Non-peptide Antagonist Research Articles

Unveiling Wide Spectrum Therapeutic Implications and Signaling Mechanisms of Valsartan in Diverse Disorders: A Comprehensive Review.

Valsartan is an orally active non-peptide angiotensin receptor antagonist, an effective and well-tolerated anti-hypertensive drug. Besides its antihypertensive action, it has clinical implications in many other disorders, like heart failure (HF), arrhythmia, chronic kidney disease (CKD), diabetic complications (DM), atherosclerosis, etc. Besides angiotensin receptor blocking activity, valsartan reduces circulating levels of biochemical markers, such as hs-CRP, which is responsible for its anti-inflammatory and anti-oxidant activity. Moreover, valsartan also acts by inhibiting or inducing various signalling pathways, such as inducing autophagy via the AKT/mTOR/S6K pathway or inhibiting the TLR/NF-kB pathway. The current review exhaustively discusses the therapeutic implications of valsartan with specific emphasis on the mechanism of action in various disorders. The article provides a detailed spectrum of the therapeutic profile of valsartan and will likely be very useful to researchers working in the relevant research areas.

Update on Tolvaptan for the Treatment of Refractory Ascites in Liver Cirrhosis

Ascites is the most prevalent complication of decompensated cirrhosis, and approximately 5%-10% of cirrhotic ascites will develop into refractory ascites (RA). With complicated pathogenesis, obscure treatment strategies and poor prognosis, it is still a challenge for physicians to manage RA properly. Tolvaptan (TLV) is a new type of non-peptide selective arginine vasopressin V2 receptor antagonist targeting at suppressing renal water reabsorption, promoting free water excretion and raising blood sodium levels, which provides a new option for the treatment of RA in liver cirrhosis. In this review, we summarized the mechanisms of TLV's effect and described its efficacy, safety and predictive factors of response in treating RA, intending to provide a supplement for clinical application of tolvaptan in the management of RA.

Identification of Small-Molecule Antagonists Targeting the Growth Hormone Releasing Hormone Receptor (GHRHR).

The growth hormone-releasing hormone receptor (GHRHR) belongs to Class B1 of G protein-coupled receptors (GPCRs). Class B1 GPCR peptides such, as growth hormone-releasing hormone (GHRH), have been proposed to bind in a two-step model, where first the C-terminal region of the peptide interacts with the extracellular domain of the receptor and, subsequently, the N-terminus interacts with the seven transmembrane domain of the receptor, resulting in activation. The GHRHR has recently been highlighted as a promising drug target toward several types of cancer and has been shown to be overexpressed in prostate, breast, pancreatic, and ovarian cancer. Indeed, peptide GHRHR antagonists have displayed promising results in many cancer models. However, no nonpeptide GHRHR-targeting compounds have yet been identified. We have utilized several computational tools to target GHRHR and identify potential small-molecule compounds directed at this receptor. These compounds were validated in vitro using a cyclic adenosine monophosphate (cAMP) ELISA to measure activity at the GHRHR. In vitro results suggest that several of the novel small-molecule compounds could inhibit GHRH-induced cAMP accumulation. Preliminary analysis of the specificity/selectivity of one of the most effective hit compounds indicated that the effect seen was via inhibition of the GHRHR. We therefore report the first nonpeptide antagonists of GHRHR and propose a structural basis for inhibition induced by the compounds, which may assist in the future design of lead GHRHR compounds for treating disorders attributed to dysregulated/aberrant GHRHR signaling.

Teneurin C-terminal associated peptide (TCAP)-1 attenuates the development and expression of naloxone-precipitated morphine withdrawal in male Swiss Webster mice.

Corticotropin-releasing factor (CRF), the apical stress-inducing hormone, exacerbates stress and addictive behaviors. TCAP-1 is a peptide that directly inhibits both CRF-mediated stress and addiction-related behaviors; however, the direct action of TCAP-1 on morphine withdrawal-associated behaviors has not previously been examined. To determine whether TCAP-1 administration attenuates behavioral and physiological consequences of morphine withdrawal in mice. Mice were administered via subcutaneous route TCAP-1 either before or after initial morphine exposure, after which jumping behavior was quantified to assess the effects of TCAP-1 on naloxone-precipitated morphine withdrawal. As a comparison, mice were treated with nonpeptide CRF1 receptor antagonist CP-154,526. In one experiment, plasma corticosterone (CORT) was also measured as a physiological stress indicator. Pretreatment with TCAP-1 (10-250 nmol/kg) before morphine treatment significantly inhibited the development of naloxone-precipitated withdrawal. TCAP-1 (250-500 nmol/kg) treatment administered after morphine treatment attenuated the behavioral expression of naloxone-precipitated withdrawal. TCAP-1 (250 nmol/kg) treatment during morphine treatment was more effective than the optimal dosing of CP-154,526 (20mg/kg) at suppressing the behavioral expression of naloxone-precipitated withdrawal, despite similar reduction of withdrawal-induced plasma CORT level increases. These findings establish TCAP-1 as a potential therapeutic candidate for the prevention and treatment of morphine withdrawal.

The regulatory role of central neuropeptide-S in locomotion

Central exogenous Neuropeptide-S (NPS) was demonstrated to increase locomotor activity (LMA) in rodent studies. NPS receptor (NPSR) is produced in locomotion-related brain regions including basal ganglia while NPS mediates dopaminergic neurotransmission suggesting that endogenous brain NPS is involved in the regulation of locomotion. Aim of the study was to elucidate whether antagonism of NPSR impairs locomotion and to determine the neurochemical profile of NPSR-expressing cells in basal ganglia network. In the rats received intracerebroventricular injection of selective non-peptide NPSR antagonist ML154 (20 nmol/5 µL) or vehicle, in addition to measurement of catalepsy, motor performance, and motor coordination were evaluated by assessment of LMA and RR test, respectively. The immunoreactivities for NPSR, tyrosine hydroxylase (TH), glutamate decarboxylase 67 (GAD67), and choline acetyltransferase (ChAT) were detected by immunofluorescence in frozen sections. Compared to the control rats, total LMA was significantly declined following ML154 administration. The ML154-injected rats were more prone to fall in rotarod (RR) test, while they exhibited remarkably high catalepsy time. The most robust immunoreactivity for NPSR was detected in globus pallidus externa (GPe), while moderate levels of NPSR expression were observed in substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA), but not in striatum. The NPSR-ir cell bodies were found to express GAD67 in GPe and TH in SNpc and VTA, respectively. NPSR expression was detected in SNpc-projecting pallidal cells. The present findings indicate the regulatory role of central endogenous NPS in the control of locomotion. NPSR may be a potential therapeutic target for the treatment of movement disorders.

FRI538 Discovery And Characterization Of Orally Bioavailable Nonpeptide Thyroid Stimulating Hormone Receptor (TSHR) Antagonists For The Treatment Of Graves’ Disease

Abstract Disclosure: M.A. Fowler: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. C. Regan: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. J. Zhao: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. E. Coutinho: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. B. Fleck: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. A.A. Castellanos: Employee; Self; Crinetics Pharmaceuticals. E. Muller: Employee; Self; Crinetics Pharmaceuticals. M. Johns: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. Y. Tang: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. E. Sturchler: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. M. Chen: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. K. Retting: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. D. Dalvie: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. S.F. Betz: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. S. Markison: Employee; Self; Crinetics Pharmaceuticals. Stock Owner; Self; Crinetics Pharmaceuticals. Graves’ disease is an autoimmune condition that affects approximately 1 in 100 people in the United States and 2-3% of the population worldwide. It is characterized by the production of autoantibodies against TSHR, and the pathology of Graves’ disease is driven by TSHR stimulatory antibodies (TSAb) that result in heightened activation of TSHR. This overstimulation results in hyperthyroidism due to excessive production of thyroid hormones. Approximately 30% of Graves’ disease patients also develop thyroid eye disease (TED or Graves’ orbitopathy) due to overactivation of TSHR in orbital fibroblasts leading to excessive production of hyaluronic acid, adipogenesis, cytokine production, and fibrosis. This can cause a myriad of debilitating symptoms including pain, swelling, blurry vision, diplopia, and proptosis. Several treatments for Graves’ hyperthyroidism are available including anti-thyroid drugs, radioactive iodine (RAI), and surgery. RAI and surgery are definitive treatments for Graves’ hyperthyroidism, but often result in hypothyroidism. In addition, none of the current treatments for Graves’ hyperthyroidism are effective in treating TED and, in some cases, such as with RAI, worsen the condition. Blocking TSHR activation directly via a TSHR antagonist may provide an important new therapeutic mechanism to treat patients with Graves’ disease that would effectively treat both the hyperthyroidism and TED. We have identified several potent and orally bioavailable nonpeptide allosteric antagonists with acceptable drug-like properties. One analog, TSHRant-1, demonstrated potent negative allosteric modulator activity at both the human and rat TSHR. To evaluate the in vivo pharmacodynamics of TSHant-1, we developed a rat model of hyperthyroidism. In this model, subcutaneous administration of the TSAb, M22, to female rats resulted in a robust and long-lasting rise in levels of the thyroid hormone thyroxin (T4). Oral administration of TSHRant-1 dose-dependently suppressed M22-stimulated T4, providing evidence that a nonpeptide allosteric antagonist of TSHR may serve as an effective treatment for Graves’ disease and associated orbitopathy (TED). Presentation: Friday, June 16, 2023

Elagolix Sodium Salt and Its Synthetic Intermediates: A Spectroscopic, Crystallographic, and Conformational Study.

Elagolix sodium salt is the first marketed orally active non-peptide gonadotropin-releasing hormone receptor antagonist (GnRHR-ant) for the management of hormone dependent diseases, such as endometriosis and uterine fibroids. Despite its presence on the market since 2018, a thorough NMR analysis of this drug, together with its synthetic intermediates, is still lacking. Hence, with the aim of filling this literature gap, we here performed a detailed NMR investigation, which allowed the complete assignment of the 1H, 13C, and 15N NMR signals. These data allowed, with the support of the conformational analysis, the determination of the stereochemical profile of the two atropisomers, detectable in solution. Moreover, these latter were also detected by means of cellulose-based chiral HPLC, starting from a sample prepared through an implemented synthetic procedure with respect to the reported ones. Overall, these results contribute to further understanding of the topic of atropisomerism in drug discovery and could be applied in the design of safe and stable analogs, endowed with improved target selectivity.

Suppressive effects of linzagolix, a novel non-peptide antagonist of gonadotropin-releasing hormone receptors, in experimental endometriosis model rats.

Endometriosis is an oestrogen-dependent disease in which endometrial-like tissue grows outside the uterus in women of reproductive age. Accordingly, control of oestradiol (E2) levels is an effective treatment for endometriosis. Because gonadotropin-releasing hormone (GnRH) is the main controller of E2 secretion, control of GnRH signalling by GnRH antagonism is an effective strategy for the treatment of sex hormone-dependent diseases such as endometriosis. The purpose of the present study was to evaluate the effects of the potent, orally available and selective GnRH antagonist linzagolix on experimental endometriosis in rats and compare them with those of dienogest, which is used clinically to treat endometriosis. Experimental endometriosis was induced in female rats at the proestrus stage of the oestrous cycle via autotransplantation of endometrial tissue into the renal subcapsular space. Linzagolix significantly decreased cyst volumes compared with the control group at doses of 50 mg/kg or more. Indeed, a suppressive effect of dienogest on cyst volume was observed only at the highest dose evaluated (1 mg/kg). The effective concentration of linzagolix, calculated as the free form of the last-observed drug concentration, was ~1 μmol/L in endometriosis model rats. The present study also reveals that linzagolix exerts a sustained inhibitory effect on E2 secretion, indicating that the suppressive effect on endometriosis cyst volumes could be attributed to its pharmacological suppression of GnRH signalling and serum E2 concentrations. Altogether, our findings indicate that linzagolix may be a useful therapeutic intervention for hormone-dependent diseases including endometriosis.

A multi-center, prospective, observational study of patients with prostate cancer being treated with relugolix: OPTYX.

TPS398 Background: Androgen deprivation therapy (ADT) with gonadotropin-releasing hormone (GnRH) receptor agonists or antagonists are the foundation of advanced prostate cancer (aPC) treatment. Relugolix is an oral non-peptide GnRH receptor antagonist approved in the US for the treatment of aPC. In the phase 3 HERO trial, relugolix maintained suppression of testosterone to castration levels in 96.7% of men from Day 29 to 48 weeks, with superiority to leuprolide acetate. Relugolix was well tolerated and associated with a 54% lower risk of major adverse cardiovascular events relative to leuprolide acetate (Shore N, NEJM 2020;382;23). The goal of this current study (OPTYX) is to generate real-world evidence about the safety and effectiveness of relugolix in patients with prostate cancer during routine clinical care. Methods: This prospective observational cohort study (registry) is enrolling patients who have planned initiation with relugolix within 1 month prior to the time of study enrollment. The study is designed to prospectively understand the actual experience of patients with prostate cancer treated with relugolix through data collection on patients selected for treatment, treatment patterns, adherence, patient reported quality of life (QoL) and safety data. Additionally, a better understanding of the trajectory of patients with prostate cancer following cessation of relugolix therapy will be gained by observing the clinical course of the disease, health outcomes, and health-related quality-of-life (HRQoL) in these patients. Inclusion criteria include patients > 18 years old with prostate cancer and planned total treatment with relugolix of at least 4 months. Estimated enrollment is 1000 patients, and patients will be followed for up to 5 years. In addition to assessing routine clinical care and disease progression, patient reported outcomes will be assessed with the Functional Assessment of Cancer Therapy-Prostate (FACT-P) for HRQoL and Simplified Medication Adherence Questionnaire (SMAQ) for adherence at 3 and 6 months then every 6 months. Clinical trial information: NCT05467176 .

Inhibitory Effects of a Novel μ-Opioid Receptor Nonpeptide Antagonist, UD-030, on Morphine-Induced Conditioned Place Preference

Although opioids are widely used to treat moderate to severe pain, opioid addiction and the opioid overdose epidemic are becoming more serious. Although opioid receptor antagonists/partial agonists, such as naltrexone and buprenorphine, have relatively low selectivity for the μ-opioid receptor (MOP), they have been used for the management of opioid use disorder. The utility of highly selective MOP antagonists remains to be evaluated. Here, we biologically and pharmacologically evaluated a novel nonpeptide ligand, UD-030, as a selective MOP antagonist. UD-030 had more than 100-fold higher binding affinity for the human MOP (Ki = 3.1 nM) than for δ-opioid, κ-opioid, and nociceptin receptors (Ki = 1800, 460, and 1800 nM, respectively) in competitive binding assays. The [35S]-GTPγS binding assay showed that UD-030 acts as a selective MOP full antagonist. The oral administration of UD-030 dose-dependently suppressed the acquisition and expression of morphine-induced conditioned place preference in C57BL/6J mice, and its effects were comparable to naltrexone. These results indicate the UD-030 may be a new candidate for the treatment of opioid use disorder, with characteristics that differ from traditional medications that are in clinical use.

Structure-function relationship and physiological role of apelin and its G protein coupled receptor.

Apelin receptor (APJR) is a class A peptide (apelin) binding G protein-coupled receptor (GPCR) that plays a significant role in regulating blood pressure, cardiac output, and maintenance of fluid homeostasis. It is activated by a wide range of endogenous peptide isoforms of apelin and elabela. The apelin peptide isoforms contain distinct structural features that aid in ligand recognition and activation of the receptor. Site-directed mutagenesis and structure-based studies have revealed the involvement of extracellular and transmembrane regions of the receptor in binding to the peptide isoforms. The structural features of APJR activation of the receptor as well as mediating G-protein and β-arrestin-mediated signaling are delineated by multiple mutagenesis studies. There is increasing evidence that the structural requirements of APJR to activate G-proteins and β-arrestins are different, leading to biased signaling. APJR also responds to mechanical stimuli in a ligand-independent manner. A multitude of studies has focused on developing both peptide and non-peptide agonists and antagonists specific to APJR. Apelin/elabela-activated APJR orchestrates major signaling pathways such as extracellular signal-regulated kinase (ERKs), protein kinase B (PKB/Akt), and p70S. This review focuses on the structural and functional characteristics of apelin, elabela, APJR, and their interactions involved in the binding and activation of the downstream signaling cascade. We also focus on the diverse signaling profile of APJR and its ligands and their involvement in various physiological systems.

Structures of human gastrin-releasing peptide receptors bound to antagonist and agonist for cancer and itch therapy

Gastrin releasing peptide receptor (GRPR), a member of the bombesin (BBN) G protein-coupled receptors, is aberrantly overexpressed in several malignant tumors, including those of the breast, prostate, pancreas, lung, and central nervous system. Additionally, it also mediates non-histaminergic itch and pathological itch conditions in mice. Thus, GRPR could be an attractive target for cancer and itch therapy. Here, we report the inactive state crystal structure of human GRPR in complex with the non-peptide antagonist PD176252, as well as two active state cryo-electron microscopy (cryo-EM) structures of GRPR bound to the endogenous peptide agonist gastrin-releasing peptide and the synthetic BBN analog [D-Phe6, β-Ala11, Phe13, Nle14] Bn (6-14), in complex with Gq heterotrimers. These structures revealed the molecular mechanisms for the ligand binding, receptor activation, and Gq proteins signaling of GRPR, which are expected to accelerate the structure-based design of GRPR antagonists and agonists for the treatments of cancer and pruritus.

The role of reactive astrocytes in neurotoxicity induced by ultrafine particulate matter

Epidemiological studies have shown that ambient fine particulate matter (PM) can cause various neurodegenerative diseases, including Alzheimer's disease. Reactive astrocytes are strongly induced by ambient fine PM, although their role is poorly understood. Herein, we show that A1 reactive astrocytes (A1s) were induced by neuroinflammatory microglia activated by PM with an aerodynamic diameter ≤ 0.2 μm (PM0.2). The activated-microglia induced A1s by secreting interleukin-1α, tumor necrosis factor-α, and complement 1q, and these cytokines acting together were necessary and sufficient to induce A1s. PM0.2-induced A1s could promote synaptic damage in neurons by secreting complement 3 (C3). SB 290157, a highly selective C3aR nonpeptide antagonist, partially ameliorated glial conditioned medium-induced synaptic injury. In vitro synaptic damage was partially prevented when A1 formation was blocked by minocycline. Finally, this study showed that N-acetyl-L-cysteine ameliorated PM0.2-induced neural damage independent of A1 differentiation. Collectively, these findings explain why central nervous system neurons suffer synaptic damage and neuroinflammation after PM0.2 exposure and suggest that this exposure induces A1s to contribute to synaptic damage of neurons. This study indicates a potential approach for developing improved treatment of these diseases induced by particulate exposure. SynopsisPM0.2-activated neuroinflammatory microglia induced A1 reactive astrocytes (A1s) by secreting IL-1α, TNF-α, and C1q. PM0.2-induced A1s could promote synaptic damage of neuron by secreting complement 3.

C5aR antagonist inhibits LPS-induced inflammation in human gingival fibroblasts via NF-κB and MAPK signaling pathways.

Abnormal complement activation is associated with periodontitis. W54011 is a novel non-peptide C5aR antagonist (C5aRA) that exhibits favorable anti-inflammatory effects in various inflammatory models. However, whether W54011 inhibits periodontitis has not yet been fully elucidated. To address this, we have investigated the probable anti-inflammatory mechanism of W54011 in LPS-treated inflammation in human gingival fibroblasts (HGFs). HGFs were isolated from healthy gingival tissue samples using the tissue block method and were identified with immunofluorescence staining. The CCK8 assay and reverse transcription-PCR (RT-PCR) were used to select the optimal induction conditions for Lipopolysaccharide (LPS) and C5aRA (according to supplementary data S1, S2 and S3). The levels of inflammatory cytokines, C5aR, and the activation of NF-κB/MAPK signaling pathways were determined by RT-quantitative PCR (RT-qPCR) and Western blotting. Immunofluorescence results showed that vimentin and FSP-1 were positive in HGFs and Keratin was negative in HGFs. Immunofluorescence staining demonstrated that C5aRA inhibited LPS-stimulated nuclear translocation of p-p65. RT-qPCR and Western blotting showed that C5aRA reduced the expression of IL-1β, IL-6, TNF-α, C5aR, p-p65, p-IκBα, p-JNK, p-c-JUN, and TLR4 in LPS-induced HGFs. These findings suggested that C5aRA attenuated the release of inflammatory cytokines in LPS-induced HGFs by blocking the activation of the NF-κB and MAPK signaling pathways.

Inhibitory effects of the novel μ-opioid receptor non-peptide antagonist, UD-030, on the morphine-conditioned place preference

Inhibitory effects of the novel μ-opioid receptor non-peptide antagonist, UD-030, on the morphine-conditioned place preference

Standardized Oral Urea for the Treatment of Hyponatraemic Conditions: Pharmacological and Pharmacoeconomic Consideration

Standardized Oral Urea for the Treatment of Hyponatraemic Conditions: Pharmacological and Pharmacoeconomic Consideration

Ligand recognition and activation of neuromedin U receptor 2

Neuromedin U receptor 2 (NMU2), an emerging attractive target for treating obesity, has shown the capability in reducing food intake and regulating energy metabolism when activated. However, drug development of NMU2 was deferred partially due to the lack of structural information. Here, we present the cryo-electron microscopy (cryo-EM) structure of NMU2 bound to the endogenous agonist NmU-25 and Gi1 at 3.3 Å resolution. Combined with functional and computational data, the structure reveals the key factors that govern the recognition and selectivity of peptide agonist as well as non-peptide antagonist, providing the structural basis for design of novel and highly selective drugs targeting NMU2. In addition, a 25-degree rotation of Gi protein in reference to NMU2 is also observed compared in other structures of class A GPCR—Gi complexes, suggesting heterogeneity in the processes of G protein-coupled receptors (GPCRs) activation and G protein coupling.

Non-Peptide Agonists and Antagonists of the Prokineticin Receptors.

The prokineticin family comprises a group of secreted peptides that can be classified as chemokines based on their structural features and chemotactic and immunomodulatory functions. Prokineticins (PKs) bind with high affinity to two G protein-coupled receptors (GPCRs). Prokineticin receptor 1 (PKR1) and prokineticin receptor 2 (PKR2) are involved in a variety of physiological functions such as angiogenesis and neurogenesis, hematopoiesis, the control of hypothalamic hormone secretion, the regulation of circadian rhythm and the modulation of complex behaviors such as feeding and drinking. Dysregulation of the system leads to an inflammatory process that is the substrate for many pathological conditions such as cancer, pain, neuroinflammation and neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The use of PKR's antagonists reduces PK2/PKRs upregulation triggered by various inflammatory processes, suggesting that a pharmacological blockade of PKRs may be a successful strategy to treat inflammatory/neuroinflammatory diseases, at least in rodents. Under certain circumstances, the PK system exhibits protective/neuroprotective effects, so PKR agonists have also been developed to modulate the prokineticin system.

Investigating the Dynamic Binding Behavior of PMX53 Cooperating with Allosteric Antagonist NDT9513727 to C5a Anaphylatoxin Chemotactic Receptor 1 through Gaussian Accelerated Molecular Dynamics and Free-Energy Perturbation Simulations.

C5a anaphylatoxin chemotactic receptor 1 (C5aR1) is an important target in anti-inflammatory therapeutics. The cyclic peptide antagonist PMX53 binds to the orthosteric site located in the extracellular vestibule of C5aR1, and the non-peptide antagonist NDT9513727 binds to the allosteric site formed by the middle region of TM3 (trans-membrane helix), TM4, and TM5. We catch a sight of the variational binding mode of PMX53 during the Gaussian accelerated molecular dynamic (GaMD) simulations. In the binary complex of C5aR1 and PMX53, the PMX53 takes a dynamic binding mechanism during the simulation. Namely, the side chain of Arg6 of PMX53 extends to TM6-TM7 (pose 1) or swings to TM5 (pose 2), forming a salt bridge with Glu199. Meanwhile, in the ternary complex of C5aR1 with PMX53 and NDT9513727, the side chain of Arg6 of PMX53 swings to TM5 (pose 2) from extending to TM6-TM7 (pose 1) at the beginning of the GaMD simulation. In subsequent simulation, PMX53 stabilizes in the pose 2 binding mode by forming a stable salt bridge with Glu199. The free-energy perturbation (FEP) calculations demonstrate that pose 1 (ΔGbinding = -10.94 kcal/mol) is more stable in the binary complex and pose 2 (ΔGbinding = -7.91 kcal/mol) is unstable because of highly dynamic TM5. NDT9513727 interacts directly with TM4 and TM5 and stabilizes the hydrophobic stack between the extracellular sides of the two helices. Therefore, pose 2 (ΔGbinding = -16.27 kcal/mol) is notably stable than pose 1 (ΔGbinding = -9.78 kcal/mol) in the ternary complex. The identification of a novel binding mode of PMX53 and the detailed structural information of PMX53 interacting with a receptor obtained by GaMD simulations will be helpful in designing potent antagonists of C5aR1.

Safety, pharmacokinetics, and pharmacodynamics of SHR7280, an oral gonadotropin-releasing hormone antagonist in healthy premenopausal women.

Background: Treatment with gonadotropin-releasing hormone (GnRH) antagonists is a powerful strategy to suppress gonadotropin activity in women with sex hormone-dependent disorders. Herein, we provide the safety, pharmacokinetics (PK), and pharmacodynamics (PD) profiles of SHR7280, an oral non-peptide GnRH antagonist in healthy premenopausal women. Methods: In this randomized, double-blinded, placebo-controlled, dose-ascending, phase 1 trial, healthy premenopausal women were randomized to receive SHR7280 or placebo orally. Four doses of SHR7280 (200, 300, 400, and 500mg BID) were planned. Safety, PK, and PD parameters were evaluated. Results: SHR7280 presented tolerable toxicity and most adverse events were mild in severity. SHR7280 showed rapid onset of action (median Tmax ranged from 1.0 to 1.2h for each dose), and plasma exposure was dose-dependent. PD results showed that SHR7280 300mg BID and above suppressed estrogen concentration within the estradiol (E2) treatment window for endometriosis (20-50pg/ml), inhibited the emergence of the peak of luteinizing hormone (LH) and the concentration of follicle stimulating hormone (FSH), and maintained the concentration of progesterone (P) in an anovulatory state (2nmol/L). Conclusion: SHR7280 showed favorable safety, PK, and PD profiles in the dose range of 200-500mg BID in healthy premenopausal women. This study supports the continued clinical development of SHR7280 as a GnRH antagonist for sex hormone-dependent disorders in women. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04554043, Identifier NCT04554043.