Pretherapeutic 68Ga-PSMA-617 PET May Indicate the Dosimetry of 177Lu-PSMA-617 and 177Lu-EB-PSMA-617 in Main Organs and Tumor Lesions.

Abstract

AIM:

Combined Ga-PSMA-617 PET imaging and Lu-PSMA-617 therapy is a precise targeted theranostic approach for patients with metastatic castration-resistant prostate cancer (mCRPC). The purpose of this study was to determine whether pretherapeutic standard uptake value (SUV) in Ga-PSMA-617 PET could indicate the effective dose in the main organs and absorbed dose in tumor lesions.

METHODS:

After institutional review board approval and informed consent, 9 patients with mCRPC were recruited and underwent Ga-PSMA-617 PET/CT scans. Five patients received Lu-PSMA-617 (1.30-1.42 GBq, 35-38.4 mCi) and then underwent serial whole-body planar imaging and SPECT/CT imaging of both thoracic and abdominal regions at 0.5-, 2-, 24-, 48-, and 72-hour time points. The other 4 patients received Lu-EB-PSMA-617 (0.80-1.1 GBq, 21.5-30 mCi) and then underwent the same imaging procedures at 2-, 24-, 72-, 120-, and 168-hour time points. The effective dose in the main organs and the absorbed dose in tumor lesions were calculated. Detailed correlations between the pretherapeutic SUV in Ga-PSMA-617 PET and effective dose in the main organs as well as absorbed dose in the tumor lesions were analyzed.

RESULTS:

SUV of Ga-PSMA-617 PET was moderately correlated with effective dose in main organs (r = 0.610 for Lu-PSMA-617, r = 0.743 for Lu-EB-PSMA-617, both P < 0.001). SUV of tumor lesions in Ga-PSMA-617 PET had high correlation with those in Lu-PSMA-617 (r = 0.915, P < 0.001) and moderate correlation with those in Lu-EB-PSMA-617 (r = 0.611, P = 0.002).

CONCLUSIONS:

Pretherapeutic Ga-PSMA-617 PET may indicate the dosimetry of Lu-PSMA-617 and Lu-EB-PSMA-617. Both the effective dose in main organs and absorbed dose in tumor lesions correlate with SUV of Ga-PSMA-617 PET. This relationship may help select appropriate candidates for peptide receptor radionuclide therapy. Further investigations of larger cohorts are needed to confirm these initial findings.

• Authors: Jingnan Wang, Jie Zang, Hao Wang, Qingxing Liu, Fang Li, Yansong Lin, Li Huo, Orit Jacobson, Gang Niu, Xinrong Fan, Zhaohui Zhu, Xiaoyuan Chen
• Journal: Clinical nuclear medicine (Clin Nucl Med) Vol. 44 Issue 6 Pg. 431-438 (Jun 2019) ISSN: 1536-0229 [Electronic] United States
• PMID: 30985422 (Publication Type: Journal Article)

Chemical References

• 177Lu-PSMA-617
• Dipeptides
• Heterocyclic Compounds, 1-Ring
• PSMA-617
• Radiopharmaceuticals
• Lutetium
• Prostate-Specific Antigen

Topics

• Dipeptides (administration & dosage, pharmacokinetics)
• Heterocyclic Compounds, 1-Ring (administration & dosage, pharmacokinetics)
• Humans
• Lutetium
• Male
• Positron Emission Tomography Computed Tomography (methods)
• Prostate-Specific Antigen
• Prostatic Neoplasms, Castration-Resistant (diagnostic imaging, radiotherapy)
• Radiometry
• Radiopharmaceuticals (administration & dosage, pharmacokinetics)
• Radiotherapy Dosage
• Retrospective Studies
• Single Photon Emission Computed Tomography Computed Tomography (methods)
• Whole Body Imaging