Mineralocorticoid Receptor Antagonism Prevents the Synergistic Effect of Metabolic Challenge and Chronic Kidney Disease on Renal Fibrosis and Inflammation in Mice

Obesity and/or metabolic diseases are frequently associated with chronic kidney disease and several factors associated with obesity may contribute to proteinuria and extracellular matrix production. Mineralocorticoid receptor antagonists have proven their clinical efficacy in diabetic kidney disease with preclinical data suggesting that they may also be efficient in non-diabetic chronic kidney disease associated to metabolic diseases. In the present study we developed a novel mouse model combining severe nephron reduction and High Fat Diet challenge that led to chronic kidney disease with metabolic alterations. We showed that the Mineralocorticoid Receptor antagonist canrenoate improved metabolic function, reduced albuminuria and prevented the synergistic effect of high fat diet on renal fibrosis and inflammation in chronic kidney disease mice.

Electrolyte handling in the isolated perfused rat kidney: demonstration of vasopressin V2-receptor-dependent calcium reabsorption

BACKGROUND

The most profound effect of vasopressin on the kidney is to increase water reabsorption through V₂-receptor (V₂R) stimulation, but there are also data suggesting effects on calcium transport. To address this issue, we have established an isolated perfused kidney model with accurate pressure control, to directly study the effects of V₂R stimulation on kidney function, isolated from systemic effects.

METHODS

The role of V₂R in renal calcium handling was studied in isolated rat kidneys using a new pressure control system that uses a calibration curve to compensate for the internal pressure drop up to the tip of the perfusion cannula.

RESULTS

Kidneys subjected to V₂R stimulation using desmopressin (DDAVP) displayed stable osmolality and calcium reabsorption throughout the experiment, whereas kidneys not administered DDAVP exhibited a simultaneous fall in urine osmolality and calcium reabsorption. Epithelial sodium channel (ENaC) inhibition using amiloride resulted in a marked increase in potassium reabsorption along with decreased sodium reabsorption.

CONCLUSIONS

A stable isolated perfused kidney model with computer-controlled pressure regulation was developed, which retained key physiological functions. The preparation responds to pharmacological inhibition of ENaC channels and activation of V₂R. Using the model, the dynamic effects of V₂R stimulation on calcium handling and urine osmolality could be visualised. The study thereby provides evidence for a stimulatory role of V₂R in renal calcium reabsorption.

Safety, Tolerability, and Pharmacokinetics of the Mineralocorticoid Receptor Modulator AZD9977 in Healthy Men: A Phase I Multiple Ascending Dose Study

Excessive activation of the mineralocorticoid receptor (MR) underlies the pathophysiology of heart failure and chronic kidney disease. Hyperkalemia risk limits the therapeutic use of conventional MR antagonists. AZD9977 is a nonsteroidal, selective MR modulator that may protect nonepithelial tissues without disturbing electrolyte balance. This phase I study investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple oral doses of AZD9977 in healthy volunteers. Twenty‐seven male participants aged 23–45 years were randomized 3:1 to receive oral AZD9977 or placebo for 8 days (with twice‐daily dosing on days 2–7), in dose cohorts of 50, 150, and 300 mg (AZD9977, n = 6 per cohort; placebo, n = 3 per cohort). Adverse events occurred in 4 of 18 participants receiving AZD9977 (22.2%) and 6 of 9 receiving placebo (66.7%), all of mild or moderate severity; none were serious or led to withdrawal. AZD9977 was rapidly absorbed, with median time of maximum concentration of 0.50–0.84 hours across dose groups. Area under the curve and maximum concentration were approximately dose proportional but elimination and accumulation terminal half‐life increased with dose. Steady‐state was reached after 3–4 days, with dose‐dependent accumulation of 1.2–1.7‐fold. Renal clearance was 5.9–6.5 L/hour and 24–37% of AZD9977 was excreted in the urine. Serum aldosterone levels increased dose dependently from days −1 to 7 in participants receiving AZD9977, but serum potassium levels and urinary electrolyte excretion were unchanged. AZD9977 was generally well‐tolerated with no safety concerns. Exploratory outcomes suggested reduced hyperkalemia risk compared with MR antagonists. These findings support further clinical development of AZD9977.

P5713Clinical pharmacology of AZD9977, a novel, selective mineralocorticoid receptor (MR) modulator without K+-sparing properties

Background and purpose

Excessive MR activation is implicated in the pathogenesis of cardiovascular disease. MR antagonists (MRA) are effective and key guideline-directed therapy in patients with heart failure (HF) with reduced ejection fraction. However, clinical adverse events due to hyperkalaemia and a decline in renal function significantly restricts the treatment. AZD9977 is a novel, non-steroidal selective MR modulator that, compared with MRA, displays a differentiated MR-binding pattern and cofactor recruitment profile, and exerts similar organ protective effects to eplerenone with minimal effects on urinary electrolyte handling.

Methods

We performed a randomized, placebo-controlled, single-blind phase 1 study to evaluate the safety, tolerability and pharmacokinetics of oral AZD9977 in healthy men. Three sequential ascending dose cohorts were evaluated, and participants received either AZD9977 (n=6) or placebo (n=3) for 8 days. AZD9977 target doses of 50mg bid, 150mg bid and 300mg bid were explored based on a model predicted dose range comparable to and exceeding the target receptor occupancy levels achieved with approved MRA drugs. The dose of AZD9977 50mg bid is predicted to be equipotent to spironolactone 25mg daily.

Results

27 healthy male subjects aged 23–45 years completed the study. All doses of AZD9977 were well tolerated with no safety concerns identified. A total of 7 adverse events occurred in 4 participants (22.2%) receiving AZD9977 and 8 events occurred in 6 participants (66.7%) receiving placebo, none severe or resulting in withdrawal from the study. Rapid absorption of AZD9977 was observed with median Tmax values ranging from 0.5 to 0.8-hours post-dose and approximate dose proportional kinetics between 50 to 300 mg twice daily, as measured by AUCτ and Cmax. Steady-state levels in plasma were generally reached within 3–4 days. Target engagement was confirmed by a robust dose-dependent rise in mean serum aldosterone levels between Day −1 and Day 7 (Placebo = 43±172pmol/L, AZD9977 50mg bid = 132±83pmol/L, 150mg bid = 447±242pmol/L, 300mg bid = 808±330pmol/L; Figure 1). AZD9977 had no effect on blood pressure or heart rate and did not alter serum electrolyte levels, urinary Na+ excretion, log urinary Na+/K+ ratio (Figure 2), estimated GFR, or urine volumes when compared to placebo-treated subjects.

Figure 1 and Figure 2

Conclusion

These observations in humans are consistent with pre-clinical studies, demonstrating robust MR-receptor engagement without changes in serum K+ and renal electrolyte handling. These characteristics could potentially realise the therapeutic benefit of MR blockade with a low risk of hyperkalaemia. This hypothesis is currently being tested clinically in a head-to-head trial of AZD9977 versus spironolactone in patients with HF and impaired renal function (NCT03682497).

Acknowledgement/Funding

The study was Sponsored and funded by AstraZeneca

The selective mineralocorticoid receptor modulator AZD9977 reveals differences in mineralocorticoid effects of aldosterone and fludrocortisone

Introduction:

AZD9977 is a novel mineralocorticoid receptor (MR) modulator, which in preclinical studies demonstrated organ protection without affecting aldosterone-regulated urinary electrolyte excretion. However, when tested in humans, using fludrocortisone as an MR agonist, AZD9977 exhibited similar effects on urinary Na⁺/K⁺ ratio as eplerenone. The aim of this study is to understand whether the contradictory results seen in rats and humans are due to the mineralocorticoid used.

Materials and methods:

Rats were treated with single doses of AZD9977 or eplerenone in combination with either aldosterone or fludrocortisone. Urine was collected for five to six hours and total amounts excreted Na⁺ and K⁺ were assessed.

Results:

AZD9977 dose-dependently increased urinary Na⁺/K⁺ ratio in rats when tested against fludrocortisone, but not when tested against aldosterone. Eplerenone dose-dependently increased urinary Na⁺/K⁺ ratio when tested against fludrocortisone as well as aldosterone.

Conclusions:

The data suggest that the contrasting effects of AZD9977 on urinary electrolyte excretion observed in rats and humans are due to the use of the synthetic mineralocorticoid fludrocortisone. Future clinical studies are required to confirm the reduced electrolyte effects of AZD9977 and the subsequent lower predicted hyperkalemia risk.

Preclinical pharmacology of AZD9977: A novel mineralocorticoid receptor modulator separating organ protection from effects on electrolyte excretion

Excess mineralocorticoid receptor (MR) activation promotes target organ dysfunction, vascular injury and fibrosis. MR antagonists like eplerenone are used for treating heart failure, but their use is limited due to the compound class-inherent hyperkalemia risk. Here we present evidence that AZD9977, a first-in-class MR modulator shows cardio-renal protection despite a mechanism-based reduced liability to cause hyperkalemia. AZD9977 in vitro potency and binding mode to MR were characterized using reporter gene, binding, cofactor recruitment assays and X-ray crystallopgraphy. Organ protection was studied in uni-nephrectomised db/db mice and uni-nephrectomised rats administered aldosterone and high salt. Acute effects of single compound doses on urinary electrolyte excretion were tested in rats on a low salt diet. AZD9977 and eplerenone showed similar human MR in vitro potencies. Unlike eplerenone, AZD9977 is a partial MR antagonist due to its unique interaction pattern with MR, which results in a distinct recruitment of co-factor peptides when compared to eplerenone. AZD9977 dose dependently reduced albuminuria and improved kidney histopathology similar to eplerenone in db/db uni-nephrectomised mice and uni-nephrectomised rats. In acute testing, AZD9977 did not affect urinary Na+/K+ ratio, while eplerenone increased the Na+/K+ ratio dose dependently. AZD9977 is a selective MR modulator, retaining organ protection without acute effect on urinary electrolyte excretion. This predicts a reduced hyperkalemia risk and AZD9977 therefore has the potential to deliver a safe, efficacious treatment to patients prone to hyperkalemia.

Inhibition of AMP deaminase activity does not improve glucose control in rodent models of insulin resistance or diabetes

Inhibition of AMP deaminase (AMPD) holds the potential to elevate intracellular adenosine and AMP levels and, therefore, to augment adenosine signaling and activation of AMP-activated protein kinase (AMPK). To test the latter hypothesis, novel AMPD pan inhibitors were synthesized and explored using a panel of in vitro, ex vivo, and in vivo models focusing on confirming AMPD inhibitory potency and the potential of AMPD inhibition to improve glucose control in vivo. Repeated dosing of selected inhibitors did not improve glucose control in insulin-resistant or diabetic rodent disease models. Mice with genetic deletion of the muscle-specific isoform Ampd1 did not showany favorable metabolic phenotype despite being challenged with high-fat diet feeding. Therefore, these results do not support the development of AMPD inhibitors for the treatment of type 2 diabetes.

Overexpression of AMP-metabolizing enzymes controls adenine nucleotide levels and AMPK activation in HEK293T cells

We investigated whether overexpression of AMP-metabolizing enzymes in intact cells would modulate oligomycin-induced AMPK activation. Human embryonic kidney (HEK) 293T cells were transiently transfected with increasing amounts of plasmid vectors to obtain a graded increase in overexpression of AMP-deaminase (AMPD) 1, AMPD2, and soluble 5'-nucleotidase IA (cN-IA) for measurements of AMPK activation and total intracellular adenine nucleotide levels induced by oligomycin treatment. Overexpression of AMPD1 and AMPD2 slightly decreased AMP levels and oligomycin-induced AMPK activation. Increased overexpression of cN-IA led to reductions in the oligomycin-induced increases in AMP and ADP concentrations by ∼70 and 50%, respectively, concomitant with a 50% decrease in AMPK activation. The results support the view that a rise in ADP as well as AMP is important for activation of AMPK, which can thus be regulated by the adenylate energy charge. The control coefficient of cN-IA on AMP was 0.3-0.7, whereas the values for AMPD1 and AMPD2 were <0.1, suggesting that in this model cN-IA exerts a large proportion of control over intracellular AMP. Therefore, small molecule inhibition of cN-IA could be a strategy for AMPK activation.

Discovery of 4-hydroxy-1,6-naphthyridine-3-carbonitrile derivatives as novel PDE10A inhibitors

A series of 1,6-naphthyridine-based compounds was synthesized as potent phosphodiesterase 10A (PDE10A) inhibitors. Structure-based chemical modifications of the discovered chemotype served to further improve potency and selectivity over DHODH, laying the foundation for future optimization efforts.