The CNS-penetrant soluble guanylate cyclase stimulator CYR119 attenuates markers of inflammation in the central nervous system.

BACKGROUND: Inflammation in the central nervous system (CNS) is observed in many neurological disorders. Nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling plays an essential role in modulating neuroinflammation. CYR119 is a CNS-penetrant sGC stimulator that amplifies endogenous NO-sGC-cGMP signaling. We evaluated target engagement and the effects of CYR119 on markers of neuroinflammation in vitro in mouse microglial cells and in vivo in quinolinic acid (QA)-induced and high-fat diet-induced rodent neuroinflammation models. METHODS: Target engagement was verified in human embryonic kidney (HEK) cells, rat primary neurons, mouse SIM-A9 cells, and in rats by measuring changes in cGMP and downstream targets of sGC signaling [phosphorylated vasodilator-stimulated phosphoprotein (pVASP), phosphorylated cAMP-response element binding (pCREB)]. In SIM-A9 cells stimulated with lipopolysaccharides (LPS), markers of inflammation were measured when cells were treated with or without CYR119. In rats, microinjections of QA and vehicle were administered into the right and left hemispheres of striatum, respectively, and then rats were dosed daily with either CYR119 (10 mg/kg) or vehicle for 7 days. The activation of microglia [ionized calcium binding adaptor molecule 1 (Iba1)] and astrocytes [glial fibrillary acidic protein (GFAP)] was measured by immunohistochemistry. Diet-induced obese (DIO) mice were treated daily with CYR119 (10 mg/kg) for 6 weeks, after which inflammatory genetic markers were analyzed in the prefrontal cortex. RESULTS: In vitro, CYR119 synergized with exogenous NO to increase the production of cGMP in HEK cells and in primary rat neuronal cell cultures. In primary neurons, CYR119 stimulated sGC, resulting in accumulation of cGMP and phosphorylation of CREB, likely through the activation of protein kinase G (PKG). CYR119 attenuated LPS-induced elevation of interleukin 6 (IL-6) and tumor necrosis factor (TNF) in mouse microglial cells. Following oral dosing in rats, CYR119 crossed the blood-brain barrier (BBB) and stimulated an increase in cGMP levels in the cerebral spinal fluid (CSF). In addition, levels of proinflammatory markers associated with QA administration or high-fat diet feeding were lower in rodents treated with CYR119 than in those treated with vehicle. CONCLUSIONS: These data suggest that sGC stimulation could provide neuroprotective effects by attenuating inflammatory responses in nonclinical models of neuroinflammation.

The CNS-Penetrant Soluble Guanylate Cyclase Stimulator CY6463 Reveals its Therapeutic Potential in Neurodegenerative Diseases.

Effective treatments for neurodegenerative diseases remain elusive and are critically needed since the burden of these diseases increases across an aging global population. Nitric oxide (NO) is a gasotransmitter that binds to soluble guanylate cyclase (sGC) to produce cyclic guanosine monophosphate (cGMP). Impairment of this pathway has been demonstrated in neurodegenerative diseases. Normalizing deficient NO-cGMP signaling could address multiple pathophysiological features of neurodegenerative diseases. sGC stimulators are small molecules that synergize with NO, activate sGC, and increase cGMP production. Many systemic sGC stimulators have been characterized and advanced into clinical development for a variety of non-central nervous system (CNS) pathologies. Here, we disclose the discovery of CY6463, the first brain-penetrant sGC stimulator in clinical development for the treatment of neurodegenerative diseases, and demonstrate its ability to improve neuronal activity, mediate neuroprotection, and increase cognitive performance in preclinical models. In several cellular assays, CY6463 was demonstrated to be a potent stimulator of sGC. In agreement with the known effects of sGC stimulation in the vasculature, CY6463 elicits decreases in blood pressure in both rats and mice. Relative to a non-CNS penetrant sGC stimulator, rodents treated with CY6463 had higher cGMP levels in cerebrospinal fluid (CSF), functional-magnetic-resonance-imaging-blood-oxygen-level-dependent (fMRI-BOLD) signals, and cortical electroencephalographic (EEG) gamma-band oscillatory power. Additionally, CY6463 improved cognitive performance in a model of cognitive disruption induced by the administration of a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. In models of neurodegeneration, CY6463 treatment increased long-term potentiation (LTP) in hippocampal slices from a Huntington's disease mouse model and decreased the loss of dendritic spines in aged and Alzheimer's disease mouse models. In a model of diet-induced obesity, CY6463 reduced markers of inflammation in the plasma. Furthermore, CY6463 elicited an additive increase in cortical gamma-band oscillatory power when co-administered with donepezil: the standard of care in Alzheimer's disease. Together, these data support the clinical development of CY6463 as a novel treatment for neurodegenerative disorders.

Discovery of CYR715: A novel carboxylic acid-containing soluble guanylate cyclase stimulator.

Soluble guanylate cyclase (sGC) is a clinically validated therapeutic target in the treatment of pulmonary hypertension. Modulators of sGC have the potential to treat diseases that are affected by dysregulation of the NO-sGC-cGMP signal transduction pathway. This letter describes the SAR efforts that led to the discovery of CYR715, a novel carboxylic acid-containing sGC stimulator, with an improved metabolic profile relative to our previously described stimulator, IWP-051. CYR715 addressed potential idiosyncratic drug toxicity (IDT) liabilities associated with the formation of reactive, migrating acyl glucuronides (AG) found in related carboxylic acid-containing analogs and demonstrated high oral bioavailability in rat and dose-dependent hemodynamic pharmacology in normotensive Sprague-Dawley rats.

Utility of the APACHE IV, PPI, and combined APACHE IV with PPI for predicting overall and disease-specific ICU and ACU mortality.

BACKGROUND: The Acute Physiology and Chronic Health Evaluation (APACHE) IV and Palliative Performance Index (PPI) are scales commonly used to assess prognosis in intensive care units (ICUs) and acute care units (ACUs). OBJECTIVE: To compare the utility of APACHE IV, PPI, and combined APACHE IV with PPI for predicting overall and disease-specific mortality. DESIGN: This is a prospective cohort study using admission data during the first 24 hours. Chi-square contingency tables were used to analyze mortality data for each scale. SETTING: This study was conducted at a community hospital. PATIENTS: Participants were admitted between December 24, 2008 and April 2, 2010. RESULTS: The APACHE IV, PPI, and APACHE IV plus PPI (n = 599) were significant for predicting overall mortality (P < .0001 each). The APACHE IV was also significant in predicting mortality in patients with congestive heart failure (CHF), pulmonary edema (PULEDEM), stroke (cerebrovascular accident [CVA]), terminal or metastatic cancer (CA), and dementia. The PPI was significant for predicting mortality in PULEDEM, CA, and dementia but not CVA or CHF, while the APACHE IV with PPI was significant for all diseases but CVA. The APACHE IV was the most robust in predicting ICU/ACU mortality. The combined APACHE IV and PPI improved the specificity of the PPI to predict mortality but caused a decline in sensitivity. LIMITATIONS: Limitations are due to the subjective nature of the PPI and Glasgow Coma scale (GCS), differences in illness trajectories, and a lack of reliable follow-up of all participants. CONCLUSION: The benefits of combining scales were best exemplified in participants with dementia. Inconsistencies in the predictive value of specific participant populations are likely due to difference in the illness trajectories of disease processes.

APACHE IV versus PPI for predicting community hospital ICU mortality.

BACKGROUND: Both the Acute Physiology and Chronic Health Evaluation (APACHE) IV and Palliative Performance Index (PPI) are scales used to estimate intensive care unit (ICU) prognosis and mortality. OBJECTIVE: To Compare the diagnostic utility of the PPI and APACHE IV and their subsequent implications in predicting ICU mortality at a community hospital. DESIGN: This was a Prospective Cohort Study. SETTING: The study was conducted at the Community hospital ICU. PATIENTS: Participants were 211 patients admitted from December 24, 2008 to June 11, 2009. MEASUREMENTS: An observer gathered appropriate data and performed the APACHE IV and PPI scales within 24 hours of admission. Results were then analyzed using standard formulae. RESULTS: The study included 211 participants in total with 211 participants in the PPI group (n = 211) and 162 in the APACHE IV group (n = 162). The APACHE score and PPI were found to be significant for predicting ICU mortality (P value of P < .002 and 99% CI of 13.74 to 20.32, P value of P < .001and 99% CI of 3.70 to 4.61, respectively). APACHE IV demonstrated a sensitivity of 84.6%, specificity of 96.0%, PPV of 64.7%, and NPV of 98.6%. In contrast, the PPI possessed a sensitivity of 69.2%, specificity of 96.0%, PPV of 64.7%, and NPV of 97.8%. LIMITATIONS: Limitations may have occurred with the subjective nature of the PPI and Glasgow Coma Scale (GCS), along with meeting criterion for the APACHE IV. CONCLUSION: This prospective cohort study in the ICU of a community hospital demonstrated that both the APACHE IV and PPI were significant tools for predicting ICU mortality. When contrasting the 2 scales, the APACHE IV could more accurately rule in mortality when mortality occurred and rule out mortality when survival occurred.

Validation of diacyl glycerolacyltransferase I as a novel target for the treatment of obesity and dyslipidemia using a potent and selective small molecule inhibitor.

A highly potent and selective DGAT-1 inhibitor was identified and used in rodent models of obesity and postprandial chylomicron excursion to validate DGAT-1 inhibition as a novel approach for the treatment of metabolic diseases. Specifically, compound 4a conferred weight loss and a reduction in liver triglycerides when dosed chronically in DIO mice and depleted serum triglycerides following a lipid challenge in a dose-dependent manner, thus, reproducing major phenotypical characteristics of DGAT-1(-/-) mice.

Lead optimization strategies and tactics applied to the discovery of melanin concentrating hormone receptor 1 antagonists.

The discovery of small molecule melanin concentrating hormone receptor (MCHr1) antagonists as novel therapeutic agents for the treatment of obesity has been actively pursued across the pharmaceutical industry. While multiple chemotypes of small molecule MCHr1 antagonists have been identified and shown to deliver weight loss in animal models of obesity, many of these lead compounds have been found to cross-react with the hERG channel and/or demonstrate deleterious effects on cardiovascular hemodynamic parameters. This review describes an approach to rapidly identifying safer MCHr1 antagonists by placing assays to assess cardiovascular safety early in the lead optimization compound prioritization process. Ultimately, despite putting significant effort toward the discovery of a MCHr1 antagonist for the treatment of obesity, we were unable to deliver a candidate compound that attained an acceptable therapeutic index (TI = 30-100) in our in vivo models. Our inability to identify a compound with an acceptable therapeutic index was driven by two primary factors: 1) high levels of sustained drug exposure in the brain was required to achieve efficacy; and 2) many small molecule MCHR1 receptor antagonists suffer from receptor cross-reactivity that leads to cardiovascular toxicity at low multiples of their therapeutic plasma concentration.

Discovery and SAR development of thienopyridones: a class of small molecule AMPK activators.

AMP-activated protein kinase (AMPK) is well established as a sensor and regulator of intracellular and whole-body energy metabolism. A high-throughput screen was performed in order to identify chemotypes that are bound by AMPK. A novel thienopyridone compound (1) was identified and subsequently optimized. The structure-activity relationships that emerged from this effort are described.

Identification of diamino chromone-2-carboxamides as MCHr1 antagonists with minimal hERG channel activity.

A series of potent 2-carboxychromone-based melanin-concentrating hormone receptor 1 (MCHr1) antagonists were synthesized and evaluated for hERG (human Ether-a-go-go Related Gene) channel affinity and functional blockade. Basic dialkylamine-terminated analogs were found to weakly bind the hERG channel and provided marked improvement in a functional patch-clamp assay versus previously reported antagonists of the series.

An evaluation of 3,4-methylenedioxy phenyl replacements in the aminopiperidine chromone class of MCHr1 antagonists.

The optimization of potent MCHr1 antagonist 1 with respect to improving its in vitro profile by replacement of the 3,4-methylenedioxy phenyl (piperonyl) moiety led to the discovery of 19, a compound that showed excellent MCHr1 binding and functional potencies in addition to possessing superior hERG separation, CYP3A4 profile, and receptor cross-reactivity profiles.

Constrained 7-fluorocarboxychromone-4-aminopiperidine based Melanin-concentrating hormone receptor 1 antagonists: the effects of chirality on substituted indan-1-ylamines.

The incorporation of constrained tertiary amines into an existing class of N-benzyl-4-aminopiperidinyl chromone-based MCHr1 antagonists led to the identification of a series of chiral racemic compounds that displayed good to excellent functional potency, binding affinity, and selectivity over the hERG channel. Further separation of two distinct chiral racemic compounds into their corresponding pairs of enantiomers revealed a considerable selectivity for MCHr1 for one configuration, in addition to a striking difference in oral exposure between one pair of enantiomers in diet-induced obese mice. Oral administration of the most potent compound in this class in the same animal model led to significant reduction of fat mass in a semi-chronic model for weight loss.

Optimization of chromone-2-carboxamide melanin concentrating hormone receptor 1 antagonists: assessment of potency, efficacy, and cardiovascular safety.

Evaluation of multiple structurally distinct series of melanin concentrating hormone receptor 1 antagonists in an anesthetized rat cardiovascualar assay led to the identification of a chromone-2-carboxamide series as having excellent safety against the chosen cardiovascular endpoints at high drug concentrations in the plasma and brain. Optimization of this series led to considerable improvements in affinity, functional potency, and pharmacokinetic profile. This led to the identification of a 7-fluorochromone-2-carboxamide (22) that was orally efficacious in a diet-induced obese mouse model, retained a favorable cardiovascular profile in rat, and demonstrated dramatic improvement in effects on mean arterial pressure in our dog cardiovascular model compared to other series reported by our group. However, this analogue also led to prolongation of the QT interval in the dog that was linked to affinity for hERG channel and unexpectedly potent functional blockade of this ion channel.

Identification and characterization of a small molecule AMPK activator that treats key components of type 2 diabetes and the metabolic syndrome.

AMP-activated protein kinase (AMPK) is a key sensor and regulator of intracellular and whole-body energy metabolism. We have identified a thienopyridone family of AMPK activators. A-769662 directly stimulated partially purified rat liver AMPK (EC50 = 0.8 microM) and inhibited fatty acid synthesis in primary rat hepatocytes (IC50 = 3.2 microM). Short-term treatment of normal Sprague Dawley rats with A-769662 decreased liver malonyl CoA levels and the respiratory exchange ratio, VCO2/VO2, indicating an increased rate of whole-body fatty acid oxidation. Treatment of ob/ob mice with 30 mg/kg b.i.d. A-769662 decreased hepatic expression of PEPCK, G6Pase, and FAS, lowered plasma glucose by 40%, reduced body weight gain and significantly decreased both plasma and liver triglyceride levels. These results demonstrate that small molecule-mediated activation of AMPK in vivo is feasible and represents a promising approach for the treatment of type 2 diabetes and the metabolic syndrome.

Lack of efficacy of melanin-concentrating hormone-1 receptor antagonists in models of depression and anxiety.

The aim of this study was to validate melanin-concentrating hormone (MCH)-1 receptor antagonism as a potential treatment of mood disorders. We attempted to replicate the effects previously reported with SNAP-7941 and expanded the investigation to three other orally bioavailable MCH-1 receptor antagonists with good brain penetration. SNAP-7941 (3-30 mg/kg, i.p.) and T-226296 (5-60 mg/kg, p.o.) (+/- racemate), were evaluated in the rat forced swim and mouse tail suspension tests. (+)SNAP-7941 (3-10 mg/kg, p.o.) was also tested in a modified 5-min rat forced swim protocol as previously reported. A-665798 (3-30 mg/kg, p.o.) and A-777903 (3-30 mg/kg, p.o.) were tested in mouse tail suspension and rat Vogel tests. None of the compounds showed meaningful efficacy in the paradigms tested. The lack of efficacy with four structurally different MCH-1 receptor antagonists does not support a role for therapeutic treatment of depression/anxiety via this mechanism of action.

Screening for cardiovascular safety: a structure-activity approach for guiding lead selection of melanin concentrating hormone receptor 1 antagonists.

An inactin-anesthetized rat cardiovascular (CV) assay was employed in a screening mode to triage multiple classes of melanin-concentrating hormone receptor 1 (MCHr1) antagonists. Lead identification was based on a compound profile producing high drug concentration in both plasma (>40 microM) and brain (>20 microg/g) with <15% change in cardiovascular endpoints. As a result of these stringent requirements, lead optimization activities on multiple classes of MCHr1 antagonists were terminated. After providing evidence that the cardiovascular liabilities were not a function of MCHr1 antagonism, continued screening identified the chromone-substituted aminopiperidine amides as a class of MCHr1 antagonists that demonstrated a safe cardiovascular profile at high drug concentrations in both plasma and brain. The high incidence of adverse cardiovascular effects associated with an array of MCHr1 antagonists of significant chemical diversity, combined with the stringent safety requirements for antiobesity drugs, highlight the importance of incorporating cardiovascular safety assessment early in the lead selection process.

Revisiting a classic approach to the Aspidosperma alkaloids: an intramolecular Schmidt reaction mediated synthesis of (+)-aspidospermidine.

[reaction: see text] A total synthesis of (+)-aspidospermidine (1) is described. The key reactions used in the synthesis of this pentacyclic Aspidosperma alkaloid were a deracemizing imine alkylation/Robinson annulation sequence, a selective "redox ketalization", and an intramolecular Schmidt reaction. A Fischer indolization step carried out on a tricyclic ketone mirrored the sequence reported by Stork and Dolfini in their classic aspidospermine synthesis.

Discovery and characterization of aminopiperidinecoumarin melanin concentrating hormone receptor 1 antagonists.

4-(1-Benzo[1,3]dioxol-5-ylmethylpiperidine-4-ylmethyl)-6-chlorochromen-2-one (7) is a potent, orally bioavailable melanin concentrating hormone receptor 1 (MCHr1) antagonist that causes dose-dependent weight loss in diet-induced obese mice. Further evaluation of 7 in an anesthetized dog model of cardiovascular safety revealed adverse hemodynamic effects at a plasma concentration comparable to the minimally effective therapeutic concentration. These results highlight the need for scrutiny of the cardiovascular safety profile of MCHr1 antagonists.