A Systematic Assessment of Cardiovascular Outcomes in the Saxagliptin Drug Development Program for Type 2 Diabetes

DPP-4 inhibitors for treating T2DM - hype or hope? an analysis based on the current literature

DPP-4 inhibition is an interesting line of therapy for treating Type 2 Diabetes Mellitus (T2DM) and is based on promoting the incretin effect. Here, the authors have presented a brief appraisal of DPP-4 inhibitors, their modes of action, and the clinical efficiency of currently available drugs based on DPP-4 inhibitors. The safety profiles as well as future directions including their potential application in improving COVID-19 patient outcomes have also been discussed in detail. This review also highlights the existing queries and evidence gaps in DPP-4 inhibitor research. Authors have concluded that the excitement surrounding DPP-4 inhibitors is justified because in addition to controlling blood glucose level, they are good at managing risk factors associated with diabetes.

Effect of vitamin D3 supplementation on cardiometabolic disease risk among overweight/obese adult males in the UK: A pilot randomised controlled trial

BACKGROUND

Observational studies suggest links between reduced serum 25(OH)D concentration and increased cardiometabolic disease risk. However, these studies provide limited evidence of causation, with few conclusive randomised controlled trials (RCT) having been carried out to date. This RCT investigated the effect of vitamin D₃ supplementation on vascular function and cardiometabolic disease risk markers, in 55 healthy males aged 18-65 years with plasma 25(OH)D concentration <75 mol L^-1 and body mass index ≥24.9 kg m^-2 .

METHODS

Participants were assigned to consume 125 µg day^-1 (5000 IU day^-1 ) vitamin D₃ or placebo for 8 weeks. Blood samples and vascular function measures were obtained at baseline, as well as at weeks 4 and 8. The primary outcome was arterial stiffness, an indicator of cardiovascular disease (CVD) risk, assessed by pulse wave velocity. Biomarkers of CVD risk, insulin resistance and endothelial function were measured using an enzyme-linked immunosorbent assay.

RESULTS

Daily oral intake of 125 µg supplemental vitamin D₃ led to a significant improvement in plasma 25(OH)D concentrations over the 8-week intervention in the vitamin D group compared to the change in the placebo group (p ˂ 0.001). In the vitamin D group, the baseline mean ± SD 25(OH)D concentration was 38.4 ± 15.9 and this increased to 72.8 ± 16.1 nmol L^-1 after 8 weeks of supplementation. The intervention had no effect on arterial stiffness, as measured by pulse wave velocity, although vitamin D₃ supplementation did lead to a decrease in mean ± SD brachial pulse pressure from baseline to 8 weeks of -2.9 ± 3.4 mmHg (p = 0.027) in the vitamin D group compared to the same period in the placebo group. The intervention had no effect on the remaining cardiometabolic parameters.

CONCLUSIONS

Overall, treatment significantly improved brachial pulse pressure but no other cardiometabolic disease risk markers. To follow on from this pilot RCT, future large-scale clinical trials over longer durations may offer further insights.

The effects of saxagliptin on cardiac structure and function using cardiac MRI (SCARF)

PURPOSE

A recent large cardiovascular outcome trial in patients with type 2 diabetes (T2DM) demonstrated excess heart failure hospitalization with saxagliptin. We sought to evaluate the impact of saxagliptin on cardiac structure and function using cardiac magnetic resonance imaging (CMR) in patients with T2DM without pre-existing heart failure.

METHODS

In this prospective study, patients with T2DM without heart failure were prescribed saxagliptin as part of routine guideline-directed management. Clinical assessment, CMR imaging and biomarkers were assessed in a blinded fashion and compared following 6 months of continued treatment. The primary outcome was the change in left ventricular (LV) ejection fraction (LVEF) after 6 months of therapy. Key secondary outcomes included changes in LV and right ventricular (RV) end-diastolic volume, ventricular mass, LV global strain and cardiac biomarkers [N terminal pro B-type natriuretic peptide (NT-proBNP) and high sensitivity C-reactive protein (hsCRP)] over 6 months.

RESULTS

The cohort (n = 16) had a mean age of 59.9 years with 69% being male. The mean hemoglobin A1c (HbA1c) was 8.3%. Mean baseline LVEF was 57% ± 3.4, with no significant change over 6 months (- 0.2%, 95% CI - 2.5, 2.1, p = 0.86). Detailed CMR analyses that included LV/RV volumes, LV mass, and feature tracking-derived strain showed no significant change (all p > 0.50). NT-proBNP and hsCRP levels did not significantly change (p > 0.20).

CONCLUSIONS

In this cohort of stable ambulatory patients with T2DM without heart failure, saxagliptin treatment was not associated with adverse ventricular remodeling over 6 months as assessed using CMR and biomarkers.

Dipeptidyl peptidase-4 inhibitors as new tools for cardioprotection

Previous studies have demonstrated that individuals with type 2 diabetes mellitus (T2DM) have a two- to fourfold propensity to develop cardiovascular disease (CVD) than nondiabetic population, making CVD a major cause of death and disability among people with T2DM. The present treatment options for management of diabetes propose the earlier and more frequent use of new antidiabetic drugs that could control hyperglycaemia and reduce the risk of cardiovascular events. Findings from basic and clinical studies pointed out DPP-4 inhibitors as potentially novel pharmacological tools for cardioprotection. There is a growing body of evidence suggesting that these drugs have ability to protect the heart against acute ischaemia-reperfusion injury as well as reduce the size of infarction. Consequently, the prevention of degradation of the incretin hormones by the use of DPP-4 inhibitors represents a new strategy in the treatment of patients with T2DM and reduction of CV events in these patients. Here, we discuss the cardioprotective effects of DPP-4 inhibitors as well as proposed pathways that these hypoglycaemic agents target in the cardiovascular system.

A review of therapeutic options for managing the metabolic aspects of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age. Metabolic sequelae associated with PCOS range from insulin resistance to type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Insulin resistance plays a significant role in the pathophysiology of PCOS and it is a reliable marker for cardiometabolic risk. Although insulin sensitising agents such as metformin have been traditionally used for managing metabolic aspects of PCOS, their efficacy is low in terms of weight reduction and cardiovascular risk reduction compared with newer agents such as incretin mimetics and SGLT2 inhibitors. With current pharmaceutical advances, potential therapeutic options have increased, giving patients and clinicians more choices. Incretin mimetics are a promising therapy with a unique metabolic target that could be used widely in the management of PCOS. Likewise, bariatric procedures have become less invasive and result in effective weight loss and the reversal of metabolic morbidities in some patients. Therefore, surgical treatment targeting weight loss becomes increasingly common in the management of obese women with PCOS. Newer emerging therapies, including twincretins, triple GLP-1 agonists, glucagon receptor antagonists and imeglemin, are promising therapeutic options for treating T2DM. Given the similarity of metabolic and pathological features between PCOS and T2DM and the variety of therapeutic options, there is the potential to widen our strategy for treating metabolic disorders in PCOS in parallel with current therapeutic advances. The review was conducted in line with the recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome 2018.

Characterization of cardiovascular clinical events and impact of event adjudication on the treatment effect of darapladib versus placebo in patients with stable coronary heart disease: Insights from the STABILITY trial

BACKGROUND

Clinical Endpoint Classification (CEC) in clinical trials allows FOR standardized, systematic, blinded, and unbiased adjudication of investigator-reported events. We quantified the agreement rates in the STABILITY trial on 15,828 patients with stable coronary heart disease.

METHODS

Investigators were instructed to report all potential events. Each reported event was reviewed independently by 2 reviewers according to prespecified processes and prespecified end point definitions. Concordance between reported and adjudicated cardiovascular (CV) events was evaluated, as well as event classification influence on final study results.

RESULTS

In total, CEC reviewed 7,096 events: 1,064 deaths (696 CV deaths), 958 myocardial infarctions (MI), 433 strokes, 182 transient ischemic attacks, 2,052 coronary revascularizations, 1,407 hospitalizations for unstable angina, and 967 hospitalizations for heart failure. In total, 71.8% events were confirmed by CEC. Concordance was high (>80%) for cause of death and nonfatal MI and lower for hospitalization for unstable angina (25%) and heart failure (50%). For the primary outcome (composite of CV death, MI, and stroke), investigators reported 2,086 events with 82.5% confirmed by CEC. The STABILITY trial treatment effect of darapladib versus placebo on the primary outcome was consistent using investigator-reported events (hazard ratio 0.96 [95% CI 0.87-1.06]) or adjudicated events (hazard ratio 0.94 [95% CI 0.85-1.03]).

CONCLUSIONS

The primary outcome results of the STABILITY trial were consistent whether using investigator-reported or CEC-adjudicated events. The proportion of investigator-reported events confirmed by CEC varied by type of event. These results should help improve event identification in clinical trials to optimize ascertainment and adjudication.

A Review on Cardiovascular Outcome Studies of Dipeptidyl Peptidase-4 Inhibitors

The U.S. Food and Drug Administration issued a guidance for pharmaceutical industry defining preapproval and postapproval requirements for the demonstration of cardiovascular (CV) safety for all new medications developed for glycemic management in type 2 diabetes. However, results published from the studies of dipeptidyl peptidase-4 (DPP-4) inhibitors are conflicting with regard to different CV endpoints. Upcoming CV outcome studies perhaps will be able to provide additional insights related to diabetes management and help to provide the answers to some of these concerns. This article provides a brief overview regarding how various CV safety evidence of DPP-4 inhibitor evolved over time that highlights possible implication in clinical practice and translates them into effective diabetes management.

Cardiovascular Safety of Empagliflozin Versus Dipeptidyl Peptidase-4 (DPP-4) Inhibitors in Type 2 Diabetes: Systematic Literature Review and Indirect Comparisons

INTRODUCTION

Clinical trials conducted in patients with type 2 diabetes (T2DM) treated with glucose-lowering drugs and examining cardiovascular-related outcomes have yielded mixed results. In this work, we aimed to assess the relative treatment effects of empagliflozin versus sitagliptin and saxagliptin (dipeptidyl peptidase-4 (DPP-4) inhibitors) on cardiovascular-related outcomes in patients with T2DM.

METHODS

We conducted a systematic literature review to identify clinical trials assessing cardiovascular-related outcomes for sitagliptin-, saxagliptin-, and empagliflozin-treated patients with T2DM. A network meta-analysis of indirect treatment comparisons was conducted in a Bayesian framework. Hazard ratios (HR) and 95% credible intervals (CrI) were computed for six cardiovascular-related outcomes to estimate the relative efficacies of these agents.

RESULTS

Empagliflozin showed a statistically significant superiority over saxagliptin (HR 0.60; 95% CrI 0.46-0.80) and sitagliptin (HR 0.60; 95% CrI 0.46-0.79) to reduce the risk for cardiovascular-related mortality. For all-cause mortality, empagliflozin showed a statistically significant risk reduction compared to saxagliptin (HR 0.61; 95% CrI 0.49-0.76) and sitagliptin (HR 0.67; 95% CrI 0.54-0.83). A similar pattern was observed in the risk reduction for hospitalization due to heart failure, where empagliflozin was found to be statistically significantly superior to saxagliptin (HR 0.51; 95% CrI 0.37-0.70) and sitagliptin (HR 0.65; 95% CrI 0.47-0.90). Empagliflozin was not statistically significantly different to sitagliptin and saxagliptin with regard to the risk of a composite endpoint composed of death, stroke or myocardial infarction.

CONCLUSION

In this indirect comparison to the DPP-4 inhibitors saxagliptin and sitagliptin, empagliflozin significantly lowered the risk of cardiovascular-related mortality, all-cause mortality and hospitalizations due to heart failure.

FUNDING

Boehringer Ingelheim GmbH.

Inhibiting DPP4 in a mouse model of HHT1 results in a shift towards regenerative macrophages and reduces fibrosis after myocardial infarction

AIMS

Hereditary Hemorrhagic Telangiectasia type-1 (HHT1) is a genetic vascular disorder caused by haploinsufficiency of the TGFβ co-receptor endoglin. Dysfunctional homing of HHT1 mononuclear cells (MNCs) towards the infarcted myocardium hampers cardiac recovery. HHT1-MNCs have elevated expression of dipeptidyl peptidase-4 (DPP4/CD26), which inhibits recruitment of CXCR4-expressing MNCs by inactivation of stromal cell-derived factor 1 (SDF1). We hypothesize that inhibiting DPP4 will restore homing of HHT1-MNCs to the infarcted heart and improve cardiac recovery.

METHODS AND RESULTS

After inducing myocardial infarction (MI), wild type (WT) and endoglin heterozygous (Eng+/-) mice were treated for 5 days with the DPP4 inhibitor Diprotin A (DipA). DipA increased the number of CXCR4+ MNCs residing in the infarcted Eng+/- hearts (Eng+/- 73.17±12.67 vs. Eng+/- treated 157.00±11.61, P = 0.0003) and significantly reduced infarct size (Eng+/- 46.60±9.33% vs. Eng+/- treated 27.02±3.04%, P = 0.03). Echocardiography demonstrated that DipA treatment slightly deteriorated heart function in Eng+/- mice. An increased number of capillaries (Eng+/- 61.63±1.43 vs. Eng+/- treated 74.30±1.74, P = 0.001) were detected in the infarct border zone whereas the number of arteries was reduced (Eng+/- 11.88±0.63 vs. Eng+/- treated 6.38±0.97, P = 0.003). Interestingly, while less M2 regenerative macrophages were present in Eng+/- hearts prior to DipA treatment, (WT 29.88±1.52% vs. Eng+/- 12.34±1.64%, P<0.0001), DPP4 inhibition restored the number of M2 macrophages to wild type levels.

CONCLUSIONS

In this study, we demonstrate that systemic DPP4 inhibition restores the impaired MNC homing in Eng+/- animals post-MI, and enhances cardiac repair, which might be explained by restoring the balance between the inflammatory and regenerative macrophages present in the heart.

DPP-4 inhibition with linagliptin ameliorates the progression of premature aging in klotho-/- mice

BACKGROUND

The potential of anti-aging effect of DPP-4 inhibitors is unknown. This study was performed to determine whether linagliptin, a DPP-4 inhibitor, could protect against premature aging in klotho-/- mice.

METHODS

Klotho-/- mice exhibit multiple phenotypes resembling human premature aging, including extremely shortened life span, cognitive impairment, hippocampal neurodegeneration, hair loss, muscle atrophy, hypoglycemia, etc. To investigate the effect of linagliptin on these aging-related phenotypes, male klotho-/- mice were divided into two groups: (1) control group fed the standard diet, and (2) linagliptin group fed the standard diet containing linagliptin. Treatment with linagliptin was performed for 4 weeks. The effect of linagliptin on the above mentioned aging-related phenotypes was examined.

RESULTS

Body weight of klotho-/- mice was greater in linagliptin group than in control group (11.1 ± 0.3 vs 9.9 ± 0.3 g; P < 0.01), which was associated with greater gastrocnemius muscle weight (P < 0.01) and greater kidney weight (P < 0.05) in linagliptin group. Thus, linagliptin significantly prevented body weight loss in klotho-/- mice. Survival rate of klotho-/- mice was greater in linagliptin group (93%) compared to control group (67%), although the difference did not reach statistical significance (P = 0.08). None of linagliptin-treated klotho-/- mice had alopecia during the treatment (P < 0.05 vs control klotho-/- mice). Latency of klotho-/- mice in passive avoidance test was larger in linagliptin group than in control group (P < 0.05), indicating the amelioration of cognitive impairment by linagliptin. Cerebral blood flow of klotho-/- mice was larger in linagliptin group than in control group (P < 0.01), being associated with greater cerebral phospho-eNOS levels (P < 0.05) in linagliptin group. Neuronal cell number in hippocampal CA1 region was greater in linagliptin group than in control group (P < 0.05). Linagliptin group had greater cerebral phospho-Akt (P < 0.05) and phospho-CREB (P < 0.05) than control group. Thus, linagliptin ameliorated brain aging in klotho-/- mice. The degree of hypoglycemia in klotho-/- mice was less in linagliptin group than in control group, as estimated by the findings of OGTT.

CONCLUSIONS

Out work provided the evidence that DPP-4 inhibition with linagliptin slowed the progression of premature aging in klotho-/- mice, and provided a novel insight into the potential role of DPP-4 in the mechanism of premature aging.

Cardiovascular Actions and Clinical Outcomes With Glucagon-Like Peptide-1 Receptor Agonists and Dipeptidyl Peptidase-4 Inhibitors

Potentiation of glucagon-like peptide-1 (GLP-1) action through selective GLP-1 receptor (GLP-1R) agonism or by prevention of enzymatic degradation by inhibition of dipeptidyl peptidase-4 (DPP-4) promotes glycemic reduction for the treatment of type 2 diabetes mellitus by glucose-dependent control of insulin and glucagon secretion. GLP-1R agonists also decelerate gastric emptying, reduce body weight by reduction of food intake and lower circulating lipoproteins, inflammation, and systolic blood pressure. Preclinical studies demonstrate that both GLP-1R agonists and DPP-4 inhibitors exhibit cardioprotective actions in animal models of myocardial ischemia and ventricular dysfunction through incompletely characterized mechanisms. The results of cardiovascular outcome trials in human subjects with type 2 diabetes mellitus and increased cardiovascular risk have demonstrated a cardiovascular benefit (significant reduction in time to first major adverse cardiovascular event) with the GLP-1R agonists liraglutide (LEADER trial [Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Ourcome Results], -13%) and semaglutide (SUSTAIN-6 trial [Trial to Evaluate Cardiovascular and Other Long-term Outcomes with Semaglutide], -24%). In contrast, cardiovascular outcome trials examining the safety of the shorter-acting GLP-1R agonist lixisenatide (ELIXA trial [Evaluation of Lixisenatide in Acute Coronary Syndrom]) and the DPP-4 inhibitors saxagliptin (SAVOR-TIMI 53 trial [Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus-Thrombolysis in Myocardial Infarction 53]), alogliptin (EXAMINE trial [Examination of Cardiovascular Outcomes With Alogliptin Versus Standard of Care in Patients With Type 2 Diabetes Mellitus and Acute Coronary Syndrome]), and sitagliptin (TECOS [Trial Evaluating Cardiovascular Outcomes With Sitagliptin]) found that these agents neither increased nor decreased cardiovascular events. Here we review the cardiovascular actions of GLP-1R agonists and DPP-4 inhibitors, with a focus on the translation of mechanisms derived from preclinical studies to complementary findings in clinical studies. We highlight areas of uncertainty requiring more careful scrutiny in ongoing basic science and clinical studies. As newer more potent GLP-1R agonists and coagonists are being developed for the treatment of type 2 diabetes mellitus, obesity, and nonalcoholic steatohepatitis, the delineation of the potential mechanisms that underlie the cardiovascular benefit and safety of these agents have immediate relevance for the prevention and treatment of cardiovascular disease.

Health-related quality-of-life implications of cardiovascular events in individuals with type 2 diabetes mellitus: A subanalysis from the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus (SAVOR)-TIMI 53 trial

BACKGROUND

The impact of cardiovascular complications on health-related quality-of-life (HRQoL) in type 2 diabetes mellitus has not been clearly established. Using EQ5D utility data from SAVOR-TIMI 53, a large phase IV trial of saxagliptin versus placebo, we quantified the impact of cardiovascular and other major events on HRQoL.

METHODS

EQ5D utilities were recorded annually and following myocardial infarction (MI) or stroke. Utilities among patients experiencing major cardiovascular events were analyzed using linear mixed-effects regression, adjusting for baseline characteristics (including EQ5D utility), and compared to those not experiencing major cardiovascular events. Mean utility decrements with standard errors (SE) were estimated as the difference in utility before and after the event.

FINDINGS

The mean EQ5D utility of the sample was 0.776 at all time points, and did not differ by treatment. However, mean baseline and month 12 utilities among those with a major cardiovascular event were 0.751 and 0.714. Mean utilities were 0.691 within 3months of, 0.691 3-6months after, and 0.714 6-12months after, a major cardiovascular event. Cardiovascular event-specific utility decrements were 0.05 (0.007) for major cardiovascular events over the same time periods. Decrements of 0.051 (0.012; myocardial infarction), 0.111 (0.022; stroke), 0.065 (0.014; hospitalization for heart failure) 0.019 (0.024; hospitalization for hypoglycemia) were estimated; all coefficients were statistically significant.

INTERPRETATION

Consistent with clinical outcomes reported elsewhere, saxagliptin did not improve HRQoL. Cardiovascular complications were associated with significantly decreased HRQoL, most substantial earlier after the event.

FUNDING

BMS/AZ.

Interpreting Cardiovascular Endpoints in Trials of Antihyperglycemic Drugs

In view of the significant cardiovascular (CV) morbidity and mortality in patients with type 2 diabetes mellitus, and concerns raised about the CV safety of some glucose-lowering drugs, the US Food and Drug Administration (FDA) issued guidance for the industry in 2008 to demonstrate CV safety for the approval of all new antihyperglycemic drugs. Seven randomized controlled trials involving around 60,000 participants have been completed so far and have demonstrated the CV safety of dipeptidyl peptidase 4 inhibitors (saxagliptin, alogliptin and sitagliptin), glucagon-like peptide-1 receptor agonists (lixisenatide, liraglutide and semaglutide) and a sodium-glucose co-transporter 2 inhibitor (empagliflozin) in patients with type 2 diabetes. Three of these trials have in fact reported superiority of the study drug over placebo in terms of CV outcomes. However, all these trials were primarily designed as non-inferiority trials to exclude an unacceptable risk of CV events with these drugs in the shortest possible time period. The potential long-term benefit or risks were not assessed effectively as the median follow-up in these studies was limited to 1.5-3 years. Also, these trials included patients with relatively long duration of diabetes, advanced atherosclerosis and higher CV risk. Thus, these trials were not intended to assess CV benefit and are best interpreted as evidence for CV safety of these antihyperglycemic medications.

Comparative cardiovascular risks of dipeptidyl peptidase 4 inhibitors with other second- and third-line antidiabetic drugs in patients with type 2 diabetes

AIMS

Dipeptidyl peptidase 4 inhibitors (DPP4is) are suggested as a second- and third-line antidiabetic treatment for type 2 diabetes. Previous studies assessed only the cardiovascular effects of DPP4is as a second-line treatment, included sulphonylurea as the only comparator, and yielded inconclusive results on the risk of heart failure. The present study therefore evaluated the comparative cardiovascular risks of DPP4is with other second- and third-line antidiabetic drugs.

METHODS

Based on a large nationwide diabetic cohort, 113 051 patients with type 2 diabetes newly on metformin-based dual or triple therapy were identified in 2009-2011 and followed until 2013, or death if this occurred sooner. Primary interest targeted hospitalizations for ischaemic stroke, myocardial infarction and heart failure. Secondary outcomes were hypoglycaemia and all-cause mortality. Cox proportional hazards models were performed to assess time-to-event hazard ratio between propensity score-matched antidiabetic treatment groups.

RESULTS

DPP4is as a second-line add-on to metformin had a significantly lower stroke risk [hazard ratio (HR) 0.817 (95% confidence interval 0.687, 0.971)] and all-cause mortality [HR 0.825 (0.687, 0.992)] than those for sulphonylurea. DPP4is as a third-line add-on to metformin and sulphonylurea combined dual therapy had a significantly lower risk for stroke [HR 0.826 (0.740, 0.923)] and all-cause mortality [HR 0.784 (0.701, 0.878)] than those for acarbose, and significantly lower risks for stroke [HR 0.653 (0.542, 0.786)], heart failure [HR 0.721 (0.568, 0.917)] and all-cause mortality [HR 0.689 (0.594, 0.703)] than those for meglitinide.

CONCLUSIONS

DPP4is as a second- or third-line add-on treatment provided cardiovascular benefits and posed no increased risks for heart failure, hypoglycaemia or death.

Mechanisms of Cardiovascular Injury in Type 2 Diabetes and Potential Effects of Dipeptidyl Peptidase-4 Inhibition

BACKGROUND

Cardiovascular (CV) disease is the major cause of mortality and morbidity in patients with type 2 diabetes mellitus (T2DM). The pathogenesis of CV disease in T2DM is complex and multifactorial and involves direct and indirect injury to the vasculature and heart. The impact of intensive glucose-lowering therapy with antihyperglycemic agents on CV outcomes is not clear, and questions remain as to which glucose-lowering agents may be beneficial to CV health in patients with T2DM.

PURPOSE

This review discusses findings regarding the known mechanisms of CV injury in T2DM and current knowledge regarding the potential cardioprotective effects of dipeptidyl peptidase-4 (DPP-4) inhibitors.

CONCLUSIONS

Dipeptidyl peptidase-4 inhibitors are relatively new antihyperglycemic agents. Their main mechanism of action is to inhibit the degradation of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic peptide by DPP-4. By increasing levels of glucagon-like peptide-1, glucose-dependent insulin secretion is enhanced, glucagon secretion is suppressed, and the rate of gastric emptying is decreased. Dipeptidyl peptidase-4 also degrades other substances that are important in the regulation of CV function and inflammation. Animal studies, small observational studies in humans, and analyses of clinical trial data suggest that DPP-4 inhibitors may have beneficial CV effects. Recent prospectively designed CV outcomes trials with saxagliptin and alogliptin in patients with T2DM and high CV risk presented evidence that these DPP-4 inhibitors neither increased nor decreased adverse CV outcomes in this select patient population.

CLINICAL IMPLICATIONS

Dipeptidyl peptidase-4 inhibitors are promising therapies for the treatment of T2DM. Able to improve glycemic control without the risk of weight gain or hypoglycemia, they provide a safe alternative to sulfonylureas and are an effective adjunct to metformin. To date, this class of drugs seems to be at least neutral in terms of CV effects. Time will tell if these findings translate into a benefit for our patients.

Cardiovascular Safety of Incretin-Based Therapies in Type 2 Diabetes: Systematic Review of Integrated Analyses and Randomized Controlled Trials

Introduction

Regulatory requirements mandate that new drugs for treatment of patients with type 2 diabetes mellitus (T2DM), such as dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists, are evaluated to show that they do not increase cardiovascular (CV) risk.

Methods

A systematic review was undertaken to evaluate the association between DPP-4 inhibitor and GLP-1 receptor agonist use and major adverse cardiac events (MACE). The National Institutes of Health Medline database was searched for pooled analyses, meta-analyses, and randomized controlled trials (RCTs) of DPP-4 inhibitors and GLP-1 receptor agonists that included CV endpoints.

Results

Thirty-six articles met the inclusion criteria encompassing 11 pooled analyses, 17 meta-analyses, and eight RCTs (including secondary analyses). Over the short term (up to 4 years), patients with T2DM exposed to a DPP-4 inhibitor or GLP-1 receptor agonist were not at increased risk for MACE (or its component endpoints) compared with those who received comparator agents. Two meta-analyses showed a significant reduction in the incidence of MACE associated with DPP-4 inhibitor therapy as a drug class, but this beneficial effect was not observed in other meta-analyses that included large RCT CV outcome studies. In four RCTs that evaluated alogliptin, saxagliptin, sitagliptin, or lixisenatide, there was no overall increased risk for MACE relative to placebo in T2DM patients at high risk for CV events or with established CV disease, although there was an increased rate of hospitalization for heart failure associated with saxagliptin. A fifth RCT showed that liraglutide reduced MACE risk by 13% versus placebo.

Conclusion

Overall, incretin therapy does not appear to increase risk for MACE in the short term.

Postauthorization safety study of the DPP-4 inhibitor saxagliptin: a large-scale multinational family of cohort studies of five outcomes

OBJECTIVE

To evaluate the risk of serious adverse events among patients with type 2 diabetes mellitus initiating saxagliptin compared with oral antidiabetic drugs (OADs) in classes other than dipeptidyl peptidase-4 (DPP-4) inhibitors.

RESEARCH DESIGN AND METHODS

Cohort studies using 2009-2014 data from two UK medical record data sources (Clinical Practice Research Datalink, The Health Improvement Network) and two USA claims-based data sources (HealthCore Integrated Research Database, Medicare). All eligible adult patients newly prescribed saxagliptin (n=110 740) and random samples of up to 10 matched initiators of non-DPP-4 inhibitor OADs within each data source were selected (n=913 384). Outcomes were hospitalized major adverse cardiovascular events (MACE), acute kidney injury (AKI), acute liver failure (ALF), infections, and severe hypersensitivity events, evaluated using diagnostic coding algorithms and medical records. Cox regression was used to determine HRs with 95% CIs for each outcome. Meta-analyses across data sources were performed for each outcome as feasible.

RESULTS

There were no increased incidence rates or risk of MACE, AKI, ALF, infection, or severe hypersensitivity reactions among saxagliptin initiators compared with other OAD initiators within any data source. Meta-analyses demonstrated a reduced risk of hospitalization/death from MACE (HR 0.91, 95% CI 0.85 to 0.97) and no increased risk of hospitalization for infection (HR 0.97, 95% CI 0.93 to 1.02) or AKI (HR 0.99, 95% CI 0.88 to 1.11) associated with saxagliptin initiation. ALF and hypersensitivity events were too rare to permit meta-analysis.

CONCLUSIONS

Saxagliptin initiation was not associated with increased risk of MACE, infection, AKI, ALF, or severe hypersensitivity reactions in clinical practice settings.

TRIAL REGISTRATION NUMBER

NCT01086280, NCT01086293, NCT01086319, NCT01086306, and NCT01377935; Results.

CARDIOVASCULAR OUTCOME TRIALS OF THE INCRETIN-BASED THERAPIES: WHAT DO WE KNOW SO FAR?

OBJECTIVE

Diabetes is a well-established pro-inflammatory state with an increased risk for cardiovascular (CV) diseases. In recent years, the number of different classes of agents for the treatment of type 2 diabetes has increased substantially, and while glycemic control is the major focus of these medications, CV safety has become of interest. Two incretin-based therapies are currently available: glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors.

METHODS

The literature was reviewed for information regarding the incretin-based therapies and their effects on the CV system.

RESULTS

Independent of their glucose-lowering action, incretin-based therapies may have incretin-dependent mechanisms that positively affect blood pressure, weight, and other markers of CV disease risk, and, in the case of DPP-4 inhibition, nonincretin-dependent actions such as improving endothelial function. Several CV outcomes trials (CVOTs) with incretin-based therapies have recently completed with no excess CV risk observed, and positive effects have been reported in at least 1 trial of GLP-1 RAs, with more studies ongoing. Results for the risk for heart failure with DPP-4 inhibitor use are mixed, but no increase has been demonstrated with GLP-1 RAs.

CONCLUSION

Future CVOTs will need to be redesigned to help address these questions in the context of the emerging scope of the underlying mechanisms of cardio-metabolic disease in populations with diabetes.

ABBREVIATIONS

A1C = hemoglobin A1C ACS = acute coronary syndrome CHD = coronary heart disease CI = confidence interval CV = cardiovascular CVOT = Cardiovascular Outcome Trial DPP-4 = dipeptidyl peptidase 4 FDA = U.S. Food and Drug Administration GIP = glucose-dependent insulinotropic polypeptide GLP-1 = glucagon-like protein 1 GLP-1 RA = glucagon-like protein 1 receptor agonist HF = heart failure HR = hazard ratio LVEF = left ventricular ejection fraction MACE = major adverse cardiovascular events MI = myocardial infarction T2D = type 2 diabetes.

Microvascular Outcomes in Patients with Type 2 Diabetes Treated with Vildagliptin vs. Sulfonylurea: A Retrospective Study Using German Electronic Medical Records

INTRODUCTION

Preliminary data suggest that dipeptidyl peptidase-4 (DPP-4) inhibitors may reduce microvascular events, but there is a little evidence to support this from adequate real-world studies. This study aimed to compare microvascular outcomes between patients-prescribed vildagliptin and those prescribed sulfonylurea (SU).

METHODS

This retrospective cohort study was conducted on a large sample from the German electronic medical records database IMS Lifelink Disease Analyzer. We used propensity score-matched samples of patients prescribed either vildagliptin or SU. Exposure was defined as therapy (SU or vildagliptin); primary outcomes were a diagnosis of retinopathy, nephropathy, neuropathy, or diabetic foot ulcer over the observation period in patients with no previous record of these outcomes. Secondary outcome was a composite of any primary outcome occurring in the observation period.

RESULTS

In total, 16,321 patients prescribed SU and 4481 prescribed vildagliptin met the inclusion criteria. After propensity score matching, each sample comprised 3015 patients. Mean age was 63.7/64.6 years for SU/vildagliptin, respectively, with mean disease duration of 3.2/3.1 years, and mean treatment duration of 2.5/2.3 years. Treatment with vildagliptin was associated with a significant lower incidence of retinopathy [odds ratio (OR) = 0.55, P = 0.0004], neuropathy (OR 0.71, P = 0.0001), and composite outcome (OR 0.70, P < 0.0001). Incidences of nephropathy and diabetic foot ulcer were lower for vildagliptin, but not significantly so (OR 0.90, P = 0.3920; OR 0.76, P = 0.0742, respectively). There were no significant differences in incident rate ratios (all P > 0.05).

CONCLUSION

Treatment with vildagliptin was associated with a reduced incidence of microvascular complications, especially neuropathy and retinopathy, compared to treatment with SU in this clinical practice setting.

FUNDING

Novartis Pharma AG.

Glucagon-Like Peptide 1 Receptor Activation Attenuates Platelet Aggregation and Thrombosis

Short-term studies in subjects with diabetes receiving glucagon-like peptide 1 (GLP-1)-targeted therapies have suggested a reduced number of cardiovascular events. The mechanisms underlying this unexpectedly rapid effect are not known. We cloned full-length GLP-1 receptor (GLP-1R) mRNA from a human megakaryocyte cell line (MEG-01), and found expression levels of GLP-1Rs in MEG-01 cells to be higher than those in the human lung but lower than in the human pancreas. Incubation with GLP-1 and the GLP-1R agonist exenatide elicited a cAMP response in MEG-01 cells, and exenatide significantly inhibited thrombin-, ADP-, and collagen-induced platelet aggregation. Incubation with exenatide also inhibited thrombus formation under flow conditions in ex vivo perfusion chambers using human and mouse whole blood. In a mouse cremaster artery laser injury model, a single intravenous injection of exenatide inhibited thrombus formation in normoglycemic and hyperglycemic mice in vivo. Thrombus formation was greater in mice transplanted with bone marrow lacking a functional GLP-1R (Glp1r(-/-)), compared with those receiving wild-type bone marrow. Although antithrombotic effects of exenatide were partly lost in mice transplanted with bone marrow from Glp1r(-/-) mice, they were undetectable in mice with a genetic deficiency of endothelial nitric oxide synthase. The inhibition of platelet function and the prevention of thrombus formation by GLP-1R agonists represent potential mechanisms for reduced atherothrombotic events.

Association of Sitagliptin with cardiovascular outcome in diabetic patients: a nationwide cohort study

AIMS

Although dipeptidyl peptidase-4 (DPP-4) inhibitor improves glycemic control, the actual cardiovascular outcomes remain unclear. The objective of this cohort study was to thus evaluate the cardiovascular outcome in diabetic patients who received DPP-4 inhibitors (Sitagliptin).

METHODS

A total of 104,756 new diabetic patients were identified from the Taiwan National Health Insurance Research Database during the period from March 1, 2003 to December 31, 2011. Patients who received Sitagliptin therapy were included as exposures, and up to four age- and sex-matched controls were selected by risk-set sampling. Outcomes such as major adverse cardiovascular diseases (CVD) and deaths were assessed. Logistic regression models were applied to estimate the hazard ratios and 95 % CIs between DPP-4 inhibitor use and cardiovascular outcome.

RESULTS

Over a mean of 14 months, the rates of total CVD per 1000 person-months were significantly lower in Sitagliptin users (3.41 vs. 5.17, p < 0.001), whereas other different CVDs (hazard ratio [HR] 0.59; 95 % confidence interval [CI] 0.48-0.72 for coronary heart disease; HR 0.75; 95 % CI 0.59-0.96 for ischemic stroke; HR 0.86; 95 % CI 0.45-1.65 for peripheral artery occlusive disease) and all-cause mortality (HR 0.56; 95 % CI 0.41-0.74]) were also fewer after adjustment for covariates.

CONCLUSIONS

The results showed a favorable outcome of Sitagliptin as a class on lowering CVD incidence in patients with type 2 diabetes.

Major adverse cardiovascular events with basal insulin peglispro versus comparator insulins in patients with type 1 or type 2 diabetes: a meta-analysis

BACKGROUND

To identify possible differences in cardiovascular (CV) risk among different insulin therapies, we performed pre-specified meta-analyses across the clinical program for basal insulin peglispro (BIL), in patients randomized to treatment with BIL or comparator insulin [glargine (IG) or NPH].

METHODS

One phase 2 (12-week) and 6 phase 3 (26 to 78-week) randomized studies of BIL compared to IG or NPH, in patients with type 1 or type 2 diabetes, were included. The participants were diverse with respect to demographics, baseline glycemic control, and concomitant disease or medications, but treatment groups were comparable in each study. For any potential CV or neurovascular event, relevant medical information was provided to a blinded external clinical events committee (C5Research, Cleveland Clinic, Cleveland, OH, USA) for adjudication. Cox regression analysis was used to compare treatment groups. The primary endpoint was a composite of adjudicated MACE+ [CV death, myocardial infarction (MI), stroke, or hospitalization for unstable angina].

RESULTS

The pooled population included 5862 patients in the safety evaluation, with randomization to BIL:IG:NPH of 3578:2072:212. Mean age was 54.1 years, 27 % had type 1 diabetes, 56 % were male, and 88 % were white. Baseline demographic and clinical characteristics, including use of statins or other lipid-lowering drugs, were comparable between BIL and comparators. A total of 83 patients experienced at least 1 MACE+ and 70 patients experienced at least 1 MACE (CV death, MI, or stroke). Overall, there were no treatment-associated differences in time to MACE+ [hazard ratio (HR) for BIL versus comparator insulin (95 % CI): 0.82 (0.53-1.27)] or MACE [0.83 (0.51-1.33)]. In 4297 patients with type 2 diabetes, there were 71 MACE+ events [HR: 1.02 (95 % CI: 0.63-1.65), p = 0.94]. In 1565 patients with type 1 diabetes, there were only 12 MACE+ [0.24 (0.07-0.85), p = 0.027]. There were no differences in all-cause death between BIL and comparators. Sub-group analyses did not identify any sub-population with increased risk with BIL versus comparator insulins.

CONCLUSIONS

Treatment with BIL versus comparator insulin in patients with type 1 diabetes or type 2 diabetes was not associated with increased risk for major CV events in the studies analyzed.

Cardiovascular safety assessment of pramlintide in type 2 diabetes: results from a pooled analysis of five clinical trials

BACKGROUND

This report evaluated the cardiovascular safety of the amylin analog pramlintide-an existing diabetes injectable treatment-by comparing relevant cardiovascular adverse events (AEs) reported in previous phase 3 and 4 clinical trials among patients receiving pramlintide and those receiving control treatments.

METHODS

Cardiovascular safety of pramlintide was assessed using accepted regulatory medical definitions of AEs reported in five randomized, controlled phase 3 and 4 trials of 16-52 weeks' duration in adults with type 2 diabetes. The original trials compared pramlintide (90-120 mcg twice daily or 30-150 mcg three times daily) with placebo (four studies) or a mealtime rapid-acting insulin analog (one study). Background therapies included insulin alone or in combination with oral glucose-lowering agents. AE data obtained from clinical study reports were combined into one database and analyzed for the intention-to-treat population of 2016 patients (pramlintide, n = 1434; pooled comparator, n = 582). The primary analysis compared reported major adverse cardiovascular events (MACE) between pramlintide and control.

RESULTS

The incidence of reported MACE was similar between pramlintide (4.7 %) and pooled comparators (4.5 %). Secondary analyses included MACE relative risk and hazard ratio point estimates, which ranged from 0.86 to 0.93 for pramlintide relative to comparator treatment; the upper limit of the two-sided 95 % confidence interval did not exceed the threshold of 1.8.

CONCLUSIONS

Both the point estimate of the reported MACE frequency and estimated risk ratios showed that mealtime pramlintide as an adjunct to insulin conferred no increased risk of cardiovascular AEs in patients with type 2 diabetes using insulin.

Cardiovascular outcome trials for anti-diabetes medication: A holy grail of drug development?

Since the time questions arose on cardiovascular safety of Rosiglitazone, FDA has suggested guidelines on conduct of studies on anti-diabetic drugs so as to prove that the cardiovascular risk is acceptable. Based on the cardiovascular risks of pre-approval clinical trials, guidelines have been made to conduct cardiovascular safety outcome trials (CVSOTs) prior to the drug approval or after the drug has been approved. Unlike the trials comparing the efficacy of antidiabetic agents, the CVSOTs examine the cardiovascular safety of a drug in comparison to standard of care. These trials are expensive aspects of drug development and are associated with various technical and operational challenges. More cost effective models of assessing cardiovascular safety like use of biomarkers, electronic medical records, pragmatic and factorial designs can be adopted. This article critically looks at the antidiabetic drug approval from a cardiovascular perspective by asking a few questions and arriving at answers.

DPP-4 inhibitors and cardiovascular disease in type 2 diabetes mellitus. Expectations, observations and perspectives

AIMS

Cardiovascular disease (CVD) is the greatest burden of type 2 diabetes mellitus (T2DM) in terms of morbility, mortality and costs for individuals and societies. Therefore, its prevention is a major goal in diabetes care. Optimal treatment of hyperglycemia is certainly instrumental to CVD prevention. Optimal treatment means both establishing the most appropriate glycemic target for the given individual and selecting the medication(s) with the most favourable benefit/safety ratio. CVD safety, if not a clear CVD benefit, is certainly required for all antidiabetic agents. Dipeptidyl-peptidase-4 (DPP-4) inhibitors are among the classes of antidiabetic agents most recently made available for diabetes care. A major question to be addressed is the effect of these compounds on CVD. Expectations were high for their mechanism of action, which targets also post-prandial glucose and minimize hypoglycemia risk, thereby providing a sort of global glucose control, and for some potentially beneficial extra-glycemic effects. This article reviews the existing literature on this issue.

DATA SYNTHESIS

Data published so far document that DPP-4 inhibitors have a wide spectrum of glycemic and extra-glycemic effects potentially reducing the risk of CVD as well as favourable effects on intermediate or surrogate CVD endpoints. These data heralded a better CVD outcome. Accordingly, pooling CVD safety data from phase 3 and 4 studies conducted with DPP-4 inhibitors suggested that their use might translate into a better CVD outcome. Data from three CVD outcome RCTs with alogliptin, saxagliptin and sitagliptin documented no harm but did not show any benefit on major CVD events. A modest but significant increased risk of hospitalization for heart failure was observed with saxagliptin and with alogliptin (only in subjects with no history of heart failure before randomization) but not with sitagliptin. A study currently in progress with linagliptin will provide further insights in the issue of CVD safety and benefit.

CONCLUSIONS

It should be considered that most alternative oral antidiabetic agents generally do not possess a better CVD risk profile than DPP-4 inhibitors and that some of them, indeed, should be used with caution because of potentially adverse effects on heart and vasculature. Overall, the selection of antidiabetic agent(s) with the most favourable CVD profile is mandatory but still challenging in diabetes care.

Saxagliptin for the treatment of diabetes - a focus on safety

INTRODUCTION

The safety of agents used to treat type 2 diabetes (T2D), a chronic disease requiring life-long intervention, is of particular interest. Saxagliptin is a potent and selective DPP-4 inhibitor that has emerged as a therapeutic option for T2D.

AREAS COVERED

Its safety was assessed in a development program of 20 phase 2/3 randomized clinical trials and in SAVOR-TIMI 53 trial that evaluated the cardiovascular outcomes. In order to capture any further safety signals, mainly in the long-term, a post-marketing safety surveillance is ongoing. This paper discusses the tolerability and safety profile of the agent, including cardiovascular, renal, pancreatic, hepatic and bone adverse events.

EXPERT OPINION

Saxagliptin is a safe therapeutic option for patients with T2D, with low risk of hypoglycemia and good tolerability. It demonstrated cardiovascular safety (including in patients with pre-existing cardiovascular disease and/or HF) and safety with respect to all-cause mortality and adverse events of special interest. In SAVOR-TIMI53, saxagliptin was associated with an unexpected increased risk of HF hospitalization, mainly in the first 12 months; a mechanistic explanation for this has not been found. Further research needs to elucidate the effect of antidiabetic drugs on the heart, by including biomarkers and echocardiographic sub-studies within large outcome trials.

The effect of sitagliptin on cardiovascular risk profile in Korean patients with type 2 diabetes mellitus: a retrospective cohort study

BACKGROUND

A 2013 postmarketing study suggested a possible link between saxagliptin use and hospital admission for heart failure. Cardiovascular (CV) effects of sitagliptin, the most commonly prescribed antidiabetic in the same class as saxagliptin, have not been evaluated much in Asian patients with type 2 diabetes. This study sought to ascertain the CV safety of sitagliptin in Korean patients.

METHODS

A retrospective cohort study of 4,860 patients who were classified into the sitagliptin and metformin groups was conducted using electronic patient data retrieved from a major tertiary care medical center in Korea. Primary composite end points included CV death, myocardial infarction, and ischemic stroke. Secondary composite end points included the aforementioned individual primary outcomes plus hospitalization due to unstable angina, heart failure, or coronary revascularization. A Cox proportional-hazards model was used to compare CV risk associated with drug exposure.

RESULTS

Following propensity score (PS) matching in a 1:2 ratio, 1,620 patients in the sitagliptin group and 3,240 patients in the metformin group were identified for cohort entry. The PS-matched hazard ratio (HR) and 95% confidence interval (CI) for sitagliptin relative to metformin were, respectively, 0.831 and 0.536-1.289 (P=0.408) for primary end point and 1.140 and 0.958-1.356 (P=0.139) for secondary end point. Heart failure hospitalization rates did not differ significantly between the two groups, with the PS-matched HR of 0.762 and 95% CI of 0.389-1.495 (P=0.430). When only those patients at high risk of ischemic heart disease were included for analysis, no excess CV risk was observed with sitagliptin compared with metformin. Overall, there were no substantial between-group differences in rates of adverse events, such as hypoglycemia and incident pancreatic disease.

CONCLUSION

Sitagliptin was not associated with elevated risk of CV complications including myocardial infarction, ischemic stroke, heart failure, and coronary revascularization, compared to metformin therapy among Korean patients with type 2 diabetes.

Pharmacokinetic, pharmacodynamic and clinical evaluation of saxagliptin in type 2 diabetes

INTRODUCTION

Dipeptide peptidase-4 (DPP-4) inhibitors such as saxagliptin are established and efficacious oral therapies in the management of type 2 diabetes. These agents have the potential to confer significant benefits in glycemic control without the risk of weight gain and hypoglycemia, which may be associated with other medications used to treat type 2 diabetes.

AREAS COVERED

This review examines the pharmacokinetics, efficacy and tolerability of saxagliptin for the management of type 2 diabetes.

EXPERT OPINION

Saxagliptin is routinely used in the management of type 2 diabetes as monotherapy, and in combination with other oral agents and insulin. Robust clinical trials have shown consistent improvements in glycated hemoglobin, fasting and postprandial glucose levels, with few adverse effects. The agent is well tolerated with low rates of hypoglycemia in the absence of insulin or sulphonylurea therapy.

A Multifactorial Approach to Reduce Cardiovascular Disease in Type 2 Diabetes Mellitus: Now More Than Ever

Managing cardiovascular (CV) risk is an important part of caring for patients with type 2 diabetes mellitus, as the disease itself confers CV risk. Many CV risk factors (such as hypertension, dyslipidemia, and obesity) have been found to be more common among individuals with diabetes than in the general population. A growing body of evidence provides guidance for clinicians on how to balance control of hyperglycemia with management of these risk factors. Newer classes of antihyperglycemic agents have been associated with beneficial effects on several CV risk factors; several studies evaluating the effect of these newer diabetic medications on CV outcomes have been published, and several more are in progress. While evidence continues to unfold about the benefits of risk factor control in patients with type 1 diabetes mellitus, this article reviews evidence related to risk-factor control in patients with type 2 diabetes mellitus as well as recent findings on the effect of newer drug classes on CV risk factors and outcomes. Favorably altering CV risk factors appears to improve outcomes, and is more important now than ever before.

Dipeptidyl peptidase-4 inhibition improves cardiac function in experimental myocardial infarction: Role of stromal cell-derived factor-1α

BACKGROUND

In addition to degrading glucagon-like peptide-1 (GLP-1), dipeptidyl peptidase-4 (DPP-4) inactivates several chemokines, including stromal cell-derived factor-1α (SDF-1α), a pro-angiogenic and cardiomyocyte protective protein. We hypothesized that DPP-4 inhibition may confer benefit following myocardial infarction (MI) in the diabetic setting as a consequence of enhanced SDF-1α availability rather than potentiating GLP-1. To test this we compared the effects of saxagliptin with those of liraglutide and used the SDF-1α receptor (CXCR4) antagonist plerixafor.

METHODS

Studies were conducted in streptozotocin-diabetic rats. Rats were randomized to receive saxagliptin (10 mg/kg per day), liraglutide (0.2 mg/kg, s.c., b.i.d.), plerixafor (1 mg/kg per day, s.c.), saxagliptin plus plerixafor or vehicle (1% phosphate-buffered saline). Two weeks later, rats underwent experimental MI, with cardiac function examined 4 weeks after MI.

RESULTS

Glycemic control and MI size were similar in all groups. Four weeks after MI, mortality was reduced in saxagliptin-treated rats compared with vehicle treatment (P < 0.05). Furthermore, rats receiving saxagliptin had improved cardiac function compared with vehicle-treated rats (P < 0.05). Antagonism of CXCR4 prevented the improvement in cardiac function in saxagliptin-treated rats and was associated with increased mortality (P < 0.05).

CONCLUSION

Saxagliptin-mediated DPP-4 inhibition, but not liraglutide-mediated GLP-1R agonism, improved cardiac function after MI independent of glucose lowering. These findings suggest that non-GLP-1 actions of DPP-4 inhibition, such as SDF-1α potentiation, mediate biological effects.

Plasma Glucagon-Like Peptide-1 and Tissue Characteristics of Coronary Plaque in Non-Diabetic Acute Coronary Syndrome Patients

BACKGROUND

The relationship between plasma glucagon-like peptide-1 (GLP-1) and coronary plaque characteristics in humans remains unclear.

METHODS AND RESULTS

A total of 85 culprit coronary vessels excluding the 10-mm culprit segments in non-diabetic patients with acute coronary syndrome (ACS) were examined using integrated backscatter intravascular ultrasound, performed using a 40-MHz intravascular catheter before PCI. All patients underwent 75-g oral glucose tolerance test (OGTT), and the plasma GLP-1 response was evaluated on the basis of the area under the GLP-1 concentration-time curve (GLP-1 AUC) from 0 to 120 min. Patients in the low GLP-1 AUC tertile had a significantly greater percentage lipid area than did patients in the intermediate and high tertiles (low tertile vs. intermediate tertile vs. high tertile: 57.3 ± 12.1% vs. 47.2 ± 15.4% vs. 46.3 ± 12.7%, P<0.01, ANOVA) and a smaller percentage fibrosis area (38.1 ± 9.4% vs. 44.6 ± 11.5% vs. 45.7 ± 9.0%; P=0.01, ANOVA). On multiple regression analysis, low GLP-1 AUC tertile was independently associated with percentage lipid area.

CONCLUSIONS

Low plasma GLP-1 during 75-g OGTT is associated with increased lipid content in non-diabetic patients with ACS, suggesting that plaque vulnerability is increased in this subgroup of patients.

Incretin-based therapies are associated with acute pancreatitis: Meta-analysis of large randomized controlled trials

Previous studies have offered weak and conflicting evidence regarding the impact of incretin-based oral antihyperglycemic agents on risk of acute pancreatitis. This meta-analysis of three recent mega-trials found an 82% increase in the odds of acute pancreatitis with the use of these agents compared to usual care (95% CI, 1.17-2.82).

Effects of telmisartan and linagliptin when used in combination on blood pressure and oxidative stress in rats with 2-kidney-1-clip hypertension

OBJECTIVE

To investigate the effects of linagliptin alone and in combination with the angiotensin II receptor blocker (ARB), telmisartan on blood pressure (BP), kidney function, heart morphology and oxidative stress in rats with renovascular hypertension.

METHODS

Fifty-seven male Wistar rats underwent unilateral surgical stenosis of the renal artery [2-kidney-1-clip (2k1c) method]. Animals were randomly divided into four treatment groups (n = 14-18 per group) receiving: telmisartan (10 mg/kg per day in drinking water), linagliptin (89 ppm in chow), combination (linagliptin 89 ppm + telmisartan 10 mg/kg per day) or placebo. An additional group of 12 rats underwent sham surgery. BP was measured one week after surgery. Hypertensive animals entered a 16-week dosing period. BP was measured 2, 4, 8, 12 and 16 weeks after the initiation of treatment. Blood and urine were tested for assessment of kidney function and oxidative stress 6, 10, 14 and 18 weeks after surgery. Blood and urine sampling and organ harvesting were finally performed.

RESULTS

Renal stenosis caused an increase in mean ± SD systolic BP as compared with the sham group (157.7 ± 29.3 vs. 106.2 ± 20.5 mmHg, respectively; P < 0.001). Telmisartan alone and in combination with linagliptin, normalized SBP (111.1 ± 24.3 mmHg and 100.4 ± 13.9 mmHg, respectively; P < 0.001 vs. placebo). Telmisartan alone and in combination with linagliptin significantly prevented cardiac hypertrophy, measured by heart weight and myocyte diameter. Renal function measured by cystatin C was not affected by 2k1c surgery. Telmisartan significantly increased plasma concentration of cystatin C. 2k1c surgery initiated fibrosis in both kidneys. Telmisartan promoted further fibrotic changes in the clipped kidney, as measured by protein expression of Col1a1 and histology for interstitial fibrosis and glomerulosclerosis. In non-clipped kidneys, telmisartan demonstrated antifibrotic properties, reducing Col1a1 protein expression. Plasma levels of oxidized low-density lipoprotein were higher in the placebo-treated 2k1c rats as compared to sham-operated animals. The increase was abolished by linagliptin alone (P = 0.03 vs. placebo) and in combination with telmisartan (P = 0.02 vs. placebo). Combination therapy also significantly reduced plasma concentration of carbonyl proteins (P = 0.04 vs. placebo).

CONCLUSION

Inhibition of type 4 dipeptidyl peptidase with linagliptin did not counter BP-lowering effects of ARB in 2k1c rats. Linagliptin reduced lipid and protein oxidation in 2k1c rats, and this effect was BP-independent.

Insights from cardiovascular outcome trials with novel antidiabetes agents: what have we learned? An industry perspective

Owing to the close association of cardiovascular (CV) disease with type 2 diabetes and the uncertainty surrounding the CV safety of antidiabetes agents, in 2008 the Food and Drug Administration issued guidance for the demonstration of CV safety for new antidiabetes drugs. Recently the results from CV outcomes trials of three dipeptidyl peptidase-4 (DPP-4) inhibitors and a glucagon-like peptide-1 receptor agonist have been reported. The Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus (SAVOR) trial, the Examination of Cardiovascular Outcomes with Alogliptin versus Standard of Care in Patients with Type 2 Diabetes Mellitus and Acute Coronary Syndrome (EXAMINE) trial, and the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS) assessed the safety of saxagliptin, alogliptin, and sitagliptin, respectively, in patients with type 2 diabetes with CV disease or at high risk for CV disease. The Evaluation of Lixisenatide in Acute Coronary Syndrome (ELIXA) assessed the safety of lixisenatide in patients with type 2 diabetes and a recent acute coronary syndrome event. The results show that these agents neither increased nor deceased major adverse CV events (CV death, nonfatal myocardial infarction, and nonfatal stroke) compared with placebo. However, the resources needed to conduct these studies may detract from the ability to understand the potential long-term benefit and risk in the majority of patients that are candidates for use of these medications.

Dipeptidyl Peptidase 4 Inhibitors and the Risk of Cardiovascular Disease in Patients with Type 2 Diabetes: A Tale of Three Studies

Dipeptidyl peptidase 4 (DPP4) inhibitors have been touted as promising antihyperglycemic agents due to their beneficial effects on glycemia without inducing hypoglycemia or body weight gain and their good tolerability. Beyond their glucose-lowering effects, numerous clinical trials and experimental studies have suggested that DPP4 inhibitors may exert cardioprotective effects through their pleiotropic actions via glucagon-like peptide 1-dependent mechanisms or involving other substrates. Since 2008, regulatory agencies have required an assessment of cardiovascular disease (CVD) safety for the approval of all new anti-hyperglycemic agents, including incretin-based therapies. Three large prospective DPP4 inhibitor trials with cardiovascular (CV) outcomes have recently been published. According to the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus (SAVOR-TIMI 53) and EXamination of cArdiovascular outcoMes with alogliptIN versus standard of carE in patients with type 2 diabetes mellitus and acute coronary syndrome (EXAMINE) trials, DPP4 inhibitors, including saxagliptin and alogliptin, did not appear to increase the risk of CV events in patients with type 2 diabetes and established CVD or high risk factors. Unexpectedly, saxagliptin significantly increased the risk of hospitalization for heart failure by 27%, a finding that has not been explained and that requires further exploration. More recently, the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS) trial demonstrated the CV safety of sitagliptin, including assessments of the primary composite CV endpoint and hospitalization for heart failure in patients with type 2 diabetes and established CVD. The CV outcomes of an ongoing linagliptin trial are expected to provide new evidence about the CV effects of a DPP4-inhibitor in patients with type 2 diabetes.

Incretins and selective renal sodium-glucose co-transporter 2 inhibitors in hypertension and coronary heart disease

Hyperglycemia is associated with an increased risk of cardiovascular disease, and the consequences of intensive therapy may depend on the mechanism of the anti-diabetic agent(s) used to achieve a tight control. In animal models, stable analogues of glucagon-like peptide-1 (GLP-1) were able to reduce body weight and blood pressure and also had favorable effects on ischemia following coronary reperfusion. In a similar way, dipeptidyl peptidase IV (DPP-IV) showed to have favorable effects in animal models of ischemia/reperfusion. This could be due to the fact that DPP-IV inhibitors were able to prevent the breakdown of GLP-1 and glucose-dependent insulinotropic polypeptide, but they also decreased the degradation of several vasoactive peptides. Preclinical data for GLP-1, its derivatives and inhibitors of the DPP-IV enzyme degradation suggests that these agents may be able to, besides controlling glycaemia, induce cardio-protective and vasodilator effects. Notwithstanding the many favorable cardiovascular effects of GLP-1/incretins reported in different studies, many questions remain unanswered due the limited number of studies in human beings that aim to examine the effects of GLP-1 on cardiovascular endpoints. For this reason, long-term trials searching for positive cardiovascular effects are now in process, such as the CAROLINA and CARMELINA trials, which are supported by small pilot studies performed in humans (and many more animal studies) with incretin-based therapies. On the other hand, selective renal sodium-glucose co-transporter 2 inhibitors were also evaluated in the prevention of cardiovascular outcomes in type 2 diabetes. However, it is quite early to draw conclusions, since data on cardiovascular outcomes and cardiovascular death are limited and long-term studies are still ongoing. In this review, we will analyze the mechanisms underlying the cardiovascular effects of incretins and, at the same time, we will present a critical position about the real value of these compounds in the cardiovascular system and its protection.

Cardiovascular safety of albiglutide in the Harmony programme: a meta-analysis

BACKGROUND

Albiglutide is a glucagon-like peptide-1 receptor agonist, a new class of drugs used to treat type 2 diabetes. We did a prospective meta-analysis of the cardiovascular safety of albiglutide as stipulated by the US Food and Drug Administration recommendations for the assessment of new treatments for diabetes.

METHODS

We did a meta-analysis of eight phase 3 trials and one phase 2b trial in which patients were randomly assigned to albiglutide, placebo, or active comparators (glimepiride, insulin glargine, insulin lispro, liraglutide, pioglitazone, or sitagliptin). The safety population included 5107 patients, of whom 2524 took albiglutide (4870 person-years) and 2583 took comparators (5213 person-years). Possible major cardiovascular events were recorded prospectively and adjudicated by an independent endpoint committee masked to treatment allocation. The primary endpoint was a composite of first occurrence of major adverse cardiovascular events (ie, cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke) or hospital admission for unstable angina. Secondary endpoints were major adverse cardiovascular events alone, all-cause mortality, silent myocardial infarction, hospital admission for heart failure, chest pain, other angina, and subdural or extradural haemorrhage. The occurrence of all other adverse events classified by the investigators as cardiovascular events were documented, but these were not adjudicated.

FINDINGS

The primary endpoint was not significantly different between albiglutide and all comparators (58 events vs 58 events; hazard ratio [HR] 1·00, 95% CI 0·68-1·49, p=0·0019 for non-inferiority). Major adverse cardiovascular event alone was also not significantly different (52 events vs 53; HR, 0·99; 95% CI, 0·65-1·49). When albiglutide was compared separately with placebo or active comparators, we noted no significant differences. We detected no significant differences in the other secondary endpoints. More patients had atrial fibrillation or atrial flutter in the albiglutide group (35 [1·4%] of 2524 patients; 8·6 events per 1000 patient-years) than in the all-comparators group (16 [0·6%] of 2583 patients; 3·4 events per 1000 patient-years).

INTERPRETATION

Cardiovascular events were not significantly more likely to occur with albiglutide than with all comparators. Because the upper bound of the 95% CI for major adverse cardiovascular event plus hospital admission for unstable angina was greater than 1·3, a dedicated study with a cardiovascular endpoint is underway to confirm the safety of albiglutide.

FUNDING

GlaxoSmithKline.

Impact of glucose-lowering drugs on cardiovascular disease in type 2 diabetes

Type 2 diabetes mellitus (T2DM) is characterized by multiple pathophysiologic abnormalities. With time, multiple glucose-lowering medications are commonly required to reduce and maintain plasma glucose concentrations within the normal range. Type 2 diabetes mellitus individuals also are at a very high risk for microvascular complications and the incidence of heart attack and stroke is increased two- to three-fold compared with non-diabetic individuals. Therefore, when selecting medications to normalize glucose levels in T2DM patients, it is important that the agent not aggravate, and ideally even improve, cardiovascular risk factors (CVRFs) and reduce cardiovascular morbidity and mortality. In this review, we examine the effect of oral (metformin, sulfonylureas, meglitinides, thiazolidinediones, DPP4 inhibitors, SGLT2 inhibitors, and α-glucosidase inhibitors) and injectable (glucagon-like peptide-1 receptor agonists and insulin) glucose-lowering drugs on established CVRFs and long-term studies of cardiovascular outcomes. Firm evidence that in T2DM cardiovascular disease can be reversed or prevented by improving glycaemic control is still incomplete and must await large, long-term clinical trials in patients at low risk using modern treatment strategies, i.e., drug combinations designed to maximize HbA1c reduction while minimizing hypoglycaemia and excessive weight gain.

Dipeptidyl Peptidase 4: A New Link between Diabetes Mellitus and Atherosclerosis?

Type 2 diabetes mellitus (T2DM) has become one of the most prevalent noncommunicable diseases in the past years. It is undoubtedly associated with atherosclerosis and increased risk for cardiovascular diseases. Incretins, which are intestinal peptides secreted during digestion, are able to increase insulin secretion and its impaired function and/or secretion is involved in the pathophysiology of T2DM. Dipeptidyl peptidase 4 (DPP4) is an ubiquitous enzyme that regulates incretins and consequently is related to the pathophysiology of T2DM. DPP4 is mainly secreted by endothelial cells and acts as a regulatory protease for cytokines, chemokines, and neuropeptides involved in inflammation, immunity, and vascular function. In T2DM, the activity of DPP4 seems to be increased and there are a growing number of in vitro and in vivo studies suggesting that this enzyme could be a new link between T2DM and atherosclerosis. Gliptins are a new class of pharmaceutical agents that acts by inhibiting DPP4. Thus, it is expected that gliptin represents a new pharmacological approach not only for reducing glycemic levels in T2DM, but also for the prevention and treatment of atherosclerotic cardiovascular disease in diabetic subjects. We aimed to review the evidences that reinforce the associations between DPP4, atherosclerosis, and T2DM.

Cardiovascular safety of linagliptin in type 2 diabetes: a comprehensive patient-level pooled analysis of prospectively adjudicated cardiovascular events

BACKGROUND

The cardiovascular (CV) safety of linagliptin was evaluated in subjects with type 2 diabetes (T2DM).

METHODS

Pre-specified patient-level pooled analysis of all available double-blind, randomized, controlled trials, ≥ 12 weeks' duration (19 trials, 9459 subjects) of linagliptin versus placebo/active treatment. Primary end point: composite of prospectively adjudicated CV death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization for unstable angina (4P-MACE). Hospitalization for congestive heart failure (CHF) was also evaluated; adjudication of CHF was introduced during the phase 3 program (8 trials; 3314 subjects). 4P-MACE was assessed in placebo-controlled trials (subgroup of 18 trials; 7746 subjects). Investigator-reported events suggestive of CHF from 24 placebo-controlled trials (including trials <12 weeks' duration, 8778 subjects) were also analyzed.

RESULTS

5847 patients received linagliptin (5 mg: 5687, 10 mg: 160) and 3612 comparator (glimepiride: 775, voglibose: 162, placebo: 2675); cumulative exposure, 4421.3 and 3254.7 patient-years, respectively. 4P-MACE incidence rates: 13.4 per 1000 patient-years, linagliptin (60 events), 18.9, total comparators (62 events); overall hazard ratio (HR), 0.78 (95% confidence interval [CI], 0.55-1.12). HR for adjudicated hospitalization for CHF (n = 21): 1.04 (0.43-2.47). For placebo-controlled trials, 4P-MACE incidence rates: 14.9 per 1000 patient-years, linagliptin (43 events), 16.4, total comparators (29 events); overall HR, 1.09 (95% CI, 0.68-1.75). Occurrence of investigator-reported events suggestive of CHF was low for linagliptin- (26 events, 0.5%; serious: 16 events, 0.3%) and placebo-treated (8 events, 0.2%; serious: 6 events, 0.2%) patients.

CONCLUSIONS

Linagliptin is not associated with increased CV risk versus pooled active comparators or placebo in patients with T2DM.

Differential cardiovascular outcomes after dipeptidyl peptidase-4 inhibitor, sulfonylurea, and pioglitazone therapy, all in combination with metformin, for type 2 diabetes: a population-based cohort study

Background/Objectives

Data on the comparative effectiveness of oral antidiabetics on cardiovascular outcomes in a clinical practice setting are limited. This study sought to determine whether a differential risk of cardiovascular disease (CVD) exists for the combination of a dipeptidyl peptidase-4 (DPP-4) inhibitor plus metformin versus a sulfonylurea derivative plus metformin or pioglitazone plus metformin.

Methods

We conducted a cohort study of 349,476 patients who received treatment with a DPP-4 inhibitor, sulfonylurea, or pioglitazone plus metformin for type 2 diabetes using the Korean national health insurance claims database. The incidence of total CVD and individual outcomes of myocardial infarction (MI), heart failure (HF), and ischemic stroke (IS) were assessed using the hazard ratios (HRs) estimated from a Cox proportional-hazards model weighted for a propensity score.

Results

During follow-up, 3,881 patients developed a CVD, including 428 MIs, 212 HFs, and 1,487 ISs. The adjusted HR with 95% confidence interval (CI) for a sulfonylurea derivative plus metformin compared with a DPP-4 inhibitor plus metformin was 1.20 (1.09-1.32) for total CVD; 1.14 (1.04-1.91) for MI; 1.07 (0.71-1.62) for HF; and 1.51 (1.28-1.79) for IS. The HRs with 95% CI for total CVD, MI, HF, and IS for pioglitazone plus metformin were 0.89 (0.81-0.99), 1.05 (0.76-1.46), 4.81 (3.53-6.56), and 0.81 (0.67-0.99), respectively.

Conclusions

Compared with a DPP-4 inhibitor plus metformin, treatment with a sulfonylurea drug plus metformin was associated with increased risks of total CVD, MI, and IS, whereas the use of pioglitazone plus metformin was associated with decreased total CVD and IS risks.

Cardiovascular effects of dipeptidyl peptidase-4 inhibitors in patients with type 2 diabetes

Cardiovascular (CV) disease is the leading cause of mortality and morbidity in patients with type 2 diabetes mellitus (T2DM). However, improving glycaemic control alone has not decreased CV events. Therapies that improve glycaemic control, CV disease risk factors and CV function are more likely to be successful. Dipeptidyl peptidase-4 (DPP-4) inhibitors prevent breakdown of incretin hormones glucagon-like peptide-1(GLP-1) and glucose-dependent insulinotropic peptide and improve glycaemic control in patients with T2DM. DPP-4 acts on other substrates, many associated with cardioprotection. Thus, inhibition of DPP-4 may lead to elevations in these potentially beneficial substrates. Data from animal studies and small observational studies in humans suggest that DPP-4 inhibitors may potentially reduce CV risk. However, recently completed CV outcome trials in patients with T2DM and CV disease or at high risk of adverse CV events have shown that the DPP-4 inhibitors saxagliptin and alogliptin neither increased nor decreased major adverse CV events.

THE RATIONALE FOR USE OF INCRETINS IN THE MANAGEMENT OF NEW ONSET DIABETES AFTER TRANSPLANTATION (NODAT)

OBJECTIVE

Owing to advances in transplant science, increasing numbers of patients are receiving solid organ transplantation. New onset diabetes after transplantation (NODAT) frequently develops in transplant patients and requires acute and often ongoing management of hyperglycemia. The metabolic derangements of NODAT are similar to those of classic type 2 diabetes, and treatment has typically followed diabetes standards of care. Best practices for NODAT management remain to be developed.

METHODS

The mechanistic suitability of incretins to treat NODAT pathogenesis has been hitherto underappreciated. This review details the specific mechanistic value of incretins in patients with immunosuppression-associated hyperglycemia.

RESULTS

Corticosteroids have long been known to exert their effects on glucose metabolism by decreasing glucose utilization and enhancing hepatic gluconeogenesis. Corticosteroids also significantly and directly reduce insulin secretion, as do calcineurin inhibitors (CNIs), another commonly used group of immunosuppressive drugs that cause hyperglycemia and NODAT. The ability of incretins to counteract immunosuppressant-induced disruptions in insulin secretion suggest that the insulinotropic, glucagonostatic, and glucose-lowering actions of incretins are well suited to treat immunosuppressant-induced hyperglycemia in NODAT. Additional benefits of incretins include decreased glucagon levels and improved insulin resistance. In the case of glucagon-like peptide-1 (GLP-1) receptor agonists, weight loss is another benefit, countering the weight gain that is a common consequence of both hyperglycemia and transplantation. These benefits make incretins very attractive and deserving of more investigation.

CONCLUSION

Among diabetes treatment options, incretin therapies uniquely counteract immunosuppressant drugs' interference with insulin secretion. We propose an incretin-based treatment paradigm for NODAT management.