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Biodistribution, Radiation Dosimetry, and Clinical Application of a Melanin-Targeted PET Probe, 18F-P3BZA, in Patients

N-(2-(diethylamino)-ethyl)-18F-5-fluoropicolinamide (18F-P3BZA) is a radiotracer that demonstrates high binding selectivity and affinity in melanoma. The aim of the present study was to estimate the biodistribution and clinical radiation dosimetry of 18F-P3BZA in healthy volunteers and perform a preliminary clinical application for PET/CT imaging in melanoma patients. Methods: 18F-P3BZA was produced efficiently with a radiosynthesizer. Six healthy volunteers were injected with 18F-P3BZA (211.7 ± 15.4 MBq) followed by serial whole-body PET/CT scans and blood tests to assess biodistribution, pharmacokinetic, and radiation dosimetry at 10 min, 1 h, 2 h, and 4 h after injection. The vital signs of volunteers were recorded in regular intervals during the imaging sessions. The effective dose for each subject after the medical internal radiation dosimetry schema was calculated with OLINDA/EXM software. For the preliminary clinical application, 5 patients with suspected melanomas underwent 18F-P3BZA PET/CT imaging at 10 min and 1 h after injection. All patients also underwent 18F-FDG PET/CT scans on the third day to compare the potential diagnostic ability of 18F-P3BZA with 18F-FDG. Results: The radiochemistry yield of 18F-P3BZA labeling was 12.3% ± 3.9%, and the purity of 18F-P3BZA after purification and formulation was higher than 99.5%. The highest uptake of 18F-P3BZA was in the liver with an SUVmean of 8.3 ± 1.0 at 10 min after injection. The resultant whole-body effective dose was 0.0193 mSv/MBq. 18F-P3BZA showed high uptake and suggested an ability for specific imaging of melanoma and its metastasis in patients. The average SUVmean of 18F-P3BZA and 18F-FDG in tumors was 19.7 ± 5.3 and 10.8 ± 2.7 at 60 min after injection. Conclusion: Our study suggests that 18F-P3BZA is safe and compatible for clinical use. The first-in-human clinical application to melanoma showed favorable delineated tumors in patients, demonstrating the potential of 18F-P3BZA for diagnostic PET imaging of melanoma.