Biodistribution and Radiation Dosimetry for a Probe Targeting Prostate-Specific Membrane Antigen for Imaging and Therapy

Abstract

Prostate-specific membrane antigen (PSMA) is a promising target for diagnosis and treatment of prostate cancer. EuK-Subkff-68Ga-DOTAGA (68Ga-PSMA Imaging & Therapy [PSMA I&T]) is a recently introduced PET tracer for imaging PSMA expression in vivo. Whole-body distribution and radiation dosimetry of this new probe were evaluated. Methods Five patients with a history of prostate cancer were injected intravenously with 91–148 MBq of 68Ga-PSMA I&T (mean ± SD, 128 ± 23 MBq). After an initial series of rapid whole-body scans, 3 static whole-body scans were acquired at 1, 2, and 4 h after tracer injection. Time-dependent changes of the injected activity per organ were determined. Mean organ-absorbed doses and effective doses were calculated using OLINDA/EXM. Results Injection of 150 MBq of 68Ga-PSMA I&T resulted in an effective dose of 3.0 mSv. The kidneys were the critical organ (33 mGy), followed by the urinary bladder wall and spleen (10 mGy each), salivary glands (9 mGy each), and liver (7 mGy). Conclusion 68Ga-PSMA I&T exhibits a favorable dosimetry, delivering organ doses that are comparable to (kidneys) or lower than those delivered by 18F-FDG.

The Theranostic PSMA Ligand PSMA-617 in the Diagnosis of Prostate Cancer by PET/CT: Biodistribution in Humans, Radiation Dosimetry, and First Evaluation of Tumor Lesions

“…For instance, a low-dose 68 Ga-PSMA-617 PET/CT with an administered activity of 203 MBq results in an effective overall dose of 4.3 mSv (PET) 1 3.5 mSv (lowdose CT), which equals 7.8 mSv. These results are similar compared with other most recently introduced PSMA ligands (14,33).…”

Safety, Dosimetry, and Tumor Detection Ability of 68Ga-NOTA-AE105: First-in-Human Study of a Novel Radioligand for uPAR PET Imaging

“…Importantly, the radiation dose to bone marrow was below the recommended threshold value of 3 mSv (23) Therefore, the radiation burden of uPAR PET with 68 Ga-NOTA-AE105 is of no clinical concern, and the effective dose is comparable to that of other clinically applied 68 Ga-based PET radioligands, such as 68 Ga-labeled prostate-specific membrane antigen (24) and 68 Ga-DOTATATE/DOTATOC (25).…”

“…The optimal administered dose of 68 Ga-NOTA-AE105 and time for PET/CT scan after injection still needs to be established, but it is likely within the first 60 min, which is also the case for other peptide-based radioligands such as 68 Ga-prostate-specific membrane antigen (24), 68 Ga-DOTATATE/DOTATOC (31), and RGD peptides (32).…”

Glu-Ureido–Based Inhibitors of Prostate-Specific Membrane Antigen: Lessons Learned During the Development of a Novel Class of Low-Molecular-Weight Theranostic Radiotracers

“…Tracer accumulation in normal organs, such as the salivary and lacrimal glands, the kidneys, the spleen, and the intestines (which is not directly comparable to the preclinical in vivo and ex vivo results [lesson 3]), must be assessed in patients as well, especially from the safety (radiation dosimetry) perspective. The outcome of such assessments (18,26,29,40,(93)(94)(95)(96)(97) will show whether future generations of PSMA radioligands should still be considered for first-inhuman studies or whether efforts targeting new complementary molecules should be undertaken to further increase the efficacy of the diagnosis and treatment of PC.…”