Magnetic Resonance Assessment of Victoza Efficacy in the Regression of Cardiovascular Dysfunction In Type 2 Diabetes Mellitus

1. INTRODUCTION AND RATIONALE

Type 2 diabetes mellitus is an endemic disease associated with obesity and a sedentary lifestyle. In the year 2025 the prevalence of DM2 patients worldwide is expected to be 334 million. In the year 2000 there were an estimated 2,9 million diabetes-related deaths worldwide. Especially cardiovascular disease contributes for a great deal to the high mortality rates. Diabetes patients have a two-fold excess risk for a wide range of vascular diseases, independently of other risk factors, making cardiovascular disease the leading cause of death of diabetes patients. Therefore, treatment of DM2 is focused on the prevention of cardiovascular disease and other diabetes related complications such as retinopathy, neuropathy and nephropathy. Unfortunately, despite lifestyle advises, glucose lowering therapy and co-treatment of other risk factors such as hypertension and dyslipidemia, complication rates remain high. Classical glucose lowering treatment strategies such as sulfonylurea derivatives and insulin ultimately can not control the disease, partly because they participate in the vicious cycle of increasing body weight and insulin resistance. A hopeful new therapeutic agent is the Glucagon Like Peptide -1 analogue Liraglutide. Next to its glucose lowering effect, it reduces body weight resulting in increased insulin sensitivity. The group of GLP-1 analogues are therefore widely prescribed nowadays. However, the effect on the cardiovascular system has not been investigated yet. Since cardiovascular disease is the major threat for the DM2 patient, the effect of this new drug on the cardiovascular system is a very important issue. Interestingly, a cardio-protective effect from Liraglutide can be expected on the basis of both the associated weight loss and because of a direct protective effect on the heart. The investigators hypothesize that treatment with Liraglutide improves cardiac function in DM2 patients. The pathogenesis of cardiovascular disease in DM2 is rather complex and multifactorial. Ultimately most patients develop myocardial infarction and / or heart failure. Often DM2 patients already have subclinical signs of cardiac dysfunction before DM2 is recognized, the main early sign being diastolic dysfunction. Diastolic dysfunction is a strong predictor of mortality. The subclinical characteristics of cardiac dysfunction are highly associated with a condition called the metabolic syndrome. The metabolic syndrome consists of the existence of three out of five of the following risk factors: 1. elevated waist circumference; 2. elevated triglycerides; 3. reduced HDL-C; 4. elevated blood pressure; 5. elevated fasting blood glucose including diabetic-range elevated blood glucose level. With these criteria most patients with diabetes meet the criteria for the metabolic syndrome. A key element in the pathogenesis of the metabolic syndrome might be ectopic fat deposition; the earliest sign of the syndrome being visceral adiposity. Next to visceral adiposity, there is significant deposition of ectopic fat stores in the liver, heart, skeletal muscle and kidney. Triglyceride accumulation in the cardiomyocyte is called myocardial steatosis. Studies performed by our group have proven that caloric restriction results in a reduction in myocardial steatosis and improvement of diastolic function. Hence, myocardial steatosis and associated cardiac dysfunction seem to be reversible as is the case for hepatic steatosis. The putative mechanism of steatosis resulting in cardiac dysfunction is thought to be explained by a phenomenon called lipotoxicity. Altered substrate metabolism and insulin resistance of cardiomyocytes may also play an important role in the pathogenesis of cardiac dysfunction in obesity and DM2. Systemic and cardiac insulin resistance was proven to be associated with increased production of toxic lipids such as diacylglycerol and ceramide. The ultimate treatment for obesity and diabetes related cardiac disease seems to be weight loss. However, lifestyle intervention programs have repeatedly been unsuccessful to have a sustained long term effect. Liraglutide is characterized as a long-acting, human GLP-1 analogue as it shows 97% homology with the amino acid sequence of human GLP-1. The phase 3a program for Liraglutide encompasses five clinical trials in which Liraglutide treatment was studied in each stage of the treatment cascade for type 2 diabetes mellitus. In five studies, Liraglutide was compared directly to standard treatment. The phase 3a clinical development program, included 3,978 exposed patients with DM2, investigated the efficacy and tolerability of Liraglutide 1.2 or 1.8 mg daily (n = 2735) as monotherapy and in combination with various oral antidiabetic drugs. The phase 3a studies showed HBA1C reductions of 1-1.5% and fasting plasma glucose reductions of 0,83 - 2,39 mmol/L. In addition, weight reduction was consistent: Liraglutide 1.8 mg as monotherapy was accompanied by a mean weight loss of 2.5 kg over a 52-week period. A substudy of two phase 3a trials showed that the weight loss caused by Liraglutide, is predominantly caused by a reduction in fat mass; the visceral fat compartment was reduced by 16% from baseline during 26 weeks of Liraglutide 1,2 mg daily. Recent experimental data suggest GLP-1 and its analogues to have direct effects on the heart. In studies on rat heart, the size of an infarct was diminished by more than 50% by an infusion of GLP-1. Post conditioning efficacy of GLP-1 was also demonstrated in an ex vivo rat heart. Exendin-4 was shown to diminish infarct size by approximately 56% and 39%, respectively, in rat global and pig focal models of heart ischemia. The GLP-1 receptor (GLP-1R) is present in the cardiomyocytes as well as in the endothelium and smooth muscle cells of myocardial vasculature. The cell death effector mechanisms targeted by the GLP-1R appear to be mitochondrial permeability transition and apoptosis. Animal studies have suggested myocardial contractility improvement after GLP-1 administration. For instance, dogs with dilated cardiomyopathy treated with GLP-1 for 48 h showed strong improvements in myocardial contractility and cardiac output. GLP-1 infusion was associated with increased myocardial glucose uptake, suggesting ameliorated insulin sensitivity of the cardiomyocytes. In a few small clinical studies, GLP-1 was infused to patients after PCI for approximately 72 h and to patients selected for elective coronary artery bypass grafting from 12 h before to 48 h after the surgery. The latter group showed an improved metabolic profile but no hemodynamic change. In contrast, a left ventricular ejection fraction (LVEF) increase from 29% to 39% was found in the former study, as well as in a study of 12 diabetic, overweight heart failure patients (New York Heart Association class III/IV, LVEF ≤ 40%), given GLP-1 infusion for 5 weeks: at the end of the treatment, these patients showed an increased LVEF, cardiac output, and improved scores in a life quality questionnaire. A number of laboratory studies have suggested a vasorelaxant effect of GLP-1. No pressor effect has been found associated with GLP-1 treatment in studies on diabetic patients. In fact, a decrease of both systolic and diastolic blood pressure values was noted in DM2 patients after an 82-week exenatide trial [33], in a manner correlated to weight loss. Recent experiments (unpublished data) have shown that the GLP-1 analogue exendin - 4 can protect against atherosclerosis and non-alcoholic steatohepatitis (NASH) in APOE 3 - Leiden.CETP mice on a western diet probably due to decreased hepatic CETP expression as well as reduced monocyte recruitment from the circulation to the vessel wall. In addition, hepatic steatosis was improved by a GLP-1 receptor agonist in mice. So far, no dedicated clinical studies have been performed to systematically study the effects of GLP-1 analogues on cardiovascular function. Given the consistency of the results from animal experiments and clinical observations, this area appears ripe for clinical studies. Beneficial effects on cardiovascular endpoints will be crucial to consolidate the therapeutic profile of Liraglutide. Although large scale studies on cardiovascular endpoints are underway, an attractive option is to perform small scale, short-term studies with advanced cardiovascular imaging techniques. Thereby gaining insight in what way GLP-1 therapy affects the cardiovascular system. Advanced cardiovascular magnetic resonance imaging and spectroscopy (MRI/S) enables to assess effects of interventions, in relatively small groups of patients in a limited period of time. As these cardiovascular parameters are strong and clinically relevant predictors of cardiovascular events, measurements of these parameters with MRI/S are worthwhile. Our research group has developed advanced cardiovascular MRI and MRS techniques and algorithms and gained extended experience in the field of DM2 related cardiac function and lipid metabolism. 2. RECRUITMENT AND SCREENING PROCEDURE OF STUDY POPULATION

Patients will be recruited from the outpatient clinics of the Leiden University Medical Center, general practitioners, local hospitals and by advertisement. Patients own physicists will be asked to point eligible patients to the opportunity of study participation. If interested, patients will be informed by the principal investigator. Patients will be given oral and written explanation about the study. After a consideration time of two weeks, patients are asked to give written acknowledgement of informed consent to participate. Then a medical screening will take place. Screening will be performed after an overnight fast of at least 12 hours. The screening will consist of a medical history, physical examination consisting of measurement of height, body weight, heart rate, blood pressure and examination of thorax and abdomen. Furthermore laboratory tests and rest-ECG will be performed. If the patient is eligible- and willing to participate in the study, and has signed the informed consent, the patient will be included. Informed consent must be obtained before any trial related activities take place. After inclusion in the study protocol, the patient's treating physician and general practitioner will be notified. Although the patients are free to leave the study at any time, it will be attempted to recruit patients who are likely to continue the study to completion. 3. SAMPLE SIZE CALCULATION

Because of the absence of data on the effects of GLP-1 in DM2 patients without heart failure, it is hard to calculate the sample size needed to detect differences between myocardial function at 26 weeks between active treatment and controls. Clinically relevant differences and standard deviations of two studies were chosen to generate data for the sample size calculation. The data we used to incorporate the precision of MRI assessment of cardiac function was generated by a study performed by our group with pioglitazone vs metformin on cardiac function parameters. To estimate the effect of GLP-1 therapy on cardiac function, we only have data of a pilot study with eight DM2 patients with heart failure. Calculations for diastolic function parameters were based on the "early deceleration peak" and for systolic function on the basis of "ejection fraction". With a power of 90% and alfa = 0.05, groups varying from 9 to 17 patients will be needed. In a comparable trial the drop-out rate was 10%. Taken into consideration that the population studied will have a significant better systolic function than the heart failure patients studied by Sokos et al, differences may be smaller. In conclusion, investigators estimate to be able to detect a clinically relevant, significant result with 90% power and alfa = 0.05 with 25 patients in each group. 4. USE OF CO-INTERVENTION

Patients should continue to use the oral glucose lowering medicament metformin during the study. For glycaemic control after initiation of the study drug, the current clinical guideline will be followed. Excluded concomitant therapy: thiazolidinediones, other GLP-1 analogues or DPP-IV inhibitors, fibrates, prednisone, cytostatic and antiretroviral therapy.