Characterization of Selective and Potent JAK1 Inhibitors Intended for the Inhaled Treatment of Asthma.

Purpose: Janus kinase 1 (JAK1) is implicated in multiple inflammatory pathways that are critical for the pathogenesis of asthma, including the interleukin (IL)-4, IL-5, IL-13, and thymic stromal lymphopoietin cytokine signaling pathways, which have previously been targeted to treat allergic asthma. Here, we describe the development of AZD0449 and AZD4604, two novel and highly selective JAK1 inhibitors with promising properties for inhalation. Methods: The effects of AZD0449 and AZD4604 in JAK1 signaling pathways were assessed by measuring phosphorylation of signal transducer and activator of transcription (STAT) proteins and chemokine release using immunoassays of whole blood from healthy human volunteers and rats. Pharmacokinetic studies performed on rats evaluated AZD0449 at a lung deposited dose of 52 µg/kg and AZD4604 at 30 µg/kg. The efficacy of AZD0449 and AZD4604 was assessed by evaluating lung inflammation (cell count and cytokine levels) and the late asthmatic response (average enhanced pause [Penh]). Results: Both compounds inhibited JAK1-dependent cytokine signaling pathways in a dose-dependent manner in human and rat leukocytes. After intratracheal administration in rats, both compounds exhibited low systemic exposures and medium-to-long terminal lung half-lives (AZD0449, 34 hours; AZD4604, 5 hours). Both compounds inhibited STAT3 and STAT5 phosphorylation in lung tissue from ovalbumin (OVA)-challenged rats. AZD0449 and AZD4604 also inhibited eosinophilia in the lung and reduced the late asthmatic response, measured as Penh in the OVA rat model. Conclusion: AZD0449 and AZD4604 show potential as inhibitors of signaling pathways involved in asthmatic immune responses, with target engagement demonstrated locally in the lung. These findings support the clinical development of AZD0449 and AZD4604 for the treatment of patients with asthma.

AZD0284, a Potent, Selective, and Orally Bioavailable Inverse Agonist of Retinoic Acid Receptor-Related Orphan Receptor C2.

Inverse agonists of the nuclear receptor RORC2 have been widely pursued as a potential treatment for a variety of autoimmune diseases. We have discovered a novel series of isoindoline-based inverse agonists of the nuclear receptor RORC2, derived from our recently disclosed RORC2 inverse agonist 2. Extensive structure-activity relationship (SAR) studies resulted in AZD0284 (20), which combined potent inhibition of IL-17A secretion from primary human TH17 cells with excellent metabolic stability and good PK in preclinical species. In two preclinical in vivo studies, compound 20 reduced thymocyte numbers in mice and showed dose-dependent reduction of IL-17A containing γδ-T cells and of IL-17A and IL-22 RNA in the imiquimod induced inflammation model. Based on these data and a favorable safety profile, 20 was progressed to phase 1 clinical studies.

Potent and Orally Bioavailable Inverse Agonists of RORγt Resulting from Structure-Based Design.

Retinoic acid receptor related orphan receptor γt (RORγt), has been identified as the master regulator of TH17-cell function and development, making it an attractive target for the treatment of autoimmune diseases by a small-molecule approach. Herein, we describe our investigations on a series of 4-aryl-thienyl acetamides, which were guided by insights from X-ray cocrystal structures. Efforts in targeting the cofactor-recruitment site from the 4-aryl group on the thiophene led to a series of potent binders with nanomolar activity in a primary human-TH17-cell assay. The observation of a DMSO molecule binding in a subpocket outside the LBD inspired the introduction of an acetamide into the benzylic position of these compounds. Hereby, a hydrogen-bond interaction of the introduced acetamide oxygen with the backbone amide of Glu379 was established. This greatly enhanced the cellular activity of previously weakly cell-active compounds. The best compounds combined potent inhibition of IL-17 release with favorable PK in rodents, with compound 32 representing a promising starting point for future investigations.

Benzoxazepines Achieve Potent Suppression of IL-17 Release in Human T-Helper 17 (TH 17) Cells through an Induced-Fit Binding Mode to the Nuclear Receptor RORγ.

RORγt, an isoform of the retinoic acid-related orphan receptor gamma (RORc, RORγ), has been identified as the master regulator of T-helper 17 (TH 17) cell function and development, making it an attractive target for the treatment of autoimmune diseases. Validation for this target comes from antibodies targeting interleukin-17 (IL-17), the signature cytokine produced by TH 17 cells, which have shown impressive results in clinical trials. Through focused screening of our compound collection, we identified a series of N-sulfonylated benzoxazepines, which displayed micromolar affinity for the RORγ ligand-binding domain (LBD) in a radioligand binding assay. Optimization of these initial hits resulted in potent binders, which dose-dependently decreased the ability of the RORγ-LBD to interact with a peptide derived from steroid receptor coactivator 1, and inhibited the release of IL-17 secretion from isolated and cultured human TH 17 cells with nanomolar potency. A cocrystal structure of inverse agonist 15 (2-chloro-6-fluoro-N-(4-{[3-(trifluoromethyl)phenyl]sulfonyl}-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl)benzamide) bound to the RORγ-LBD illustrated that both hydrophobic interactions, leading to an induced fit around the substituted benzamide moiety of 15, as well as a hydrogen bond from the amide NH to His479 seemed to be important for the mechanism of action. This structure is compared with the structure of agonist 25 (N-(2-fluorophenyl)-4-[(4-fluorophenyl)sulfonyl]-2,3,4,5-tetrahydro-1,4-benzoxazepin-6-amine ) and structures of other known RORγ modulators.

Characterization of species-related differences in the pharmacology of tachykinin NK receptors 1, 2 and 3.

Tachykinin NK receptors (NKRs) differ to a large degree among species with respect to their affinities for small molecule antagonists. The aims of the present study were to clone NKRs from gerbil (NK2R and NK3R) and dog (NK1R, NK2R and NK3R) in which the sequence was previously unknown and to investigate the potency of several NKR antagonists at all known human, dog, gerbil and rat NKRs. The NKR protein coding sequences were cloned and expressed in CHO cells. The inhibitory concentrations of selective and non-selective NKR antagonists were determined by inhibition of agonist-induced mobilization of intracellular Ca2+. Receptor homology models were constructed based on the rhodopsin crystal structure to investigate and identify the antagonist binding sites and interaction points in the transmembrane (TM) regions of the NKRs. Data collected using the cloned dog NK1R confirmed that the dog NK1R displays similar pharmacology as the human and the gerbil NK1R, but differs greatly from the mouse and the rat NK1R. Despite species-related amino acid (AA) differences located close to the antagonist binding pocket of the NK2R, they did not affect the potency of the antagonists ZD6021 and saredutant. Two AA differences located close to the antagonist binding site of NK3R likely influence the NK3R antagonist potency, explaining the 3-10-fold decrease in potency observed for the rat NK3R. For the first time, detailed pharmacological experiments in vitro with cloned NKRs demonstrate that not only human, but also dog and gerbil NKR displays similar antagonist pharmacology while rat diverges significantly with respect to NK1R and NK3R.

Senktide-induced gerbil foot tapping behaviour is blocked by selective tachykinin NK1 and NK3 receptor antagonists.

Intracerebroventricular (i.c.v.) administration of tachykinin NK(1) receptor agonists induces tapping of the hind legs in gerbils, so-called gerbil foot tapping, which is thought to reflect a fear-related response. The aim of the present study was to examine how ligands selective for NK(1), NK(2) and NK(3) receptors affect the gerbil foot tap response. Agonists selective for NK receptor subtypes were administered i.c.v. and the gerbil foot tap response was monitored. The effect of systemically administered antagonists was also studied. The interaction of ligands with gerbil NK(1) receptors was evaluated using autoradiography on gerbil brain slices with [(3)H]-Sar,Met(O(2))-substance P or [(3)H]GR205171 as radioligand. The effects of ligands on NK(1) and NK(3) receptor-mediated increases in intracellular calcium in vitro were studied in Chinese hamster ovary cells expressing the cloned gerbil receptors. The selective NK(1) receptor agonist ASMSP and the selective NK(3) receptor agonist senktide induced dose-dependent increases in gerbil foot tapping with similar potency. The maximal effect of senktide was approximately 40% of the maximal response evoked by ASMSP. The effects of ASMSP and senktide were blocked by administration of the selective NK(1) receptor antagonist CP99,994 (10 micromol/kg s.c.). The effects of senktide, but not ASMSP, were blocked by administration of the selective NK(3) receptor antagonist SB223412 (50 micromol/kg i.p.). Senktide did not displace NK(1) receptor radioligand binding and was >1000-fold less potent than ASMSP at activating gerbil NK(1) receptors. The selective NK(3) receptor agonist senktide evokes fear-related gerbil foot tapping, an effect which probably involves indirect enhancement of NK(1) receptor signalling.

Molecular cloning, mutations and effects of NK1 receptor antagonists reveal the human-like pharmacology of gerbil NK1 receptors.

The present study investigates the pharmacology of the cloned neurokinin 1 receptor from the gerbil (gNK(1)R), a species claimed to have human-like NK(1)R (hNK(1)R) pharmacology. The amino acid sequence of NK(1)R was cloned. The hNK(1)R, rat NK(1)R (rNK(1)R), gNK(1)R and mutants of the gNK(1)R were expressed in CHO cells. The affinity and potency of NKR agonists and the NK(1)R antagonists CP99994 and RP67580 (NK(1)R-selective) and ZD6021 (NK1/2R) were assessed in vitro by monitoring [(3)H]-SarMet SP binding and substance P-evoked mobilization of intracellular Ca(2+). The gerbil foot tap (GFT) method was used to assess the potency of the antagonists in vivo. The gNK(1)R coding sequence displayed an overall 95% and 97% homology with hNK(1)R and rNK(1)R, respectively. The affinity of the NK(1)R-selective agonist (3)H-SarMet SP for human and gerbil NK(1)R was similar (2.0 and 3.1 nM) but lower for rNK(1)R (12.4 nM). The rank order potency of the agonists for NK(1)R was SP > or = ASMSP > or = NKA >>> pro7NKB in all species. The NK(1)R antagonists, ZD6021 and CP99994, had comparable affinity and potency for gerbil and human NK(1)R, but were 1000-fold less potent for rNK(1)R. In contrast, RP67580 had comparable affinity and potency for all three species. Mutations in positions 116 and 290 did not affect agonist potency at the gNK(1)R while the potency of the antagonists ZD6021 and CP99994 were markedly decreased (10-20-fold). It is concluded that gNK(1)R has similar antagonist pharmacology as the human-like orthologue and that species differences in antagonist function depend on key residues in the coding sequence and antagonist structure.