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.

Safety, pharmacokinetics, and pharmacodynamics of single doses of LXR-623, a novel liver X-receptor agonist, in healthy participants.

Liver X-receptor (LXR) agonists have been postulated to enhance reverse cholesterol transport (RCT), a process believed to shuttle cholesterol from the periphery back to the liver. Enhancing RCT via the upregulation of cholesterol transporters such as the adenosine triphosphate-binding cassettes ABCA1 and ABCG1 could therefore inhibit the progression of atherosclerosis. LXR-623 is a synthetic ligand for LXRs alpha and beta that has shown promise in animal models of atherosclerosis. The authors present results from a single ascending-dose study of the safety, pharmacokinetics, and pharmacodynamics of LXR-623 in healthy participants. LXR-623 was absorbed rapidly with peak concentrations (C(max)) achieved at approximately 2 hours. The C(max) and area under the concentration-time curve increased in a dose-proportional manner. The mean terminal disposition half-life was between 41 and 43 hours independently of dose. LXR activation resulted in a dose-dependent increase in ABCA1 and ABCG1 expression. The effect of LXR-623 concentration on ABCA1 and ABCG1 expression was further characterized via a population pharmacokinetic-pharmacodynamic analysis, yielding EC(50) estimates of 526 ng/mL and 729 ng/mL, respectively. Central nervous system-related adverse events were observed at the 2 top doses tested. The pharmacodynamic effects described here are the first demonstration of "target engagement" by an LXR agonist in humans.

Effects of Dapagliflozin on 24-Hour Glycemic Control in Patients with Type 2 Diabetes: A Randomized Controlled Trial.

BACKGROUND: Glycated hemoglobin (HbA1c) and measures of short-term glycemia do not fully capture daily patterns in plasma glucose dynamics. This study evaluated 24-h glycemic profiles in patients with type 2 diabetes (T2D) initiated on dapagliflozin treatment using continuous glucose monitoring (CGM). METHODS: This randomized double-blind placebo-controlled multicenter parallel-design 4-week study compared dapagliflozin (10 mg/d; n = 50) with placebo (n = 50) in adult patients with T2D uncontrolled (HbA1c 7.5%-10.5%) on either stable doses of metformin monotherapy (≥1500 mg/d) or insulin (≥30 U/d with or without up to two oral antidiabetes drugs). CGM was used to measure 24-h glycemic profiles for 7 days pretreatment and during week 4 of treatment. The primary outcome was change from baseline in 24-h mean glucose (MG) at week 4. RESULTS: The 24-h MG decreased 18.2 mg/dL with dapagliflozin and increased 5.8 mg/dL with placebo (P < 0.001). The proportion of time spent in the target glucose range (70-180 mg/dL) increased significantly with dapagliflozin versus placebo (69.6% vs. 52.9%; P < 0.001), with a small (0.3%) increase in time spent in the hypoglycemic range (<70 mg/dL), driven by those on background insulin therapy. Dapagliflozin reduced postprandial glucose and significantly decreased overall glucose variability. Few events of symptomatic hypoglycemia occurred. The most common adverse event was urinary tract infection (6% in each treatment arm). CONCLUSIONS: Compared with placebo, dapagliflozin improved measures of glycemic control and variability as assessed by CGM. Glycemic improvements were more pronounced in the group on background metformin than those receiving basal insulin.

Intravenously administered vitamin C as cancer therapy: three cases.

Early clinical studies showed that high-dose vitamin C, given by intravenous and oral routes, may improve symptoms and prolong life in patients with terminal cancer. Double-blind placebo-controlled studies of oral vitamin C therapy showed no benefit. Recent evidence shows that oral administration of the maximum tolerated dose of vitamin C (18 g/d) produces peak plasma concentrations of only 220 micromol/L, whereas intravenous administration of the same dose produces plasma concentrations about 25-fold higher. Larger doses (50-100 g) given intravenously may result in plasma concentrations of about 14,000 micromol/L. At concentrations above 1000 micromol/L, vitamin C is toxic to some cancer cells but not to normal cells in vitro. We found 3 well-documented cases of advanced cancers, confirmed by histopathologic review, where patients had unexpectedly long survival times after receiving high-dose intravenous vitamin C therapy. We examined clinical details of each case in accordance with National Cancer Institute (NCI) Best Case Series guidelines. Tumour pathology was verified by pathologists at the NCI who were unaware of diagnosis or treatment. In light of recent clinical pharmacokinetic findings and in vitro evidence of anti-tumour mechanisms, these case reports indicate that the role of high-dose intravenous vitamin C therapy in cancer treatment should be reassessed.

Cystatin C- and Creatinine-Based Estimates of Glomerular Filtration Rate in Dapagliflozin Phase 3 Clinical Trials.

INTRODUCTION: To compare estimated glomerular filtration rate measured by serum creatinine (eGFRcr) and serum cystatin C (eGFRcys) in patients with type 2 diabetes mellitus from dapagliflozin clinical trials. METHODS: Post hoc analysis of data pooled from 9 phase 3, randomized, placebo-controlled, 24-week trials of dapagliflozin. The correlation between eGFRcr and eGFRcys was modeled by a simple linear regression. The proportions of patients with eGFR 30 to <60 and ≥60 mL/min/1.73 m(2) based on creatinine versus cystatin C were compared. RESULTS: Of 4745 total patients, 4294 (90.5%) had serum cystatin C data available for calculation of eGFRcys. The correlation between eGFRcr and eGFRcys was poor (R (2) = 30%). Of patients with eGFRcr 30 to <60 mL/min/1.73 m(2), 66% had eGFR ≥60 when recalculated based on cystatin C. Among patients with eGFRcr ≥60 mL/min/1.73 m(2), 95.8% had eGFR ≥60 when estimated using cystatin C. Decreases in HbA1c, body weight, and systolic blood pressure with dapagliflozin were similar among patient subgroups defined by either eGFR estimate and were statistically significant and clinically meaningful with dapagliflozin 10 mg/day in most subgroups. CONCLUSION: The correlation between eGFRcr and eGFRcys was poor. Renal function assessed by eGFRcr may be underestimated, and some patients may be misdiagnosed with chronic kidney disease and/or unjustifiably deemed ineligible for certain antidiabetes medications. This is in consonance with guidelines suggesting using eGFRcys as a confirmatory measure when eGFRcr is between 45 and <60 mL/min/1.73 m(2) with no evidence of kidney damage and/or in other situations where eGFRcr may be unreliable. FUNDING: AstraZeneca.

Sodium-glucose cotransporter-2 inhibitor combination therapy to optimize glycemic control and tolerability in patients with type 2 diabetes: focus on dapagliflozin-metformin.

In type 2 diabetes (T2D), early combination therapy using agents that target a number of the underlying pathophysiologic defects contributing to hyperglycemia may improve patient outcomes. For many patients, the combination of metformin with a sodium-glucose cotransporter-2 (SGLT-2) inhibitor may be a good option because these agents have complementary mechanisms of action, neutral-to-positive effects on body weight, and a low risk of hypoglycemia. This review focuses on the combination of metformin with dapagliflozin, a member of the SGLT-2 inhibitor class of antidiabetes agents. In clinical trials, the combination of dapagliflozin with metformin produced significant and sustained reductions in glycated hemoglobin and body weight in a broad range of adult patients with T2D, including those initiating pharmacotherapy and those with more advanced disease. These reductions were accompanied by modest decreases in blood pressure. Dapagliflozin as add-on therapy to metformin was well tolerated and associated with low rates of hypoglycemia. Genital infections and, in some studies, urinary tract infections were more frequent with dapagliflozin than with placebo. Early combination therapy with dapagliflozin and metformin may be a safe and appropriate treatment option that enables patients with T2D to achieve individualized glycemic goals as either initial combination therapy in treatment-naïve patients or as dapagliflozin add-on in patients inadequately controlled with metformin therapy.

Quality measure attainment with dapagliflozin plus metformin extended-release as initial combination therapy in patients with type 2 diabetes: a post hoc pooled analysis of two clinical studies.

BACKGROUND: The use of quality measures attempts to improve safety and health outcomes and to reduce costs. In two Phase III trials in treatment-naive patients with type 2 diabetes, dapagliflozin 5 or 10 mg/d as initial combination therapy with metformin extended-release (XR) significantly reduced glycated hemoglobin (A1C) from baseline to 24 weeks and allowed higher proportions of patients to achieve A1C <7% vs dapagliflozin or metformin monotherapy. OBJECTIVE: A pooled analysis of data from these two studies assessed the effect of dapagliflozin 5 or 10 mg/d plus metformin XR (combination therapy) compared with placebo plus metformin XR (metformin monotherapy) on diabetes quality measures. Quality measures include laboratory measures of A1C and low-density lipoprotein cholesterol (LDL-C) as well as vital status measures of blood pressure (BP) and body mass index (BMI). The proportion of patients achieving A1C, BP, and LDL-C individual and composite measures was assessed, as was the proportion with baseline BMI ≥25 kg/m2 who lost ≥4.5 kg. Subgroup analyses by baseline BMI were also performed. RESULTS: A total of 194 and 211 patients were treated with dapagliflozin 5- or 10-mg/d combination therapy, respectively, and 409 with metformin monotherapy. Significantly higher proportions of patients achieved A1C ≤6.5%, <7%, or <8% with combination therapy vs metformin monotherapy (P<0.02). Significantly higher proportions of patients achieved BP <140/90 mmHg (P<0.02 for each dapagliflozin dose) and BP <130/80 mmHg (P<0.02 with dapagliflozin 5 mg/d only) with combination therapy vs metformin monotherapy. Similar proportions (29%-33%) of patients had LDL-C <100 mg/dL across treatment groups. A higher proportion of patients with baseline BMI ≥25 kg/m2 lost ≥4.5 kg with combination therapy. Combination therapy had a more robust effect on patients with higher baseline BMI. CONCLUSION: Initial combination therapy with dapagliflozin 5 or 10 mg/d and metformin improved quality measures relevant to clinical outcomes and diabetes care.

Dapagliflozin in the treatment of patients with type 2 diabetes presenting with high baseline A1C.

OBJECTIVES: To evaluate the efficacy and safety of dapagliflozin 5 and 10 mg/d versus placebo in patients with type 2 diabetes and high baseline A1C defined as A1C ≥ 9% or ≥ 10%. METHODS: A post-hoc analysis was conducted of pooled data from 9, 24-week, placebo-controlled clinical studies investigating dapagliflozin as monotherapy, add-on therapy to other oral antidiabetes drugs or insulin, or initial combination therapy with metformin. RESULTS: At week 24, dapagliflozin 5 and 10 mg/d decreased A1C (≥ 9%: -1.37% and -1.39%, respectively, vs. -0.65% with placebo, both P < 0.0001 and ≥ 10%: -2.13% [P < 0.0001] and -1.59% [P = 0.0003], respectively, vs. -0.82% with placebo), reduced fasting plasma glucose as early as week 1 (P < 0.001 for each dose at all time points for both treatments), and decreased body weight (≥ 9%: P < 0.0001 vs. placebo for both doses; ≥ 10%: P = 0.0065 vs. placebo, 10 mg/d only). Among patients with baseline A1C ≥ 9% who received dapagliflozin 5 or 10 mg/d, 15.7% and 18.9%, respectively, achieved a ≥ 5% decrease in body weight (both P < 0.0001 vs. 3.6% with placebo). Dapagliflozin 10 mg/d decreased systolic and diastolic blood pressure (P < 0.0001 and P = 0.0074 vs. placebo). Adverse events were generally similar across treatment groups, with the exception of a greater frequency of genital infections and hypoglycemia (mostly minor episodes not requiring third-party assistance) in patients receiving dapagliflozin. CONCLUSION: In patients with poorly controlled type 2 diabetes defined as A1C ≥ 9% or ≥ 10%, dapagliflozin provided clinically meaningful improvements in glycemic parameters, body weight, and blood pressure, and was generally well tolerated, making it a good therapeutic option for patients with high A1C.

Vitamin C pharmacokinetics: implications for oral and intravenous use.

BACKGROUND: Vitamin C at high concentrations is toxic to cancer cells in vitro. Early clinical studies of vitamin C in patients with terminal cancer suggested clinical benefit, but 2 double-blind, placebo-controlled trials showed none. However, these studies used different routes of administration. OBJECTIVE: To determine whether plasma vitamin C concentrations vary substantially with the route of administration. DESIGN: Dose concentration studies and pharmacokinetic modeling. SETTING: Academic medical center. PARTICIPANTS: 17 healthy hospitalized volunteers. MEASUREMENTS: Vitamin C plasma and urine concentrations were measured after administration of oral and intravenous doses at a dose range of 0.015 to 1.25 g, and plasma concentrations were calculated for a dose range of 1 to 100 g. RESULTS: Peak plasma vitamin C concentrations were higher after administration of intravenous doses than after administration of oral doses (P < 0.001), and the difference increased according to dose. Vitamin C at a dose of 1.25 g administered orally produced mean (+/-sd) peak plasma concentrations of 134.8 +/- 20.6 micromol/L compared with 885 +/- 201.2 micromol/L for intravenous administration. For the maximum tolerated oral dose of 3 g every 4 hours, pharmacokinetic modeling predicted peak plasma vitamin C concentrations of 220 micromol/L and 13 400 micromol/L for a 50-g intravenous dose. Peak predicted urine concentrations of vitamin C from intravenous administration were 140-fold higher than those from maximum oral doses. LIMITATIONS: Patient data are not available to confirm pharmacokinetic modeling at high doses and in patients with cancer. CONCLUSIONS: Oral vitamin C produces plasma concentrations that are tightly controlled. Only intravenous administration of vitamin C produces high plasma and urine concentrations that might have antitumor activity. Because efficacy of vitamin C treatment cannot be judged from clinical trials that use only oral dosing, the role of vitamin C in cancer treatment should be reevaluated.

Effect of PSI-697, a novel P-selectin inhibitor, on platelet-monocyte aggregate formation in humans.

BACKGROUND: Platelet activation is central to the pathogenesis of acute coronary syndromes. Surface expression of P-selectin on activated platelets induces formation of platelet-monocyte aggregates and promotes vascular inflammation and thrombosis. P-selectin antagonism may represent a novel therapeutic strategy in vascular disease. We aimed to investigate the effects of the novel P-selectin antagonist PSI-697 on platelet-monocyte aggregate formation in humans. METHODS AND RESULTS: In a double-blind, randomized, placebo-controlled crossover study, healthy smokers were randomized to receive either oral PSI-697 600 mg or matched placebo. The sequence of treatment was also randomized, with all subjects receiving both PSI-697 and placebo. Platelet-monocyte aggregates were measured by flow cytometry at 4 and 24 hours in the presence and absence of thrombin receptor-activating peptide (TRAP; 0.1 to 1.0 µm/L). The ex vivo addition of TRAP caused a concentration-dependent increase in platelet-monocyte aggregates from 8.2% to 94.8% (P<0.001). At 4 and 24 hours, plasma concentrations of PSI-697 increased to 1906 and 83 ng/mL, respectively (P<0.001). PSI-697 had no demonstrable effect on either stimulated or unstimulated platelet-monocyte aggregates at 4 or 24 hours (P>0.05). P-selectin-blocking antibody (CLB-Thromb6), but not PSI-697, inhibited both stimulated and unstimulated platelet-monocyte aggregate formation in vitro (P<0.001). CONCLUSIONS: The novel small-molecule P-selectin antagonist PSI-697 did not inhibit basal or stimulated platelet-monocyte aggregate formation in humans at the dose tested. Its clinical efficacy remains to be established. CLINICAL TRIAL REGISTRATION: URL: http://EudraCT.ema.europa.eu Unique identifier: 2007-005695-14.

Bioequivalence among three methods of administering pantoprazole granules in healthy subjects.

PURPOSE: The bioequivalence among three methods of administering pantoprazole granules was studied in healthy subjects. METHODS: In this randomized, open-label, three-period, crossover study, 25 healthy adults received a single 40-mg dose of pantoprazole granules with applesauce orally, with apple juice orally, and with apple juice administered via a nasogastric tube. Subjects were randomly assigned to one of six treatment sequences. Blood samples were collected within 2 hours before treatment administration on study day 1 and at 0.33, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, and 24 hours after treatment administration. Plasma pantoprazole concentrations were analyzed by a validated liquid chromatography-tandem mass spectrometry method. The plasma pantoprazole concentration-time data for each subject were analyzed using noncompartmental methods. The 90% confidence intervals (CIs) for the test:reference geometric mean ratio were calculated for the peak pantoprazole concentration (C(max) ) and area under the concentration-time curve (AUC). RESULTS: Of the 25 subjects enrolled, 100% completed the study. The mean C(max) and AUC values were similar for the three administration methods. The 90% CIs for the ratios of the geometric means of the granules in apple juice orally (92.4-112.5%) and in apple juice administered through a nasogastric tube (102.7-125.2%), relative to the granules administered with applesauce orally, were essentially within the bioequivalent limits of 80-125%. No serious adverse events or study discontinuations occurred. CONCLUSION: Three methods of administering pantoprazole delayed-release granules for oral suspension-with apple juice orally, with applesauce orally, and with apple juice through a nasogastric tube--were bioequivalent in healthy subjects.

High-dose oral vitamin C partially replenishes vitamin C levels in patients with Type 2 diabetes and low vitamin C levels but does not improve endothelial dysfunction or insulin resistance.

Endothelial dysfunction is a hallmark of Type 2 diabetes related to hyperglycemia and oxidative stress. Nitric oxide-dependent vasodilator actions of insulin may augment glucose disposal. Thus endothelial dysfunction may worsen insulin resistance. Intra-arterial administration of vitamin C improves endothelial dysfunction in diabetes. In the present study, we investigated effects of high-dose oral vitamin C to alter endothelial dysfunction and insulin resistance in Type 2 diabetes. Plasma vitamin C levels in 109 diabetic subjects were lower than healthy (36 +/- 2 microM) levels. Thirty-two diabetic subjects with low plasma vitamin C (<40 microM) were subsequently enrolled in a randomized, double-blind, placebo-controlled study of vitamin C (800 mg/day for 4 wk). Insulin sensitivity (determined by glucose clamp) and forearm blood flow in response to ACh, sodium nitroprusside (SNP), or insulin (determined by plethysmography) were assessed before and after 4 wk of treatment. In the placebo group (n = 17 subjects), plasma vitamin C (22 +/- 3 microM), fasting glucose (159 +/- 12 mg/dl), insulin (19 +/- 7 microU/ml), and SI(Clamp) [2.06 +/- 0.29 x 10(-4) dl x kg(-1) x min(-1)/(microU/ml)] did not change significantly after placebo treatment. In the vitamin C group (n = 15 subjects), basal plasma vitamin C (23 +/- 2 microM) increased to 48 +/- 6 microM (P < 0.01) after treatment, but this was significantly less than that expected for healthy subjects (>80 microM). No significant changes in fasting glucose (156 +/- 11 mg/dl), insulin (14 +/- 2 microU/ml), SI(Clamp) [2.71 +/- 0.46 x 10(-4) dl x kg(-1) x min(-1)/(microU/ml)], or forearm blood flow in response to ACh, SNP, or insulin were observed after vitamin C treatment. We conclude that high-dose oral vitamin C therapy, resulting in incomplete replenishment of vitamin C levels, is ineffective at improving endothelial dysfunction and insulin resistance in Type 2 diabetes.

Vitamin C as an antioxidant: evaluation of its role in disease prevention.

Vitamin C in humans must be ingested for survival. Vitamin C is an electron donor, and this property accounts for all its known functions. As an electron donor, vitamin C is a potent water-soluble antioxidant in humans. Antioxidant effects of vitamin C have been demonstrated in many experiments in vitro. Human diseases such as atherosclerosis and cancer might occur in part from oxidant damage to tissues. Oxidation of lipids, proteins and DNA results in specific oxidation products that can be measured in the laboratory. While these biomarkers of oxidation have been measured in humans, such assays have not yet been validated or standardized, and the relationship of oxidant markers to human disease conditions is not clear. Epidemiological studies show that diets high in fruits and vegetables are associated with lower risk of cardiovascular disease, stroke and cancer, and with increased longevity. Whether these protective effects are directly attributable to vitamin C is not known. Intervention studies with vitamin C have shown no change in markers of oxidation or clinical benefit. Dose concentration studies of vitamin C in healthy people showed a sigmoidal relationship between oral dose and plasma and tissue vitamin C concentrations. Hence, optimal dosing is critical to intervention studies using vitamin C. Ideally, future studies of antioxidant actions of vitamin C should target selected patient groups. These groups should be known to have increased oxidative damage as assessed by a reliable biomarker or should have high morbidity and mortality due to diseases thought to be caused or exacerbated by oxidant damage.