Prostate-specific membrane antigen (PSMA) is present in high amounts in salivary glands, but it is unclear whether labeled binders of PSMA are excreted in the saliva.
Ten patients with prostate cancer underwent whole-body [18F]DCFPyL PET/CT (NCT03181867), and saliva samples were collected between 0-120 minutes post-injection. [18F]DCFPyL salivary excretion was measured over 120 minutes and expressed as %ID/g. Protein-associated binding was estimated by the percentage of [18F]DCFPyL versus parent radiotracer.
All PET scans of 10 patients (69 ± 8 years) with histologically confirmed prostate cancer (PSA= 2.4 ± 2.4, and Gleason Grade = 6-9) showed high uptake of [18F]-DCFPyL in salivary glands while 8 patients demonstrated high uptake in the saliva at 45 minutes. The intact [18F]-DCFPyL (98%) was also confirmed in the saliva samples at 120 min with increasing salivary radioactivity between 30-120 min.
Systemically injected [18F]DCFPyL shows salivary gland uptake, an increasing amount of which is secreted in saliva over time and is not maximized by 120 minutes post-injection. Although probably insignificant for diagnostic studies, patients undergoing PSMA-targeted therapies should be aware of radioactivity in saliva.
Frontiers in oncology. 2024 Apr 23*** epublish ***
Bruna Fernandes, Jyoti Roy, Falguni Basuli, Blake M Warner, Liza Lindenberg, Esther Mena, Steven S Adler, Gary L Griffiths, Peter L Choyke, Frank I Lin
Molecular Imaging Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States., Chemistry and Synthesis Center, National Heart, Lung and Blood Institute, Bethesda, MD, United States., Salivary Disorders Unit, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States., Clinical Research Directorate, Frederick National Laboratory for Cancer Research, Frederick, MD, United States.