Pharmacokinetics and Dosimetry of [ ⁶⁸ Ga]Ga-PSMA-11 in Chinese Participants with Progressive Metastatic Castration-Resistant Prostate Cancer: A Phase 2 Study

Introduction: [ 68 Ga]Ga-prostate-specific membrane antigen (PSMA)-11 positron emission tomography (PET)/computed tomography (CT) imaging has demonstrated clinical value for individuals with prostate cancer (PC). In this phase 2 study, we measured the pharmacokinetics and dosimetry of [ 68 Ga]Ga-PSMA-11 in Chinese participants. Methods: Adult Chinese participants with progressive metastatic castration-resistant PC (mCRPC) received a single intravenous [ 68 Ga]Ga-PSMA-11 dose of approximately 150 MBq. Blood samples were collected at 5, 15, 30, 45, 85, 175, and 245 min post injection for pharmacokinetics assessments. Whole-body PET scans and low/ultra-low-dose CT scans were acquired at 30, 60, 120, and 255 min post injection for dosimetry assessments. Results: Pharmacokinetics and dosimetry assessments were completed in seven participants who received a [ 68 Ga]Ga-PSMA-11 dose (range: 108.3–236.7 MBq). In the blood, the geometric mean effective terminal half-life was 1.34 h (geometric coefficient of variation [geo-CV], 182%); geometric mean clearance was 9.80 L/h (geo-CV, 106%). The highest absorbed doses were seen in the kidneys, urinary bladder walls, and lacrimal glands. In the study population, the geometric mean (geo-CV) effective dose of [ 68 Ga]Ga-PSMA-11 was 4.2 mSv (32.9%). Conclusions: The pharmacokinetic and dosimetry profiles of [ 68 Ga]Ga-PSMA-11, assessed using a validated method in participants with progressive mCRPC, make it very suitable as an imaging agent.