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Simple Summary: Peptide receptor radionuclide therapy with 177Lu-DOTATATE is an efficient treatment for patients suffering from metastasized neuroendocrine tumours. Nevertheless, suboptimal effects have been observed in the majority of patients. Hence, strategies to improve 177Lu-DOTATATE efficacy are desirable. Lu-177 induces oxidative stress, eventually leading to tumour cell death. Inhibition of the antioxidant defence mechanisms, using buthionine sulfoximine (BSO), represents an attractive strategy to increase 177Lu-DOTATATE efficacy. In cells and an animal model, the combination of 177Lu-DOTATATE and BSO was more effective than 177Lu-DOTATATE alone. In addition, it did not result in additional toxicity. Targeting the antioxidant defence system opens new safe treatment combination opportunities with 177Lu-DOTATATE. Peptide receptor radionuclide therapy with 177Lu-DOTATATE improves the outcome of patients with somatostatin receptor (SSTR)-expressing neuroendocrine tumours. Nevertheless, stable disease has been the main response pattern observed, with some rare complete responses. Lu-177 exerts about two-thirds of its biological effects via the indirect effects of ionizing radiation that generate reactive oxygen species, eventually leading to oxidative damage and cell death. This provides a rationale for targeting the antioxidant defence system in combination with 177Lu-DOTATATE. In the present study, the radiosensitizing potential and the safety of depleting glutathione (GSH) levels using buthionine sulfoximine (BSO) during 177Lu-DOTATATE therapy were assessed in vitro and in vivo using a xenograft mouse model. In vitro, the combination resulted in a synergistic effect in cell lines exhibiting a BSO-mediated GSH decrease. In vivo, BSO neither influenced 177Lu-DOTATATE biodistribution nor induced liver, kidney or bone marrow toxicity. In terms of efficacy, the combination resulted in reduced tumour growth and metabolic activity. Our results showed that disturbing the cell redox balance using a GSH synthesis inhibitor increased 177Lu-DOTATATE efficacy without additional toxicity. Targeting the antioxidant defence system opens new safe treatment combination opportunities with 177Lu-DOTATATE. [ABSTRACT FROM AUTHOR]

Background: Gastroenteropancreatic neuroendocrine neoplasms (GEPNENs) are heterogeneous in clinical course, biology, and outcomes. The NETPET score predicts survival by scoring uptake on dual [68Ga]DOTATATE and [18F]FDG PET/CT scans. We aimed to validate previous single-centre findings in a multicentre, international study.Methods: Dual scans were assigned a NETPET score of P1 (DOTATATE positive/FDG negative), P2-4 (DOTATATE positive/FDG positive), or P5 (DOTATATE negative/FDG positive). NETPET score, histological grade, age at diagnosis, and presence/absence of extrahepatic disease were compared to overall survival/time to progression on univariate and multivariate analysis.Results: 319 metastatic/unresectable GEPNEN patients were included. The NETPET score was significantly associated with overall survival and time to progression on univariate and multivariate analysis (all p < 0.01). Median overall survival/time to progression was 101.8/25.5 months for P1, 46.5/16.7 months for P2-4, and 11.5/6.6 months for P5. Histological grade correlated with overall survival and time to progression on univariate and multivariate analysis (all p < 0.01), while presence/absence of extrahepatic disease did not. Age at diagnosis correlated with overall survival on univariate and multivariate analysis (p < 0.01). The NETPET score also correlated with histological grade (p < 0.001).Conclusion: This study validates the NETPET score as a prognostic biomarker in metastatic GEPNENs, capturing the complexity of dual PET imaging. [ABSTRACT FROM AUTHOR]

Introduction: Neuroendocrine neoplasms encompass well-differentiated tumors (NETs) and poorly differentiated carcinomas (neuroendocrine carcinomas [NECs]), which are distinguished by their clinical behavior and molecular characteristics. They can cause paraneoplastic syndromes, such as ectopic adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome (CS), necessitating prompt recognition and management due to severe hypercortisolism. Case Presentation: A 66-year-old patient with a 3-year history of metastatic mixed neuroendocrine-non-neuroendocrine neoplasm with a NEC and adenocarcinoma component originating from the vulva presented to the emergency department with dyspnea and fatigue. Upon clinical examination, we found widespread hyperpigmentation, a moon-face appearance, hirsutism, buffalo hump, and muscle atrophy. Laboratory investigations revealed severe hypokalemia (2.3 mmol/L), elevated serum cortisol (1,726 nmol/L) and ACTH (194 ng/L) levels. Urinary free cortisol measurement was 21-fold the upper limit of the reference range (3,614.0 nmol/24 h), and cortisol concentration did not decrease after 1mg-dexamethasone suppression test (1,812 nmol/L for an expected value <50 nmol/L), confirming the ACTH-dependent CS. Thoracoabdominal computed tomography (CT) scan demonstrated progressive neoplastic disease in the liver, kidney, lymph nodes, peritoneum, and lungs. Brain magnetic resonance imaging indicated multifocal metastatic infiltration but no evidence of pituitary adenoma. Interestingly, despite a previously negative 68Ga-DOTATATE positron emission tomography (PET)/CT performed 1 year prior, there was moderate somatostatin receptor (SSTR) expression in lymphatic, pulmonary, peritoneal, and bone tissues, suggesting the presence of a component with redifferentiation and re-expression of the SSTR. After the workup, the patient was admitted to a supportive care facility. Hypercortisolism symptoms were effectively managed with an adrenal enzyme inhibitor (ketoconazole) in combination with somatostatin analogs. Unfortunately, the patient was too frail to benefit from peptide receptor radionuclide therapy (PRRT). Conclusion: This redifferentiation phenomenon in neuroendocrine tumors should be further investigated as patients might be, under certain conditions, eligible for PRRT. Therefore, we suggest that newly occurring paraneoplastic syndromes in patients with NEC should always be evaluated using 68Ga-DOTATATE PET/CT. [ABSTRACT FROM AUTHOR]

Background: In order to obtain a reliable Lu-DOTATATE therapy dosimetry, it is crucial to acquire accurate and precise activity measurements with the radionuclide calibrator, the SPECT/CT camera, and the NaI(Tl) well counter. The aim of this study was to determine, in a clinical context, the accuracy and the precision of their activity quantification over a range of activities and time. Ninety-three Lu sources from the manufacturer were measured in the radionuclide calibrator over 2.5 years to evaluate its calibration accuracy and precision compared to the manufacturer's value. A NEMA 2012/IEC 2008 phantom was filled with a Lu activity concentration sphere-to-background ratio of five. It was acquired with the SPECT/CT camera to determine the reconstruction parameters offering the best compromise between partial volume effect and signal-to-noise ratio. The calibration factor was computed accordingly. The calibration quality was monitored over 2.5 years with 33 phantom acquisitions with activities ranging from 7040 to 0.6 MBq. Home-made sources were used to calibrate the well counter. Its reliability was evaluated with activities ranging from 150 to 0.2 kBq measured 34 times over 2.5 years. Results: For the radionuclide calibrator, median [interquartile range] for the error on activity measurement was −0.99 [1.31] %. The optimal SPECT reconstruction parameters were obtained with 16 iterations, 16 subsets and a 12-mm Gaussian post-filter. The calibration factor was 9.87 cps/MBq with an error of −1.05 [2.12] %. The well counter was calibrated with 31.5 cps/kBq, and the error was evaluated to −12.89 [16.55] %. Conclusions: The accuracy and the precision of activity quantification using dedicated quality control were found to be sufficient for use in dosimetry implemented in clinical routine. The proposed methodology could be implemented in other centres to obtain reproducible Lu-based treatment dosimetry. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the association among toxicity, dosimetry of organs-at-risk, and disease progression in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) treated with 177 Lu-DOTATATE., Patients and Methods: Thirty-seven patients with GEP-NETs underwent 177 Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in a single-arm, prospective, phase 2 study, where patients were followed up with blood tests, isotopic glomerular filtration rate (iGFR), and imaging examinations (CT/MRI and PET) every 6 months until disease progression. Adverse events (AEs) graded per CTCAEv4.03 and occurring during treatment were collected and followed up until resolution. Dosimetry, including biologically effective doses (BEDs) to kidneys, BED to bone marrow, and absorbed dose (AD) to spleen, was performed after each PRRT cycle. Statistical analyses explored associations among dosimetry, toxicity, and patient progression free-survival., Results: The most common AEs were anemia and lymphopenia (65%), followed by thrombocytopenia and fatigue (each 51%), alopecia (46%), and nausea (41%). The most common grade ≥3 AE was lymphopenia (43%). There was no grade ≥3 nephrotoxicity. The median iGFR % decrease was 11% ( P < 0.001), at a median follow-up of 23 months. iGFR %decrease and renal BED did not correlate (Spearman ρ = -0.09). Similarly, no significant association was found between bone marrow BED or spleen AD and the grades of hematological toxicities. We observed no association between progression free-survival and either the decline of renal function or the occurrence of hematological toxicities during PRRT., Conclusions: This study confirms the safety profile of 177 Lu-DOTATATE PRRT in patients with GEP-NETs irrespective of the dosimetry of organs at risk. Kidney, bone marrow, and spleen dosimetry measures were not associated with renal or hematological toxicity., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Our objective was to predict the outcome of peptide receptor radionuclide therapy (PRRT) using multimodality imaging and tumor dosimetry on gastroenteropancreatic neuroendocrine tumor (GEP-NET) lesions and patients. Methods: This prospective study included patients with progressive GEP-NETs. Treatment consisted of 4 cycles of 7.4 GBq of 177 Lu-DOTATATE. Imaging parameters were measured on 68 Ga-DOTATATE PET/CT (SUV max/mean , somatostatin receptor [SSTR] tumor volume [TV], total lesion SSTR expression, and tumor-to-blood and tumor-to-spleen ratios), 18 F-FDG PET/CT (SUV max/mean , metabolically active TV, and total lesion glycolysis), and diffusion-weighted MRI (apparent diffusion coefficient) in a maximum of 5 target lesions per patient at approximately 10 wk after each injection. Tumor dosimetry was performed using SPECT/CT at 3 time points for every cycle. Baseline imaging parameters, their relative changes after PRRT cycle 1 (C1), and the tumor-absorbed dose at C1 were correlated with lesion morphologic outcome. The average values of the imaging parameters and the minimal, maximal, and mean C1 tumor-absorbed dose in each patient were tested for association with progression-free survival (PFS) and best objective response (RECIST 1.1). Results: In the 37 patients, the median PFS was 28 mo. Eleven of the 37 (30%) achieved a partial response (RECIST 1.1). After a median follow-up of 57 mo, the median time to lesion progression had not been reached in 84 morphologically evaluable lesions, with only 12 (14%) progressing (size increase ≥ 20% from baseline). Patients receiving a minimal C1 dose of 35 Gy in all target lesions exhibited a significantly longer PFS (48.1 vs. 26.2 mo; hazard ratio, 0.37; 95% CI, 0.17-0.82; P = 0.02). Volumetric 68 Ga-DOTATATE PET parameters correlated with lesion and patient outcome: patients with an SSTR TV decrease of more than 10% after C1 had a longer PFS (51.3 vs. 22.8 mo; hazard ratio, 0.35; 95% CI, 0.16-0.75; P = 0.003). There was no statistical evidence of an association between other dosimetric or imaging parameters and the lesion or patient outcome. Conclusion: Minimal tumor-absorbed dose at C1 is predictive of outcome in patients with GEP-NETs treated with PRRT, providing a basis for personalized dosimetry-guided treatment strategies. An SSTR TV decrease after C1 could be used for early therapy response assessment as a predictor of PRRT outcome., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

[ 18 F]FDG PET/CT and [ 68 Ga]Ga-DOTATATE PET/CT are both used to predict tumor biology in neuroendocrine neoplasms. Although the presence of discordant ([ 18 F]FDG-avid/non-[ 68 Ga]Ga-DOTATATE-avid) disease predicts poor prognosis, the significance of the volume of such discordant disease remains undetermined. The aim of this study is to investigate discordant tumor volume as a potential biomarker in patients with advanced gastroenteropancreatic neuroendocrine neoplasms (GEPNENs). Methods: A multicenter retrospective study in patients with advanced GEPNENs and paired [ 18 F]FDG and [ 68 Ga]Ga-DOTATATE PET/CT no more than 85 d apart was conducted. Patients with discordant disease were identified by the NETPET score, and discordant lesions were contoured with a flat [ 18 F]FDG SUV cutoff of 4. The primary variable of interest was the total discordant volume (TDV), which was the sum of the volumes of discordant lesions. Patients were dichotomized into high- and low-TDV cohorts by the median value. The primary endpoint was overall survival. Results: In total, 44 patients were included (50% men; median age, 60 y), with primary cancers in the pancreas (45%), small bowel (23%), colon (20%), and other (12%). Of the patients, 5% had grade 1 disease, 48% had grade 2 disease, and 48% had grade 3 disease (24% well differentiated, 67% poorly differentiated, 10% unknown within the grade 3 cohort). The overall median survival was 14.1 mo. Overall survival was longer in the low-TDV cohort than in the high-TDV cohort (median volume, 43.7 cm 3 ; survival time, 23.8 mo vs. 9.4 mo; hazard ratio, 0.466 [95% CI, 0.229-0.948]; P = 0.0221). Patients with no more than 2 discordant intrahepatic lesions survived longer than those with 2 or more lesions (31.8 mo vs. 10.2 mo, respectively; hazard ratio, 0.389 [95% CI, 0.194-0.779]; P = 0.0049). Conclusion: TDV is a potential prognostic biomarker in GEPNENs and should be investigated in future neuroendocrine neoplasm trials., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

We aimed to evaluate the role of PET targeting the prostate-specific membrane antigen (PSMA) for response assessment in metastatic prostate cancer (PCa) patients treated with taxane-based chemotherapy (docetaxel or cabazitaxel) and its predictive value on patient outcome. Methods: We retrospectively evaluated 37 patients with metastatic hormone-sensitive PCa or metastatic castration-resistant PCa (mCRPC) who underwent 68 Ga-PSMA-11 PET/CT at baseline and after the last cycle of taxane-based chemotherapy (docetaxel or cabazitaxel) without treatment modification between scans. Biochemical response (BR) was defined as an undetectable or at least 50% decreased level of prostate-specific antigen, compared with baseline. Associations between BR and different PET parameters were tested. A cutoff of at least a 30% decrease in PSMA total tumor volume (PSMA-TV) was used to define a PSMA response (PSMA-R) versus a PSMA nonresponse (PSMA-NR). Correlations between PSMA PET/CT response and BR were evaluated using the ϕ-coefficient. Associations between PET response and overall survival (OS) was tested using Cox regression and the Kaplan-Meier method. Results: Our cohort comprised 8 (22%) metastatic hormone-sensitive PCa and 29 (78%) mCRPC patients. Twenty-one patients received docetaxel treatment, and 16 received cabazitaxel (median, 6 cycles; interquartile range, 5-8 cycles). BR was found in 18 of 37 patients. Using PSMA total tumor volume, PSMA PET/CT response was concordant with BR in 35 of 37 patients (ϕ = 0.89, P  < 0.0001). Eighteen of 37 patients had PSMA-R (6, complete response; 12, partial response), and 19 had PSMA-NR (17, progressive disease; 2, stable disease). After a median follow-up of 23 mo, there was a statistically significant longer OS for PSMA-R than for PSMA-NR (median OS not reached vs. 12 mo, respectively; hazard ratio, 0.10; 95% CI, 0.03-0.39; P  = 0.001) for the entire population. Among the mCRPC subgroup, differences in OS were also observed (median, 22 vs. 12 mo, respectively; hazard ratio, 0.22; 95% CI, 0.06-0.82; P  = 0.023), with a 12-mo OS rate of 100% for PSMA-R and 52% for PSMA-NR ( P  = 0.011). Conclusion: This retrospective analysis suggests that 68 Ga-PSMA-11 PET/CT is a promising imaging modality for assessing response to taxane-based chemotherapy in metastatic PCa. Changes in PSMA expression might be used as a predictive biomarker for OS to help tailor individual therapy and select eligible patients for clinical trials., (© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)

We investigated on the added prognostic value of a three-scale combined molecular imaging with 68 Ga-DOTATATE and 18 F-FDG PET/CT, (compared to Ki-67 based histological grading), in gastroenteropancreatic neuroendocrine neoplasia patients. 85 patients with histologically proven metastatic gastroenteropancreatic neuroendocrine neoplasias, who underwent combined PET/CT imaging were retrospectively evaluated. Highest Ki-67 value available at time of 18 F-FDG PET/CT was recorded. Patients were classified according to World Health Organization/European Neuroendocrine Tumor Society histological grades (G1, G2, G3) and into three distinct imaging categories (C1: all lesions are 18 F-FDG negative/ 68 Ga-DOTATATE positive, C2: patients with one or more 18 F-FDG positive lesions, all of them 68 Ga-DOTATATE positive, C3: patients with one or more 18 F-FDG positive lesions, at least one of them 68 Ga-DOTATATE negative). The primary endpoint of the study was Progression-Free Survival, assessed from the date of 18 F-FDG PET/CT to the date of radiological progression according to Response Evaluation Criteria In Solid Tumors version 1.1. Classification according to histological grade did not show significant statistical difference in median Progression-Free Survival between G1 and G2 but was significant between G2 and G3 patients. In contrast, median Progression-Free Survival was significantly higher in C1 compared to C2 and in C2 compared to C3 patients, revealing three distinctive imaging categories, each with highly distinctive prognosis. Our three-scale combined 68 Ga-DOTATATE/ 18 F-FDG PET imaging classification holds high prognostic value in patients with metastatic gastroenteropancreatic neuroendocrine neoplasias., Competing Interests: CONFLICTS OF INTEREST All authors have declared that no conflicts of interest exist., (Copyright: © 2020 Karfis et al.)

We present herein a case of unusual 18 F-FDG PET-CT diffuse hypermetabolic liver uptake in melanoma patient treated by ipilimumab.

Myocardial bridges are congenital structural abnormalities with debated clinical relevance; they may be traditionally asymptomatic or associated with various clinical manifestations, some of which may be potentially fatal. We report on a 60 years old man, who underwent a follow-up stress/rest myocardial perfusion scintigraphy developing asymptomatic exercise-induced ST-elevation and demonstrating completely reversible ischaemia in the scintigraphic images. Subsequent coronary angiography showed no artery stenosis, but revealed an intramyocardial pathway of the left anterior descending artery throughout a myocardial bridge. In conclusion, to our knowledge, this is the first reported case of asymptomatic exercise-induced ST-elevation secondary to a myocardial bridge.