Lysophosphatidic acid receptor 1 antagonist (EPGN2154) causes regression of NASH in preclinical NASH models.

BACKGROUND: NASH causes a tremendous health care burden in the United States. A glucagon-like peptide-1 agonist, semaglutide (Sema), treatment resulted in hepatic steatosis reduction in clinical trials of NASH. Lysophosphatidic acid receptor 1 antagonists are known to have antifibrotic effects in several organs. We tested Sema and a novel lysophosphatidic acid receptor 1 antagonist, EPGN2154, individually and in combination to evaluate their efficacy for NASH remission in preclinical models. METHODS: In the present study, we used (1) C57Bl6/J wild-type mice fed on a high-fat, high-carbohydrate (HFHC) diet for 16 weeks and (2) leptin-deficient mice (ob/ob) fed on an Amylin liver NASH diet for 16 weeks. After 16 weeks, the mice were randomly distributed in equal numbers in (1) no-drug, (2) EPGN2154, (3) Sema, and (4) EPGN2154+Sema treatment groups for 8 additional weeks at a dosage of 10 mg/kg body weight for EPGN2154 (oral gavage, 5 days a week) and 6.17 µg/kg body weight of Sema (subcutaneous injection every alternate day, 3 days a week). RESULTS: In the wild-type-high-fat, high-carbohydrate model, we observed the most body weight loss in the EPGN2154+Sema combination group compared to the other treatment groups. All groups led to a significant reduction in alanine transaminase levels when compared to high-fat, high-carbohydrate-fed wild type. However, no significant difference in alanine transaminase levels was observed among the treatment groups. In the ob/ob mice study, Sema did not cause body weight loss. Moreover, the EPGN2154 and the combination groups had a lower NAFLD Activity Score and incidence of advanced-stage hepatic fibrosis than the Sema group. CONCLUSIONS: EPGN2154 demonstrated a hepato-protective effect independent of body weight loss in preclinical NASH models.

Endogenous adenine mediates kidney injury in diabetic models and predicts diabetic kidney disease in patients.

Diabetic kidney disease (DKD) can lead to end-stage kidney disease (ESKD) and mortality; however, few mechanistic biomarkers are available for high-risk patients, especially those without macroalbuminuria. Urine from participants with diabetes from the Chronic Renal Insufficiency Cohort (CRIC) study, the Singapore Study of Macro-angiopathy and Micro-vascular Reactivity in Type 2 Diabetes (SMART2D), and the American Indian Study determined whether urine adenine/creatinine ratio (UAdCR) could be a mechanistic biomarker for ESKD. ESKD and mortality were associated with the highest UAdCR tertile in the CRIC study and SMART2D. ESKD was associated with the highest UAdCR tertile in patients without macroalbuminuria in the CRIC study, SMART2D, and the American Indian study. Empagliflozin lowered UAdCR in nonmacroalbuminuric participants. Spatial metabolomics localized adenine to kidney pathology, and single-cell transcriptomics identified ribonucleoprotein biogenesis as a top pathway in proximal tubules of patients without macroalbuminuria, implicating mTOR. Adenine stimulated matrix in tubular cells via mTOR and stimulated mTOR in mouse kidneys. A specific inhibitor of adenine production was found to reduce kidney hypertrophy and kidney injury in diabetic mice. We propose that endogenous adenine may be a causative factor in DKD.

Role of endogenous adenine in kidney failure and mortality with diabetes.

Diabetic kidney disease (DKD) can lead to end-stage kidney disease (ESKD) and mortality, however, few mechanistic biomarkers are available for high risk patients, especially those without macroalbuminuria. Urine from participants with diabetes from Chronic Renal Insufficiency Cohort (CRIC), Singapore Study of Macro-Angiopathy and Reactivity in Type 2 Diabetes (SMART2D), and the Pima Indian Study determined if urine adenine/creatinine ratio (UAdCR) could be a mechanistic biomarker for ESKD. ESKD and mortality were associated with the highest UAdCR tertile in CRIC (HR 1.57, 1.18, 2.10) and SMART2D (HR 1.77, 1.00, 3.12). ESKD was associated with the highest UAdCR tertile in patients without macroalbuminuria in CRIC (HR 2.36, 1.26, 4.39), SMART2D (HR 2.39, 1.08, 5.29), and Pima Indian study (HR 4.57, CI 1.37-13.34). Empagliflozin lowered UAdCR in non-macroalbuminuric participants. Spatial metabolomics localized adenine to kidney pathology and transcriptomics identified ribonucleoprotein biogenesis as a top pathway in proximal tubules of patients without macroalbuminuria, implicating mammalian target of rapamycin (mTOR). Adenine stimulated matrix in tubular cells via mTOR and stimulated mTOR in mouse kidneys. A specific inhibitor of adenine production was found to reduce kidney hypertrophy and kidney injury in diabetic mice. We propose that endogenous adenine may be a causative factor in DKD.

Therapeutic efficacy of α7 ligands after acute ischaemic stroke is linked to conductive states of α7 nicotinic ACh receptors.

BACKGROUND AND PURPOSE: Targeting α7 nicotinic ACh receptors (nAChRs) in neuroinflammatory disorders including acute ischaemic stroke holds significant therapeutic promise. However, therapeutically relevant signalling mechanisms remain unidentified. Activation of neuronal α7 nAChRs triggers ionotropic signalling, but there is limited evidence for it in immunoglial tissues. The α7 ligands which are effective in reducing acute ischaemic stroke damage promote α7 ionotropic activity, suggesting a link between their therapeutic effects for treating acute ischaemic stroke and activation of α7 conductive states. EXPERIMENTAL APPROACH: This hypothesis was tested using a transient middle cerebral artery occlusion (MCAO) model of acute ischaemic stroke, NS6740, a known selective non-ionotropic agonist of α7 nAChRs and 4OH-GTS-21, a partial α7 agonist. NS6740-like ligands exhibiting low efficacy/potency for ionotropic activity will be referred to as non-ionotropic agonists or "metagonists". KEY RESULTS: 4OH-GTS-21, used as a positive control, significantly reduced neurological deficits and brain injury after MCAO as compared to vehicle and NS6740. By contrast, NS6740 was ineffective in identical assays and reversed the effects of 4OH-GTS-21 when these compounds were co-applied. Electrophysiological recordings from acute hippocampal slices obtained from NS6740-injected animals demonstrated its remarkable brain availability and protracted effects on α7 nAChRs as evidenced by sustained (>8 h) alterations in α7 ionotropic responsiveness. CONCLUSION AND IMPLICATIONS: These results suggest that α7 ionotropic activity may be obligatory for therapeutic efficacy of α7 ligands after acute ischaemic stroke yet, highlight the potential for selective application of α7 ligands to disease states based on their mode of receptor activation.

Limited fibrosis accompanies triple-negative breast cancer metastasis in multiple model systems and is not a preventive target.

The lysophosphatidic acid receptor 1 (LPAR1) is mechanistically implicated in both tumor metastasis and tissue fibrosis. Previously, metastasis was increased when fulminant fibrosis was first induced in mice, suggesting a direct connection between these processes. The current report examined the extent of metastasis-induced fibrosis in breast cancer model systems, and tested the metastasis preventive efficacy and fibrosis attenuation of antagonists for LPAR1 and Idiopathic Pulmonary Fibrosis (IPF) in breast and ovarian cancer models. Staining analysis demonstrated only focal, low-moderate levels of fibrosis in lungs from eleven metastasis model systems. Two orally available LPAR1 antagonists, SAR100842 and EPGN9878, significantly inhibited breast cancer motility to LPA in vitro. Both compounds were negative for metastasis prevention and failed to reduce fibrosis in the experimental MDA-MB-231T and spontaneous murine 4T1 in vivo breast cancer metastasis models. SAR100842 demonstrated only occasional reductions in invasive metastases in the SKOV3 and OVCAR5 ovarian cancer experimental metastasis models. Two approved drugs for IPF, nintedanib and pirfenidone, were investigated. Both were ineffective at preventing MDA-MB-231T metastasis, with no attenuation of fibrosis. In summary, metastasis-induced fibrosis is only a minor component of metastasis in untreated progressive breast cancer. LPAR1 antagonists, despite in vitro evidence of specificity and efficacy, were ineffective in vivo as oral agents, as were approved IPF drugs. The data argue against LPAR1 and fibrosis as monotherapy targets for metastasis prevention in triple-negative breast cancer and ovarian cancer.

Systemic TAK-242 prevents intrathecal LPS evoked hyperalgesia in male, but not female mice and prevents delayed allodynia following intraplantar formalin in both male and female mice: The role of TLR4 in the evolution of a persistent pain state.

OBJECTIVE: Pain resulting from local tissue injury or inflammation typically resolves with time. Frequently, however, this pain may unexpectedly persist, becoming a pathological chronic state. Increasingly, the innate and adaptive immune systems are being implicated in the initiation and maintenance of these persistent conditions. In particular, Toll-like receptor 4 (TLR4) signaling has been shown to mediate the transition to a persistent pain state in a sex-dependent manner. In the present work, we explored this contribution using the TLR4 antagonist, TAK-242. METHODS: Male and female C57Bl/6 mice were given intravenous (IV), intrathecal (IT), or intraperitoneal (IP) TAK-242 prior to IT delivery of lipopolysaccharide (LPS), and tactile reactivity was assessed at regular intervals over 72-h. Additional groups of mice were treated with IP TAK-242 prior to intraplantar formalin, and flinching was monitored for 1-h. Tactile reactivity was assessed at 7-days after formalin delivery. RESULTS: LPS evoked TNF release from male and female macrophages and RAW267.4 cells, which was blocked in a concentration dependent fashion by TAK-242. In vivo, IT LPS evoked tactile allodynia to a greater degree in male than female mice. TAK-242, given by all routes, prevented development of IT LPS-induced tactile allodynia in male animals, but did not reverse their established allodynia. TLR4 deficiency and TAK-242 treatment attenuated IT LPS-induced allodynia in male, but not female mice. In the formalin model, pre-treatment with TAK-242 did not affect Phase 1 or Phase 2 flinching, but prevented the delayed tactile allodynia in both male and unexpectedly in female mice (Phase 3). CONCLUSIONS: Together, these results suggest that TAK-242 is a TLR4 antagonist that has efficacy after systemic and intrathecal delivery and confirms the role of endogenous TLR4 signaling in triggering the development of a delayed allodynia in both male and female mice.

Lead optimization of 2-(piperidin-3-yl)-1H-benzimidazoles: identification of 2-morpholin- and 2-thiomorpholin-2-yl-1H-benzimidazoles as selective and CNS penetrating H1-antihistamines for insomnia.

The structure-activity relationships of 2-(piperidin-3-yl)-1H-benzimidazoles, 2-morpholine and 2-thiomorpholin-2-yl-1H-benzimidazoles are described. In the lead optimization process, the pK(a) and/or logP of benzimidazole analogs were reduced either by attachment of polar substituents to the piperidine nitrogen or incorporation of heteroatoms into the piperidine heterocycle. Compounds 9a and 9b in the morpholine series and 10g in the thiomorpholine series demonstrated improved selectivity and CNS profiles compared to lead compound 2 and these are potential candidates for evaluation as sedative hypnotics.

Influence of pKa on the biotransformation of indene H1-antihistamines by CYP2D6.

Structure-activity relationship studies were conducted to reduce CYP2D6-mediated metabolism in a series of indene H(1)-antihistamines. Reductions in pK(a) via incorporation of a ß-fluoro substituent or a heteroaryl moiety were shown to reduce contributions to metabolism through this pathway. Several compounds, including 8l, 8o, and 12f were identified with promising primary in vitro profiles and reduced biotransformation via CYP2D6.

Identification of a novel selective H1-antihistamine with optimized pharmacokinetic properties for clinical evaluation in the treatment of insomnia.

Analogs of the known H(1)-antihistamine R-dimethindene with suitable selectivity for key GPCRs, P450 enzymes and hERG channel were assessed for metabolism profile and in vivo properties. Several analogs were determined to exhibit diverse metabolism. One of these compounds, 10a, showed equivalent efficacy in a rat EEG/EMG model to a previously identified clinical candidate and a potentially superior pharmacokinetic profile as determined from a human microdose study.

Novel benzothiophene H1-antihistamines for the treatment of insomnia.

SAR of lead benzothiophene H(1)-antihistamine 2 was explored to identify backup candidates with suitable pharmacokinetic profiles for an insomnia program. Several potent and selective H(1)-antihistamines with a range of projected half-lives in humans were identified. Compound 16d had a suitable human half-life as demonstrated in a human microdose study, but variability in pharmacokinetic profile, attributed to metabolic clearance, prevented further development of this compound. Compound 28b demonstrated lower predicted clearance in preclinical studies, and may represent a more suitable backup compound.

Discovery of sodium R-(+)-4-{2-[5-(2-fluoro-3-methoxyphenyl)-3-(2-fluoro-6-[trifluoromethyl]benzyl)-4-methyl-2,6-dioxo-3,6-dihydro-2H-pyrimidin-1-yl]-1-phenylethylamino}butyrate (elagolix), a potent and orally available nonpeptide antagonist of the human gonadotropin-releasing hormone receptor.

The discovery of novel uracil phenylethylamines bearing a butyric acid as potent human gonadotropin-releasing hormone receptor (hGnRH-R) antagonists is described. A major focus of this optimization was to improve the CYP3A4 inhibition liability of these uracils while maintaining their GnRH-R potency. R-4-{2-[5-(2-fluoro-3-methoxyphenyl)-3-(2-fluoro-6-[trifluoromethyl]benzyl)-4-methyl-2,6-dioxo-3,6-dihydro-2H-pyrimidin-1-yl]-1-phenylethylamino}butyric acid sodium salt, 10b (elagolix), was identified as a potent and selective hGnRH-R antagonist. Oral administration of 10b suppressed luteinizing hormone in castrated macaques. These efforts led to the identification of 10b as a clinical compound for the treatment of endometriosis.

Structure-activity relationship studies on a series of piperazinebenzylalcohols and their ketone and amine analogs as melanocortin-4 receptor ligands.

A series of piperazinebenzylalcohols were prepared and studied to compare with their ketone and amine analogs as MC4R antagonists. Several benzylalcohols such as 14a and 14g displayed low nanomolar binding affinities (K(i)<10 nM), and high selectivities over other melanocortin receptor subtypes.

5-Aryluracils as potent GnRH antagonists-Characterization of atropisomers.

Optimization of a series of uracils bearing a 2-fluoro- or 2-chloro-3-methoxyphenyl group at the 5-position resulted in compounds such as 3d and 3f with subnanomolar binding affinity at the human GnRH receptor. While the 2-fluoro-3-methoxyphenyl compound 3a was characterized as a mixture of interchangeable atropisomers, the diastereoisomers of 2-chloro-3-methoxyphenyl analogs were separated. It was found that the aR-atropisomer was much more potent than the aS-isomer based on the X-ray crystal structure of 3h-II.

Potent and orally bioavailable zwitterion GnRH antagonists with low CYP3A4 inhibitory activity.

Incorporation of a carboxylic acid into a series of uracil derivatives as hGnRH-R antagonists resulted in a significant reduction of CYP3A4 inhibitory activity. Highly potent hGnRH antagonists with low CYP3A4 inhibitory liability, such as 8a and 8d, were identified. Thus, 8a had a K(i) of 2.2 nM at GnRH-R and an IC(50) of 36 microM at CYP3A4.

Pharmacological and pharmacokinetic characterization of 2-piperazine-alpha-isopropyl benzylamine derivatives as melanocortin-4 receptor antagonists.

A series of 2-piperazine-alpha-isopropylbenzylamine derivatives were synthesized and characterized as melanocortin-4 receptor (MC4R) antagonists. Attaching an amino acid to benzylamines 7 significantly increased their binding affinity, and the resulting compounds 8-12 bound selectively to MC4R over other melanocortin receptor subtypes and behaved as functional antagonists. These compounds were also studied for their permeability using Caco-2 cell monolayers and metabolic stability in human liver microsomes. Most compounds exhibited low permeability and high efflux ratio possibly due to their high molecular weights. They also showed moderate metabolic stability which might be associated with their moderate to high lipophilicity. Pharmacokinetic properties of these MC4R antagonists, including brain penetration, were studied in mice after oral and intravenous administrations. Two compounds identified to possess high binding affinity and selectivity, 10d and 11d, were studied in a murine cachexia model. After intraperitoneal (ip) administration of 1mg/kg dose, mice treated with 10d had significantly more food intake and weight gain than the control animals, demonstrating efficacy by blocking the MC4 receptor. Similar in vivo effects were also observed when 11d was dosed orally at 20mg/kg. These results provide further evidence that a potent and selective MC4R antagonist has potential in the treatment of cancer cachexia.

Design and synthesis of 3-arylpyrrolidine-2-carboxamide derivatives as melanocortin-4 receptor ligands.

Based on 3-phenylpropionamides, a series of 3-arylpyrrolidine-2-carboxamide derivatives was designed and synthesized to study the effect of cyclizations as melanocortin-4 receptor ligands. It was found that the 2R,3R-pyrrolidine isomer possessed the most potent affinity among the four stereoisomers.

Studies on the structure-activity relationship of the basic amine of phenylpiperazines as melanocortin-4 receptor antagonists.

A series of piperazinephenethylamines were synthesized to study the contribution of a basic amine to binding affinity at the melanocortin-4 receptor. Several potent compounds from this series possessed subnanomolar K(i) values in a competition binding assay.

Syntheses of tetrahydrothiophenes and tetrahydrofurans and studies of their derivatives as melanocortin-4 receptor ligands.

Piperazinebenzylamine derivatives from trans-4-(4-chlorophenyl)tetrahydrothiophene-3-carboxylic acid 6 and its S-oxide 7 and sulfone 8, and the tetrahydrofuran 9 and its two regioisomers 11 and 13 were synthesized and studied for their binding affinities at the human melanocortin-4 receptor. These five-membered ring constrained compounds possessed similar or lower potency compared to the acyclic analogs.

Identification and characterization of pyrrolidine diastereoisomers as potent functional agonists and antagonists of the human melanocortin-4 receptor.

A series of trans-4-phenylpyrrolidine-3-carboxamides were synthesized and characterized as potent ligands of the human melanocortin-4 receptor. Interestingly, a pair of diastereoisomers 13b displayed potent functional agonist and antagonist activity, respectively. Thus, the 3S,4R-pyrrolidine 13b-1 possessed a Ki of 1.0 nM and an EC50 of 3.8 nM, while its 3R,4S-isomer 13b-2 exhibited a Ki of 4.7 and an IC50 of 64 nM. Both compounds were highly selective over other melanocortin receptor subtypes. The MC4R agonist 13b-1 also demonstrated efficacy in a diet-induced obesity model in rats.

Design, synthesis, in vitro, and in vivo characterization of phenylpiperazines and pyridinylpiperazines as potent and selective antagonists of the melanocortin-4 receptor.

Benzylamine and pyridinemethylamine derivatives were synthesized and characterized as potent and selective antagonists of the melanocortin-4 receptor (MC4R). These compounds were also profiled in rodents for their pharmacokinetic properties. Two compounds with diversified profiles in chemical structure, pharmacological activities, and pharmacokinetics, 10 and 12b, showed efficacy in an established murine cachexia model. For example, 12b had a K(i) value of 3.4 nM at MC4R, was more than 200-fold selective over MC3R, and had a good pharmacokinetic profile in mice, including high brain penetration. Moreover, 12b was able to stimulate food intake in the tumor-bearing mice and reverse their lean body mass loss. Our results provided further evidence that a potent and selective MC4R antagonist with appropriate pharmacokinetic properties might potentially be useful for the treatment of cancer cachexia.