Identification of novel GPR81 agonist lead series for target biology evaluation.

GPR81 is a novel drug target that is implicated in the control of glucose and lipid metabolism. The lack of potent GPR81 modulators suitable for in vivo studies has limited the pharmacological characterization of this lactate sensing receptor. We performed a high throughput screen (HTS) and identified a GPR81 agonist chemical series containing a central acyl urea scaffold linker. During SAR exploration two additional new series were evolved, one containing cyclic acyl urea bioisosteres and another a central amide bond. These three series provide different selectivity and physicochemical properties suitable for in-vivo studies.

Discovery of AZD4831, a Mechanism-Based Irreversible Inhibitor of Myeloperoxidase, As a Potential Treatment for Heart Failure with Preserved Ejection Fraction.

Myeloperoxidase is a promising therapeutic target for treatment of patients suffering from heart failure with preserved ejection fraction (HFpEF). We aimed to discover a covalent myeloperoxidase inhibitor with high selectivity for myeloperoxidase over thyroid peroxidase, limited penetration of the blood-brain barrier, and pharmacokinetics suitable for once-daily oral administration at low dose. Structure-activity relationship, biophysical, and structural studies led to prioritization of four compounds for in-depth safety and pharmacokinetic studies in animal models. One compound (AZD4831) progressed to clinical studies on grounds of high potency (IC50, 1.5 nM in vitro) and selectivity (>450-fold vs thyroid peroxidase in vitro), the mechanism of irreversible inhibition, and the safety profile. Following phase 1 studies in healthy volunteers and a phase 2a study in patients with HFpEF, a phase 2b/3 efficacy study of AZD4831 in patients with HFpEF started in 2021.

Design of small molecule inhibitors of acetyl-CoA carboxylase 1 and 2 showing reduction of hepatic malonyl-CoA levels in vivo in obese Zucker rats.

Inhibition of acetyl-CoA carboxylases has the potential for modulating long chain fatty acid biosynthesis and mitochondrial fatty acid oxidation. Hybridization of weak inhibitors of ACC2 provided a novel, moderately potent but lipophilic series. Optimization led to compounds 33 and 37, which exhibit potent inhibition of human ACC2, 10-fold selectivity over inhibition of human ACC1, good physical and in vitro ADME properties and good bioavailability. X-ray crystallography has shown this series binding in the CT-domain of ACC2 and revealed two key hydrogen bonding interactions. Both 33 and 37 lower levels of hepatic malonyl-CoA in vivo in obese Zucker rats.

Discovery of the Oral Leukotriene C4 Synthase Inhibitor (1S,2S)-2-({5-[(5-Chloro-2,4-difluorophenyl)(2-fluoro-2-methylpropyl)amino]-3-methoxypyrazin-2-yl}carbonyl)cyclopropanecarboxylic Acid (AZD9898) as a New Treatment for Asthma.

While bronchodilators and inhaled corticosteroids are the mainstay of asthma treatment, up to 50% of asthmatics remain uncontrolled. Many studies show that the cysteinyl leukotriene cascade remains highly activated in some asthmatics, even those on high-dose inhaled or oral corticosteroids. Hence, inhibition of the leukotriene C4 synthase (LTC4S) enzyme could provide a new and differentiated core treatment for patients with a highly activated cysteinyl leukotriene cascade. Starting from a screening hit (3), a program to discover oral inhibitors of LTC4S led to (1S,2S)-2-({5-[(5-chloro-2,4-difluorophenyl)(2-fluoro-2-methylpropyl)amino]-3-methoxypyrazin-2-yl}carbonyl)cyclopropanecarboxylic acid (AZD9898) (36), a picomolar LTC4S inhibitor (IC50 = 0.28 nM) with high lipophilic ligand efficiency (LLE = 8.5), which displays nanomolar potency in cells (peripheral blood mononuclear cell, IC50,free = 6.2 nM) and good in vivo pharmacodynamics in a calcium ionophore-stimulated rat model after oral dosing (in vivo, IC50,free = 34 nM). Compound 36 mitigates the GABA binding, hepatic toxicity signal, and in vivo toxicology findings of an early lead compound 7 with a human dose predicted to be 30 mg once daily.

Involvement of the metabolic sensor GPR81 in cardiovascular control.

GPR81 is a receptor for the metabolic intermediate lactate with an established role in regulating adipocyte lipolysis. Potentially novel GPR81 agonists were identified that suppressed fasting plasma free fatty acid levels in rodents and in addition improved insulin sensitivity in mouse models of insulin resistance and diabetes. Unexpectedly, the agonists simultaneously induced hypertension in rodents, including wild-type, but not GPR81-deficient mice. Detailed cardiovascular studies in anesthetized dogs showed that the pressor effect was associated with heterogenous effects on vascular resistance among the measured tissues: increasing in the kidney while remaining unchanged in hindlimb and heart. Studies in rats revealed that the pressor effect could be blocked, and the renal resistance effect at least partially blocked, with pharmacological antagonism of endothelin receptors. In situ hybridization localized GPR81 to the microcirculation, notably afferent arterioles of the kidney. In conclusion, these results provide evidence for a potentially novel role of GPR81 agonism in blood pressure control and regulation of renal vascular resistance including modulation of a known vasoeffector mechanism, the endothelin system. In addition, support is provided for the concept of fatty acid lowering as a means of improving insulin sensitivity.

Discovery of Second Generation Reversible Covalent DPP1 Inhibitors Leading to an Oxazepane Amidoacetonitrile Based Clinical Candidate (AZD7986).

A novel series of second generation DPP1 inhibitors free from aorta binding liabilities found for earlier compound series was discovered. This work culminated in the identification of compound 30 (AZD7986) as a highly potent, reversible, and selective clinical candidate for COPD, with predicted human PK properties suitable for once daily human dosing.

AT2-selective angiotensin II analogues containing tyrosine-functionalized 5,5-bicyclic thiazabicycloalkane dipeptide mimetics.

This paper reports the synthesis of two angiotensin II analogues with tyrosine-functionalized 5,5-bicyclic thiazabicycloalkane dipeptide mimetics replacing the Tyr(4)-Ile(5) residues. The preparation of these analogues relies on the synthesis and incorporation of an alpha,alpha-disubstituted chimeric amino acid derivative and on-resin bicyclization to a cysteine residue. The synthesized analogues both displayed high angiotensin AT(2)/AT(1) receptor binding preferences and had AT(2) receptor affinities in the same low nanomolar range as angiotensin II itself. Conformational analysis, using experimental constraints derived from NMR studies, indicated that the Tyr(4) and His(6) residues in one of the angiotensin II analogues were in close proximity to each other.

Vinyl sulfide cyclized analogues of angiotensin II with high affinity and full agonist activity at the AT(1) receptor.

Vinyl sulfide cyclized analogues of the octapeptide angiotensin II that are structurally related to the cyclic disulfide agonist c[Hcy(3,5)]Ang II have been prepared. The synthesis relies on the reaction of the mercapto group of a cysteine residue in position 3 with the formyl group of allysine incorporated in position 5 of angiotensin II. A mixture of the cis and the trans isomers was formed, and these were separated and isolated by RP-HPLC. Thus, the three-atom CH(2)[bond]S[bond]S element of the AT(1) receptor agonist c[Hcy(3,5)]Ang II has been displaced by a bioisosteric three-atom S[bond]CH[double bond]CH element. A comparative conformational analysis of the 13-membered ring systems of c[Hcy(3,5)]Ang II and the 13-membered cyclic vinyl sulfides with cis and trans configuration, respectively, suggested that all three systems adopted very similar low-energy conformations. This similarity was also reflected in the bioactivity. Both of the compounds that contained the ring systems encompassing the cis or trans vinyl sulfide elements between positions 3 and 5 exhibited K(i) values less than 2 nM and exerted full agonism at the AT(1) receptor. In contrast, vinyl sulfide cyclization involving the amino acid residues 5 and 7 rendered inactive compounds. The cyclic vinyl sulfides that have agonist activity were both shown to possess low-energy conformers compatible with the previously proposed 3D model for the bioactive conformation of Ang II.

Synthesis and functionalization of cyclic sulfonimidamides: a novel chiral heterocyclic carboxylic Acid bioisostere.

An efficient synthesis of aryl substituted cyclic sulfonimidamides designed as chiral nonplanar heterocyclic carboxylic acid bioisosteres is described. The cyclic sulfonimidamide ring system could be prepared in two steps from a trifluoroacetyl protected sulfinamide and methyl ester protected amino acids. By varying the amino acid, a range of different C-3 substituted sulfonimidamides could be prepared. The compounds could be further derivatized in the aryl ring using standard cross-coupling reactions to yield highly substituted cyclic sulfonimidamides in excellent yields. The physicochemical properties of the final compounds were examined and compared to those of the corresponding carboxylic acid and tetrazole derivatives. The unique nonplanar shape in combination with the relatively strong acidity (pK a 5-6) and the ease of modifying the chemical structure to fine-tune the physicochemical properties suggest that this heterocycle can be a valuable addition to the range of available carboxylic acid isosteres.

Design and optimization of pyrazinecarboxamide-based inhibitors of diacylglycerol acyltransferase 1 (DGAT1) leading to a clinical candidate dimethylpyrazinecarboxamide phenylcyclohexylacetic acid (AZD7687).

A new series of pyrazinecarboxamide DGAT1 inhibitors was designed to address the need for a candidate drug with good potency, selectivity, and physical and DMPK properties combined with a low predicted dose in man. Rational design and optimization of this series led to the discovery of compound 30 (AZD7687), which met the project objectives for potency, selectivity, in particular over ACAT1, solubility, and preclinical PK profiles. This compound showed the anticipated excellent pharmacokinetic properties in human volunteers.

Making medicinal chemistry more effective--application of Lean Sigma to improve processes, speed and quality.

The pharmaceutical industry, particularly the small molecule domain, faces unprecedented challenges of escalating costs, high attrition as well as increasing competitive pressure from other companies and from new treatment modes such as biological products. In other industries, process improvement approaches, such as Lean Sigma, have delivered benefits in speed, quality and cost of delivery. Examining the medicinal chemistry contributions to the iterative improvement process of design-make-test-analyse from a Lean Sigma perspective revealed that major improvements could be made. Thus, the cycle times of synthesis, as well as compound analysis and purification, were reduced dramatically. Improvements focused on team, rather than individual, performance. These new ways of working have consequences for staff engagement, goals, rewards and motivation, which are also discussed.