Sodium-glucose cotransporter 2 (SGLT2) inhibition reduces cardiovascular morbidity and mortality in individuals with type 2 diabetes. Beneficial effects have been attributed to increased ketogenesis, reduced cardiac fatty acid oxidation and diminished cardiac oxygen consumption. We therefore studied whether SGLT2 inhibition altered cardiac oxidative substrate consumption, efficiency, and perfusion. <p>13 individuals with type 2 diabetes were studied after four weeks treatment with empagliflozin and placebo in a randomized, double-blind, placebo-controlled crossover study. Myocardial palmitate and glucose uptake were measured with <sup>11</sup>C-palmitate and <sup>18</sup>F-FDG PET/CT. Oxygen consumption and myocardial external efficiency (MEE) were measured with <sup>11</sup>C-acetate PET/CT. Resting and adenosine stress myocardial blood flow (MBF) and myocardial flow reserve (MFR) were measured using <sup>15</sup>O-H<sub>2</sub>O PET/CT. </p> <p>Empagliflozin did not affect myocardial FFA uptake but reduced myocardial glucose uptake by 57% (p<0.001). Empagliflozin did not change myocardial oxygen consumption or MEE. Empagliflozin reduced resting MBF by 13% (p<0.01), but did not significantly affect stress MBF or MFR.</p> <p>In conclusion, SGLT2 inhibition did not affect myocardial FFA uptake, but channeled myocardial substrate utilization from glucose towards other sources and reduced resting MBF. However, the observed metabolic and hemodynamic changes were modest and most likely contribute only partially to the cardioprotective effect of SGLT2 inhibition. </p>
Introduction:Despite the decades long use of [11C]palmitate positron emission tomography (PET)/computed tomography in basic metabolism studies, only personal communications regarding dosimetry and biodistribution data have been published.Methods:Dosimetry and biodistribution studies were performed in 2 pigs and 2 healthy volunteers by whole-body [11C]palmitate PET scans. Metabolite studies were performed in 40 participants (healthy and with type 2 diabetes) under basal and hyperinsulinemic conditions. Metabolites were estimated using 2 approaches and subsequently compared: Indirect [11C]CO2 release and parent [11C]palmitate measured by a solid-phase extraction (SPE) method. Finally, myocardial fatty acid uptake was calculated in a patient cohort using input functions derived from individual metabolite correction compared with population-based metabolite correction.Results:In humans, mean effective dose was 3.23 (0.02) µSv/MBq, with the liver and myocardium receiving the highest absorbed doses. Metabolite correction using only [11C]CO2 estimates underestimated the fraction of metabolites in studies lasting more than 20 minutes. Population-based metabolite correction showed excellent correlation with individual metabolite correction in the cardiac PET validation cohort.Conclusion:First, mean effective dose of [11C]palmitate is 3.23 (0.02) µSv/MBq in humans allowing multiple scans using ∼300 MBq [11C]palmitate, and secondly, population-based metabolite correction compares well with individual correction.
Background: Aggressive non-Hodgkin lymphoma (aNHL) relapsing after high-dose therapy or, in not transplant-eligible patients, after 1st-line chemotherapy represents an unmet clinical need. Therefore, we aimed at evaluating a salvage combination regimen based on pixantrone, an aza-anthracenadione recently approved in Europe for patients with multiply relapsed aNHL. Etoposide and bendamustine were chosen as companion compounds due to available feasibility data in combination with anthracenadions, and a well-documented efficacy in salvage regimens for relapsed aNHL. Rituximab was added, if the relapse tumor biopsy was CD20+. Aim: The aim of the present analysis was to summarize the preliminary clinical experience with the PREBEN/PEBEN regimen gathered, on a compassionate need basis, at different European sites and representing the platform for a currently ongoing Nordic phase 1/2 trial in relapsed aNHL. Methods: The adopted schedule consisted of pixantrone 50 mg/m2 i.v. day 1+8, etoposide 100 mg i.v. day 1, bendamustine 90 mg i.v. day 1 with or without the addition of rituximab 375 mg/m2 i.v. day 1 (PREBEN/PEBEN). If feasible, each cycle was given at 3-weekly intervals for a maximum of 6 cycles. All patients were assessed for chemosensitivity with PET/CT, already after cycle 1 or 2. G-CSF support was applied and administered according to local practice. Results: A total of 30 heavily pre-treated patients (19 males and 11 females, age range 49-81 yrs; mean N of previous regimens: 3, range 1-7) with aNHL were treated according to the PREBEN/PEBEN schedule. Seventeen had diffuse large B-cell (DLBCL), six transformed indolent (tIND), and seven peripheral T-cell lymphoma (PTCL). All patients had intermediate or high risk IPI prior to start of salvage therapy. Eight patients (27%) had a complete metabolic response (CMR) and seven (23%) a partial one (PMR), resulting in an overall response rate (ORR) of 50%. Among the histological subtypes, the patients with DLBCL, PTCL and tIND had an ORR of 53% (CMR 35%), 57% (CMR 14%), and 33% (CMR in one out of two responders), respectively. Most responses were achieved early (prior to course nr. 4). Response durations ranged between 2 and 23+ months. Among the 17 patients with DLBCL, nine were frail, non transplant-eligible with relapsed disease, six had primary refractory lymphoma progressing through anthracycline-containing 1st line and platinum-containing salvage therapies, and two had relapses occurring after a post-transplant remission period. While most of the relapsed patients with DLBCL responded , i.e. seven (five CMR and two PMR) of the nine (78%) frail relapsed patients and one of the two (50%) patients with post-transplant relapses, only one out six (17%) primary refractory patients exhibited some chemosensitivity. Interestingly, four out of seven PTCL patients achieved a PMR or CMR allowing them to undergo non-myeloablative allogeneic transplant with subsequent sustained response durations. The treatment schedule was feasible and most patients received it on an out-patient basis. The most common grade 3-4 toxicity was of hematological type (mainly neutropenia and thrombocytopenia), occurring in 52% of the patients. Grade 3-4 infections were observed at a frequency of 21%. No septic deaths were recorded. A previously anthracycline exposed, heavily pre-treated 60-year old female PTCL patient developed symptomatic congestive heart failure effectively reversed by angiotensin converting enzyme inhibitors with normalization of the myocardial ejection fraction. One previously ibritumomab tiuxetan exposed, heavily pretreated patient with tIND developed acute myeloid leukemia with therapy-related cytogenetic features. Conclusions: The PREBEN/PEBEN salvage regimen was feasible in a heavily pre-treated cohort of elderly patients with high-risk aNHL. In individual patients it elicited substantial and durable responses early in the course of therapy. In some younger patients, it proved useful as bridging strategy to a non-myeloablative allogeneic transplant. A phase 1/2 study in relapsed (non-refractory) aNHL was launched in June 2016 (ClinicalTrial.gov identifier: NCT02678299; EudraCT number: 2015-000758-39) and is currently accruing (N=5 pr. Aug 1st, 2016). Disclosures Clausen: Takeda: Research Funding; Novartis: Other: Travel expences; Abbvie: Other: Travel expences. Leppa:Mundipharma: Research Funding; Roche: Honoraria, Other: Travel expenses, Research Funding; Bayer: Research Funding; Janssen: Research Funding; Takeda: Honoraria, Other: Travel expenses; CTI Life Sciences: Honoraria; Amgen: Research Funding; Merck: Other: Travel expenses. Willenbacher:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; European Commision: Research Funding. d'Amore:Servier: Honoraria, Other: Advisory Boards; CTI LIfe Sciences: Honoraria, Other: Advisory Boards.
Purpose: Copper is essential for enzymatic processes throughout the body. [64Cu]copper (64Cu) positron emission tomography (PET) has been investigated as a diagnostic tool for certain malignancies, but has not yet been used to study copper homeostasis in humans. In this study, we determined the hepatic removal kinetics, biodistribution and radiation dosimetry of 64Cu in healthy humans by both intravenous and oral administration of the radiotracer. Methods: Six healthy participants underwent PET/CT studies with intravenous or oral administration of 64Cu. A 90 min dynamic PET scan of the liver was followed by three whole-body PET/CT scans at 1.5, 6, and 20 h after tracer administration. PET data were used for estimation of hepatic kinetics, biodistribution, effective doses, and absorbed doses for critical organs. Results: After intravenous administration, 64Cu uptake was highest in the liver, intestinal walls and pancreas; the gender-averaged effective dose was 62 ± 5 μSv/MBq (mean ± SD). After oral administration, 64Cu was almost exclusively taken up by the liver while leaving a significant amount of residual radiotracer in the gastrointestinal lumen, resulting in an effective dose of 113 ± 1 μSv/MBq. Excretion of 64Cu in urine and faeces after intravenous administration was negligible. Hepatic removal kinetics showed that 64Cu clearance from blood was 0.10 ± 0.02 mL blood/min/mL liver tissue, and the rate constant for excretion into bile or blood was 0.003 ± 0.002 min-1. Conclusion: 64Cu biodistribution and radiation dosimetry are affected by the manner of tracer administration with high uptake by the liver, intestinal walls, and pancreas after intravenous administration; after oral administration, 64Cu is rapidly absorbed from the gastrointestinal tract and deposited primarily in the liver. Administration of 50 MBq 64Cu yielded images of high quality for both administration forms with radiation doses approximately 3.1 and 5.7 mSv, respectively, allowing for sequential studies in humans.Trial Registration Number: EudraCT no. 2016-001975-59. Registration date: 19/09/2016.
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