Discovery and Preclinical Characterization of BIIB129, a Covalent, Selective, and Brain-Penetrant BTK Inhibitor for the Treatment of Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic disease with an underlying pathology characterized by inflammation-driven neuronal loss, axonal injury, and demyelination. Bruton's tyrosine kinase (BTK), a nonreceptor tyrosine kinase and member of the TEC family of kinases, is involved in the regulation, migration, and functional activation of B cells and myeloid cells in the periphery and the central nervous system (CNS), cell types which are deemed central to the pathology contributing to disease progression in MS patients. Herein, we describe the discovery of BIIB129 (25), a structurally distinct and brain-penetrant targeted covalent inhibitor (TCI) of BTK with an unprecedented binding mode responsible for its high kinome selectivity. BIIB129 (25) demonstrated efficacy in disease-relevant preclinical in vivo models of B cell proliferation in the CNS, exhibits a favorable safety profile suitable for clinical development as an immunomodulating therapy for MS, and has a low projected total human daily dose.

Cardiovascular response to small-molecule APJ activation.

Heart failure (HF) remains a grievous illness with poor prognosis even with optimal care. The apelin receptor (APJ) counteracts the pressor effect of angiotensin II, attenuates ischemic injury, and has the potential to be a novel target to treat HF. Intravenous administration of apelin improves cardiac function acutely in patients with HF. However, its short half-life restricts its use to infusion therapy. To identify a longer acting APJ agonist, we conducted a medicinal chemistry campaign, leading to the discovery of potent small-molecule APJ agonists with comparable activity to apelin by mimicking the C-terminal portion of apelin-13. Acute infusion increased systolic function and reduced systemic vascular resistance in 2 rat models of impaired cardiac function. Similar results were obtained in an anesthetized but not a conscious canine HF model. Chronic oral dosing in a rat myocardial infarction model reduced myocardial collagen content and improved diastolic function to a similar extent as losartan, a RAS antagonist standard-of-care therapy, but lacked additivity with coadministration. Collectively, this work demonstrates the feasibility of developing clinical, viable, potent small-molecule agonists that mimic the endogenous APJ ligand with more favorable drug-like properties and highlights potential limitations for APJ agonism for this indication.

Discovery of AM-6226: A Potent and Orally Bioavailable GPR40 Full Agonist That Displays Efficacy in Nonhuman Primates.

GPR40 (FFA1) is a G-protein-coupled receptor, primarily expressed in pancreatic islets and enteroendocrine L-cells, and, when activated, elicits increased insulin secretion only in the presence of elevated glucose levels. We recently reported the discovery of AM-1638 (2), a full agonist of GPR40. Herein, we present further structure-activity relationships progressing from AM-1638 (2) to AM-6226 (14) that possesses a profile acceptable for dosing cynomolgus monkeys. The GPR40 full agonist AM-6226 (14) is the first molecule to display significant glucose lowering in cynomolgus monkeys providing additional evidence that GPR40 full agonists afford access to a powerful mechanism for maintaining glycemic control.

5-Alkyl-2-urea-Substituted Pyridines: Identification of Efficacious Glucokinase Activators with Improved Properties.

Two 1-(4-aryl-5-alkyl-pyridin-2-yl)-3-methylurea glucokinase activators were identified with robust in vivo efficacy. These two compounds possessed higher solubilities than the previously identified triaryl compounds (i.e., AM-2394). Structure-activity relationship studies are presented along with relevant pharmacokinetic and in vivo data.

Novel Series of Potent Glucokinase Activators Leading to the Discovery of AM-2394.

Glucokinase (GK) catalyzes the phosphorylation of glucose to glucose-6-phosphate. We present the structure-activity relationships leading to the discovery of AM-2394, a structurally distinct GKA. AM-2394 activates GK with an EC50 of 60 nM, increases the affinity of GK for glucose by approximately 10-fold, exhibits moderate clearance and good oral bioavailability in multiple animal models, and lowers glucose excursion following an oral glucose tolerance test in an ob/ob mouse model of diabetes.

Discovery and in vivo evaluation of (S)-N-(1-(7-fluoro-2-(pyridin-2-yl)quinolin-3-yl)ethyl)-9H-purin-6-amine (AMG319) and related PI3Kδ inhibitors for inflammation and autoimmune disease.

The development and optimization of a series of quinolinylpurines as potent and selective PI3Kδ kinase inhibitors with excellent physicochemical properties are described. This medicinal chemistry effort led to the identification of 1 (AMG319), a compound with an IC50 of 16 nM in a human whole blood assay (HWB), excellent selectivity over a large panel of protein kinases, and a high level of in vivo efficacy as measured by two rodent disease models of inflammation.

C5-Alkyl-2-methylurea-Substituted Pyridines as a New Class of Glucokinase Activators.

Glucokinase (GK) activators represent a class of type 2 diabetes therapeutics actively pursued due to the central role that GK plays in regulating glucose homeostasis. Herein we report a novel C5-alkyl-2-methylurea-substituted pyridine series of GK activators derived from our previously reported thiazolylamino pyridine series. Our efforts in optimizing potency, enzyme kinetic properties, and metabolic stability led to the identification of compound 26 (AM-9514). This analogue showed a favorable combination of in vitro potency, enzyme kinetic properties, acceptable pharmacokinetic profiles in preclinical species, and robust efficacy in a rodent PD model.

Discovery and Optimization of Potent GPR40 Full Agonists Containing Tricyclic Spirocycles.

GPR40 (FFAR1 or FFA1) is a target of high interest being pursued to treat type II diabetes due to its unique mechanism leading to little risk of hypoglycemia. We recently reported the discovery of AM-1638 (2), a potent full agonist of GPR40. In this report, we present the discovery of GPR40 full agonists containing conformationally constrained tricyclic spirocycles and their structure-activity relationships leading to more potent agonists such as AM-5262 (26) with improved rat PK profile and general selectivity profile. AM-5262 enhanced glucose stimulated insulin secretion (mouse and human islets) and improved glucose homeostasis in vivo (OGTT in HF/STZ mice) when compared to AM-1638.

Discovery and in vivo evaluation of dual PI3Kß/δ inhibitors.

Structure-based rational design led to the synthesis of a novel series of potent PI3K inhibitors. The optimized pyrrolopyridine analogue 63 was a potent and selective PI3Kß/δ dual inhibitor that displayed suitable physicochemical properties and pharmacokinetic profile for animal studies. Analogue 63 was found to be efficacious in animal models of inflammation including a keyhole limpet hemocyanin (KLH) study and a collagen-induced arthritis (CIA) disease model of rheumatoid arthritis. These studies highlight the potential therapeutic value of inhibiting both the PI3Kß and δ isoforms in the treatment of a number of inflammatory diseases.

Discovery of AM-1638: A Potent and Orally Bioavailable GPR40/FFA1 Full Agonist.

GPR40 (FFA1) is a G-protein-coupled receptor, primarily expressed in pancreatic islets, the activation of which elicits increased insulin secretion only in the presence of elevated glucose levels. A potent, orally bioavailable small molecule GPR40 agonist is hypothesized to be an effective antidiabetic posing little or no risk of hypoglycemia. We recently reported the discovery of AMG 837 (1), a potent partial agonist of GPR40. Herein, we present the optimization from the GPR40 partial agonist 1 to the structurally and pharmacologically distinct GPR40 full agonist AM-1638 (21). Moreover, we demonstrate the improved in vivo efficacy that GPR40 full agonist 21 exhibits in BDF/DIO mice as compared to partial agonist 1.

Discovery of Dual VEGFR-2 and Tubulin Inhibitors with in Vivo Efficacy.

In an effort to develop potent, orally bioavailable compounds for the treatment of neoplastic diseases, we developed a class of dual VEGFR-2 kinase and tubulin inhibitors. Targeting the VEGFR receptor kinase and tubulin structure allows for inhibition of both tumor cells and tumor vasculature. Previously, a combination of two compounds, a VEGF receptor tyrosine kinase inhibitor and tubulin agent, was demonstrated to produce an enhanced antitumor response in animal studies. We have reaffirmed their results, with the added benefit that both activities are found in one compound.

Oxadiazole derivatives as a novel class of antimitotic agents: Synthesis, inhibition of tubulin polymerization, and activity in tumor cell lines.

Oxadiazole derivatives were synthesized and evaluated for their ability to inhibit tubulin polymerization and to cause mitotic arrest in tumor cells. The most potent compounds inhibited tubulin polymerization at concentrations below 1 microM. Lead analogs caused mitotic arrest of A431 human epidermoid cells and cells derived from multi-drug resistant tumors (10, EC(50)=7.8 nM). Competition for the colchicine binding site and pharmacokinetic properties of selected potent compounds were also investigated and are reported herein, along with structure-activity relationships for this novel series of antimitotic agents.

Synthesis and structure-activity relationships of 1,2,4-triazoles as a novel class of potent tubulin polymerization inhibitors.

A novel triazole-containing chemical series was shown to inhibit tubulin polymerization and cause cell cycle arrest in A431 cancer cells with EC(50) values in the single digit nanomolar range. Binding experiments demonstrated that representative active compounds of this class compete with colchicine for its binding site on tubulin. The syntheses and structure-activity relationship studies for the triazole derivatives are described herein.