Svanberg,† Karolina Lawitz,§ Jesper Malmberg,† Antonios Nikitidis,† Roine I. Olsson,† James Bird,† Antoni Llinas,† Tove Hegelund-Myrbac̈ k,† Markus Berger,∥ Philip Thorne,⊥ Richard Harrison,⊥ Christian Köhler,‡ and Tomas Drmota† †

Respiratory, Inflammation and Autoimmunity, IMED Biotech Unit, AstraZeneca Gothenburg, Pepparedsleden 1, Mölndal 43183, Sweden ‡ Discovery Sciences, IMED Biotech Unit, AstraZeneca Gothenburg, Pepparedsleden 1, Mölndal431 83, Sweden § AstraZeneca R&D Lund, Scheelevägen 1, Lund 22187, Sweden ∥ Medicinal Chemistry Berlin, Drug Discovery, Pharmaceuticals, Bayer AG, Berlin 13353, Germany ⊥ AstraZeneca R&D Charnwood, Bakewell Road, Loughborough, Leicestershire LE11 5RH, U.K. S Supporting Information *

ABSTRACT: Synthetic glucocorticoids (GC) are essential for the treatment of a broad range of inflammatory diseases. However, their use is limited by target related adverse effects on, e.g., glucose homeostasis and bone metabolism. Starting from a nonsteroidal GR ligand (4) that is a full agonist in reporter gene assays, we exploited key functional triggers within the receptor, generating a range of structurally diverse partial agonists. Of these, only a narrow subset exhibited full anti-inflammatory efficacy and a significantly reduced impact on adverse effect markers in human cell assays compared to prednisolone. This led to the discovery of AZD9567 (15) with excellent in vivo efficacy when dosed orally in a rat model of joint inflammation. Compound 15 is currently being evaluated in clinical trials comparing the efficacy and side effect markers with those of prednisolone.

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INTRODUCTION The glucocorticoid receptor (GR) is a ligand activated transcription factor and a member of the steroid hormone receptor family comprising the estrogen receptors (ERα and ERβ), the androgen receptor (AR), the progesterone receptor (PR), and the mineralocorticoid receptor (MR). GR is activated by the glucocorticoid (GC) hormone cortisol. It is of fundamental importance for regulating development, metabolism, inflammation, and stress response. GCs were introduced to treat patients with rheumatoid arthritis (RA) nearly 70 years ago.1 Since then, the use of synthetic GCs has transformed the treatment of inflammatory and autoimmune diseases,2 but the chronic use of GCs at optimal efficacy doses is still limited by severe adverse effects including hyperglycemia, muscle wasting, hypertension, and osteoporosis. Several © 2018 American Chemical Society

programs to discover safer GR ligands have been reported, and new classes of oral nonsteroidal ligands have been identified.3 However, only limited progress has been reported for the most advanced compounds 13e,f and 23g (Figure 1), thus the need for safer GR modulators remains.4 In the resting state, GR predominantly resides as a chaperone complex in the cytoplasm. Ligand activation leads to nuclear translocation where GR binds to the DNA response elements and recruits co-regulators to modulate the transcriptional activity in a context dependent manner. Several genomic mechanisms have been described.5 The typical activation process is transactivation (TA) where GR binds as a dimer to Received: November 17, 2017 Published: February 9, 2018 1785

DOI: 10.1021/acs.jmedchem.7b01690 J. Med. Chem. 2018, 61, 1785−1799

Journal of Medicinal Chemistry

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Drug Annotation

COMPOUND DESIGN AND HYPOTHESIS FOR INTRODUCING PARTIAL AGONIST/ANTAGONIST ACTIVITY GR ligands bind in a fully occluded pocket in the GR ligand binding domain (LBD)11 and allosterically modulate the receptor conformation. The resulting structural state controls the co-regulator recruitment and DNA interaction pattern and ultimately the functional response. A large number of GR− ligand complex structures have been published to date.12 They provide a solid foundation for understanding the molecular drivers of receptor activation. We have previously described the discovery of phenyl indazole based nonsteroidal GR modulators, where compound 4 (Figure 1) displayed excellent in vivo efficacy in a rat model of joint inflammation after oral dosing.10 With respect to its side effect profile, 4 was found to have limited advantage compared to prednisolone and was not progressed further. However, this chemical series provided a good starting point for designing compounds with a potential for a differentiated functional profile. The X-ray structure of GR LBD in complex with 4 clearly indicates that it maintains key pharmacophore elements for receptor activation (Figure 2). The amide functionality interacts with Asn564 and Gln642 and the p-fluoro phenyl residue extends through the gatekeeper region by rearranging Gln570 and Arg611, creating nonpolar contacts to helices 3 and 5 (Figure 2A). Compound 4 exhibits full efficacy in the reporter gene assay measuring transrepression13 (TR) (Table 1), full efficacy in the transactivation assay14 (TAag), and was completely inactive in concentrations up to 1 μM in the reporter gene assay measuring inhibition of dexamethasone induced transactivation15 (TAantag). Following the project hypothesis, namely to identify compounds with partial efficacy for TA (defined as 50% efficacy in TAantag), but full efficacy in the TR assay (>80% efficacy), we needed to modulate the mechanistic profile of 4. The structural overlay of GR LBD in complex with 4 onto the structure of GR LBD in complex with the antagonist 516 (mifepristone, Figure 1) is shown in Figure 2B. While both compounds occupy the central volume of the ligand binding pocket, they extend into different subpockets. Specifically, the dimethylamino phenyl residue of 5 pushes toward Leu753 in helix 12. Helix 12 is part of the activation function 2 (AF-2), which is a key element for interaction with co-regulator proteins and ultimately the genomic response. The presence of the dimethylamino phenyl residue results in a considerable

Figure 1. (A) Oral GR modulators that have entered clinical trials: BI 653,0483e,f (1) and fosdagrocorat3g (2) (prodrug of 3). (B) Tool compounds used in design: AZD290610 (4) and mifepristone (5).

the consensus glucocorticoid DNA response element (GRE) to upregulate gene transcription (e.g., tyrosine aminotransferase, TAT, and glucocorticoid-induced leucine zipper, GILZ). However, GR can also bind to negative GRE (nGRE), resulting in repression of transcription6 (e.g., thymic stromal lymphopoietin, TSLP). In addition, GR may also interfere with other transcription factors, such as activator protein 1 (AP-1) and nuclear factor κΒ (NF-κB), through a mechanism called transrepression (TR), resulting in repression of gene products such as TNFα and IL-6.7 Early observations indicated that while many genes controlling adverse effects are regulated by TA, several key pro-inflammatory genes could be suppressed through TR. However, several exceptions have been identified (e.g., GILZ, IL-10), and drug discovery campaigns based upon full agonists with separation of TR over TA alone have been unsuccessful.5b,8 Looking across the steroid receptor family, partial agonism was key in the development of selective ER modulators9 (SERMs) to achieve tissue and/or pathway specific pharmacology. In accordance with this, we adopted a strategy hypothesizing that a potent GR modulator with partial efficacy in the TA assay and full efficacy in the TR assay would be well positioned to provide differentiation. Compounds with such a mechanistic profile would then be progressed to functional human cell assays measuring markers of anti-inflammatory and adverse effects focusing on hyperglycemia and bone resorption.

Figure 2. (A) X-ray structure of GR LBD (green) in complex with compound 4 (magenta). Key residues in the ligand binding pocket are highlighted in orange stick representation. Putative hydrogen bonds are marked with dashed lines. (B) Superimposition of GR LBD in complex with 5 (white, PDB 3H52) onto GR LBD in complex with 4 (magenta). 1786

DOI: 10.1021/acs.jmedchem.7b01690 J. Med. Chem. 2018, 61, 1785−1799

Journal of Medicinal Chemistry

Drug Annotation

Table 1a

cell TAb compound prednisolone 1 3 4 5 6 7 8 9 10 11

R1

R2

benzyl i-propyl t-butoxymethyl methyl F

b

c

cell TRb,e d

GR IC50 nM

agonist EC50 nM (eff%)

antagonist IC50 nM (eff %)

IC50 nM (eff %)

cLogP/sol (μM)

7.0 19