The Importance of Short-Term Off-Target Effects in Estimating the Long-Term Renal and Cardiovascular Protection of Angiotensin Receptor Blockers

The importance of targeting multiple risk markers in patients with type 2 diabetes: A post-hoc study from the CANVAS programme

AIMS

To investigate the extent to which improvements in multiple cardiovascular risk markers are associated with a lower risk of cardiovascular and kidney outcomes in patients with type 2 diabetes and high cardiovascular risk participating in the CANVAS programme.

MATERIALS AND METHODS

Clinically relevant improvements in cardiovascular risk factors were defined as a reduction in glycated haemoglobin ≥1.0%, systolic blood pressure ≥10 mmHg, body weight ≥3 kg, urinary-albumin-creatinine ratio ≥30%, uric acid ≥0.5 mg/dl, and an increase in haemoglobin of ≥1.0 g/dl from baseline to week 26. Participants were categorized according to the number of improvements in cardiovascular risk markers: zero, one, two, three, or four or more risk marker improvements. The Cox proportional hazard regression adjusted for treatment assignment, demographic variables and laboratory measurements was performed to determine the association between the number of risk marker improvements and risk of a composite cardiovascular, heart failure or kidney outcomes.

RESULTS

We included 9487 (93.5%) participants with available data at baseline and week 26. After week 26, 566 composite cardiovascular, 370 heart failure/cardiovascular death and 153 composite kidney outcomes occurred. The multivariable adjusted hazard ratios associated with four or more improvements in risk markers versus no risk marker improvement were 0.67 (95% CI 0.48, 0.92), 0.58 (95% CI 0.39, 0.87) and 0.49 (95% CI 0.25, 0.96) for the three outcomes respectively. We observed a trend of decreased hazard ratios across subgroups of increasing number of risk marker improvements (p for trend = .008, .02 and .047, respectively).

CONCLUSIONS

In patients with type 2 diabetes, improvements in multiple risk markers were associated with a reduced risk of cardiovascular and kidney outcomes as compared with no risk marker improvement.

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

Aims: The LEADER trial demonstrated that the glucagon-like peptide-1 receptor agonist (GLP1-RA) liraglutide reduces kidney and cardiovascular (CV) risk in patients with type 2 diabetes. We previously developed a Parameter Response Efficacy (PRE) score that translates multiple short-term risk marker changes, from baseline to first available follow-up measurement, into a predicted long-term drug effect on clinical outcomes. The objective of this study was to assess the accuracy of the PRE score in predicting the efficacy of liraglutide in reducing the risk of kidney and CV outcomes.

Methods: Short-term changes in glycated hemoglobin (HbA1c), systolic blood pressure (BP), urinary-albumin-creatinine-ratio (UACR), hemoglobin, body weight, high-density-lipoprotein (HDL) cholesterol, low-density-lipoprotein (LDL) cholesterol, and potassium were monitored in the LEADER trial. Associations between risk markers and kidney or CV outcomes were established using a multivariable Cox proportional hazards model in a separate pooled database of 6,355 patients with type 2 diabetes. The regression coefficients were then applied to the short-term risk markers in the LEADER trial to predict the effects of liraglutide on kidney (defined as a composite of doubling of serum creatinine or end-stage kidney disease) and CV (defined as a composite of non-fatal myocardial infarction, non-fatal stroke, and CV death) outcomes.

Results: Liraglutide compared to placebo reduced HbA1c (1.4%), systolic BP (3.0 mmHg), UACR (13.2%), body weight (2.3 kg), hemoglobin (2.6 g/L), and increased HDL-cholesterol (0.01 mmol/L) (all p-values <0.01). Integrating multiple risk marker changes in the PRE score resulted in a predicted relative risk reduction (RRR) of 16.2% (95% CI 13.7–18.6) on kidney outcomes which was close to the observed RRR of 15.5% (95% CI -9.0–34.6). For the CV outcome, the PRE score predicted a 7.6% (95% CI 6.8–8.3) RRR, which was less than the observed 13.2% (95% CI 3.2–22.2) RRR.

Conclusion: Integrating multiple short-term risk markers using the PRE score adequately predicted the effect of liraglutide on the composite kidney outcome. However, the PRE score underestimated the effect of liraglutide for the composite CV outcome, suggesting that the risk markers included in the PRE score do not fully capture the CV benefit of liraglutide.

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.

Precision medicine approaches for diabetic kidney disease: opportunities and challenges

The prevalence of end-stage kidney disease (ESKD) continuously increases worldwide. The increasing prevalence parallels the growth in the number of people with diabetes, which is the leading cause of ESKD. Early diagnosis of chronic kidney disease (CKD) in patients with diabetes and appropriate intervention is important to delay the progression of kidney function decline and prevent ESKD. Rate of CKD progression and response to treatment varies among patients with diabetes, highlighting the need to tailor individual treatment. In this review, we describe recent advances and areas for future studies with respect to precision medicine in diabetic kidney disease (DKD). DKD is a multi-factorial disease that is subject in part to genetic heritability, but is also influenced by various exogenous mediators, such as environmental or dietary factors. Genetic testing so far has limited utility to facilitate early diagnosis, classify progression or evaluate response to therapy. Various biomarker-based approaches are currently explored to identify patients at high risk of ESKD and to facilitate decision-making for targeted therapy. These studies have led to discovery and validation of a couple of inflammatory proteins such as circulating tumour necrosis factor receptors, which are strong predictors of kidney disease progression. Moreover, risk and drug-response scores based on multiple biomarkers are developed to predict kidney disease progression and long-term drug efficacy. These findings, if implemented in clinical practice, will pave the way to move from a one-size-fits-all to a one-fit-for-everyone approach.

A Review of the Dose Justification of Phase 3 Trials to Regulatory Authorities for Drugs Intended for the Treatment of Type 2 Diabetes in Europe

Aims: Cardiovascular outcome trials with anti-diabetic drugs suggest that additional cardiovascular benefit can be achieved independent of improving glycaemic control. Nonetheless, dose selection of anti-diabetic drugs is typically based solely on glycaemic effects. We evaluated whether off-target drug effects are currently considered for dose justification to regulatory agencies.

Methods: In the European Union, anti-diabetic drugs are registered by the European Medicines Agency. We extracted available information regarding dose selection from public assessment reports and marketing application dossiers. Descriptive statistics were used to summarise the extracted information.

Results: In total, 14 drugs of three drug classes were included; sodium-glucose co-transporter-2 inhibitors (n = 4), dipeptidyl peptidase-4 inhibitors (n = 4) and glucagon-like peptide-1 receptor agonists (n = 6). For these drugs, 21 dose-finding trials were submitted including results of multiple off-target effects, of which body weight (n = 18) and low-density lipoprotein cholesterol (n = 14) were most frequently reported. Dose-response curves for off-target effects appeared to be different compared to the glycaemic dose-response curve. Glycated hemoglobin (100%) and fasting plasma glucose (42.9%), were used most frequently for the dose justification, but generally off-target effects (<25%) were not.

Conclusions: Dose justification to regulatory authorities was mainly based on glycaemic effects. The dose-response relationship for the off-target effects did not necessarily follow the dose-response relationship of the on-target effects suggesting that selection of the optimal anti-diabetic dose could benefit from including off-target effects in the dose selection process as well.

Prediction of the effect of dapagliflozin on kidney and heart failure outcomes based on short-term changes in multiple risk markers

BACKGROUND

Besides improving glucose control, sodium-glucose co-transporter 2 inhibition with dapagliflozin reduces blood pressure, body weight and urinary albumin:creatinine ratio (UACR) in patients with type 2 diabetes (T2DM). The parameter response efficacy (PRE) score was developed to predict how short-term drug effects on cardiovascular risk markers translate into long-term changes in clinical outcomes. We applied the PRE score to clinical trials of dapagliflozin to model the effect of the drug on kidney and heart failure (HF) outcomes in patients with T2DM and impaired kidney function.

METHODS

The relationships between multiple risk markers and long-term outcome were determined in a background population of patients with T2DM with a multivariable Cox model. These relationships were then applied to short-term changes in risk markers observed in a pooled database of dapagliflozin trials (n = 7) that recruited patients with albuminuria to predict the drug-induced changes to kidney and HF outcomes.

RESULTS

A total of 132 and 350 patients had UACR >200 mg/g and >30 mg/g at baseline, respectively, and were selected for analysis. The PRE score predicted a risk change for kidney events of -40.8% [95% confidence interval (CI) -51.7 to -29.4) and -40.4% (95% CI -48.4 to -31.1) with dapagliflozin 10 mg compared with placebo for the UACR >200 mg/g and >30 mg/g subgroups. The predicted change in risk for HF events was -27.3% (95% CI -47.7 to -5.1) and -21.2% (95% CI -35.0 to -7.8), respectively. Simulation analyses showed that even with a smaller albuminuria-lowering effect of dapagliflozin (10% instead of the observed 35% in both groups), the estimated kidney risk reduction was still 26.5 and 26.8%, respectively.

CONCLUSIONS

The PRE score predicted clinically meaningful reductions in kidney and HF events associated with dapagliflozin therapy in patients with diabetic kidney disease. These results support a large long-term outcome trial in this population to confirm the benefits of the drug on these endpoints.

A novel drug response score more accurately predicts renoprotective drug effects than existing renal risk scores

BACKGROUND

Risk factor-based equations are used to predict risk of kidney disease progression in patients with type 2 diabetes order to guide treatment decisions. It is, however, unknown whether these models can also be used to predict the effects of drugs on clinical outcomes.

METHODS

The previously developed Parameter Response Efficacy (PRE) score, which integrates multiple short-term drug effects, was first compared with the existing risk scores, Kidney Failure Risk Equation (KFRE) and The Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) renal risk score, in its performance to predict end-stage renal disease (ESRD; KFRE) and doubling of serum creatinine or ESRD (ADVANCE). Second, changes in the risk scores were compared after 6 months' treatment to predict the long-term effects of losartan on these renal outcomes in patients with type 2 diabetes and chronic kidney disease.

RESULTS

The KFRE, ADVANCE and PRE scores showed similarly good performance in predicting renal risk. However, for prediction of the effect of losartan, the KFRE risk score predicted a relative risk change in the occurrence of ESRD of 3.1% [95% confidence interval (CI) -5 to 12], whereas the observed risk change was -28.8% (95% CI -42.0 to -11.5). For the composite endpoint of doubling of serum creatinine or ESRD, the ADVANCE score predicted a risk change of -12.4% (95% CI -17 to -7), which underestimated the observed risk change -21.8% (95% CI -34 to -6). The PRE score predicted renal risk changes that were close to the observed risk changes with losartan treatment [-24.0% (95% CI -30 to -17) and -22.6% (95% CI -23 to -16) for ESRD and the composite renal outcome, respectively].

CONCLUSION

A drug response score such as the PRE score may assist in improving clinical decision making and implement precision medicine strategies.

Prediction and validation of exenatide risk marker effects on progression of renal disease: Insights from EXSCEL

AIM

To assess whether the previously developed multivariable risk prediction framework (PRE score) could predict the renal effects observed in the EXSCEL cardiovascular outcomes trial using short-term changes in cardio-renal risk markers.

MATERIALS AND METHODS

Changes from baseline to 6 months in HbA1c, systolic blood pressure (SBP), body mass index (BMI), haemoglobin, total cholesterol, and new micro- or macroalbuminuria were evaluated. The renal outcomes were defined as a composite of a sustained 30% or 40% decline in estimated glomerular filtration rate (eGFR) or end-stage renal disease (ESRD). Relationships between risk markers and long-term renal outcomes were determined in patients with type 2 diabetes from the ALTITUDE study using multivariable Cox regression analysis, and then applied to short-term changes in risk markers observed in EXSCEL to predict the exenatide-induced impact on renal outcomes.

RESULTS

Compared with placebo, mean HbA1c, BMI, SBP and total cholesterol were lower at 6 months with exenatide, as was the incidence of new microalbuminuria. The PRE score predicted a relative risk reduction for the 30% eGFR decline + ESRD endpoint of 11.3% (HR 0.89; 95% CI 0.83-0.94), compared with 12.7% (HR 0.87; 0.77-0.99) observed risk reduction. For the 40% eGFR decline + ESRD endpoint, the predicted and observed risk reductions were 11.0% (HR 0.89; 0.82-0.97) and 13.7% (HR 0.86, 0.72-1.04), respectively.

CONCLUSIONS

Integrating short-term risk marker changes into a multivariable risk score predicted the magnitude of renal risk reduction observed in EXSCEL.

Administration of losartan preserves cardiomyocyte size and prevents myocardial dysfunction in tail-suspended mice by inhibiting p47phox phosphorylation, NADPH oxidase activation and MuRF1 expression

Background

Spaceflight or microgravity conditions cause myocardial atrophy and dysfunction, contributing to post-flight orthostatic intolerance. However, the underlying mechanisms remain incompletely understood and preventive approaches are limited. This study investigated whether and how losartan, a blocker of angiotensin-II receptor, preserved cardiomyocyte size and prevented myocardial dysfunction during microgravity.

Method

Adult male mice were suspended with their tails to simulate microgravity. Echocardiography was performed to assess myocardial function. Heart weight and cardiomyocyte size were measured. NADPH oxidase activation was determined by analyzing membrane translocation of its cytosolic subunits including p47^phox, p67^phox and Rac1. Heart tissues were also assayed for oxidative stress, p47^phox phosphorylation (Ser345), MuRF1 protein levels and angiotensin-II production.

Results

Tail-suspension for 28 days increased angiotensin-II production in hearts, decreased cardiomyocyte size and heart weight, and induced myocardial dysfunction. Administration of losartan preserved cardiomyocyte size and heart weight, and prevented myocardial dysfunction in tail-suspended mice. These cardioprotective effects of losartan were associated with inhibition of p47^phox phosphorylation (Ser345), NADPH oxidase and oxidative stress in tail-suspended mouse hearts. Additionally, the NADPH oxidase inhibitor, apocynin, also reduced oxidative stress, preserved cardiomyocyte size and heart weight, and improved myocardial function in tail-suspended mice. Furthermore, losartan but not apocynin attenuated tail-suspension-induced up-regulation of MuRF1 protein in mouse hearts.

Conclusions

Administration of losartan preserves cardiomyocyte size and prevents myocardial dysfunction under microgravity by blocking p47^phox phosphorylation and NADPH oxidase activation, and by inhibiting MuRF1 expression. Thus, losartan may be a useful drug to prevent microgravity-induced myocardial abnormalities.

Multimarker Panels in Diabetic Kidney Disease: The Way to Improved Clinical Trial Design and Clinical Practice?

Diabetic kidney disease (DKD) is a complex and multifactorial disorder associated with deregulations in a large number of different biological pathways on the molecular level. Using the 2 established biomarkers, estimated glomerular filtration rate (eGFR) and albuminuria will not allow allocating patients to tailored therapy. Molecular multimarker panels as sensors for the deregulation of the various disease mechanisms combined with a better understanding of how investigational as well as approved drugs interfere with these disease processes forms the basis for platform trials in DKD. In these platform trials, patients with DKD are assigned to the most suitable treatment arm based on their molecular marker profile. Close monitoring of biomarkers after treatment initiation together with assessment of renal function and "off-target" effects will allow identification of therapy responders, with nonresponders shifted to the next-best treatment arm based on their molecular profile. In this viewpoint article, we summarize evidence on the variation of DKD disease progression as well as the response to therapy and outline procedures to model disease pathophysiology supporting biomarker panel construction. Finally, the use of biomarkers in clinical trial setup is discussed.

Prognostic clinical and molecular biomarkers of renal disease in type 2 diabetes

Diabetic kidney disease occurs in ∼ 25-40% of patients with type 2 diabetes. Given the high risk of progressive renal function loss and end-stage renal disease, early identification of patients with a renal risk is important. Novel biomarkers may aid in improving renal risk stratification. In this review, we first focus on the classical panel of albuminuria and estimated glomerular filtration rate as the primary clinical predictors of renal disease and then move our attention to novel biomarkers, primarily concentrating on assay-based multiple/panel biomarkers, proteomics biomarkers and metabolomics biomarkers. We focus on multiple biomarker panels since the molecular processes of renal disease progression in type 2 diabetes are heterogeneous, rendering it unlikely that a single biomarker significantly adds to clinical risk prediction. A limited number of prospective studies of multiple biomarkers address the predictive performance of novel biomarker panels in addition to the classical panel in type 2 diabetes. However, the prospective studies conducted so far have small sample sizes, are insufficiently powered and lack external validation. Adequately sized validation studies of multiple biomarker panels are thus required. There is also a paucity of studies that assess the effect of treatments on novel biomarker panels and determine whether initial treatment-induced changes in novel biomarkers predict changes in long-term renal outcomes. Such studies can not only improve our healthcare but also our understanding of the mechanisms of actions of existing and novel drugs and may yield biomarkers that can be used to monitor drug response. We conclude that this will be an area to focus research on in the future.

Individual long-term albuminuria exposure during angiotensin receptor blocker therapy is the optimal predictor for renal outcome

BACKGROUND

Albuminuria reduction due to angiotensin receptor blockers (ARBs) predicts subsequent renoprotection. Relating the initial albuminuria reduction to subsequent renoprotection assumes that the initial ARB-induced albuminuria reduction remains stable during follow-up. The aim of this study was to assess individual albuminuria fluctuations after the initial ARB response and to determine whether taking individual albuminuria fluctuations into account improves renal outcome prediction.

METHODS

Patients with diabetes and nephropathy treated with losartan or irbesartan in the RENAAL and IDNT trials were included. Patients with >30% reduction in albuminuria 3 months after ARB initiation were stratified by the subsequent change in albuminuria until Month 12 in enhanced responders (>50% albuminuria reduction), sustained responders (between 20 and 50% reduction), and response escapers (<20% reduction). Predictive performance of the individual albuminuria exposure until Month 3 was compared with the exposure over the first 12 months using receiver operating characteristics (ROC) curves.

RESULTS

Following ARB initiation, 388 (36.3%) patients showed an >30% reduction in albuminuria. Among these patients, the albuminuria level further decreased in 174 (44.8%), remained stable in 123 (31.7%), and increased in 91 (23.5%) patients. Similar albuminuria fluctuations were observed in patients with <30% albuminuria reduction. Renal risk prediction improved when using the albuminuria exposure during the first 12 months versus the initial Month 3 change [ROC difference: 0.78 (95% CI 0.75-0.82) versus 0.68 (0.64-0.72); P < 0.0001].

CONCLUSIONS

Following the initial response to ARBs, a large within-patient albuminuria variability is observed. Hence, incorporating multiple albuminuria measurements over time in risk algorithms may be more appropriate to monitor treatment effects and quantify renal risk.

Prediction of the effect of atrasentan on renal and heart failure outcomes based on short-term changes in multiple risk markers

BACKGROUND

A recent phase II clinical trial (Reducing Residual Albuminuria in Subjects with Diabetes and Nephropathy with AtRasentan trial and an identical trial in Japan (RADAR/JAPAN)) showed that the endothelin A receptor antagonist atrasentan lowers albuminuria, blood pressure, cholesterol, hemoglobin, and increases body weight in patients with type 2 diabetes and nephropathy. We previously developed an algorithm, the Parameter Response Efficacy (PRE) score, which translates short-term drug effects into predictions of long-term effects on clinical outcomes.

DESIGN

We used the PRE score on data from the RADAR/JAPAN study to predict the effect of atrasentan on renal and heart failure outcomes.

METHODS

We performed a post-hoc analysis of the RADAR/JAPAN randomized clinical trials in which 211 patients with type-2 diabetes and nephropathy were randomly assigned to atrasentan 0.75 mg/day, 1.25 mg/day, or placebo. A PRE score was developed in a background set of completed clinical trials using multivariate Cox models. The score was applied to baseline and week-12 risk marker levels of RADAR/JAPAN participants, to predict atrasentan effects on clinical outcomes. Outcomes were defined as doubling serum creatinine or end-stage renal disease and hospitalization for heart failure.

RESULTS

The PRE score predicted renal risk changes of -23% and -30% for atrasentan 0.75 and 1.25 mg/day, respectively. PRE scores also predicted a small non-significant increase in heart failure risk for atrasentan 0.75 and 1.25 mg/day (+2% vs. +7%). Selecting patients with >30% albuminuria reduction from baseline (responders) improved renal outcome to almost 50% risk reduction, whereas non-responders showed no renal benefit.

CONCLUSIONS

Based on the RADAR/JAPAN study, with short-term changes in risk markers, atrasentan is expected to decrease renal risk without increased risk of heart failure. Within this population albuminuria responders appear to contribute to the predicted improvements, whereas non-responders showed no benefit. The ongoing hard outcome trial (SONAR) in type 2 diabetic patients with >30% albuminuria reduction to atrasentan will allow us to assess the validity of these predictions.

The renal protective effect of angiotensin receptor blockers depends on intra-individual response variation in multiple risk markers

AIMS

Angiotensin receptor blockers (ARBs) are renoprotective and targeted to blood pressure. However, ARBs have multiple other (off-target) effects which may affect renal outcome. It is unknown whether on-target and off-target effects are congruent within individuals. If not, this variation in short term effects may have important implications for the prediction of individual long term renal outcomes. Our aim was to assess intra-individual variability in multiple parameters in response to ARBs in type 2 diabetes.

METHODS

Changes in systolic blood pressure (SBP), albuminuria, potassium, haemoglobin, cholesterol and uric acid after 6 months of losartan treatment were assessed in the RENAAL database. Improvement in predictive performance of renal outcomes (ESRD or doubling serum creatinine) for each individual using ARB-induced changes in all risk markers was assessed by the relative integrative discrimination index (RIDI).

RESULTS

SBP response showed high variability (mean -5.7 mmHg, 5(th) to 95(th) percentile -36.5 to +24.0 mmHg) between individuals. Changes in off-target parameters also showed high variability between individuals. No congruency was observed between responses to losartan in multiple parameters within individuals. Using individual responses in all risk markers significantly improved renal risk prediction (RIDI 30.4%, P < 0.01) compared with using only SBP changes. Results were successfully replicated in two independent trials with irbesartan, IDNT and IRMA-2.

CONCLUSIONS

In this post hoc analysis we showed that ARBs have multiple off-target effects which vary between and within individuals. Combining all ARB-induced responses beyond SBP provides a more accurate prediction of who will benefit from ARB therapy. Prospective trials are required to validate these findings.

Aberrant circulating levels of purinergic signaling markers are associated with several key aspects of peripheral atherosclerosis and thrombosis

RATIONALE

Purinergic signaling plays an important role in inflammation and vascular integrity, but little is known about purinergic mechanisms during the pathogenesis of atherosclerosis in humans.

OBJECTIVE

The objective of this study is to study markers of purinergic signaling in a cohort of patients with peripheral artery disease.

METHODS AND RESULTS

Plasma ATP and ADP levels and serum nucleoside triphosphate diphosphohydrolase-1 (NTPDase1/CD39) and ecto-5'-nucleotidase/CD73 activities were measured in 226 patients with stable peripheral artery disease admitted for nonurgent invasive imaging and treatment. The major findings were that ATP, ADP, and CD73 values were higher in atherosclerotic patients than in controls without clinically evident peripheral artery disease (P<0.0001). Low CD39 activity was associated with disease progression (P=0.01). In multivariable linear regression models, high CD73 activity was associated with chronic hypoxia (P=0.001). Statin use was associated with lower ADP (P=0.041) and tended to associate with higher CD73 (P=0.054), while lower ATP was associated with the use of angiotensin receptor blockers (P=0.015).

CONCLUSIONS

Purinergic signaling plays an important role in peripheral artery disease progression. Elevated levels of circulating ATP and ADP are especially associated with atherosclerotic diseases of younger age and smoking. The antithrombotic and anti-inflammatory effects of statins may partly be explained by their ability to lower ADP. We suggest that the prothrombotic nature of smoking could be a cause of elevated ADP, and this may explain why cardiovascular patients who smoke benefit from platelet P2Y12 receptor antagonists more than their nonsmoking peers.

The use of surrogate endpoints in regulating medicines for cardio-renal disease: opinions of stakeholders

Aim

There is discussion whether medicines can be authorized on the market based on evidence from surrogate endpoints. We assessed opinions of different stakeholders on this topic.

Methods

We conducted an online questionnaire that targeted various stakeholder groups (regulatory agencies, pharmaceutical industry, academia, relevant public sector organisations) and medical specialties (cardiology or nephrology vs. other). Participants were enrolled through purposeful sampling. We inquired for conditions under which surrogate endpoints can be used, the validity of various cardio-renal biomarkers and new approaches for biomarker use.

Results

Participants agreed that surrogate endpoints can be used when the surrogate is scientifically valid (5-point Likert response format, mean score: 4.3, SD: 0.9) or when there is an unmet clinical need (mean score: 3.8, SD: 1.2). Industry participants agreed to a greater extent than regulators and academics. However, out of four proposed surrogates (blood pressure (BP), HbA1c, albuminuria, CRP) for cardiovascular outcomes or end-stage renal disease, only use of BP for cardiovascular outcomes was deemed moderately accurate (mean: 3.6, SD: 1.1). Specialists in cardiology or nephrology tended to be more positive about the use of surrogate endpoints.

Conclusion

Stakeholders in drug development do not oppose to the use of surrogate endpoints in drug marketing authorization, but most surrogates are not considered valid. To solve this impasse, increased efforts are required to validate surrogate endpoints and to explore alternative ways to use them.