Estimating and reporting treatment effects in clinical trials for weight management: using estimands to interpret effects of intercurrent events and missing data.

In the approval process for new weight management therapies, regulators typically require estimates of effect size. Usually, as with other drug evaluations, the placebo-adjusted treatment effect (i.e., the difference between weight losses with pharmacotherapy and placebo, when given as an adjunct to lifestyle intervention) is provided from data in randomized clinical trials (RCTs). At first glance, this may seem appropriate and straightforward. However, weight loss is not a simple direct drug effect, but is also mediated by other factors such as changes in diet and physical activity. Interpreting observed differences between treatment arms in weight management RCTs can be challenging; intercurrent events that occur after treatment initiation may affect the interpretation of results at the end of treatment. Utilizing estimands helps to address these uncertainties and improve transparency in clinical trial reporting by better matching the treatment-effect estimates to the scientific and/or clinical questions of interest. Estimands aim to provide an indication of trial outcomes that might be expected in the same patients under different conditions. This article reviews how intercurrent events during weight management trials can influence placebo-adjusted treatment effects, depending on how they are accounted for and how missing data are handled. The most appropriate method for statistical analysis is also discussed, including assessment of the last observation carried forward approach, and more recent methods, such as multiple imputation and mixed models for repeated measures. The use of each of these approaches, and that of estimands, is discussed in the context of the SCALE phase 3a and 3b RCTs evaluating the effect of liraglutide 3.0 mg for the treatment of obesity.

The effect of semaglutide 2.4 mg once weekly on energy intake, appetite, control of eating, and gastric emptying in adults with obesity.

AIM: To investigate the effects of once-weekly subcutaneous (s.c.) semaglutide 2.4 mg on gastric emptying, appetite, and energy intake in adults with obesity. MATERIALS AND METHODS: A double-blind, parallel-group trial was conducted in 72 adults with obesity, randomized to once-weekly s.c. semaglutide (dose-escalated to 2.4 mg) or placebo for 20 weeks. Gastric emptying was assessed using paracetamol absorption following a standardized breakfast. Participant-reported appetite ratings and Control of Eating Questionnaire (CoEQ) responses were assessed, and energy intake was measured during ad libitum lunch. RESULTS: The area under the concentration-time curve (AUC) for paracetamol 0 to 5 hours after a standardized meal (AUC0-5h,para ; primary endpoint) was increased by 8% (P = 0.005) with semaglutide 2.4 mg versus placebo at week 20 (non-significant when corrected for week 20 body weight; P = 0.12). No effect was seen on AUC0-1h,para , maximum observed paracetamol concentration, or time to maximum observed paracetamol concentration. Ad libitum energy intake was 35% lower with semaglutide versus placebo (1736 versus 2676 kJ; estimated treatment difference -940 kJ; P <0.0001). Semaglutide reduced hunger and prospective food consumption, and increased fullness and satiety when compared with placebo (all P <0.02). The CoEQ indicated better control of eating and fewer/weaker food cravings with semaglutide versus placebo (P <0.05). Body weight was reduced by 9.9% with semaglutide and 0.4% with placebo. Safety was consistent with the known profile of semaglutide. CONCLUSIONS: In adults with obesity, once-weekly s.c. semaglutide 2.4 mg suppressed appetite, improved control of eating, and reduced food cravings, ad libitum energy intake and body weight versus placebo. There was no evidence of delayed gastric emptying at week 20, assessed indirectly via paracetamol absorption.

Chronic hyperglycemia, hypercholesterolemia, and metabolic syndrome are associated with risk of tendon injury.

Tendon injury is a considerable problem affecting both physically active and sedentary people. The aim of this study was to examine the relationship between markers for metabolic disorders (hyperglycemia, hypercholesterolemia, and metabolic syndrome) and the risk of developing tendon injuries requiring referral to a hospital. The Copenhagen City Heart Study is a prospective study of diabetic and non-diabetic individuals from the Danish general population with different physical activity levels. The cohort was followed for 3 years via national registers with respect to tendon injuries. Data from 5856 individuals (median age 62 years) were included. The overall incidence of tendon injury in both upper and lower extremities that required an out-patient or in-house visit to a hospital was ~5.7/1000 person years. Individuals with elevated HbA1c (glycated hemoglobin) even in the prediabetic range (HbA1c>5.7%) had a ~3 times higher risk of tendon injury in the lower extremities only, as compared to individuals with normal HbA1C levels. Hypercholesterolemia (total cholesterol>5 mmol/L) increased risk of tendon injury in the upper extremities by ~1.5 times, and individuals with metabolic syndrome had ~2.5 times higher risk of tendon injury in both upper and lower extremities. In conclusion, these data demonstrate for the first time in a large cohort with different physical activity levels that the indicators for metabolic syndrome are a powerful systemic determinant of tendon injury, and two of its components, hyperglycemia and hypercholesterolemia, each independently make tendons susceptible for damage and injury.

Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy on Body Weight in Adults With Overweight or Obesity: The STEP 3 Randomized Clinical Trial.

Importance: Weight loss improves cardiometabolic risk factors in people with overweight or obesity. Intensive lifestyle intervention and pharmacotherapy are the most effective noninvasive weight loss approaches. Objective: To compare the effects of once-weekly subcutaneous semaglutide, 2.4 mg vs placebo for weight management as an adjunct to intensive behavioral therapy with initial low-calorie diet in adults with overweight or obesity. Design, Setting, and Participants: Randomized, double-blind, parallel-group, 68-week, phase 3a study (STEP 3) conducted at 41 sites in the US from August 2018 to April 2020 in adults without diabetes (N = 611) and with either overweight (body mass index ≥27) plus at least 1 comorbidity or obesity (body mass index ≥30). Interventions: Participants were randomized (2:1) to semaglutide, 2.4 mg (n = 407) or placebo (n = 204), both combined with a low-calorie diet for the first 8 weeks and intensive behavioral therapy (ie, 30 counseling visits) during 68 weeks. Main Outcomes and Measures: The co-primary end points were percentage change in body weight and the loss of 5% or more of baseline weight by week 68. Confirmatory secondary end points included losses of at least 10% or 15% of baseline weight. Results: Of 611 randomized participants (495 women [81.0%], mean age 46 years [SD, 13], body weight 105.8 kg [SD, 22.9], and body mass index 38.0 [SD, 6.7]), 567 (92.8%) completed the trial, and 505 (82.7%) were receiving treatment at trial end. At week 68, the estimated mean body weight change from baseline was -16.0% for semaglutide vs -5.7% for placebo (difference, -10.3 percentage points [95% CI, -12.0 to -8.6]; P < .001). More participants treated with semaglutide vs placebo lost at least 5% of baseline body weight (86.6% vs 47.6%, respectively; P < .001). A higher proportion of participants in the semaglutide vs placebo group achieved weight losses of at least 10% or 15% (75.3% vs 27.0% and 55.8% vs 13.2%, respectively; P < .001). Gastrointestinal adverse events were more frequent with semaglutide (82.8%) vs placebo (63.2%). Treatment was discontinued owing to these events in 3.4% of semaglutide participants vs 0% of placebo participants. Conclusions and Relevance: Among adults with overweight or obesity, once-weekly subcutaneous semaglutide compared with placebo, used as an adjunct to intensive behavioral therapy and initial low-calorie diet, resulted in significantly greater weight loss during 68 weeks. Further research is needed to assess the durability of these findings. Trial Registration: ClinicalTrials.gov Identifier: NCT03611582.

Regional differences in turnover, composition, and mechanics of the porcine flexor tendon.

PURPOSE: Recent data suggest that there is a lack of turnover in the core of human tendon, but it remains unknown whether there are regional differences between core and periphery of the cross section. The purpose of this project was to investigate regional differences in turnover as estimated by the accumulation of fluorescent Advanced Glycation End-products (AGEs) and regional differences in mechanical properties. MATERIALS AND METHODS: Tendons were obtained from lean control (n = 4) and diabetic Göttingen minipigs (streptozotocin-induced, n = 6). The deep digital flexor tendon of one hind limb was separated into a proximal, central and distal part. Autofluorescence was measured in the core and periphery of the proximal and distal parts of the tendon, and mechanical properties were tested on fascicles taken from the core and periphery of the central tendon (only diabetic animals). RESULTS: Autofluorescence was greater in the proximal than the distal part. In the distal part of the lean control animals, autofluorescent AGE accumulation was also greater in the core than the periphery. Peak modulus in the core region (704 ± 79 MPa) was higher than the periphery (466 ± 53 MPa, p < 0.05) in diabetic tendons. CONCLUSION: Taken together, autofluorescence varied both along the length and across the tendon cross section, indicating higher turnover in the distal and peripheral regions. In addition, mechanical properties differed across the tendon cross-section.

Prevalence of Baseline Cardiac Arrhythmias in Participants with Overweight or Obesity in Phase 1 Clinical Trials: Analysis of 24-Hour Holter Electrocardiogram Recordings.

Although estimates of the prevalence of cardiac arrhythmias in healthy volunteers exist, there is a lack of baseline data in other specific populations, such as people living with overweight and obesity, who are increasingly involved in clinical trials. This study investigated the baseline prevalence of arrhythmias in participants with overweight or obesity in 2 phase 1 trials of weight management medications (NCT03661879, NCT03308721). Participants aged 18-55 years, without a history of cardiovascular disease, and with body mass index (BMI) of 25.0-39.9 kg/m2 , were screened for abnormalities in vital signs, electrocardiogram (ECG) recordings, and electrolytes. Baseline 24-hour ECG (Holter) data were collected and manually reviewed by a cardiologist. The primary endpoint was the proportion of participants with ≥1 episode of the predefined cardiac arrhythmias. Continuous 12-lead ECG data were obtained from 207 participants. Most arrhythmias occurred in <3% of participants. Atrioventricular blocks and other potentially malignant arrhythmias were uncommon. There were no associations with age, sex, or BMI. Prevalence of atrioventricular blocks, nonsustained ventricular tachycardia, and other potentially malignant arrhythmias mirrored those reported in healthy participants with normal weight. In clinical trials of weight management medication, knowledge of the baseline prevalence of arrhythmias in people with overweight and obesity may inform trial eligibility criteria, improve on-trial decisions, and could be useful in discussions with health authorities. Baseline Holter readings and real-time ECG telemetry monitoring should be considered in such trials if arrhythmia risk is intrinsic to the molecule, or when signals have been observed in preclinical studies.

Efficacy and Safety of Liraglutide 3.0 mg in Individuals With Overweight or Obesity and Type 2 Diabetes Treated With Basal Insulin: The SCALE Insulin Randomized Controlled Trial.

OBJECTIVE: Most individuals with type 2 diabetes also have obesity, and treatment with some diabetes medications, including insulin, can cause further weight gain. No approved chronic weight management medications have been prospectively investigated in individuals with overweight or obesity and insulin-treated type 2 diabetes. The primary objective of this study was to assess the effect of liraglutide 3.0 mg versus placebo on weight loss in this population. RESEARCH DESIGN AND METHODS: Satiety and Clinical Adiposity-Liraglutide Evidence (SCALE) Insulin was a 56-week, randomized, double-blind, placebo-controlled, multinational, multicenter trial in individuals with overweight or obesity and type 2 diabetes treated with basal insulin and ≤2 oral antidiabetic drugs. RESULTS: Individuals were randomized to liraglutide 3.0 mg (n = 198) or placebo (n = 198), combined with intensive behavioral therapy (IBT). At 56 weeks, mean weight change was -5.8% for liraglutide 3.0 mg versus -1.5% with placebo (estimated treatment difference -4.3% [95% CI -5.5; -3.2]; P < 0.0001). With liraglutide 3.0 mg, 51.8% of individuals achieved ≥5% weight loss versus 24.0% with placebo (odds ratio 3.41 [95% CI 2.19; 5.31]; P < 0.0001). Liraglutide 3.0 mg was associated with significantly greater reductions in mean HbA1c and mean daytime glucose values and less need for insulin versus placebo, despite a treat-to-glycemic-target protocol. More hypoglycemic events were observed with placebo than liraglutide 3.0 mg. No new safety or tolerability issues were observed. CONCLUSIONS: In individuals with overweight or obesity and insulin-treated type 2 diabetes, liraglutide 3.0 mg as an adjunct to IBT was superior to placebo regarding weight loss and improved glycemic control despite lower doses of basal insulin and without increases in hypoglycemic events.

Noninvasive 64Cu-ATSM and PET/CT assessment of hypoxia in rat skeletal muscles and tendons during muscle contractions.

UNLABELLED: The purpose of the present study was to investigate exercise-related changes in oxygenation in rat skeletal muscles and tendons noninvasively with PET/CT and the hypoxia-selective tracer (64)Cu-diacetyl bis(N(4)-methylthiosemicarbazone) (ATSM) and to quantitatively study concomitant changes in gene expression of 2 hypoxia-related genes, hypoxia-inducible factor 1alpha (HIF1alpha) and carbonic anhydrase III (CAIII). METHODS: Two groups of Wistar rats performed 1-leg contractions of the calf muscle by electrostimulation of the sciatic nerve. After 10 min of muscle contractions, (64)Cu-ATSM was injected and contractions were continued for 20 min. PET/CT of both hind limbs was performed immediately and 1 h after the contractions. The exercise group (n = 8) performed only muscle contractions as described, whereas the other group, exercise plus cuff (n = 8), in addition underwent cuff-induced hypoxia during the first PET/CT scan. Standardized uptake values (SUVs) were calculated for the Achilles tendons and triceps surae muscles and were correlated to gene expression of HIF1alpha and CAIII using real-time polymerase chain reaction. RESULTS: Immediately after the contractions, uptake of (64)Cu-ATSM was significantly increased, by approximately 1.5-fold in muscles and 1.3-fold in tendons, compared with resting conditions. The significant increase was maintained in late PET scans in stimulated muscles and tendons independently of cuff application. In muscles, SUV correlated significantly with gene expression of HIF1alpha and CAIII, whereas this coherence was not found in tendons. CONCLUSION: We found enhanced uptake of (64)Cu-ATSM in both early and late PET scans, thereby supporting the possibility that (64)Cu-ATSM registers exercise-induced transient hypoxia in both skeletal muscles and force-transmitting tendons. The fact that skeletal muscles but not tendons showed upregulation of HIF1alpha and CAIII could indicate that healthy tendons are less responsive than skeletal muscles to low levels of oxygen.

18F-fluorodeoxyglucose and PET/CT for noninvasive study of exercise-induced glucose uptake in rat skeletal muscle and tendon.

PURPOSE: To investigate exercise-related glucose uptake in rat muscle and tendon using PET/CT and to study possible explanatory changes in gene expression for the glucose transporters (GLUT1 and GLUT4). METHODS: The sciatic nerve in eight Wistar rats was subjected to electrostimulation to cause unilateral isometric contractions of the calf muscle. (18)F-Fluorodeoxyglucose was administered and a PET/CT scan of the hindlimbs was performed. SUVs were calculated in both Achilles tendons and the triceps surae muscles. To exclude a spill-over effect the tendons and muscles from an ex vivo group of eight rats were cut out and scanned separately (distance>or=1 cm). RESULTS: Muscle contractions increased glucose uptake approximately sevenfold in muscles (p<0.001) and 36% in tendons (p<0.01). The ex vivo group confirmed the increase in glucose uptake in intact animals. GLUT1 and GLUT4 were expressed in both skeletal muscle and tendon, but no changes in mRNA levels could be detected. CONCLUSION: PET/CT can be used for studying glucose uptake in rat muscle and tendon in relation to muscle contractions; however, the increased uptake of glucose was not explained by changes in gene expression of GLUT1 and GLUT4.

Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women.

The knowledge about the effect of estradiol on tendon connective tissue is limited. Therefore, we studied the influence of estradiol on tendon synthesis, structure, and biomechanical properties in postmenopausal women. Nonusers (control, n = 10) or habitual users of oral estradiol replacement therapy (ERT, n = 10) were studied at rest and in response to one-legged resistance exercise. Synthesis of tendon collagen was determined by stable isotope incorporation [fractional synthesis rate (FSR)] and microdialysis technique (NH(2)-terminal propeptide of type I collagen synthesis). Tendon area and fibril characteristics were determined by MRI and transmission electron microscopy, whereas tendon biomechanical properties were measured during isometric maximal voluntary contraction by ultrasound recording. Tendon FSR was markedly higher in ERT users (P < 0.001), whereas no group difference was seen in tendon NH(2)-terminal propeptide of type I collagen synthesis (P = 0.32). In ERT users, positive correlations between serum estradiol (s-estradiol) and tendon synthesis were observed, whereas change in tendon synthesis from rest to exercise was negatively correlated to s-estradiol. Tendon area, fibril density, fibril volume fraction, and fibril mean area did not differ between groups. However, the percentage of medium-sized fibrils was higher in ERT users (P < 0.05), whereas the percentage of large fibrils tended to be greater in control (P = 0.10). A lower Young's modulus (GPa/%) was found in ERT users (P < 0.05). In conclusion, estradiol administration was associated with higher tendon FSR and a higher relative number of smaller fibrils. Whereas this indicates stimulated collagen turnover in the resting state, collagen responses to exercise were negatively associated with s-estradiol. These results indicate a pivotal role for estradiol in maintaining homeostasis of female connective tissue.

Imaging of Prostate Cancer Using Urokinase-Type Plasminogen Activator Receptor PET.

Urokinase-type plasminogen activator receptor (uPAR) overexpression is an important biomarker for aggressiveness in cancer including prostate cancer (PC) and provides independent clinical information in addition to prostate-specific antigen and Gleason score. This article focuses on uPAR PET as a new diagnostic and prognostic imaging biomarker in PC. Many preclinical uPAR-targeted PET imaging studies using AE105 in cancer models have been undertaken with promising results. A major breakthrough was obtained with the recent human translation of uPAR PET in using 64Cu- and 68Ga-labelled versions of AE105, respectively. Clinical results from patients with PC included in these studies are encouraging and support continuation with large-scale clinical trials.

Urokinase Plasminogen Activator Receptor-PET with 68Ga-NOTA-AE105: First Clinical Experience with a Novel PET Ligand.

Urokinase plasminogen activator receptor (uPAR) is a key component in proteolysis and extracellular matrix degradation during cancer invasion and metastasis. uPAR overexpression is an important biomarker for aggressiveness in several solid tumors and provides independent clinical information. A recent major breakthrough was obtained with human translation of uPAR PET using 68Ga-NOTA-AE105. Clinical results are encouraging and several large-scale clinical trials are now ongoing. This review focuses on uPAR PET with 68Ga-NOTA-AE105 as a new broadly applicable diagnostic and prognostic imaging biomarker in cancer.

An advanced glycation endproduct (AGE)-rich diet promotes accumulation of AGEs in Achilles tendon.

Advanced Glycation Endproducts (AGEs) accumulate in long-lived tissue proteins like collagen in bone and tendon causing modification of the biomechanical properties. This has been hypothesized to raise the risk of orthopedic injury such as bone fractures and tendon ruptures. We evaluated the relationship between AGE content in the diet and accumulation of AGEs in weight-bearing animal Achilles tendon. Two groups of mice (C57BL/6Ntac) were fed with either high-fat diet low in AGEs high-fat diet (HFD) (n = 14) or normal diet high in AGEs (ND) (n = 11). AGE content in ND was six to 50-fold higher than HFD The mice were sacrificed at week 40 and Achilles and tail tendons were carefully excised to compare weight and nonweight-bearing tendons. The amount of the AGEs carboxymethyllysine (CML), methylglyoxal-derived hydroimidazolone (MG-H1) and carboxyethyllysine (CEL) in Achilles and tail tendon was measured using ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and pentosidine with high-pressure liquid chromatography (HPLC) with fluorescent detection. AGEs in Achilles tendon were higher than in tail tendon for CML (P < 0.0001), CEL (P < 0.0001), MG-H1 and pentosidine (for both ND and HFD) (P < 0.0001). The AGE-rich diet (ND) resulted in an increase in CML (P < 0.0001), MG-H1 (P < 0.001) and pentosidine (P < 0.0001) but not CEL, in Achilles and tail tendon. This is the first study to provide evidence for AGE accumulation in injury-prone, weight-bearing Achilles tendon associated with intake of an AGE-rich diet. This indicates that food-derived AGEs may alter tendon properties and the development of tendon injuries.

Safety, Dosimetry, and Tumor Detection Ability of 68Ga-NOTA-AE105: First-in-Human Study of a Novel Radioligand for uPAR PET Imaging.

The overexpression of urokinase-type plasminogen activator receptors (uPARs) represents an established biomarker for aggressiveness in most common malignant diseases, including breast cancer (BC), prostate cancer (PC), and urinary bladder cancer (UBC), and is therefore an important target for new cancer therapeutic and diagnostic strategies. In this study, uPAR PET imaging using a 68Ga-labeled version of the uPAR-targeting peptide (AE105) was investigated in a group of patients with BC, PC, and UBC. The aim of this first-in-human, phase I clinical trial was to investigate the safety and biodistribution in normal tissues and uptake in tumor lesions. Methods: Ten patients (6 PC, 2 BC, and 2 UBC) received a single intravenous dose of 68Ga-NOTA-AE105 (154 ± 59 MBq; range, 48-208 MBq). The biodistribution and radiation dosimetry were assessed by serial whole-body PET/CT scans (10 min, 1 h, and 2 h after injection). Safety assessment included measurements of vital signs with regular intervals during the imaging sessions and laboratory blood screening tests performed before and after injection. In a subgroup of patients, the in vivo stability of 68Ga-NOTA-AE105 was determined in collected blood and urine. PET images were visually analyzed for visible tumor uptake of 68Ga-NOTA-AE105, and SUVs were obtained from tumor lesions by manually drawing volumes of interest in the malignant tissue. Results: No adverse events or clinically detectable pharmacologic effects were found. The radioligand exhibited good in vivo stability and fast clearance from tissue compartments primarily by renal excretion. The effective dose was 0.015 mSv/MBq, leading to a radiation burden of 3 mSv when the clinical target dose of 200 MBq was used. In addition, radioligand accumulation was seen in primary tumor lesions as well as in metastases. Conclusion: This first-in-human, phase I clinical trial demonstrates the safe use and clinical potential of 68Ga-NOTA-AE105 as a new radioligand for uPAR PET imaging in cancer patients.

PET imaging of urokinase-type plasminogen activator receptor (uPAR) in prostate cancer: current status and future perspectives.

Overexpression of urokinase-type plasminogen activator receptors (uPAR) represents an important biomarker for aggressiveness in most common malignant diseases, including prostate cancer (PC). Accordingly, uPAR expression either assessed directly in malignant PC tissue or assessed directly in plasma (intact/cleaved forms)-provides independent additional clinical information to that contributed by PSA, Gleason score, and other relevant pathological and clinical parameters. In this respect, non-invasive molecular imaging by positron emission tomography (PET) offers a very attractive technology platform, which can provide the required quantitative information on the uPAR expression profile, without the need for invasive procedures and the risk of missing the target due to tumor heterogeneity. These observations support non-invasive PET imaging of uPAR in PC as a clinically relevant diagnostic and prognostic imaging method. In this review, we will focus on the recent development of uPAR PET and the relevance within prostate cancer imaging. Novel antibody and small-molecule radiotracers-targeting uPAR, including a series of uPAR-targeting PET ligands, based on the high affinity peptide ligand AE105, have been synthesized and tested in vitro and in vivo in preclinical murine xenograft models and, recently, in a first-ever clinical uPAR PET study in cancer patients, including patients with PC. In this phase I study, a high and specific uptake of the tracer 64Cu-DOTA-AE105 was found in both primary tumors and lymph node metastases. The results are encouraging and support large-scale clinical trials to determine the utility of uPAR PET in the management of patients with PC with the goal of improving outcome.

Urokinase-Type Plasminogen Activator Receptor as a Potential PET Biomarker in Glioblastoma.

UNLABELLED: Glioblastoma is one of the most malignant types of human cancer, and the prognosis is poor. The development and validation of novel molecular imaging biomarkers has the potential to improve tumor detection, grading, risk stratification, and treatment monitoring of gliomas. The aim of this study was to explore the potential of PET imaging of the urokinase-type plasminogen activator receptor (uPAR) in glioblastoma. METHODS: The uPAR messenger RNA expression of tumors from 19 glioblastoma patients was analyzed, and a cell culture derived from one of these patients was used to establish an orthotopic xenograft model of glioblastoma. Tumor growth was monitored using bioluminescence imaging. Five to six weeks after inoculation, all mice were scanned with small-animal PET/CT using two new uPAR PET ligands ((64)Cu-NOTA-AE105 and (68)Ga-NOTA-AE105) and, for comparison, O-(2-(18)F-fluoroethyl)-l-tyrosine ((18)F-FET). One MRI scan was obtained for each mouse to confirm tumor location. The uPAR specificity of (64)Cu-NOTA-AE105 was confirmed by alignment of hematoxylin- and eosin-stained and uPAR immunohistochemistry-stained slides of the brain with the activity distribution as determined using autoradiography. RESULTS: uPAR expression was found in all 19 glioblastoma patient tumors, and high expression of uPAR correlated with decreased overall survival (P = 0.04). Radiolabeling of NOTA-AE105 with (64)Cu and (68)Ga was straightforward, resulting in a specific activity of approximately 20 GBq/µmol and a radiochemical purity of more than 98% for (64)Cu-NOTA-AE105 and more than 97% for (68)Ga-NOTA-AE105. High image contrast resulting in clear tumor delineation was found for both (68)Ga-NOTA-AE105 and (64)Cu-NOTA-AE105. Absolute uptake in tumor was higher for (18)F-FET (3.5 ± 0.8 percentage injected dose [%ID]/g) than for (64)Cu-NOTA-AE105 (1.2 ± 0.4 %ID/g) or (68)Ga-NOTA-AE105 (0.4 ± 0.1 %ID/g). A similar pattern was observed in background brain tissue, where uptake was 1.9 ± 0.1 %ID/g for (18)F-fluorothymidine, compared with 0.05 ± 0.01 %ID/g for (68)Ga-NOTA-AE105 and 0.11 ± 0.02 %ID/g for (64)Cu-NOTA-AE105. The result was a significantly higher tumor-to-background ratio for both (68)Ga-NOTA-AE105 (7.6 ± 2.1, P < 0.05) and (64)Cu-NOTA-AE105 (10.6 ± 2.3, P < 0.01) than for (18)F-FET PET (1.8 ± 0.3). Autoradiography of brain slides confirmed that the accumulation of (64)Cu-NOTA-AE105 corresponded well with uPAR-positive cancer cells. CONCLUSION: On the basis of our translational study, uPAR PET may be a highly promising imaging biomarker for glioblastoma. Further clinical exploration of uPAR PET in glioblastoma is therefore justified.

(123)I-MIBG Scintigraphy in the Subacute State of Takotsubo Cardiomyopathy.

OBJECTIVES: The study sought to investigate adrenergic activity in patients with takotsubo cardiomyopathy (TTC). BACKGROUND: TTC is a specific type of reversible heart failure possibly caused by excessive catecholamine stimulation of the myocardium. Scintigraphic iodine-123-meta-iodobenzylguanidine (mIBG) imaging of the heart and measurement of plasma catecholamines can be used to assess adrenergic activity in vivo. The authors hypothesized that sympathetic nerve activity is increased in the subacute state of TTC, and this study used cardiac mIBG imaging and plasma levels of norepinephrine and epinephrine as markers to assess this hypothesis. METHODS: In this study, 32 patients with TTC and 20 controls were examined at admission and again on follow-up with echocardiography, mIBG scintigraphy, and plasma catecholamine measurements. RESULTS: Ejection fraction (EF) was initially 36 ± 9% but increased to >60% (p = 0.0004) in all patients with TTC. In the control subjects EF was initially higher (51 ± 11%; p = 0.0004) than in the patients with TTC. However, EF of the patients with TTC exceeded that of the control subjects on follow-up (56 ± 8%; p = 0.0007). The mIBG imaging showed a lower late (4-h) heart-to-mediastinum ratio (H/Mlate) (2.00 ± 0.38) and a higher washout rate (WR) (45 ± 12%) in the subacute state of TTC, both when compared with follow-up (H/Mlate: 2.42 ± 0.45; p = 0.0004; WR: 33 ± 14%; p = 0.0004) and when compared with the control group in the subacute state (H/Mlate: 2.34 ± 0.60, p = 0.035; WR: 33 ± 19%, p = 0.026). On follow-up, no differences in mIBG parameters were observed between the TTC and control groups (H/Mlate: 2.41 ± 0.51, p = 0.93; WR: 30 ± 13%, p = 0.48) group. In the TTC group, plasma epinephrine levels were elevated in the subacute state (Log2[epinephrine]: 6.13 ± 1.04 pg/ml), both when compared with follow-up (5.25 ± 0.62 pg/ml; p = 0.0004) and when compared with the control group in the subacute state (5.46 ± 0.69 pg/ml; p = 0.044), and these levels remained elevated in the TTC group on follow-up compared with the control group (4.56 ± 0.95 pg/ml; p = 0.014). No significant differences in plasma norepinephrine levels were observed. CONCLUSIONS: The present study supports a possible role of adrenergic hyperactivity in TTC.

First-in-human uPAR PET: Imaging of Cancer Aggressiveness.

A first-in-human clinical trial with Positron Emission Tomography (PET) imaging of the urokinase-type plasminogen activator receptor (uPAR) in patients with breast, prostate and bladder cancer, is described. uPAR is expressed in many types of human cancers and the expression is predictive of invasion, metastasis and indicates poor prognosis. uPAR PET imaging therefore holds promise to be a new and innovative method for improved cancer diagnosis, staging and individual risk stratification. The uPAR specific peptide AE105 was conjugated to the macrocyclic chelator DOTA and labeled with (64)Cu for targeted molecular imaging with PET. The safety, pharmacokinetic, biodistribution profile and radiation dosimetry after a single intravenous dose of (64)Cu-DOTA-AE105 were assessed by serial PET and computed tomography (CT) in 4 prostate, 3 breast and 3 bladder cancer patients. Safety assessment with laboratory blood screening tests was performed before and after PET ligand injection. In a subgroup of the patients, the in vivo stability of our targeted PET ligand was determined in collected blood and urine. No adverse or clinically detectable side effects in any of the 10 patients were found. The ligand exhibited good in vivo stability and fast clearance from plasma and tissue compartments by renal excretion. In addition, high uptake in both primary tumor lesions and lymph node metastases was seen and paralleled high uPAR expression in excised tumor tissue. Overall, this first-in-human study therefore provides promising evidence for safe use of (64)Cu-DOTA-AE105 for uPAR PET imaging in cancer patients.