Rationally Designed, Conformationally Constrained Inverse Agonists of RORγt-Identification of a Potent, Selective Series with Biologic-Like in Vivo Efficacy

Discovery and SAR of JTE-151: A Novel RORγ Inhibitor for Clinical Development

A number of RORγ inhibitors have been reported over the past decade. There were also several examples advancing to human clinical trials, however, none of them has reached the market yet, suggesting that there could be common obstacles for their future development. As was expected from the general homology of nuclear receptor ligands, insufficient selectivity as well as poor physicochemical properties were identified as potential risks for a RORγ program. Based on such considerations, we conducted a SAR investigation by prioritizing drug-like properties to mitigate such potential drawbacks. After an intensive SAR exploration with strong emphasis on "drug-likeness" indices, an orally available RORγ inhibitor, JTE-151, was finally generated and was advanced to a human clinical trial. The compound was confirmed to possess highly selective profiles along with good metabolic stability, and most beneficially, no serious adverse events (SAE) and good PK profiles were observed in the human clinical trial.

Discovery of the First-in-Class RORγ Covalent Inhibitors for Treatment of Castration-Resistant Prostate Cancer

Nuclear receptor receptor-related orphan receptor γ (RORγ) is a ligand-dependent transcription factor and has been established as a key player in castration-resistant prostate cancers (CRPC) by driving androgen receptor (AR) overexpression, representing a potential therapeutical target for advanced prostate cancers. Here, we report the identification of the first-in-class RORγ covalent inhibitor 29 via the structure-based drug design approach following structure-activity relationship (SAR) exploration. Mass spectrometry assay validated its covalent inhibition mechanism. Compound 29 significantly inhibited RORγ transcriptional activity and remarkably suppressed the expression levels of AR and AR-targeted genes. Compound 29 also exhibited much superior activity in inhibiting the proliferation and colony formation and inducing apoptosis of the CRPC cell lines relative to the positive control 2 and noncovalent control 33. Importantly, it markedly suppressed the tumor growth in a 22Rv1 mouse tumor xenograft model with good safety. These results clearly demonstrate that 29 is a highly potent and selective RORγ covalent inhibitor.

Direct electrophilic and radical isoperfluoropropylation with i-C3F7-Iodine(III) reagent (PFPI reagent)

The isoperfluoropropyl group (i-C3F7) is an emerging motif in pharmaceuticals, agrichemicals and functional materials. However, isoperfluoropropylated compounds remain largely underexplored, presumably due to the lack of efficient access to these compounds. Herein, we disclose the practical and efficient isoperfluoropropylation of aromatic C-H bonds through the invention of a hypervalent-iodine-based reagent-PFPI reagent, that proceeds via a Ag-X coupling process. The activation of the PFPI reagent without any catalysts or additives was demonstrated in the synthesis of isoperfluoropropylated electron-rich heterocycles, while its activity under photoredox catalysis was shown in the synthesis of isoperfluoropropylated non-activated arenes. Detailed mechanistic experiments and DFT calculations revealed a SET-induced concerted mechanistic pathway in the photoredox reactions. In addition, the unique conformation of i-C3F7 in products, that involved intramolecular hydrogen bond was investigated by X-ray single-crystal diffraction and variable-temperature NMR experiments.

The pyridazine heterocycle in molecular recognition and drug discovery

The pyridazine ring is endowed with unique physicochemical properties, characterized by weak basicity, a high dipole moment that subtends π-π stacking interactions and robust, dual hydrogen-bonding capacity that can be of importance in drug-target interactions. These properties contribute to unique applications in molecular recognition while the inherent polarity, low cytochrome P450 inhibitory effects and potential to reduce interaction of a molecule with the cardiac hERG potassium channel add additional value in drug discovery and development. The recent approvals of the gonadotropin-releasing hormone receptor antagonist relugolix (24) and the allosteric tyrosine kinase 2 inhibitor deucravacitinib (25) represent the first examples of FDA-approved drugs that incorporate a pyridazine ring. In this review, the properties of the pyridazine ring are summarized in comparison to the other azines and its potential in drug discovery is illustrated through vignettes that explore applications that take advantage of the inherent physicochemical properties as an approach to solving challenges associated with candidate optimization.

Graphical Abstract

Modes of action insights from the crystallographic structures of retinoic acid receptor-related orphan receptor-γt (RORγt)

RORγt plays an important role in mediating IL-17 production and some tumor cells. It has four functional domains, of which the ligand-binding domain (LBD) is responsible for binding agonists to recruit co-activators or inverse agonists to prevent co-activator recruiting the agonists. Thus, potent ligands targeting the LBD of this protein could provide novel treatments for cancer and autoimmune diseases. In this perspective, we summarized and discussed various modes of action (MOA) of RORγt-ligand binding structures. The ligands can bind with RORγt at either orthosteric site or the allosteric site, and the binding modes at these two sites are different for agonists and inverse agonist. At the orthosteric site, the binding of agonist is to stabilize the H479-Y502-F506 triplet interaction network of RORγt. The binding of inverse agonist features as these four apparent ways: (1) blocking the entrance of the agonist pocket in RORγt; (2) directly breaking the H479-Y502 pair interactions; (3) destabilizing the triplet H479-Y502-F506 interaction network through perturbing the conformation of the side chain in M358 at the bottom of the binding pocket; (4) and destabilizing the triplet H479-Y502-F506 through changing the conformation of the side chain of residue W317 side chain. At the allosteric site of RORγt, the binding of inverse agonist was found recently to inhibit the activation of protein by interacting directly with H12, which results in unfolding of helix 11' and orientation of H12 to directly block cofactor peptide binding. This overview of recent advances in the RORγt structures is expected to provide a guidance of designing more potent drugs to treat RORγt-related diseases.

Statistical Analysis of Protein-Ligand Interaction Patterns in Nuclear Receptor RORγ

The receptor RORγ belongs to the nuclear receptor superfamily that senses small signaling molecules and regulates at the gene transcription level. Since RORγ has a high basal activity and plays an important role in immune responses, inhibitors targeting this receptor have been a focus for many studies. The receptor-ligand interaction is complex, and often subtle differences in ligand structure can determine its role as an inverse agonist or an agonist. We examined more than 130 existing RORγ crystal structures that have the same receptor complexed with different ligands. We reported the features of receptor-ligand interaction patterns and the differences between agonist and inverse agonist binding. Specific changes in the contact interaction map are identified to distinguish active and inactive conformations. Further statistical analysis of the contact interaction patterns using principal component analysis reveals a dominant mode which separates allosteric binding vs. canonical binding and a second mode which may indicate active vs. inactive structures. We also studied the nature of constitutive activity by performing a 100-ns computer simulation of apo RORγ. Using constitutively active nuclear receptor CAR as a comparison, we identified a group of conserved contacts that have similar contact strength between the two receptors. These conserved contact interactions, especially a couple key contacts in H11–H12 interaction, can be considered essential to the constitutive activity of RORγ. These protein-ligand and internal protein contact interactions can be useful in the development of new drugs that direct receptor activity.

An approach to pharmacological targets of pyrrole family from a medicinal chemistry viewpoint

Pyrrole is one of the most widely used heterocycles in the pharmaceutical industry. Due to the importance of pyrrole structure in drug design and development, herein, we tried to conduct an extensive review of the bioactive pyrrole based compounds reported recently. The bioactivity of pyrrole derivatives varies, so in the review, we categorized them based on their direct pharmacologic targets. Therefore, readers are able to find the variety of biologic targets for pyrrole containing compounds easily. This review explains around seventy different biologic targets for pyrrole based derivatives, so, it is helpful for medicinal chemists in design and development novel bioactive compounds for different diseases. This review presents an extensive meaningful structure activity relationship for each reported structure as much as possible. The review focuses on papers published between 2018 and 2020.

The evolution paths of some reprehensive scaffolds of RORγt modulators, a perspective from medicinal chemistry

The ligand binding domain (LBD) of retinoid-related orphan nuclear receptor γt (RORγt) has been exploited as a promising target for the new small molecule therapeutics to cure autoimmune diseases via modulating the IL-17 and IL-22 production by Th17 cells. Diverse chemical scaffolds of these small molecules have been discovered by multiple groups with methods such as high throughput screening (HTS) and virtual screening. These different scaffolds are further developed by medicinal chemists to afford lead compounds the best of which enter clinical trials. In this review, we summarize these chemical scaffolds and their evolution paths according to the groups in which they have been discovered or studied. We combine the data of the chemistry, biological assays and structural biology of each chemical scaffold, in order to afford insight to develop new RORγt modulators with higher potency, less toxicity and elucidated working mechanism.

Radical Perfluoroalkylation of Arenes via Carbanion Intermediates

The use of sodium dithionite with perfluoroalkyl iodides under basic conditions facilitates the direct perfluoroalkylation of arenes with pendant benzylic electron-withdrawing groups. This occurs via attack of the arene on the electrophilic perfluoroalkyl radical, through the donation of electron density from a benzylic anion. The substrate scope was expanded beyond benzylic nitriles with cyclic substrates bearing electron-withdrawing groups at the benzylic position-enforcing donation of electron density to the aromatic ring and enabling attack on the perfluoroalkyl radical.

Retinoic acid-related orphan receptor gamma t (RORγt) inverse agonists/antagonists for the treatment of inflammatory diseases - where are we presently?

Introduction: The transcription factor retinoic acid-related orphan receptor gamma t (RORγt) has been identified as the master regulator of T_H17 cell differentiation and IL-17/22 production and is therefore an attractive target for the treatment of inflammatory diseases. Several orally or topically administered small molecule RORγt inverse agonists (RIAs) have progressed up to the end of clinical Phase 2.Areas covered: Based on publications and patent evaluations this review summarizes the evolution of the chemical matter for all 16 pharmaceutical companies, who develop(ed) a clinical-stage RIAs (until March 2021). Structure proposals for some clinical stage RIAs are presented and the outcome of the clinical trials is discussed.Expert opinion: So far, the clinical trials have been plagued with a high attrition rate. Main reasons were lack of efficacy (topical) or safety signals (oral) as well as, amongst other things, thymic lymphomas as seen with BMS-986251 in a preclinical study and liver enzyme elevations in humans with VTP-43742. Possibilities to mitigate these risks could be the use of RIAs with different chemical structures not interfering with thymocytes maturation and no livertox-inducing properties. With new frontrunners (e.g., ABBV-157 (cedirogant), BI 730357 or IMU-935) this is still an exciting time for this treatment approach.

Discovery and Characterization of Benzimidazole Derivative XY123 as a Potent, Selective, and Orally Available RORγ Inverse Agonist

Receptor-related orphan receptor γ (RORγ) has emerged as an attractive therapeutic target for the treatment of cancer and inflammatory diseases. Herein, we report our effort on the discovery, optimization, and evaluation of benzothiazole and benzimidazole derivatives as novel inverse agonists of RORγ. The representative compound 27h (designated as XY123) potently inhibited the RORγ transcription activity with a half-maximal inhibitory concentration (IC50) value of 64 nM and showed excellent selectivity against other nuclear receptors. 27h also potently suppressed cell proliferation, colony formation, and the expression of androgen receptor (AR)-regulated genes in AR-positive prostate cancer cell lines. In addition, 27h demonstrated good metabolic stability and a pharmacokinetic property with reasonable oral bioavailability (32.41%) and moderate half-life (t1/2 = 4.98 h). Significantly, oral administration of compound 27h achieved complete and long-lasting tumor regression in the 22Rv1 xenograft tumor model in mice. Compound 27h may serve as a new valuable lead compound for further development of drugs for the treatment of prostate cancer.

Designing Out PXR Activity on Drug Discovery Projects: A Review of Structure-Based Methods, Empirical and Computational Approaches

This perspective discusses the role of pregnane xenobiotic receptor (PXR) in drug discovery and the impact of its activation on CYP3A4 induction. The use of structural biology to reduce PXR activity on drug discovery projects has become more common in recent years. Analysis of this work highlights several important molecular interactions, and the resultant structural modifications to reduce PXR activity are summarized. The computational approaches undertaken to support the design of new drugs devoid of PXR activation potential are also discussed. Finally, the SAR of empirical design strategies to reduce PXR activity is reviewed, and the key SAR transformations are discussed and summarized. In conclusion, this perspective demonstrates that PXR activity can be greatly diminished or negated on active drug discovery projects with the knowledge now available. This perspective should be useful to anyone who seeks to reduce PXR activity on a drug discovery project.

Azatricyclic Inverse Agonists of RORγt That Demonstrate Efficacy in Models of Rheumatoid Arthritis and Psoriasis

Structure-activity relationship studies directed toward the replacement of the fused phenyl ring of the lead hexahydrobenzoindole RORγt inverse agonist series represented by 1 with heterocyclic moieties led to the identification of three novel aza analogs 5-7. The hexahydropyrrolo[3,2-f]quinoline series 5 (X = N, Y = Z=CH) showed potency and metabolic stability comparable to series 1 but with improved in vitro membrane permeability and serum free fraction. This structural modification was applied to the hexahydrocyclopentanaphthalene series 3, culminating in the discovery of 8e as a potent and selective RORγt inverse agonist with an excellent in vitro profile, good pharmacokinetic properties, and biologic-like in vivo efficacy in preclinical models of rheumatoid arthritis and psoriasis.

Tricyclic-Carbocyclic RORγt Inverse Agonists-Discovery of BMS-986313

SAR efforts directed at identifying RORγt inverse agonists structurally different from our clinical compound 1 (BMS-986251) led to tricyclic-carbocyclic analogues represented by 3-7 and culminated in the identification of 3d (BMS-986313), with structural differences distinct from 1. The X-ray co-crystal structure of 3d with the ligand binding domain of RORγt revealed several key interactions, which are different from 1. The in vitro and in vivo PK profiles of 3d are described. In addition, we demonstrate robust efficacy of 3d in two preclinical models of psoriasis-the IMQ-induced skin lesion model and the IL-23-induced acanthosis model. The efficacy seen with 3d in these models is comparable to the results observed with 1.

Discovery of Annulating Reagents Enabling the One-Step and Highly Stereoselective Synthesis of Cyclopentyl and Cyclohexyl Cores

The use of the unprecedented annulating reagents methyl N-(tert-butylsulfinyl)-4-chlorobutanimidate and methyl N-(tert-butylsulfinyl)-5-bromopentanimidate enables the diastereoselective preparation of 5- and 6-membered carbocycles bearing three contiguous stereocenters. These synthons undergo cycloaddition with a variety of Michael acceptors to form cyclopentane/cyclohexane rings with excellent stereochemical control, generating only one of the eight possible diastereomers. This novel methodology has enabled the highly enantioselective and high yielding synthesis of novel chemotypes of pharmacological relevance.

Novel Tricyclic Pyroglutamide Derivatives as Potent RORγt Inverse Agonists Identified using a Virtual Screening Approach

Employing a virtual screening approach, we identified the pyroglutamide moiety as a nonacid replacement for the cyclohexanecarboxylic acid group which, when coupled to our previously reported conformationally locked tricyclic core, provided potent and selective RORγt inverse agonists. Structure-activity relationship optimization of the pyroglutamide moiety led to the identification of compound 18 as a potent and selective RORγt inverse agonist, albeit with poor aqueous solubility. We took advantage of the tertiary carbinol group in 18 to synthesize a phosphate prodrug, which provided good solubility, excellent exposures in mouse PK studies, and significant efficacy in a mouse model of psoriasis.

Synthesis of 1-(tert-Butyl) 4-Methyl (1R,2S,4R)-2-Methylcyclohexane-1,4-dicarboxylate from Hagemann's tert-Butyl Ester for an Improved Synthesis of BMS-986251

We describe an efficient synthetic route to differentially protected diester, 1-(tert-butyl) 4-methyl (1R,2S,4R)-2-methylcyclohexane-1,4-dicarboxylate (+)-1, via palladium-catalyzed methoxycarbonylation of an enol triflate derived from a Hagemann's ester derivative followed by a stereoselective Crabtree hydrogenation. Diester 1 is a novel chiral synthon useful in drug discovery and was instrumental in the generation of useful SAR during a RORγt inverse agonist program. In addition, we describe a second-generation synthesis of the clinical candidate BMS-986251, using diester 1 as a critical component.

Discovery of carboxyl-containing biaryl ureas as potent RORγt inverse agonists

GSK805 (1) is a potent RORγt inverse agonist, but a drawback of 1 is its low solubility, leading to a limited absorption in high doses. We have explored detailed structure-activity relationship on the amide linker, biaryl and arylsulfonyl moieties of 1 trying to improve solubility while maintaining RORγt activity. As a result, a novel series of carboxyl-containing biaryl urea derivatives was discovered as potent RORγt inverse agonists with improved drug-like properties. Compound 3i showed potent RORγt inhibitory activity and subtype selectivity with an IC₅₀ of 63.8 nM in RORγ FRET assay and 85 nM in cell-based RORγ-GAL4 promotor reporter assay. Reasonable inhibitory activity of 3i was also achieved in mouse Th17 cell differentiation assay (76% inhibition at 0.3 μM). Moreover, 3i had greatly improved aqueous solubility at pH 7.4 compared to 1, exhibited decent mouse PK profile and demonstrated some in vivo efficacy in an imiquimod-induced psoriasis mice model.

Substituted benzyloxytricyclic compounds as retinoic acid-related orphan receptor gamma t (RORγt) agonists

Substituted benzyloxy aryl compound 2 was identified as an RORγt agonist. Structure based drug design efforts resulted in a potent and selective tricyclic compound 19 which, when administered orally in an MC38 mouse tumor model, demonstrated a desired pharmacokinetic profile as well as a dose-dependent pharmacodynamic response. However, no perceptible efficacy was observed in this tumor model at the doses investigated.

Discovery of BMS-986251: A Clinically Viable, Potent, and Selective RORγt Inverse Agonist

Novel tricyclic analogues were designed, synthesized, and evaluated as RORγt inverse agonists. Several of these compounds were potent in an IL-17 human whole blood assay and exhibited excellent oral bioavailability in mouse pharmacokinetic studies. This led to the identification of compound 5, which displayed dose-dependent inhibition of IL-17F production in a mouse IL-2/IL-23 stimulated pharmacodynamic model. In addition, compound 5 was studied in mouse acanthosis and imiquimod-induced models of skin inflammation, where it demonstrated robust efficacy comparable to a positive control. As a result of this excellent overall profile, compound 5 (BMS-986251) was selected as a clinically viable developmental candidate.

One-Step Diastereoselective Pyrrolidine Synthesis Using a Sulfinamide Annulating Reagent

This communication highlights the use of chiral sulfinamides as nitrogen nucleophiles in intermolecular aza-Michael reactions. When chiral sulfinamides are coupled to a chloroethyl group, the corresponding novel annulating reagents can be used to streamline the stereoselective synthesis of complex pyrrolidine-containing molecules. As a result, it has enabled a medicinal chemistry campaign for the synthesis of biologically active RORγt inverse agonists.