br GPR is a class A GPCR expressed on

GPR119 is a class A GPCR expressed on pancreatic β-cells and certain enteroendocrine rc opiates which upon activation with an agonist, increases insulin secretion in response to rising glucose levels. Mechanistically, this insulinotropic effect is bifurcated involving both GPR119-mediated β-cell signaling and increased incretin production. GPR119 activation in the gut promotes secretion of Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) which also act on the β-cell to facilitate glucose-dependent insulin release. Given the tractability of class A GPCRs and the GLP-1 receptor-like mechanism, development of GPR119 agonists for treating Type 2 diabetes (T2D) has attracted significant attention., The chemistry effort associated with the discovery of APD597 (, ) was recently disclosed, as was the outcome from a Phase I clinical trial evaluating the safety and tolerability of this GPR119 agonist in humans. In light of the favorable clinical and preclinical results, we sought to further investigate this chemical series in order to identify a ‘follow on’ molecule with improved in vitro GPR119 efficacy and reduced CYP 2C9 inhibition. Our prior chemistry effort focused on a central 5-methoxy pyrimidine motif () as a preferred structural feature, driving both potency and efficacy in a human GPR119 HTRF cyclase assay. Absent from this earlier analysis was the analogous 5-fluoro pyrimidine (), which we have now found retains moderate GPR119 activity (). This modification however, did not address the unwanted CYP 2C9 inhibition associated with (i.e. CYP 2C9 IC=5.8μM, CYP 2C9 IC=5.5μM), and prompted us to examine the 5-fluoro-4,6-dialkoxypyrimidine analog . This compound is a potent GPR119 agonist () and does not inhibit CYP 2C9 (IC >50μM). Herein, we describe optimization of the 5-fluoro-4,6-dialkoxypyrimidines as next generation GPR119 agonists for the treatment of Type 2 Diabetes. 5-Fluoro-4,6-dialkoxypyrimidines were prepared by the synthetic route illustrated in . Our SAR effort focused on replacements for the isopropyl carbamate as the 2-methyl-6-(methylsulfonyl)pyridine motif had historically proven optimal. Piperidine substitution was introduced in the last step of the synthesis and afforded compounds – (). Carbamates, thiocarbamates, and amides were explored, together with several heterocyclic motifs (–). The analogs shown in were tested for human and rat GPR119 activity in a homogeneous time resolved fluorescence (HTRF) cyclase (cAMP) assay and mean EC values are provided. Approximately half of the compounds possess a similar, or improved, level of potency to that of , and in all instances, rat potency was reduced relative to human. Intrinsic efficacy (IE) was a key factor in selecting compounds for further analysis and is defined as the percent of response relative to our reference compound AR231453. A significant variation in both the level of intrinsic efficacy and direction of functional response was observed among the analogs prepared. Notably, functions as inverse agonist of human GPR119, while being a weak agonist of the rat receptor. was selected for further analysis as it is one of the more potent agonists that has an intrinsic efficacy value >90% for both human and rat (). was tested against mouse GPR119 and was determined to be a potent “full agonist” (EC=34nM, IE=101%). The 4,6-dialkoxypyrimidine once again conferred reduced CYP2C9 inhibition with having an IC value of 25.7μM. This is approximately four times less potent than APD597 in this assay (APD597 CYP2C9 IC=5.8μM). No inhibitory activity was observed for against 3A4, 2D6, or 1A2, and a weak signal was obtained for 2C19 (i.e. IC=23.4μM). Permeability across Caco-2 monolayers was examined and has a flux ratio of approximately 1.0, suggesting this compound is not a substrate for active transport P-glycoprotein. Hepatocyte stability in several species was determined and the pharmacokinetic profile in Sprague-Dawley rats was subsequently obtained (). Hepatocyte stability was high, with >50% of remaining after incubation for 90min. Not unexpectedly, aqueous solubility of was very low (<0.002μM) and formulation in 20% hydroxypropyl-beta-cyclodextrin (HP-β-CD) or PET (80% PEG, 10% Ethanol, 10% Tween80™) was required for in vivo experiments. exhibited good exposure in Sprague Dawley rat following oral administration in HP-β-CD (=0.376μg/mL) and had an acceptable elimination half-life of 2.71h ().