A G protein-biased S1P1 agonist, SAR247799, protects endothelial cells without affecting lymphocyte numbers.

Endothelial dysfunction is a hallmark of tissue injury and is believed to initiate the development of vascular diseases. Sphingosine-1 phosphate receptor-1 (S1P1) plays fundamental physiological roles in endothelial function and lymphocyte homing. Currently available clinical molecules that target this receptor are desensitizing and are essentially S1P1 functional antagonists that cause lymphopenia. They are clinically beneficial in autoimmune diseases such as multiple sclerosis. In patients, several side effects of S1P1 desensitization have been attributed to endothelial damage, suggesting that drugs with the opposite effect, namely, the ability to activate S1P1, could help to restore endothelial homeostasis. We found and characterized a biased agonist of S1P1, SAR247799, which preferentially activated downstream G protein signaling to a greater extent than ß-arrestin and internalization signaling pathways. SAR247799 activated S1P1 on endothelium without causing receptor desensitization and potently activated protection pathways in human endothelial cells. In a pig model of coronary endothelial damage, SAR247799 improved the microvascular hyperemic response without reducing lymphocyte numbers. Similarly, in a rat model of renal ischemia/reperfusion injury, SAR247799 preserved renal structure and function at doses that did not induce S1P1-desensitizing effects, such as lymphopenia and lung vascular leakage. In contrast, a clinically used S1P1 functional antagonist, siponimod, conferred minimal renal protection and desensitized S1P1 These findings demonstrate that sustained S1P1 activation can occur pharmacologically without compromising the immune response, providing a new approach to treat diseases associated with endothelial dysfunction and vascular hyperpermeability.

Dual Glucagon-like Peptide 1 (GLP-1)/Glucagon Receptor Agonists Specifically Optimized for Multidose Formulations.

Novel peptidic dual agonists of the glucagon-like peptide 1 (GLP-1) and glucagon receptor are reported to have enhanced efficacy over pure GLP-1 receptor agonists with regard to treatment of obesity and diabetes. We describe novel exendin-4 based dual agonists designed with an activity ratio favoring the GLP-1 versus the glucagon receptor. As result of an iterative optimization procedure that included molecular modeling, structural biological studies (X-ray, NMR), peptide design and synthesis, experimental activity, and solubility profiling, a candidate molecule was identified. Novel SAR points are reported that allowed us to fine-tune the desired receptor activity ratio and increased solubility in the presence of antimicrobial preservatives, findings that can be of general applicability for any peptide discovery project. The peptide was evaluated in chronic in vivo studies in obese diabetic monkeys as translational model for the human situation and demonstrated favorable blood glucose and body weight lowering effects.

Design of Novel Exendin-Based Dual Glucagon-like Peptide 1 (GLP-1)/Glucagon Receptor Agonists.

Dual activation of the glucagon-like peptide 1 (GLP-1) and glucagon receptor has the potential to lead to a novel therapy principle for the treatment of diabesity. Here, we report a series of novel peptides with dual activity on these receptors that were discovered by rational design. On the basis of sequence analysis and structure-based design, structural elements of glucagon were engineered into the selective GLP-1 receptor agonist exendin-4, resulting in hybrid peptides with potent dual GLP-1/glucagon receptor activity. Detailed structure-activity relationship data are shown. Further modifications with unnatural and modified amino acids resulted in novel metabolically stable peptides that demonstrated a significant dose-dependent decrease in blood glucose in chronic studies in diabetic db/db mice and reduced body weight in diet-induced obese (DIO) mice. Structural analysis by NMR spectroscopy confirmed that the peptides maintain an exendin-4-like structure with its characteristic tryptophan-cage fold motif that is responsible for favorable chemical and physical stability.

End-organ protection in hypertension by the novel and selective Rho-kinase inhibitor, SAR407899.

AIM: To compare the therapeutic efficacy of SAR407899 with the current standard treatment for hypertension [an angiotensin converting enzyme (ACE)-inhibitor and a calcium channel blocker] and compare the frequency and severity of the hypertension-related end-organ damage. METHODS: Long-term pharmacological characte-rization of SAR407899 has been performed in two animal models of hypertension, of which one is sensitive to ACE-inhibition (LNAME) and the other is insensitive [deoxycorticosterone acetate (DOCA)]. SAR407899 efficiently lowered high blood pressure and significantly reduced late-stage end organ damage as indicated by improved heart, kidney and endothelial function and reduced heart and kidney fibrosis in both models of chronic hypertension. RESULTS: Long term treatment with SAR407899 has been well tolerated and dose-dependently reduced elevated blood pressure in both models with no signs of tachyphylaxia. Blood pressure lowering effects and protective effects on hypertension related end organ damage of SAR407899 were superior to ramipril and amlodipine in the DOCA rat. Typical end-organ damage was significantly reduced in the SAR407899-treated animals. Chronic administration of SAR407899 significantly reduced albuminuria in both models. The beneficial effect of SAR407899 was associated with a reduction in leukocyte/macrophage tissue infiltration. The overall protective effect of SAR407899 was superior or comparable to that of ACE-inhibition or calcium channel blockade. Chronic application of SAR407899 protects against hypertension and hypertension-induced end organ damage, regardless of the pathophysiological mechanism of hypertension. CONCLUSION: Rho-kinases-inhibition by the SAR407899 represents a new therapeutic option for the treatment of hypertension and its complications.

Selective inhibitors of cardiac ADPR cyclase as novel anti-arrhythmic compounds.

ADP-ribosyl cyclases (ADPRCs) catalyse the conversion of nicotinamide adenine dinucleotide to cyclic adenosine diphosphoribose (cADPR) which is a second messenger involved in Ca(2+) mobilisation from intracellular stores. Via its interaction with the ryanodine receptor Ca(2+) channel in the heart, cADPR may exert arrhythmogenic activity. To test this hypothesis, we have studied the effect of novel cardiac ADPRC inhibitors in vitro and in vivo in models of ventricular arrhythmias. Using a high-throughput screening approach on cardiac sarcoplasmic reticulum membranes isolated from pig and rat and nicotinamide hypoxanthine dinuleotide as a surrogate substrate, we have identified potent and selective inhibitors of an intracellular, membrane-bound cardiac ADPRC that are different from the two known mammalian ADPRCs, CD38 and CD157/Bst1. We show that two structurally distinct cardiac ADPRC inhibitors, SAN2589 and SAN4825, prevent the formation of spontaneous action potentials in guinea pig papillary muscle in vitro and that compound SAN4825 is active in vivo in delaying ventricular fibrillation and cardiac arrest in a guinea pig model of Ca(2+) overload-induced arrhythmia. Inhibition of cardiac ADPRC prevents Ca(2+) overload-induced spontaneous depolarizations and ventricular fibrillation and may thus provide a novel therapeutic principle for the treatment of cardiac arrhythmias.

Pharmacological characterization of SAR407899, a novel rho-kinase inhibitor.

Recent advances in basic and clinical research have identified Rho kinase as an important target potentially implicated in a variety of cardiovascular diseases. Rho kinase is a downstream mediator of RhoA that leads to stress fiber formation, membrane ruffling, smooth muscle contraction, and cell motility. Increased Rho-kinase activity is associated with vasoconstriction and elevated blood pressure. We identified a novel inhibitor of Rho kinase (SAR407899) and characterized its effects in biochemical, cellular, tissue-based, and in vivo assays. SAR407899 is an ATP-competitive Rho-kinase inhibitor, equipotent against human and rat-derived Rho-kinase 2 with inhibition constant values of 36 nM and 41 nM, respectively. It is highly selective in panel of 117 receptor and enzyme targets. SAR407899 is approximately 8-fold more active than fasudil. In vitro, SAR407899 demonstrated concentration-dependent inhibition of Rho-kinase-mediated phosphorylation of myosin phosphatase, thrombin-induced stress fiber formation, platelet-derived growth factor-induced proliferation, and monocyte chemotactic protein-1-stimulated chemotaxis. SAR407899 potently (mean IC(50) values: 122 to 280 nM) and species-independently relaxed precontracted isolated arteries of different species and different vascular beds. In vivo, over the dose range 3 to 30 mg/kg PO, SAR407899 lowered blood pressure in a variety of rodent models of arterial hypertension. The antihypertensive effect of SAR407899 was superior to that of fasudil and Y-27632. In conclusion, SAR407899 is a novel and potent selective Rho-kinase inhibitor with promising antihypertensive activity.

Acyl ureas as human liver glycogen phosphorylase inhibitors for the treatment of type 2 diabetes.

Using a focused screening approach, acyl ureas have been discovered as a new class of inhibitors of human liver glycogen phosphorylase (hlGPa). The X-ray structure of screening hit 1 (IC50 = 2 microM) in a complex with rabbit muscle glycogen phosphorylase b reveals that 1 binds at the AMP site, the main allosteric effector site of the dimeric enzyme. A first cycle of chemical optimization supported by X-ray structural data yielded derivative 21, which inhibited hlGPa with an IC50 of 23 +/- 1 nM, but showed only moderate cellular activity in isolated rat hepatocytes (IC50 = 6.2 microM). Further optimization was guided by (i) a 3D pharmacophore model that was derived from a training set of 24 compounds and revealed the key chemical features for the biological activity and (ii) the 1.9 angstroms crystal structure of 21 in complex with hlGPa. A second set of compounds was synthesized and led to 42 with improved cellular activity (hlGPa IC50 = 53 +/- 1 nM; hepatocyte IC50 = 380 nM). Administration of 42 to anaesthetized Wistar rats caused a significant reduction of the glucagon-induced hyperglycemic peak. These findings are consistent with the inhibition of hepatic glycogenolysis and support the use of acyl ureas for the treatment of type 2 diabetes.