Radiosynthesis, preclinical evaluation and pilot clinical PET imaging study of a 18F-labeled tracer targeting fibroblast activation protein.

Fibroblast activation protein (FAP) is a promising molecular target for imaging in various types of cancers. Several 18F-labeled FAP inhibitor (FAPI) tracers have been evaluated in clinical study. However, these tracers display high physiological uptake in gallbladder and bile duct system. To overcome the limitation, we herein designed a novel radiotracer named 18F-FAPTG. 18F-FAPTG was produced with a non-decay-corrected radiochemical yield of 24.0 ± 6.0% and 22.0 ± 7.0% for manual and automatic synthesis, respectively. 18F-FAPTG exhibited high hydrophilicity and stability in vitro. The studies of cellular uptake, internalization, efflux properties and competitive binding to FAP of 18F-FAPTG indicated that the tracer showed high specificity, rapid internalization and low cellular efflux in FAP-positive cells. Biodistribution studies and microPET in mice bearing FAP-positive xenografts demonstrated extremely low uptake in the majority of other organs and main excretion of 18F-FAPTG through the urinary system. Furthermore, compared to 18F-FAPI-42, 18F-FAPTG showed significantly lower uptake in gallbladder, higher tumor uptake and longer tumor retention. In the pilot clinical study, 18F-FAPTG PET/CT demonstrated favorable tumor-to-background ratios in most organs and clearly displayed the malignant lesions. Our findings indicated that 18F-FAPTG had an advantage over 18F-FAPI-42 in PET imaging for cancers located in gallbladder the bile duct system. Thus, 18F-FAPTG could be an alternative to the currently available FAPI tracers.

Evaluation of Safety, Biodistribution, and Dosimetry of a Long-Acting Radiolabeled Somatostatin Analog 177 Lu-DOTA-EB-TATE With and Without Amino Acid Infusion.

PURPOSE: Kidney is considered to be one of the dose-limiting organs in peptide receptor radionuclide therapy (PRRT). Amino acid cocktail infusion has been applied to reduce renal absorbed dose by inhibiting the proximal tubular reabsorption of the radiopeptide. An Evans blue-modified 177 Lu-labeled octreotate ( 177 Lu-DOTA-EB-TATE) has an extended circulation in the blood, which may make the amino acid infusion unnecessary. The aim of this study was to evaluate the safety, biodistribution, and dosimetry of 177 Lu-DOTA-EB-TATE with and without amino acid infusion. PATIENTS AND METHODS: Ten patients with metastatic neuroendocrine tumors were randomly divided into 2 groups. The effect of amino acid infusion on renal uptake was assessed in a crossover randomized setting. Group A received 177 Lu-DOTA-EB-TATE at a dose of 3.7 GBq without amino acid infusion for the first cycle and with amino acid infusion for the second cycle; group B received 177 Lu-DOTA-EB-TATE at a dose of 3.7 GBq with amino acid infusion for the first cycle and without amino acid infusion for the second cycle. All patients underwent serial whole-body planar imaging at 1, 24, 96, and 168 hours and SPECT scan at 24 hours after radioligand administration. Abdominal CT was performed 2 days before PRRT for SPECT/CT fusion. The dosimetry was calculated using the HERMES software. Dosimetry evaluation was compared on a between-group and intrapatient basis. RESULTS: Administrations of 177 Lu-DOTA-EB-TATE with or without amino acids were well tolerated. No grade 4 hematotoxicity was observed in any of the patients. Grade 3 thrombocytopenia was reported in 1 patient. No nephrotoxicity of any grade was recorded. No significant difference was observed in creatinine (75.1 ± 21.7 vs 67.5 ± 18.1 µmol/L, P = 0.128), blood urea nitrogen (4.5 ± 0.8 vs 5.1 ± 1.4 mmol/L, P = 0.612), or GFR (109.3 ± 25.2 vs 100.9 ± 24.9 mL/min, P = 0.398) before and after PRRT. For each cycle, there was no significant difference in whole-body effective dose, kidney effective dose, as well as residence time of the kidneys between group A and B ( P > 0.05). By intrapatient comparison, without and with amino acid infusion also did not show significant difference in whole-body effective dose (0.14 ± 0.05 vs 0.12 ± 0.04 mSv/MBq, P = 0.612), kidney effective dose (1.09 ± 0.42 vs 0.73 ± 0.31 mSv/MBq, P = 0.093), and residence time of the kidneys (2.95 ± 1.58 vs 3.13 ± 1.11 hours, P = 0.674). CONCLUSIONS: 177 Lu-DOTA-EB-TATE PRRT with and without amino acid infusion demonstrated a favorable safety profile in neuroendocrine tumor patients. Administration of 177 Lu-DOTA-EB-TATE without amino acid infusion has acceptable slightly increased kidney absorbed dose and residence time of the kidneys, and does not affect kidney function. Further investigation in a larger cohort and long-term follow-up are warranted.

Peptide Receptor Radionuclide Therapy in Patients With Advanced Progressive Medullary Thyroid Cancer: Efficacy, Safety, and Survival Predictors.

PURPOSE: Progressive metastatic medullary thyroid carcinoma (MTC) is often characterized by rapid disease progression and poor prognosis, with only few therapeutic options available. Peptide receptor radionuclide therapy (PRRT) has demonstrated remarkable success in the management of gastroenteropancreatic neuroendocrine tumors and has also been suggested to treat MTC. However, evidence on its effectiveness and long-term outcome for this indication is still limited. The objective of this study was to assess the safety and efficacy of PRRT in patients with advanced, progressive MTC and to determine survival. Potential predictors of survival were also evaluated. METHODS: From September 2003 to June 2019, 28 patients (15 men and 13 women; mean age, 49 ± 14 years) with progressive, somatostatin receptor-positive advanced MTC received PRRT with 177Lu- or 90Y-labeled somatostatin analogs at Zentralklinik Bad Berka, Germany. Toxicity was graded according to Common Terminology Criteria for Adverse Events version 5.0. Treatment response was evaluated according to RECIST (Response Evaluation Criteria in Solid Tumors) 1.1, as well as molecular imaging criteria (European Organisation for Research and Treatment of Cancer). Kaplan-Meier analysis was used to calculate progression-free survival (PFS) and overall survival (OS), defined from the start of PRRT. Univariate and multivariate Cox regression analyses were performed to identify parameters associated with PFS and OS. RESULTS: Seventy-seven cycles of PRRT were administered (mean cumulative administered activity, 16.0 ± 7.8 GBq). No acute or long-term grade 3/4 toxicity was recorded with a follow-up of 3 to 140 months, except for 1 patient (4%) who suffered from grade 3 anemia (possibly related to disease progression). According to the RECIST criteria, the disease control rate after 3 to 4 months of PRRT was 56% (partial remission, 12%; stable disease, 44%). The disease control rate (72%) was higher by molecular response evaluation. Median OS and PFS were 63.7 and 10.1 months, respectively. The annual OS rates were 84% at 1 year, 65% at 3 years, 57% at 5 years, and 18% at 10 years. The annual PFS rates were 42% at 1 year, 21% at 2 years, and 13% at 5 years. Patients with bone metastases had poorer OS and PFS than those without metastases (median OS, 58.7 vs 92.3 months [P = 0.035; hazard ratio, 2.7; 95% confidence interval, 0.92-7.84]; median PFS, 8.5 vs 12.8 months [P = 0.592; hazard ratio, 1.2; 95% confidence interval, 0.56-2.76]). CONCLUSIONS: Peptide receptor radionuclide therapy was well tolerated and effective in patients with advanced, aggressive MTC. Bone metastasis was an independent adverse prognostic factor for OS.

68Ga-DOTATATE PET/CT of ACTH-Independent Cushing Syndrome Due to Ectopic Adrenocortical Adenoma.

ABSTRACT: Adrenocorticotropic hormone-independent Cushing syndrome due to ectopic adrenocortical adenoma is a very rare entity. We herein present a case of a 57-year-old woman who was referred to our hospital with persistent Cushing syndrome after undergoing unnecessary laparoscopic left adrenalectomy. 68Ga-DOTATATE PET/CT revealed increased uptake in the nodule in the right hilum, which was histologically confirmed to be ectopic adrenocortical adenoma. Removal of the tumor was followed by the disappearance of clinical symptoms of Cushing syndrome. In this case, 68Ga-DOTATATE PET/CT contributed to the diagnosis of ectopic adrenocortical adenoma.

A Single-Arm, Low-Dose, Prospective Study of 177Lu-EB-PSMA Radioligand Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer.

We aimed to investigate the safety and therapeutic efficacy of radioligand therapy (RLT) of 177Lu-EB-prostate-specific membrane antigen (PSMA) in patients with metastatic castration-resistant prostate cancer. Methods: Thirty men with progressive metastatic castration-resistant prostate cancer previously treated with taxane-based chemotherapy and second-generation androgen deprivation therapy were enrolled. All patients received up to 3 cycles of approximately 2.0 GBq (55 mCi) of 177Lu-EB-PSMA per cycle at 8-wk intervals. The primary endpoint was therapeutic safety, including changes in hematologic status, liver function, and renal function. An additional primary endpoint was therapeutic efficacy, including prostate-specific antigen (PSA) response and molecular imaging response. The secondary endpoints were PSA progression-free survival (PFS) and overall survival (OS). Another endpoint was patient-reported health-related quality of life. Results: From January 2019 to December 2021, 30, 22, and 11 patients received 1, 2, or 3 cycles of 177Lu-EB-PSMA RLT, respectively. During the entire follow-up period, 33.3% of patients experienced grade 3 hematologic adverse events. Seventeen (56.7%) patients achieved a PSA reduction of at least 50%. The median PSA PFS was 4.6 mo (95% CI, 2.7-6.5 mo), and the median OS was 12.6 mo (95% CI, 8.1-17.1 mo). A higher whole-body PSMA SUVmean correlated with a better PSA response, higher baseline alkaline phosphatase and larger total PSMA-positive tumor volume were associated with worse PSA PFS, and the existence of visceral metastases and higher PSA value at baseline were significant prognosticators of worse OS. Health-related quality-of-life outcomes improved significantly after 177Lu-EB-PSMA RLT. Conclusion: RLT based on approximately 2.0 GBq of 177Lu-EB-PSMA for up to 3 cycles may achieve a PSA response and hematologic toxicity comparable to those from 7.4-GBq doses of 177Lu-PSMA-617 for up to 4-6 cycles. Further studies with more cycles of 177Lu-EB-PSMA RLT are needed to evaluate the potential benefits in terms of PFS and OS.

Safety and efficacy of peptide receptor radionuclide therapy with 177Lu-DOTA-EB-TATE in patients with metastatic neuroendocrine tumors.

Rationale: This study aimed to assess the safety, efficacy, and survival of 177Lu-DOTA-EB-TATE in patients with metastatic neuroendocrine tumors (NETs). Methods: Thirty patients with metastatic NETs were prospectively enrolled and treated with 177Lu-DOTA-EB-TATE (3 intended cycles at 8 to 12-week intervals, 3.7 GBq/cycle). Treatment-related adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. The treatment response was graded according to RECIST 1.1 and PERCIST 1.0 criteria. Kaplan-Meier analysis was performed to calculate progression-free survival (PFS) and overall survival (OS). Results: Patients tolerated therapy well without acute adverse effects. During peptide receptor radionuclide therapy (PRRT), no grade 4 toxicity was observed in any of the patients; grade 3 hematotoxicity was recorded in 4 patients, including grade 3 thrombocytopenia in 4 patients (13.3%) and grade-3 anemia in 1 patient (3.3%); grade 3 hepatotoxicity was recorded in 1 (3.3%) patient, and no grade 2/3/4 nephrotoxicity was observed. On long-term follow-up, none of the patients developed grade 4 hematotoxicity or nephrotoxicity of any grade, reversible grade 3 hematotoxicity (thrombocytopenia) occurred in 1 patient. There was no incidence of leukemia or myelodysplastic syndrome for the duration of follow-up. Of 27 patients with RECIST-measurable disease, partial response and stable disease were seen in 9 and 14 patients, respectively, resulting in a response rate of 33.3% and disease control rate of 85.2%. Of 29 patients evaluable for response on 68Ga-DOTATATE PET/CT, 14 had partial response and 11 had stable disease, with a response rate of 48.3% and disease control rate of 86.2%. The follow-up period ranged from 5 to 57 months after the first 177Lu-DOTA-EB-TATE PRRT with a median follow-up of 46 months. The median PFS was 36 months, and the median OS was not reached. Ki-67 index of greater than 10% was associated with poorer PFS (P = 0.012). Conclusions: Our results suggest that PRRT with approximately 3.7 GBq 177Lu-DOTA-EB-TATE has acceptable toxicity profile and is effective in treating metastatic NET with high disease control rate. In addition, 177Lu-DOTA-EB-TATE achieved a favorable survival outcome with encouraging PFS.

A prospective head-to-head comparison of 68 Ga-NOTA-3P-TATE-RGD and 68 Ga-DOTATATE in patients with gastroenteropancreatic neuroendocrine tumours.

PURPOSE: The aim of this study was to compare 68 Ga-NOTA-3P-TATE-RGD, a dual somatostatin receptor 2- and integrin αVß3-targeting tracer, to 68 Ga-DOTATATE in a single group of patients with gastroenteropancreatic (GEP)-neuroendocrine tumours (NETs). METHODS: Thirty-five patients with histologically confirmed GEP-NETs (5 grade 1, 28 grade 2, and 2 grade 3 tumours) were prospectively enrolled with informed consent. The primary tumour mainly originated from the pancreas and rectum. All patients were scanned with both 68 Ga-NOTA-3P-TATE-RGD PET/CT and 68 Ga-DOTATATE PET/CT within a week and compared on a head-to-head basis. Sixteen patients also had conventional 18F-FDG PET/CT. Images were evaluated semi-quantitatively using maximum standardized uptake values (SUVmax) of tumour and tumour-to-background ratio. RESULTS: All patients had at least one positive lesion on each of the two scans. A total of 1190 and 1106 lesions were detected on 68 Ga-NOTA-3P-TATE-RGD images and 68 Ga-DOTATATE images, respectively (P = 0.152). 68 Ga-NOTA-3P-TATE-RGD PET/CT revealed significantly more lesions in the liver than 68 Ga-DOTATATE PET/CT (634 vs. 532, P = 0.021). Both tracers produced comparable results for detecting primary tumours (20 vs. 20, P = 1.000), lymph node metastases (101 vs. 102, P = 0.655), and bone metastases (381 vs. 398, P = 0.244). The tumour SUVmax in 12 patients was significantly higher for 68 Ga-NOTA-3P-TATE-RGD than for 68 Ga-DOTATATE (27.2 ± 13.6 vs. 19.5 ± 10.0, P < 0.001); among them, 9 had 18F-FDG PET/CT and all were found to be FDG-positive. The remaining 23 patients had significantly higher 68 Ga-DOTATATE uptake than 68 Ga-NOTA-3P-TATE-RGD uptake (22.3 ± 16.4 vs. 11.9 ± 7.5, P < 0.001); among them, 7 had 18F-FDG PET/CT and 6 were FDG-negative. Generally, 68 Ga-DOTATATE demonstrated higher tumour SUVmax than 68 Ga-NOTA-3P-TATE-RGD (20.8 ± 16.0 vs. 14.2 ± 8.9, P < 0.001), including primary tumours, liver lesions, lymph node lesions, and bone lesions. However, the tumour-to-background ratio of liver lesions was significantly higher when using 68 Ga-NOTA-3P-TATE-RGD compared with that when using 68 Ga-DOTATATE (8.4 ± 5.5 vs. 4.7 ± 3.7, P < 0.001). CONCLUSION: 68 Ga-NOTA-3P-TATE-RGD performed better than 68 Ga-DOTATATE in detection of liver metastases with a higher tumour-to-background ratio. Moreover, 68 Ga-NOTA-3P-TATE-RGD tended to demonstrate higher uptake over 68 Ga-DOTATATE in FDG-avid NETs. TRIAL REGISTRATION: Dual SSTR2 and Integrin αvß3 Targeting PET/CT Imaging (NCT02817945, registered 5 November 2018). URL OF REGISTRY: https://clinicaltrials.gov/ct2/show/NCT02817945.

Somatostatin Treatment for Ectopic ACTH Syndrome due to Pancreatic Neuroendocrine Tumors: Review of the Literature.

Objectives: To analyze and summarize the effect of SSA treatment on EAS due to p-NETs (EAS-p-NETs). Methods: Thirteen patients with EAS-p-NETs treated with SSAs at our center or described in the literature were included in this study. Clinical characteristics, laboratory data, imaging studies, histopathologic results, the effect of SSA treatment, and the prognosis of these EAS-p-NET patients were evaluated. Results: Four males and 9 females with an average age of 42.9 years were included in the study. The mean duration of follow-up was 38.8 ± 28.2 months. As one of the combined treatment measures, SSAs controlled the levels of ACTH and cortisol in 9 of the 13 patients (69.2%). Partial response was observed in 3 patients (23.1%), stable disease in 2 patients (15.4%), and progressive disease in 6 patients (46.2%). The median time to tumor progression was 24 months, and the median overall survival was 61 months. The side effects of SSA treatment included temporary mild abdominal pain, diarrhea, gallstones, and cholecystitis. Conclusions: As a supplemental therapy, SSA treatment led to clinical and biochemical improvement with a good safety profile in patients exhibiting EAS-p-NET with metastasis. However, tumor progression was inhibited by SSA treatment in only a few patients. Combined with other treatments, SSAs may improve the prognosis of patients with EAS-p-NETs.

Head-to-head comparison of [68 Ga]Ga-P16-093 and [68 Ga]Ga-PSMA-617 in dynamic PET/CT evaluation of the same group of recurrent prostate cancer patients.

PURPOSE: This study was prospectively designed to evaluate the early dynamic organ distribution and tumor detection capability of [68 Ga]Ga-P16-093, which was compared with [68 Ga]Ga-PSMA-617 in the same group of recurrent prostate cancer patients. METHODS: Twenty patients with recurrent prostate cancer were enrolled. In 2 consecutive days, each patient underwent a 60-min dynamic PET/CT scan after intravenous administration of 148-185 MBq (4-5 mCi) [68 Ga]Ga-P16-093 and [68 Ga]Ga-PSMA-617, respectively. Following a low-dose CT scan, serial dynamic PET scans were performed from head to proximal thigh at 9 time points (30 s/bed at 4, 7, 10, 13, and 16 min; 1 min/bed at 20, 30, and 45 min; and 2 min/bed at 60 min). Standardized uptake values were measured for semi-quantitative comparison. RESULTS: [68 Ga]Ga-P16-093 PET/CT revealed a significantly higher tumor uptake at 4 min (SUVmax 7.88 ± 5.26 vs. 6.01 ± 3.88, P < 0.001), less blood pool retention at 4 min (SUVmean 5.12 ± 1.16 vs. 6.14 ± 0.98, P < 0.001), and lower bladder accumulation at 60 min (SUVmean 31.33 ± 27.47 vs. 48.74 ± 34.01, P = 0.042) than [68 Ga]Ga-PSMA-617 scan. Significantly higher [68 Ga]Ga-P16-093 uptakes were also observed in the parotid gland, liver, spleen, and kidney. Besides, [68 Ga]Ga-P16-093 exhibited a better detectability of tumor than [68 Ga]Ga-PSMA-617 (366 vs. 321, P = 0.009). CONCLUSIONS: [68 Ga]Ga-P16-093 showed advantages over [68 Ga]Ga-PSMA-617 with higher tumor uptakes, tumor-to-blood pool ratio and detection capability, less blood pool, and bladder accumulation in recurrent prostate cancer patients. TRIAL REGISTRATION: [68 Ga]Ga-P16-093 and [68 Ga]Ga-PSMA-617 PET/CT Imaging in the Same Group of Prostate Cancer Patients (NCT04796467, Registered 12 March 2021, retrospectively registered) URL of registry: https://clinicaltrials.gov/ct2/show/NCT04796467.

Head-to-head comparison of 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT in localizing tumors with ectopic adrenocorticotropic hormone secretion: a prospective study.

PURPOSE: Localizing the source of ectopic adrenocorticotropic hormone secretion (EAS) is challenging. This study compared the diagnostic value of 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT in tumors with EAS. METHODS: Thirty-six patients with a suspicion of EAS were enrolled to undergo both 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT within 4 weeks for comparison. Twenty-three underwent surgical resection or biopsy. Immunohistochemical staining for SSTR2 and Ki-67 was performed to correlate with 68Ga-DOTATATE uptake and 18F-FDG uptake, respectively. RESULTS: EAS tumors were observed in 20/23 patients. Among the 20 patients with histologically proven EAS tumors, 68Ga-DOTATATE PET/CT correctly identified the tumor in 15 (75.0%), with an SUVmax ranging from 1.4 to 20.7 (6.7 ± 5.5). 18F-FDG PET/CT correctly identified the tumor in 12 (60.0%) patients, with an SUVmax ranging from 1.8 to 10.0 (4.0 ± 2.1). Moreover, 68Ga-DOTATATE PET/CT unmasked the sources of EAS in 6 patients with negative 18F-FDG uptake, and 18F-FDG PET/CT unmasked the sources in 3 patients with negative 68Ga-DOTATATE uptake, resulting in EAS tumors being identified in 18 (90%) patients by combining 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT. CONCLUSIONS: 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT are complementary in localizing and discriminating the source of EAS. 68Ga-DOTATATE PET/CT combined with 18F-FDG PET/CT had higher detection rate than each alone. TRIAL REGISTRATION: 68Ga-DOTATATE PET/CT in Neuroendocrine Tumors (NCT04041882) URL OF REGISTRY: https://clinicaltrials.gov/ct2/show/NCT04041882.

Ga-68 EDTA aerosols in evaluation of inhaled-particle deposition and clearance of obstructive pulmonary diseases: A pilot prospective study compared with Galligas.

PURPOSE: 68-gallium (Ga-68) ethylenediaminetetraacetic acid (EDTA) aerosols and Galligas were compared in evaluation of inhaled-particle deposition and clearance in volunteers with or without obstructive pulmonary diseases. METHODS: Nonsmoking healthy volunteers, healthy smokers, asthma patients and patients with chronic obstructive pulmonary disease (COPD) were recruited to undergo the dynamic lung ventilation positron emission tomography/computerized tomography (PET/CT) scans within two consecutive days. The inhaled particles were Ga-68-labelled carbon nanoparticles (Galligas, 30-60 nm in size) and Ga-68-labelled EDTA aerosols (1-2 µm in size), respectively. The volunteers' lung function parameters were measured for comparison. RESULTS: Central deposition and inhomogeneity of both tracers were negatively correlated with lung function parameters, including the ratio of forced expiratory volume at 1 second to forced vital capacity (FEV1 /FVC). The central or hilum deposition of Galligas, but not 68-gallium (Ga-68) EDTA, was negatively correlated with the maximal expiratory flow at 25%, 50% and 75% of the forced vital capacity. Compared with Galligas, Ga-68 EDTA aerosols were more concentrated in the central region in all groups except for the healthy nonsmokers. Ventilation inhomogeneity was more evident when using Ga-68 EDTA aerosols, especially in patients with COPD and asthma patients. In the healthy smokers, the central region accumulated more Ga-68 EDTA at 30 minutes after inhalation than immediately after inhalation. Ga-68 EDTA cleared faster in lungs than Galligas. CONCLUSIONS: Both Galligas and Ga-68 EDTA aerosols can be used for PET/CT lung ventilation scan. However, Ga-68 EDTA aerosols showed more advantages in diagnosis and evaluation of obstructive airway diseases by revealing the inhaled-particle deposition and clearance.

Experience of Ectopic Adrenocorticotropin Syndrome: 88 Cases With Identified Causes.

OBJECTIVE: Ectopic adrenocorticotropic hormone syndrome (EAS) is a rare cause of Cushing's syndrome and diagnosis and management remain challenging. The aim of this study was to present the clinical spectrum of a group of EAS cases in a single center to explore better management strategies. METHODS: A retrospective study was conducted to identify 88 confirmed EAS cases at our hospital from 1984 to 2019. The clinical, biochemical, imaging, and pathological features were analyzed. RESULTS: Of the 88 eligible patients with EAS, 38 (43.2%) cases of pulmonary neuroendocrine tumors (NETs) and a larger number of thymic/mediastinal NETs (29 cases, 33%) were identified. The clinical and biological features of EAS and Cushing's disease overlapped but were more severe in EAS. Inferior petrosal sinus sampling (97.4%) and computed tomography (85.4%) provided the highest positive diagnostic accuracy. Computed tomography is also a useful tool to identify tumors in chest cavity compared with nonchest lesions (91.2% vs 57.1%). Although a greater tumor size (4.54 cm vs 1.44 cm) and higher rate of insuppressible high-dose dexamethasone suppression test (83.3% vs 51.5%) were found in thymic/mediastinum NETs than in pulmonary NETs, the level of hormone production had no difference. CONCLUSION: EAS had more common and severe clinical presentations than Cushing's disease, and multiple imaging approaches are required for reliable diagnosis. A higher proportion of thymic/mediastinal NETs was found in our study. For patients without a certain tumor source, long-term follow-up and further evaluations are needed.

Peptide Receptor Radionuclide Therapy of Late-Stage Neuroendocrine Tumor Patients with Multiple Cycles of 177Lu-DOTA-EB-TATE.

This study aimed to evaluate the safety and efficacy of multiple cycles of 177Lu-DOTA-Evans blue (EB)-TATE peptide receptor radionuclide therapy (PRRT) at escalating doses in neuroendocrine tumors (NETs). Methods: Thirty-two NET patients were randomly divided into 3 groups and treated with escalating doses. Group A received 1.17 ± 0.09 GBq/cycle; group B, 1.89 ± 0.53 GBq/cycle; and group C, 3.97 ± 0.84 GBq/cycle. The treatment was planned for up to 3 cycles. Treatment-related adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. Treatment response was evaluated according to the European Organisation for Research and Treatment of Cancer criteria and modified PERCIST. Results: Administration of PRRT was well tolerated, without life-threatening adverse events (CTCAE grade 4). CTCAE grade 3 hematotoxicity was recorded in 1 patient (16.6%) in group B (thrombocytopenia) and 3 patients (21.4%) in group C (thrombocytopenia in 3, anemia in 1). CTCAE grade 3 hepatotoxicity (elevated aspartate aminotransferase) was recorded in 1 patient in group A (8.3%) and 1 patient in group C (7.1%). No nephrotoxicity was observed. According to the criteria of the European Organisation for Research and Treatment of Cancer, the overall disease response rates were similar in groups A, B, and C (50.0%, 50.0%, and 42.9%, respectively), and the overall disease control rates were higher in groups B (83.3%) and C (71.5%) than in group A (66.7%). According to modified PERCIST, a lower disease response rate but a similar disease control rate were found. When a comparable baseline SUVmax ranging from 15 to 40 was selected, the percentage change in SUVmax increased slightly in group A (2.1% ± 40.8%) but decreased significantly in groups B and C (-38.7% ± 10.0% and -14.7% ± 20.0%, respectively) after the first PRRT (P = 0.001) and decreased in all 3 groups after the third PRRT (groups A, B, and C: -6.9% ± 42.3%, -49.2% ± 30.9%, -11.9% ± 37.9%, respectively; P = 0.044). Conclusion: Dose escalations of up to 3.97 GBq/cycle seem to be well tolerated for 177Lu-DOTA-EB-TATE. 177Lu-DOTA-EB-TATE doses of 1.89 and 3.97 GBq/cycle were effective in tumor control and more effective than 1.17 GBq/cycle.

177Lu-EB-PSMA Radioligand Therapy with Escalating Doses in Patients with Metastatic Castration-Resistant Prostate Cancer.

This study was designed to assess the safety and therapeutic response to 177Lu-labeled Evans blue-modified prostate-specific membrane antigen (PSMA) 617 (EB-PSMA-617) treatment with escalating doses in patients with metastatic castration-resistant prostate cancer. Methods: With institutional review board approval and informed consent, patients were randomly divided into 3 groups: group A (n = 10) was treated with a 1.18 ± 0.09 GBq dose of 177Lu-EB-PSMA. Group B (n = 10) was treated with a 2.12 ± 0.19 GBq dose of 177Lu-EB-PSMA. Group C (n = 8) was treated with a 3.52 ± 0.58 GBq dose of 177Lu-EB-PSMA. Eligible patients received up to 3 cycles of 177Lu-EB-PSMA therapy, at 8-wk intervals. Results: Because of disease progression or bone marrow suppression, 4 of 10, 5 of 10, and 5 of 8 patients completed 3 cycles of therapy as planned in groups A, B, and C, respectively. The prostate-specific antigen response was correlated with treatment dose, and the prostate-specific antigen disease control rates were higher in groups B (70%) and C (75%) than in group A (10%) (P = 0.007), but no correlation between groups B and C was found. 68Ga-PSMA PET/CT showed a response in all treatment groups; however, there was no significant difference among the 3 groups. A hematologic toxicity study found that platelets decreased more in groups B and C than in group A and that grade 4 thrombocytopenia occurred in 2 (25.0%) patients in group C. No serious nephritic or hepatic side effects were observed. Conclusion: This study demonstrated that a 2.12-GBq dose of 177Lu-EB-PSMA seems to be safe and adequate in tumor treatment. Further investigations with an increased number of patients are warranted.

177Lu-DOTATOC Peptide Receptor Radionuclide Therapy in a Patient With Neuroendocrine Breast Carcinoma and Breast Invasive Ductal Carcinoma.

Radiolabeled somatostatin analogs for somatostatin receptor (SSTR)-targeted imaging and peptide receptor radionuclide therapy (PRRT) have demonstrated remarkable success in the management of SSTR-expressing neuroendocrine neoplasms. Primary neuroendocrine breast carcinoma is rare. Heterogeneous SSTR overexpression has also been documented in breast cancer, in both human breast cancer specimens and clinical studies. We report here a case of a 69-year-old woman who had both breast invasive ductal carcinoma and primary large-cell neuroendocrine breast carcinoma (Ki-67 proliferation index of 20%), with disseminated bone and lymph node metastases, demonstrating exceptional tracer uptake on Ga-DOTATOC PET/CT, and remarkably partial remission after Lu-DOTATOC PRRT.

Prognostic Value of 18F-FDG PET/CT in a Large Cohort of Patients with Advanced Metastatic Neuroendocrine Neoplasms Treated with Peptide Receptor Radionuclide Therapy.

The objective of this retrospective study was to determine the role of 18F-FDG PET/CT in a large cohort of 495 patients with metastatic neuroendocrine neoplasms (NENs) who were treated with peptide receptor radionuclide therapy (PRRT) with a long-term follow-up. Methods: The 495 patients were treated with 177Lu- or 90Y-DOTATOC/DOTATATE PRRT between February 2002 and July 2018. All subjects received both 68Ga-DOTATOC/TATE/NOC and 18F-FDG PET/CT before treatment and were followed 3-189 mo. Kaplan-Meier analysis, log-rank testing (Mantel-Cox), and Cox regression analysis were performed for overall survival (OS) and progression-free survival (PFS). Results: One hundred ninety-nine patients (40.2%) presented with pancreatic NENs, 49 with cancer of unknown primary, and 139 with midgut NENs, whereas the primary tumor was present in the rectum in 20, in the lung in 38, in the stomach in 8, and in other locations in 42. 18F-FDG PET/CT was positive in 382 (77.2%) patients and negative in 113 (22.8%) before PRRT, whereas 100% were 68Ga-DOTATOC/TATE/NOC-positive. For all patients, the median PFS and OS, defined from the start of PRRT, were 19.6 mo and 58.7 mo, respectively. Positive 18F-FDG results predicted shorter PFS (18.5 mo vs. 24.1 mo; P = 0.0015) and OS (53.2 mo vs. 83.1 mo; P < 0.001) than negative 18F-FDG results. Among the cases of pancreatic NENs, the median OS was 52.8 mo in 18F-FDG-positive subjects and 114.3 mo in 18F-FDG-negative subjects (P = 0.0006). For all patients positive for 18F-FDG uptake, and a ratio of more than 2 for the highest SUVmax on 68Ga-somatostatin receptor (SSTR) PET to the most 18F-FDG-avid tumor lesions, the median OS was 53.0 mo, compared with 43.4 mo in those patients with a ratio of less than 2 (P = 0.030). For patients with no 18F-FDG uptake (complete mismatch imaging pattern), the median OS was 108.3 mo versus 76.9 mo for an SUVmax of more than 15.0 and an SUVmax of 15.0 or less on 68Ga-SSTR PET/CT, respectively. Conclusion: The presence of positive lesions on 18F-FDG PET is an independent prognostic factor in patients with NENs treated with PRRT. Metabolic imaging with 18F-FDG PET/CT complements the molecular imaging aspect of 68Ga-SSTR PET/CT for the prognosis of survival after PRRT. High SSTR expression combined with negative 18F-FDG PET/CT results is associated with the most favorable long-term prognosis.

Combined 68Ga-NOTA-Evans Blue Lymphoscintigraphy and 68Ga-NOTA-RM26 PET/CT Evaluation of Sentinel Lymph Node Metastasis in Breast Cancer Patients.

In this study, we applied a new strategy to identify sentinel lymph node (SLN) metastasis by combining 68Ga-NOTA-Evans Blue (68Ga-NEB) for SLN mapping and 68Ga-NOTA-RM26 for LN metastasis detection in breast cancer patients. A total of 24 female patients with breast cancer diagnosed by core biopsy or suspected by mammography or ultrasonography were recruited and provided informed consent. All patients underwent 68Ga-NEB and 68Ga-NOTA-RM26 PET/CT imaging. Visual analysis of 68Ga-NEB PET/CT images was used to determine SLNs, and then compared with the 68Ga-NOTA-RM26 results and histopathological findings. SLNs were visualized in 24 of 24 patients (100.0%) within 4.0-10.0 (5.6 ± 1.4) min. All patients were pathologically diagnosed with breast cancer, and 12 patients had ipsilateral lymph node metastasis. By combining 68Ga-NEB and 68Ga-NOTA-RM26 images, 7/12 (58.3%) patients showed mild to intense uptake of 68Ga-NOTA-RM26 in SLNs, 1/12 patient (8.3%) had moderate uptake of 68Ga-NOTA-RM26 in the non-SLNs rather than SLN, indicating possible bypass lymphatic drainage, partially accounting for the false negatives in SLN biopsy during surgery. No false positives were found. The SUVmax of 68Ga-NOTA-RM26 activity in metastatic SLNs was significantly higher than that in non-metastatic SLNs (2.2 ± 2.3 vs 0.7 ± 0.1, P = 0.047). This study manifests the value of combination of 68Ga-NEB and 68Ga-NOTA-RM26 dual tracer PET/CT in preoperative evaluation of SLN metastasis in breast cancer patients, especially in those patients with lymphatic obstruction and bypass drainage. In general, positive 68Ga-NOTA-RM26 uptake in either SLN or other lymph nodes can apply lymph node dissection rather than intraoperative SLN biopsy.

Dose escalation of an Evans blue-modified radiolabeled somatostatin analog 177Lu-DOTA-EB-TATE in the treatment of metastatic neuroendocrine tumors.

PURPOSE: To evaluate the safety and efficacy of 177Lu-DOTA-EB-TATE, a radiolabeled somatostatin analog modified by Evans blue, at escalating doses, was used to increase tumor retention in patients with progressive metastatic neuroendocrine tumors (NETs). METHODS: Thirty-three patients with metastatic NETs were prospectively enrolled into four groups: group A (n = 6, 43 ± 12 years) administered approximately 3.7 GBq (100 mCi) 177Lu-DOTATATE as controls; group B (n = 7, 55 ± 7 years) administered approximately 1.11 GBq (30 mCi) 177Lu-DOTA-EB-TATE; group C (n = 6, 55 ± 10 years) administered approximately 1.85 GBq (50 mCi) 177Lu-DOTA-EB-TATE; group D (n = 14, 50 ± 10 years) administered approximately 3.7 GBq (100 mCi) 177Lu-DOTA-EB-TATE. Treatment-related adverse events were graded according to the CTCAE v.5.0. 68Ga-DOTATATE PET/CT were performed at baseline and 2-3 months after treatment for response evaluation. RESULTS: Administration was well tolerated. No CTC 3/4 hematotoxicity, nephrotoxicity, or hepatotoxicity was observed during or after treatment in groups A-C. In group D, CTC-3 hematotoxicity was recorded in 2 patients with multicourse chemotherapy previously. After one-cycle treatment, the SUVmax decreased in group C (Δ% = - 17.4 ± 29.3%) and group D (Δ% = - 15.1 ± 39.1%), but greatly increased in group B (Δ% = 30.0 ± 68.0%) and mildly increased in group A (Δ% = 5.4 ± 45.9%). Referring to EORTC criteria, 16.7% (1/6), 0% (0/7), 50% (3/6), and 50% (7/14) were evaluated as partial response in groups A, B, C, and D, respectively. When selecting lesions with comparable baseline SUVmax ranging from 15 to 40, SUVmax showed no significant decrease in group B (Δ% = - 7.3 ± 24.5%) (P = 0.214), significant decrease in group C (Δ% = - 34.9 ± 12.4%) (P = 0.001), and in group D (Δ% = - 17.9 ± 19.7%) (P = 0.012) as compared with group A with increased SUVmax (Δ% = 8.4 ± 48.8%). SUVmax significantly decreased in the EBTATE groups (groups B-D combined) (Δ% = - 19.0 ± 21.5%) as compared with the TATE group (P = 0.045). CONCLUSION: 177Lu-DOTA-EB-TATE is well tolerated and is more effective than 177Lu-DOTATATE. Both 1.85 GBq (50 mCi) and 3.7 GBq (100 mCi) doses appear to be more effective than 1.11 GBq (30 mCi) dose. Further investigation with more cycles of 177Lu-DOTA-EB-TATE treatment and longer follow-up is warranted. TRIAL REGISTRATION: Treatment Using 177Lu-DOTA-EB-TATE in Patients with Advanced Neuroendocrine Tumors (NCT03478358). URL: https://register.clinicaltrials.gov/prs/app/action/ViewOrUnrelease?uid=U0001JRW&ts=13&sid=S0007RNX&cx=y3yqv4.