Purpose To assess the clinical safety, pharmacokinetics, and tumor imaging characteristics of fluorine 18-(2S,4R)-4-fluoroglutamine (FGln), a glutamine analog radiologic imaging agent. Materials and Methods This study was approved by the institutional review board and conducted under a U.S. Food and Drug Administration-approved Investigational New Drug application in accordance with the Helsinki Declaration and the Health Insurance Portability and Accountability Act. All patients provided written informed consent. Between January 2013 and October 2016, 25 adult patients with cancer received an intravenous bolus of FGln tracer (mean, 244 MBq ± 118, <100 μg) followed by positron emission tomography (PET) and blood radioassays. Patient data were summarized with descriptive statistics. FGln biodistribution and plasma amino acid levels in nonfasting patients (n = 13) were compared with those from patients who fasted at least 8 hours before injection (n = 12) by using nonparametric one-way analysis of variance with Bonferroni correction. Tumor FGln avidity versus fluorodeoxyglucose (FDG) avidity in patients with paired PET scans (n = 15) was evaluated with the Fisher exact test. P < .05 was considered indicative of a statistically significant difference. Results FGln PET depicted tumors of different cancer types (breast, pancreas, renal, neuroendocrine, lung, colon, lymphoma, bile duct, or glioma) in 17 of the 25 patients, predominantly clinically aggressive tumors with genetic mutations implicated in abnormal glutamine metabolism. Acute fasting had no significant effect on FGln biodistribution and plasma amino acid levels. FGln-avid tumors were uniformly FDG-avid but not vice versa (P = .07). Patients experienced no adverse effects. Conclusion Preliminary human FGln PET trial results provide clinical validation of abnormal glutamine metabolism as a potential tumor biomarker for targeted radiotracer imaging in several different cancer types. RSNA, 2018 Online supplemental material is available for this article. Clinical trial registration no. NCT01697930.

Definitive diagnosis of malignancy is often challenging due to limited availability of human cell or tissue samples and morphological similarity with certain benign conditions. Our recently developed novel technology-spatial-domain low-coherence quantitative phase microscopy (SL-QPM)-overcomes the technical difficulties and enables us to obtain quantitative information about cell nuclear architectural characteristics with nanoscale sensitivity. We explore its ability to improve the identification of malignancy, especially in cytopathologically non-cancerous-appearing cells. We perform proof-of-concept experiments with an animal model of colorectal carcinogenesis-APC(Min) mouse model and human cytology specimens of colorectal cancer. We show the ability of in situ nanoscale nuclear architectural characteristics in identifying cancerous cells, especially in those labeled as "indeterminate or normal" by expert cytopathologists. Our approach is based on the quantitative analysis of the cell nucleus on the original cytology slides without additional processing, which can be readily applied in a conventional clinical setting. Our simple and practical optical microscopy technique may lead to the development of novel methods for early detection of cancer.

I-meta-iodobenzylguanidine (I-MIBG) imaging is currently a mainstay in the evaluation of many neuroendocrine tumors, especially neuroblastoma. I-MIBG imaging has several limitations that can be overcome by the use of a PET agent.F-meta-fluorobenzylguanidine (F-MFBG) is a PET analog of MIBG that may allow for single-day, high-resolution quantitative imaging. We conducted a first-in-human study of F-MFBG PET imaging to evaluate the safety, feasibility, pharmacokinetics, and dosimetry ofF-MFBG in neuroendocrine tumors (NETs). Ten patients (5 with neuroblastoma and 5 with paraganglioma/pheochromocytoma) received 148-444 MBq (4-12mCi) ofF-MFBG intravenously followed by serial whole-body imaging at 0.5-1, 1-2, and 3-4 after injection. Serial blood samples (a total of 6) were also obtained starting at 5 min after injection to as late as 4 h after injection; whole-body distribution and blood clearance data, lesion uptake, and normal-tissue uptake were determined, and radiation-absorbed doses to normal organs were calculated using OLINDA. No side effects were seen in any patient afterF-MFBG injection. Tracer distribution showed prominent activity in the blood pool, liver, and salivary glands that decreased with time. Mild uptake was seen in the kidneys and spleen, which also decreased with time. Urinary excretion was prominent, with an average of 45% of the administered activity in the bladder by 1 h after injection; whole-body clearance was monoexponential, with a mean biologic half-life of 1.95 h, whereas blood clearance was biexponential, with a mean biologic half-life of 0.3 h (58%) for the rapid α phase and 6.1 h (42%) for the slower β phase. The urinary bladder received the highest radiation dose with a mean absorbed dose of 0.186 ± 0.195 mGy/MBq. The mean total-body dose was 0.011 ± 0.011 mGy/MBq, and the effective dose was 0.023 ± 0.012 mSv/MBq. Both skeletal and soft-tissue lesions were visualized with high contrast. The SUVmax (mean ± SD ) of lesions at 1-2 h after injection was 8.6 ± 9.6. Preliminary data show thatF-MFBG imaging is safe and has favorable biodistribution and kinetics with good targeting of lesions. PET imaging with F-MFBG allows for same-day imaging of NETs.F-MFBG appears highly promising for imaging of patients with NETs, especially children with neuroblastoma.

Purpose: Radiolabeled somatostatin receptor 2 (SSTR2) antagonists have shown higher tumor uptake and tumor-toorgan ratios than somatostatin agonists in preclinical models of neuroendocrine tumors (NETs). We performed a phase I study to evaluate the safety and efficacy of SSTR2 antagonist 177 Lu-satoreotide tetraxetan.Patients and Methods: Twenty patients with advanced SSTR2-positive NETs were treated with 177 Lu-satoreotide tetraxetan. Patients first underwent a dosimetry study with 177 Lu-satoreotide tetraxetan to determine the therapeutic activity that could be safely administered. This activity was split into two equal cycles to be delivered 3 months apart. The maximum activity was 7.4 GBq per cycle.Results: Of 20 patients with NETs (one lung, seven small bowel, nine pancreatic, one gastric, one rectal, one kidney; mean prior treatments: three), six received one cycle of 177 Lu-satoreotide tetraxetan and 14 received two cycles. Hematologic toxicity after cycle 1 was mild-moderate and reversed before cycle 2. However, grade 4 hematologic toxicity occurred in four of seven (57%) patients after cycle 2 of 177 Lu-satoreotide tetraxetan. The study was suspended, and the protocol modified to limit the cumulative absorbed bone marrow dose to 1 Gy and to reduce prescribed activity for cycle 2 by 50%. The best overall response rate was 45% [5% complete response (1/20), 40% partial response (8/ 20)]; with 40% stable disease (8/20) and 15% progression of disease (3/20). Median progression-free survival (PFS) was 21.0 months (95% CI, 13.6-NR).Conclusions: In this trial of heavily treated NETs, preliminary data are promising for the use of 177 Lu-satoreotide tetraxetan. Additional studies are ongoing to determine optimal therapeutic dose/schedule.

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