PT  - JOURNAL ARTICLE
AU  - Tuula Tolvanen
AU  - Kari Kalliokoski
AU  - Simona Malaspina
AU  - Anna Kuisma
AU  - Salla Lahdenpohja
AU  - Ernst J. Postema
AU  - Matthew P. Miller
AU  - Mika Scheinin
TI  - Safety, Biodistribution, and Radiation Dosimetry of <sup>18</sup>F-rhPSMA-7.3 in Healthy Adult Volunteers
AID  - 10.2967/jnumed.120.252114
DP  - 2021 May 10
TA  - Journal of Nuclear Medicine
PG  - 679--684
VI  - 62
IP  - 5
4099  - http://jnm.snmjournals.org/content/62/5/679.short
4100  - http://jnm.snmjournals.org/content/62/5/679.full
SO  - J Nucl Med2021 May 10; 62
AB  - This first-in-humans study investigated the safety, biodistribution, and radiation dosimetry of a novel 18F-labeled radiohybrid prostate-specific membrane antigen (rhPSMA) PET imaging agent, 18F-rhPSMA-7.3. Methods: Six healthy volunteers (3 men, 3 women) underwent multiple whole-body PET acquisitions at scheduled time points up to 248 min after the administration of 18F-rhPSMA-7.3 (mean activity, 220; range, 210–228 MBq). PET scans were conducted in 3 separate sessions, and subjects were encouraged to void between sessions. Blood and urine samples were collected for up to 4 h after injection to assess metabolite-corrected radioactivity in whole blood, plasma, and urine. Quantitative measurements of 18F radioactivity in volumes of interest over target organs were determined directly from the PET images at 8 time points, and normalized time–activity concentration curves were generated. These normalized cumulated activities were then inputted into the OLINDA/EXM package to calculate the internal radiation dosimetry and the subjects’ effective dose. Results: 18F-rhPSMA-7.3 was well tolerated. One adverse event (mild headache, not requiring medication) was considered possibly related to 18F-rhPSMA-7.3. The calculated effective dose was 0.0141 mSv/MBq when using a 3.5-h voiding interval. The organs with the highest mean absorbed dose per unit of administered radioactivity were the adrenals (0.1835 mSv/MBq), the kidneys (0.1722 mSv/MBq), the submandibular glands (0.1479 mSv), and the parotid glands (0.1137 mSv/MBq). At the end of the first scanning session (mean time, 111 min after injection), an average of 7.2% (range, 4.4%–9.0%) of the injected radioactivity of 18F-rhPSMA-7.3 was excreted into urine. Conclusion: The safety, biodistribution, and internal radiation dosimetry of 18F-rhPSMA-7.3 are considered favorable for PET imaging.