Mediators of the effects of canagliflozin on kidney protection in patients with type 2 diabetes

Prediction of the Effects of Empagliflozin on Cardiovascular and Kidney Outcomes Based on Short-Term Changes in Multiple Risk Markers

Aims: The EMPA-REG OUTCOME trial demonstrated that the sodium-glucose cotransporter-2 inhibitor (SGLT2) empagliflozin reduces the risk of cardiovascular (CV) and kidney outcomes in patients with type 2 diabetes. We previously developed the parameter response efficacy (PRE) score, which translates drug effects on multiple short-term risk markers into a predicted long-term treatment effect on clinical outcomes. The main objective of this study was to assess the accuracy of the PRE score in predicting the efficacy of empagliflozin in reducing the risk of CV and kidney outcomes. Methods: Short-term (baseline to 6-months) changes in glycated hemoglobin (HbA1c), systolic blood pressure (SBP), urinary-albumin-creatinine-ratio (UACR), hemoglobin, body weight, high-density-lipoprotein (HDL) cholesterol, low-density-lipoprotein (LDL) cholesterol, uric acid, and potassium were determined among 7020 patients with type 2 diabetes and established CV disease in the EMPA-REG OUTCOME trial. The beta-coefficients, derived from a Cox proportional hazards model in a pooled database consisting of 6355 patients with type 2 diabetes, were applied to the short-term risk markers in the EMPA-REG OUTCOME trial to predict the empagliflozin-induced impact on CV (defined as a composite of non-fatal myocardial infarction, non-fatal stroke, or CV death) and kidney (defined as a composite of doubling of serum creatinine or end-stage kidney disease) outcomes. Results: Empagliflozin compared to placebo reduced HbA1c (0.6%), SBP (4.2 mmHg), UACR (13.0%), body weight (2.1 kg), uric acid (20.4 μmol/L), and increased hemoglobin (6.6 g/L), LDL-cholesterol (0.1 mmol/L) and HDL-cholesterol (0.04 mmol/L) (all p<0.01). Integrating these effects in the PRE score resulted in a predicted relative risk reduction (RRR) for the CV outcome of 6.4% (95% CI 1.4-11.7), which was less than the observed 14.7% (95% CI 1.3-26.4%) RRR. For the kidney outcome, the PRE score predicted a RRR of 33.4% (95% CI 26.2-39.8); the observed RRR was 46.9% (95% CI 26.8-61.5). In a subgroup of 2,811 patients with UACR ≥30 mg/g at baseline, the PRE score predicted RRR was 40.8% (95% CI 31.2-49.1) vs. the observed RRR of 40.8% (95% CI 12.4-60.0) for the kidney outcome. Conclusions: Integrating multiple short-term risk marker changes in the PRE score underestimated the effect of empagliflozin on CV and kidney outcomes, suggesting that the currently used risk markers do not fully capture the effect of empagliflozin. In patients with increased albuminuria, the PRE score adequately predicted the effect of empagliflozin on kidney outcomes.

Understanding the protective effects of SGLT2 inhibitors in type 2 diabetes patients with chronic kidney disease

INTRODUCTION

Sodium-glucose co-transporter type 2 inhibitors (SGLT2is) were developed as glucose-lowering agents for the management of type 2 diabetes (T2D). Unexpectedly, they showed a significant reduction in hospitalization for heart failure and hard renal outcomes in patients with and without T2D. Underlying mechanisms remain a matter of debate.

AREAS COVERED

We summarize the protective renal effects of SGLT2is in patients with cardiovascular disease, chronic kidney disease (CKD, especially with albuminuria) or heart failure; a description of the safety of SGLT2is, with a special focus on the risk/benefit balance in people with stage 3 CKD; a comprehensive discussion of mechanisms that could explain nephro-protection; a reappraisal of the positioning of SGLT2is in recent international guidelines.

EXPERT OPINION

Several mechanisms could contribute to improved renal prognosis with SGLT2is, among which a reduction in intraglomerular pressure by restoring the tubuloglomerular feedback, a diuretic effect that contributes to lower albuminuria and renal decongestion, especially if fluid overload is present, a reduction in renal oxygen consumption, an improvement of heart failure status with less cardiorenal syndrome and a lower risk of acute renal injury. All these effects may be mutually not exclusive, and their respective contribution may differ according to patient characteristics.

Renal Tubular Handling of Glucose and Fructose in Health and Disease

The proximal tubule of the kidney is programmed to reabsorb all filtered glucose and fructose. Glucose is taken up by apical sodium-glucose cotransporters SGLT2 and SGLT1 whereas SGLT5 and potentially SGLT4 and GLUT5 have been implicated in apical fructose uptake. The glucose taken up by the proximal tubule is typically not metabolized but leaves via the basolateral facilitative glucose transporter GLUT2 and is returned to the systemic circulation or used as an energy source by distal tubular segments after basolateral uptake via GLUT1. The proximal tubule generates new glucose in metabolic acidosis and the postabsorptive phase, and fructose serves as an important substrate. In fact, under physiological conditions and intake, fructose taken up by proximal tubules is primarily utilized for gluconeogenesis. In the diabetic kidney, glucose is retained and gluconeogenesis enhanced, the latter in part driven by fructose. This is maladaptive as it sustains hyperglycemia. Moreover, renal glucose retention is coupled to sodium retention through SGLT2 and SGLT1, which induces secondary deleterious effects. SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing independent of kidney function and diabetes. Dietary excess of fructose also induces tubular injury. This can be magnified by kidney formation of fructose under pathological conditions. Fructose metabolism is linked to urate formation, which partially accounts for fructose-induced tubular injury, inflammation, and hemodynamic alterations. Fructose metabolism favors glycolysis over mitochondrial respiration as urate suppresses aconitase in the tricarboxylic acid cycle, and has been linked to potentially detrimental aerobic glycolysis (Warburg effect). © 2022 American Physiological Society. Compr Physiol 12:2995-3044, 2022.

Effects of SGLT2 inhibitors on haematocrit and haemoglobin levels and the associated cardiorenal benefits in T2DM patients: A meta-analysis

To explore the effect and magnitude of effect of sodium-glucose cotransporter-2 (SGLT2) inhibitors on haematocrit and haemoglobin and the related cardiorenal benefits in patients with type 2 diabetes mellitus (T2DM), PubMed, Web of Science, CENTRAL and EMBASE were searched to identify eligible trials. Weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated using a random-effects model. Seventy-eight studies were included in the meta-analysis. SGLT2 inhibitors significantly increased haematocrit and haemoglobin levels compared with control (total WMD 2.27% [95% CI 2.08, 2.47] and 6.20 g/L [95% CI 5.68, 6.73], respectively). Except for dapagliflozin (p = 0.000), no notable dose-dependent relationship was revealed for other SGLT2 inhibitors. The effect could be sustained or even slightly increased with long-term therapy (coef. =0.009, 95% CI [0.005, 0.013], p = 0.000). In subgroup analyses, haematocrit elevation increased with higher body mass index (BMI). A greater haematocrit elevation could be observed in white patients or when compared with active controls. In conclusion, SGLT2 inhibitors increased haematocrit and haemoglobin levels in T2DM patients. Changes in haematocrit and haemoglobin seem to be surrogate markers of improvement in renal metabolic stress, and important mediators involved in cardiorenal protection.

Association Between Circulating GDF-15 and Cardio-Renal Outcomes and Effect of Canagliflozin: Results From the CANVAS Trial

Background

Studies have suggested that sodium glucose co‐transporter 2 inhibitors exert anti‐inflammatory effects. We examined the association of baseline growth differentiation factor‐15 (GDF‐15), a marker of inflammation and cellular injury, with cardiovascular events, hospitalization for heart failure (HF), and kidney outcomes in patients with type 2 diabetes in the CANVAS (Canagliflozin Cardiovascular Assessment Study) and determined the effect of the sodium glucose co‐transporter 2 inhibitor canagliflozin on circulating GDF‐15.

Methods and Results

The CANVAS trial randomized 4330 people with type 2 diabetes at high cardiovascular risk to canagliflozin or placebo. The association between baseline GDF‐15 and cardiovascular (non‐fatal myocardial infarction, non‐fatal stroke, cardiovascular death), HF, and kidney (40% estimated glomerular filtration rate decline, end‐stage kidney disease, renal death) outcomes was assessed using multivariable adjusted Cox regression models. During median follow‐up of 6.1 years (N=3549 participants with available samples), 555 cardiovascular, 129 HF, and 137 kidney outcomes occurred. Each doubling in baseline GDF‐15 was significantly associated with a higher risk of cardiovascular (hazard ratio [HR], 1.2; 95% CI, 1.0‒1.3), HF (HR, 1.5; 95% CI, 1.2‒2.0) and kidney (HR, 1.5; 95% CI, 1.2‒2.0) outcomes. Baseline GDF‐15 did not modify canagliflozin’s effect on cardiovascular, HF, and kidney outcomes. Canaglifozin treatment modestly lowered GDF‐15 compared with placebo; however, GDF‐15 did not mediate the protective effect of canagliflozin on cardiovascular, HF, or kidney outcomes.

Conclusions

In patients with type 2 diabetes at high cardiovascular risk, higher GDF‐15 levels were associated with a higher risk of cardiovascular, HF, and kidney outcomes. Canagliflozin modestly lowered GDF‐15, but GDF‐15 reduction did not mediate the protective effect of canagliflozin.

Sodium-glucose cotransporter 2 inhibitors: renal outcomes according to baseline albuminuria

Sodium-glucose co-transporter 2 inhibitors (SGLT2is) reduce albuminuria and hard renal outcomes (decline of renal function, renal replacement therapy and renal death) in patients with/without type 2 diabetes at high cardiovascular or renal risk. The question arises whether baseline albuminuria also influences renal outcomes with SGLT2is as reported with renin-angiotensin-aldosterone system inhibitors. Post hoc analyses focusing on albuminuria and renal outcomes of four cardiovascular outcome trials [EMPA-REG OUTCOME (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients), CANVAS (Canagliflozin Cardiovascular Assessment Study), DECLARE-TIMI 58 (Multicenter Trial to Evaluate the Effect of Dapagliflozin on the Incidence of Cardiovascular Events-Thrombolysis in Myocardial Infarction 58) and VERTIS CV (Evaluation of Ertugliflozin Efficacy and Safety Cardiovascular Outcomes Trial)] and some renal data from two heart failure trials [Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) and EMPEROR-Reduced (Empagliflozin Outcome Trial in Patients With Chronic Heart Failure With Reduced Ejection Fraction)] showed renal protection with SGLT2is without significant interaction (P > 0.10) when comparing renal outcomes according to baseline levels (A1, A2 and A3) of urinary albumin:creatinine ratio (UACR), a finding confirmed in a dedicated meta-analysis. Two trials [CREDENCE (Evaluation of the Effects of Canagliflozin on Renal and Cardiovascular Outcomes in Participants With Diabetic Nephropathy) and DAPA-CKD (Dapagliflozin and Prevention of Adverse Outcomes in Chronic Kidney Disease)] specifically recruited patients with CKD and UACRs of 200-5000 mg/g. A post hoc analysis of CREDENCE that distinguished three subgroups according to UACR (300-1000, 1000-3000 and >3000 mg/g) showed a greater relative reduction in UACR in patients with lower baseline albuminuria levels (P for interaction = 0.03). Patients with a UACR >1000 mg/g showed a significantly greater reduction in absolute (P for interaction < 0.001) and a trend in relative (P for interaction = 0.25) risk of renal events versus those with lower UACR levels. In conclusion, baseline UACR levels do not significantly influence the nephroprotection by SGLT2is, yet the greater protection in patients with very high UACRs in CREDENCE deserves confirmation. The underlying mechanisms of renal protection with SGLT2is might be different in patients with or without (high) UACR.

Renoprotective mechanisms of sodium-glucose co-transporter 2 (SGLT2) inhibitors against the progression of diabetic kidney disease

Sodium-glucose co-transporter 2 inhibitors (SGLT2-Is) have emerged as a promising class of antidiabetic drugs with cardioprotective and renoprotective effects in patients with type 2 diabetes (T2D). The sodium-glucose co-transporters 1 and 2 (SGLT 1 and SGLT2) located in the renal proximal tubules are responsible for glucose reabsorption from the glomerular filtrate back into the systemic circulation. Inhibition of SGLT2, which accounts for about 90% of the glucose reabsorption, leads to a significant reduction in blood glucose levels and a concomitant increase in the urinary excretion of glucose (glycosuria). Multiple mechanisms contribute to the nephroprotective effects of SGLT2-Is in T2D patients. These include: (1) Restoration of the tubuloglomerular feedback by increasing sodium delivery at macula densa, leading to afferent arteriolar constriction and reduced glomerular hyperfiltration, (2) Decreased activation of the intra-renal renin-angiotensin-aldosterone system, which also contributes to reducing glomerular hyperfiltration, (3) Increased production of ketone bodies, which serves as an alternate fuel for adenosine triphosphate production in mitochondria, which helps in attenuating inflammation, and (4) Protection against hypoxia, oxidative stress, and fibrosis. This review elaborates on the key mechanisms that underlie the nephroprotective effects and the adverse effects of SGLT2-Is in T2D patients with progressive diabetic kidney disease.

Effects of the SGLT2 inhibitor canagliflozin on plasma biomarkers TNFR-1, TNFR-2 and KIM-1 in the CANVAS trial

AIMS/HYPOTHESIS

Higher plasma concentrations of tumour necrosis factor receptor (TNFR)-1, TNFR-2 and kidney injury molecule-1 (KIM-1) have been found to be associated with higher risk of kidney failure in individuals with type 2 diabetes in previous studies. Whether drugs can reduce these biomarkers is not well established. We measured these biomarkers in samples of the CANVAS study and examined the effect of the sodium-glucose cotransporter 2 inhibitor canagliflozin on these biomarkers and assessed whether the early change in these biomarkers predict cardiovascular and kidney outcomes in individuals with type 2 diabetes in the CANagliflozin cardioVascular Assessment Study (CANVAS).

METHODS

Biomarkers were measured with immunoassays (proprietary multiplex assay performed by RenalytixAI, New York, NY, USA) at baseline and years 1, 3 and 6. Mixed-effects models for repeated measures assessed the effect of canagliflozin vs placebo on the biomarkers. Associations of baseline levels and the early change (baseline to year 1) for each biomarker with the kidney outcome were assessed using multivariable-adjusted Cox regression.

RESULTS

In total, 3523/4330 (81.4%) of the CANVAS participants had available samples at baseline. Each doubling in baseline TNFR-1, TNFR-2 and KIM-1 was associated with a higher risk of kidney outcomes, with corresponding HRs of 3.7 (95% CI 2.3, 6.1; p < 0.01), 2.7 (95% CI 2.0, 3.6; p < 0.01) and 1.5 (95% CI 1.2, 1.8; p < 0.01), respectively. Canagliflozin reduced the level of the plasma biomarkers with differences in TNFR-1, TNFR-2 and KIM-1 between canagliflozin and placebo during follow-up of 2.8% (95% CI 3.4%, 1.3%; p < 0.01), 1.9% (95% CI 3.5%, 0.2%; p = 0.03) and 26.7% (95% CI 30.7%, 22.7%; p < 0.01), respectively. Within the canagliflozin treatment group, each 10% reduction in TNFR-1 and TNFR-2 at year 1 was associated with a lower risk of the kidney outcome (HR 0.8 [95% CI 0.7, 1.0; p = 0.02] and 0.9 [95% CI 0.9, 1.0; p < 0.01] respectively), independent of other patient characteristics. The baseline and 1 year change in biomarkers did not associate with cardiovascular or heart failure outcomes.

CONCLUSIONS/INTERPRETATION

Canagliflozin decreased KIM-1 and modestly reduced TNFR-1 and TNFR-2 compared with placebo in individuals with type 2 diabetes in CANVAS. Early decreases in TNFR-1 and TNFR-2 during canagliflozin treatment were independently associated with a lower risk of kidney disease progression, suggesting that TNFR-1 and TNFR-2 have the potential to be pharmacodynamic markers of response to canagliflozin.

Potential kidney protection with liraglutide and semaglutide: Exploratory mediation analysis

AIMS

To investigate whether effects on chronic kidney disease risk factors could explain the apparent reduction in kidney outcomes (composite of macroalbuminuria, doubling of serum creatinine, renal replacement therapy, or renal death), primarily driven by changes in albuminuria, after treatment with the glucagon-like peptide-1 receptor agonists (GLP-1RAs) liraglutide and semaglutide in patients with type 2 diabetes in the LEADER and SUSTAIN 6 trials.

MATERIALS AND METHODS

We evaluated the mediation effect of glycated haemoglobin (HbA1c), systolic blood pressure (BP), and body weight on the kidney effects of GLP-1RAs. Diastolic BP, haemoglobin, heart rate, low-density lipoprotein and total cholesterol, and white blood cell count were also investigated. The mediation effect was estimated by the novel Vansteelandt statistical method. Subgroups with estimated glomerular filtration rate (eGFR) <60 and ≥60 mL/min/1.73 m² were examined in LEADER.

RESULTS

We observed that HbA1c mediated 25% (95% confidence interval [CI] -7.1; 67.3) and 26% (95% CI noncalculable), and systolic BP 9% (95% CI 2.8; 22.7) and 22% (95% CI noncalculable) of kidney effects of GLP-1RAs in LEADER and SUSTAIN 6, respectively. Small or no mediation was observed for the other parameters; for example, body weight mediated 9% (95% CI -7.9; 35.5) in the former and did not mediate effects in the latter study. Mediation by HbA1c was greater in patients with eGFR ≥60 mL/min/1.73 m² (57%) versus those with eGFR <60 mL/min/1.73 m² (no mediation).

CONCLUSIONS

Our results suggest that HbA1c and systolic BP may moderately mediate kidney benefits of liraglutide and semaglutide, with all other variables having a small to no effect. Potential kidney benefits may be driven by other mediators or potentially by direct mechanisms.

Efficacy and Safety of Dapagliflozin by Baseline Glycemic Status: A Prespecified Analysis From the DAPA-CKD Trial

OBJECTIVE

The Dapagliflozin and Prevention of Adverse outcomes in Chronic Kidney Disease (DAPA-CKD) study demonstrated risk reduction for kidney and cardiovascular outcomes with dapagliflozin versus placebo in participants with chronic kidney disease (CKD) with and without diabetes. We compared outcomes according to baseline glycemic status.

RESEARCH DESIGN AND METHODS

We enrolled participants with CKD, estimated glomerular filtration rate (eGFR) 25-75 mL/min/1.73 m², and urinary albumin-to-creatinine ratio 200-5,000 mg/g. The primary composite end point was sustained eGFR decline ≥50%, end-stage kidney disease, or kidney or cardiovascular death.

RESULTS

Of 4,304 participants, 738 had normoglycemia, 660 had prediabetes, and 2,906 had type 2 diabetes. The effect of dapagliflozin on the primary outcome was consistent (P for interaction = 0.19) in normoglycemia (hazard ratio [HR] 0.62 [95% CI 0.39, 1.01]), prediabetes (HR 0.37 [0.21, 0.66]), and type 2 diabetes (HR 0.64 [0.52, 0.79]). We found no evidence for effect modification on any outcome. Adverse events were similar, with no major hypoglycemia or ketoacidosis in participants with normoglycemia or prediabetes.

CONCLUSIONS

Dapagliflozin safely reduced kidney and cardiovascular events independent of baseline glycemic status.

Sodium-Glucose Cotransporter 2 Inhibition: Rationale and Mechanisms for Kidney and Cardiovascular Protection in People With and Without Diabetes

Large-scale randomized trials have demonstrated the remarkable capacity of sodium-glucose cotransporter 2 inhibitors to reduce the risk of cardiovascular outcomes and kidney disease progression, irrespective of the presence or absence of type 2 diabetes mellitus. Although the results of these trials have transformed clinical practice guidelines, the mechanisms underpinning the wide-ranging benefits of this class of agents remain incompletely understood and subject to ongoing investigation. Improvements in cardiometabolic risk factors such as glucose, blood pressure, body weight, and albuminuria likely contribute. However, other direct effects on physiological and cellular function, such as restoration of tubuloglomerular feedback, improvements in kidney and cardiac oxygenation and energy efficiency, as well as restoration of normal autophagy are also likely to be important. This review summarizes the rationale and potential mechanisms for cardiorenal protection with sodium-glucose cotransporter 2 inhibitors in people with and without diabetes, their relative importance, and the experimental and clinical lines of evidence supporting these hypotheses.

Sodium-glucose cotransporter-2 inhibitors and non-steroidal mineralocorticoid receptor antagonists: Ushering in a new era of nephroprotection beyond renin-angiotensin system blockade

The therapeutic options for preventing or slowing the progression of chronic kidney disease (CKD) have been thus far limited. While angiotensin converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARBs) are, without a doubt, safe and effective drugs, a significant proportion of patients with CKD still progress to end-stage kidney disease. After decades of negative trials, nephrologists have finally found cause for optimism with the introduction of sodium-glucose cotransporter-2 (SGLT2) inhibitors and non-steroidal mineralocorticoid receptor antagonists (MRAs). Recent trials such as EMPA-REG OUTCOME and CREDENCE have provided evidence of the renal benefits of SGLT2 inhibitors, which have now found widespread acceptance as first-line agents for diabetic CKD, in addition to ACEi/ARBs. Considering results from the DAPA-CKD study, it is expected that their use will soon be expanded to other causes of albuminuric CKD as well, although confirmation from further trials, such as the EMPA-KIDNEY study is awaited. Likewise, although the role of mineralocorticoid receptor overactivation in CKD progression has been known for decades, it is only now with the FIDELIO-DKD study that we have evidence of benefits of MRAs on hard renal endpoints, specifically in patients with diabetic CKD. While further research is ongoing, given the evidence of synergism between the three drug classes, it is foreseeable that a combination of two or more of these drugs may soon become the standard of care for CKD, regardless of underlying aetiology. This review describes pathophysiologic mechanisms, current evidence and future perspectives on the use of SGLT2 inhibitors and novel MRAs in CKD.

From Proteinuria to Fibrosis: An Update on Pathophysiology and Treatment Options

BACKGROUND

Proteinuria is a key biomarker in nephrology. It is central to diagnosis and risk assessment and the primary target of many important therapies. Etiologies resulting in pathological proteinuria include congenital and acquired disorders, as well as both glomerular (immune/non-immune mediated) and tubular defects.

SUMMARY

Untreated proteinuria is strongly linked to progressive loss of kidney function and kidney failure. Excess protein reaching the renal tubules is ordinarily resorbed by the tubular epithelium. However, when these mechanisms are overwhelmed, a variety of inflammatory and fibrotic pathways are activated, causing both interstitial fibrosis and glomerulosclerosis. Nevertheless, the specific mechanisms underlying this are complex and remain incompletely understood. Recently, a number of treatments, in addition to angiotensin system blockade, have been shown to effectively slow the progression of proteinuric chronic kidney disease. However, additional therapies are clearly needed. Key message: This review provides an update on the pathophysiology of proteinuria, the pathways leading to fibrosis, and an overview of current and emerging therapies.

Impact of sodium glucose linked cotransporter-2 inhibition on renal microvascular oxygen tension in a rodent model of diabetes mellitus

BACKGROUND

The mechanisms whereby inhibitors of sodium-glucose linked cotransporter-2 (SGLT2) exert their nephroprotective effects in patients with diabetes are incompletely understood but have been hypothesized to include improved tissue oxygen tension within the renal cortex. The impact of SGLT2 inhibition is likely complex and region specific within the kidney. We hypothesize that SGLT2 inhibitors have differential effects on renal tissue oxygen delivery and consumption in specific regions of the diabetic kidney, including the superficial cortex, containing SGLT2-rich components of proximal tubules, versus the deeper cortex and outer medulla, containing predominantly SGLT1 receptors.

METHODS

We measured glomerular filtration rate (GFR), microvascular kidney oxygen tension (Pk O2 ), erythropoietin (EPO) mRNA, and reticulocyte count in diabetic rats (streptozotocin) treated with the SGLT2 inhibitor, dapagliflozin. Utilizing phosphorescence quenching by oxygen and an intravascular oxygen sensitive probe (Oxyphor PdG4); we explored the effects of SGLT2 inhibition on Pk O2 in a region-specific manner, in vivo, in diabetic and non-diabetic rats. Superficial renal cortical or deeper cortical and outer medullary Pk O2 were measured utilizing excitations with blue and red light wavelengths, respectively.

RESULTS

In diabetic rats treated with dapagliflozin, measurement within the superficial cortex (blue light) demonstrated no change in Pk O2 . By contrast, measurements in the deeper cortex and outer medulla (red light) demonstrated a significant reduction in Pk O2 in dapagliflozin treated diabetic rats (p = 0.014). Consistent with these findings, GFR was decreased, hypoxia-responsive EPO mRNA levels were elevated and reticulocyte counts were increased with SGLT2 inhibition in diabetic rats (p < 0.05 for all).

CONCLUSIONS

These findings indicate that microvascular kidney oxygen tension is maintained in the superficial cortex but reduced in deeper cortical and outer medullary tissue, possibly due to the regional impact of SGLT-2 inhibition on tissue metabolism. This reduction in deeper Pk O2 had biological impact as demonstrated by increased renal EPO mRNA levels and circulating reticulocyte count.

Efficacy and Safety of Ertugliflozin in Patients with Type 2 Diabetes Inadequately Controlled by Metformin and Sulfonylurea: A Sub-Study of VERTIS CV

INTRODUCTION

VERTIS CV is the cardiovascular outcome trial for the sodium-glucose cotransporter 2 (SGLT2) inhibitor ertugliflozin. A sub-study was conducted to assess the efficacy and safety of ertugliflozin in patients with type 2 diabetes mellitus (T2DM) inadequately glycemic-controlled on metformin and a sulfonylurea (SU).

METHODS

Patients with T2DM, established atherosclerotic cardiovascular disease (ASCVD), and an HbA1c of 7.0-10.5% on stable metformin (≥ 1500 mg/day) and moderate to high SU doses were randomly assigned to once-daily ertugliflozin (5 or 15 mg) or placebo. The primary sub-study objectives were to assess the effect of ertugliflozin on HbA1c compared with placebo and to evaluate safety following 18 weeks of treatment. Key secondary endpoints included changes in fasting plasma glucose (FPG), body weight (BW), blood pressure (BP), and the proportion of patients achieving HbA1c < 7%.

RESULTS

Of the 8246 patients enrolled in VERTIS CV, 330 were eligible for this sub-study (ertugliflozin 5 mg, n = 100; ertugliflozin 15 mg, n = 113; placebo, n = 117). This subgroup had a mean (SD) age of 63.2 (8.4) years and T2DM duration of 11.4 (7.4) years. At week 18, ertugliflozin 5 mg and 15 mg were each associated with significantly greater least squares (LS) mean reductions from baseline in HbA1c relative to placebo (placebo-adjusted LS mean [95% CI] - 0.66% [- 0.89, - 0.43] and - 0.75% [- 0.98, - 0.53], respectively, p < 0.001 for each dose vs placebo). Ertugliflozin significantly reduced FPG and BW compared with placebo (p < 0.001), but not systolic BP. Adverse events were reported in 48.0%, 54.9%, and 47.0% of patients in the ertugliflozin 5 mg and 15 mg, and placebo groups. The incidences of symptomatic hypoglycemia were 11.0% (5 mg), 12.4% (15 mg), and 7.7% (placebo), and of severe hypoglycemia 2.0% (5 mg), 1.8% (15 mg), and 0.9% (placebo).

CONCLUSIONS

In patients with T2DM and ASCVD, ertugliflozin added to metformin and SU improved glycemic control, reduced BW, and was generally well tolerated.

TRIAL REGISTRATION

VERTIS CV ClinicalTrials.gov identifier, NCT01986881.

A kidney perspective on the mechanism of action of sodium glucose co-transporter 2 inhibitors

Sodium glucose co-transporter (SGLT) 2 inhibitors reduce the risk of kidney failure in patients with and without type 2 diabetes (T2D). Although the precise underlying mechanisms for these nephroprotective effects are incompletely understood, various hypotheses have been proposed including reductions in intraglomerular pressure through restoration of tubuloglomerular feedback, blood pressure reduction and favorable effects on vascular function, reduction in tubular workload and hypoxia, and metabolic effects resulting in increased autophagy. Here, we review these mechanisms, which may also explain the beneficial effects of SGLT2 inhibitors on kidney function in patients without T2D.

Cardiorenal Protection in Diabetic Kidney Disease

Over the last 5 years there have been many new developments in the management of diabetic kidney disease. Glucagon-like peptide-1 receptor agonists (GLP-1 RA) and sodium-glucose cotransporter-2 (SGLT2) inhibitors were initially used for glycemic control, but more recent studies have now shown that their benefits extend to cardiovascular and kidney outcomes. The recent addition of data on the novel mineralocorticoid receptor antagonist (MRA) gives us another approach to further decrease the residual risk of diabetic kidney disease progression. In this review we describe the mechanism of action, key studies, and possible adverse effects related to these three classes of medications. The management of type 2 diabetes now includes an increasing number of medications for the management of comorbidities in a patient population at significant risk of cardiovascular disease and progression of chronic kidney disease. It is from this perspective that we seek to outline the rationale for the sequential and/or combined use of SGLT2 inhibitors, GLP-1 RA and MRAs in patients with type 2 diabetes for heart and kidney protection.

Recent evidence on the effect of urate-lowering treatment on the progression of kidney disease

PURPOSE OF REVIEW

Several observational studies have shown that hyperuricemia is associated with chronic kidney disease (CKD) progression and is a potential therapeutic target in people with CKD. This review discusses the results of three recently published placebo-controlled randomized trials evaluating the effect of urate-lowering treatment on the progression of CKD with at least 2 years of follow-up.

RECENT FINDINGS

The Febuxostat versus Placebo Randomized Controlled Trial Regarding Reduced Renal Function in Patients with Hyperuricemia Complicated by Chronic Kidney Disease Stage 3 trial evaluated the effect of febuxostat in 443 patients with stage 3 CKD (mean estimated glomerular filtration rate [eGFR] 45 mL/min/1.73 m2) and asymptomatic hyperuricemia (mean serum urate 7.8 mg/dL). The Controlled trial of slowing of Kidney Disease progression From the Inhibition of Xanthine oxidase and Preventing Early Renal Loss in Diabetes trials respectively evaluated the effect of allopurinol in 369 adults with stage 3 or 4 CKD (mean eGFR 31.7 mL/min/1.73 m2, mean serum urate 8.2 mg/dL) with high progression risk and 530 patients with type 1 diabetes and diabetic kidney disease (mean eGFR 74.7 mL/min/1.73 m2, mean serum urate 6.1 mg/dL). Despite the large and sustained reductions in serum urate levels in all 3 trials, urate-lowering treatment with febuxostat or allopurinol did not result in clinically meaningful improvement in kidney outcomes.

SUMMARY

The results of large and well-designed placebo-controlled trials do not support the use of urate-lowering therapy to slow the progression of CKD.

Effects of SGLT2 Inhibitors on Kidney and Cardiovascular Function

SGLT2 inhibitors are antihyperglycemic drugs that protect kidneys and the heart of patients with or without type 2 diabetes and preserved or reduced kidney function from failing. The involved protective mechanisms include blood glucose-dependent and -independent mechanisms: SGLT2 inhibitors prevent both hyper- and hypoglycemia, with expectedly little net effect on HbA1C. Metabolic adaptations to induced urinary glucose loss include reduced fat mass and more ketone bodies as additional fuel. SGLT2 inhibitors lower glomerular capillary hypertension and hyperfiltration, thereby reducing the physical stress on the filtration barrier, albuminuria, and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular gluco-toxicity, may preserve tubular function and glomerular filtration rate in the long term. SGLT2 inhibitors may mimic systemic hypoxia and stimulate erythropoiesis, which improves organ oxygen delivery. SGLT2 inhibitors are proximal tubule and osmotic diuretics that reduce volume retention and blood pressure and preserve heart function, potentially in part by overcoming the resistance to diuretics and atrial-natriuretic-peptide and inhibiting Na-H exchangers and sympathetic tone.

Effects of canagliflozin on anaemia in patients with type 2 diabetes and chronic kidney disease: a post-hoc analysis from the CREDENCE trial

BACKGROUND

Sodium-glucose co-transporter 2 inhibitors might enhance erythropoiesis and increase red blood cell mass. We assessed the long-term effects of canagliflozin on anaemia-related outcomes.

METHODS

In a post-hoc analysis of the Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial, we included patients with type 2 diabetes and chronic kidney disease who were randomly assigned to treatment with canagliflozin or placebo at 690 sites in 34 countries. We assessed the effects of canagliflozin versus matched placebo on haemoglobin and haematocrit using linear mixed-effects models. The primary outcome of this post-hoc analysis was a composite outcome of investigator-reported anaemia or treatment for anaemia, which was assessed using Kaplan-Meier analysis and Cox regression models. All analyses were done by intention to treat.

FINDINGS

Between March 24, 2014, and May 5, 2017, 4401 participants were randomly assigned to receive canagliflozin (100 mg; n=2202) or placebo (n=2199). At baseline, mean haemoglobin concentration was 132·0 g/L (SD 17·7), 1599 (36%) of 4401 participants had anaemia (defined as haemoglobin <130 g/L in men or <120 g/L in women), and 33 (<1%) of 4401 participants used erythropoiesis-stimulating agents. During a median follow-up period of 2·6 years (IQR 2·1-3·1), mean haemoglobin concentration was 7·1 g/L (95% CI 6·4-7·8) higher and haematocrit was 2·4% (2·2-2·6) higher in the canagliflozin group than the placebo group. Overall, 573 of 4401 participants had either an investigator-reported anaemia event or initiation of treatment for anaemia: 358 (8%) of 4401 participants reported anaemia events, 343 (8%) initiated iron preparations, 141 (3%) initiated erythropoiesis-stimulating agents, and 114 (2%) received blood transfusion. The risk of the composite outcome of anaemia events or initiation of treatment for anaemia was lower in the canagliflozin group than the placebo group (hazard ratio 0·65, 95% CI 0·55-0·77; p<0·0001). Compared with the placebo group, participants in the canagliflozin group also had lower risks of anaemia events alone (0·58, 0·47-0·72; p<0·0001), initiation of iron preparations (0·64, 0·52-0·80; p<0·0001), and need for erythropoiesis-stimulating agents (0·65, 0·46-0·91; p=0·012).

INTERPRETATION

These data suggest that canagliflozin reduces the risk of anaemia-associated outcomes, including the need for erythropoiesis-stimulating agents, among patients with type 2 diabetes and chronic kidney disease.

FUNDING

Janssen Research and Development.

The future of Diabetic Kidney Disease management: reducing the unmet need

Patients with type 2 diabetes run a high risk for progressive renal function loss. Many interventions have been tested to reduce the risk, but we are nowadays still confronted with a high unmet need. To improve on this unmet need, we will have to change the current strategies in drug discovery, clinical trials and clinical practice. Target finding and the search for new interventions has to change to include more individual mechanistic approaches. Drugs will be selected on basis of finding the “individual” mechanism of renal function loss by looking at renal tissue biopsies or new biomarkers in urine or plasma. To test the promising drugs for clinical efficacy and safety and reduce the unmet need, trial design in type 2 diabetes will have to alter. First, selection of patients at risk for progression of renal function loss will need to be more specific. True progressors need to be identified by switching from classical risk determinants (low eGFR and high albuminuria) to new surrogates like steep eGFR slopes. In addition, the investigational drugs should only continue into registration trials in responder populations: patients that show a good response in the target/surrogate risk marker and no bad responses. This way we will improve the success of hard outcome trials, which has been poor in the past decade. We will reduce the unmet need and reduce the number of patients that are exposed to long term trial treatments without any benefit or even harm. Platform design and basket trials will catch the non-responders and switch them to other investigational drugs with different mechanism of action.

Drug registration will be much more directed to the individual patients and will lead to improved individual patient medication advices and improved individual efficacy and safety. We are entering the era of precision medicine in nephrology.