A Prospective, Randomized, Double-Blind Study to Evaluate the Safety, Biodistribution, and Dosimetry of 68Ga-NODAGA-LM3 and 68Ga-DOTA-LM3 in Patients with Well-Differentiated Neuroendocrine Tumors
- 12 February 2021
- journal article
- research article
- Published by Society of Nuclear Medicine in Journal of Nuclear Medicine
- Vol. 62 (10), 1398-1405
- https://doi.org/10.2967/jnumed.120.253096
Abstract
Purpose: 68Ga-NODAGA-LM3 and 68Ga-DOTA-LM3 are somatostatin receptor subtype 2 (SSTR2) specific antagonists used for PET/CT imaging. The purpose of this study was to evaluate the safety, biodistribution, and dosimetry of 68Ga-NODAGA-LM3 and 68Ga-DOTA-LM3 in patients with well-differentiated neuroendocrine tumors (NETs). Methods: Patients were equally randomized into two arms: Arm A, 68Ga-NODAGA-LM3; Arm B, 68Ga-DOTA-LM3. Serial PET scans were acquired at 5, 15, 30, 45, 60, and 120 minutes after 68Ga-NODAGA-LM3 (200 MBq ± 11 MBq/40 μg total peptide mass) or 68Ga-DOTA-LM3 (172 MBq ± 21 MBq/40 μg total peptide mass) injection. The biodistribution in normal organs, tumor uptake, and safety were assessed. Radiation dosimetry was calculated using OLINDA/EXM (version 1.0). Results: Sixteen patients, 8 in each arm, were recruited in the study. Both tracers were well tolerated in most patients. Two patients in Arm B had nausea (G2) and one of them had vomiting (G1). The PET images of other fourteen patients were further analyzed. Significantly lower organ uptake was observed in the pituitary, parotids, liver, spleen, pancreas, adrenal, stomach, small intestine, and kidneys with 68Ga-DOTA-LM3 compared to 68Ga-NODAGA-LM3. A total of 38 lesions were analyzed, including 18 lesions on 68Ga-NODAGA-LM3 and 20 lesions on 68Ga-DOTA-LM3. Both tracers showed good tumor uptake and retention. With 68Ga-NODAGA-LM3, the tracer accumulation in tumor lesions increased by 138%, from an average SUVmax of 31.3 ± 19.7 at 5 minutes to 74.6 ± 56.3 at 2h. With 68Ga-DOTA-LM3, the tumor uptake rapidly reached a high level at 5 minutes after injection, with an average SUVmax of 36.6 ± 23.6, and continued to increase to 45.3 ± 29.3 until 30 minutes post-injection. Urinary bladder wall is the organ receiving the highest absorbed dose in both arms. The mean effective dose was 0.026 ± 0.003 mSv/MBq for 68Ga-NODAGA-LM3 and 0.025 ± 0.002 mSv/MBq for 68Ga-DOTA-LM3. Conclusion: Both 68Ga-NODAGA-LM3 and 68Ga-DOTA-LM3 show favorable biodistribution, high tumor uptake, and good tumor retention, resulting in high image contrast. The dosimetric data is comparable to other 68Ga-labeled SSTR2 antagonists. Further studies are required to look into the potential antagonistic effects of 68Ga-NODAGA-LM3 and 68Ga-DOTA-LM3.This publication has 22 references indexed in Scilit:
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