PT  - JOURNAL ARTICLE
AU  - Martin J. Barrio
AU  - Claudio Spick
AU  - Caius G. Radu
AU  - Michael Lassmann
AU  - Uta Eberlein
AU  - Martin Allen-Auerbach
AU  - Christiaan Schiepers
AU  - Roger Slavik
AU  - Johannes Czernin
AU  - Ken Herrmann
TI  - Human Biodistribution and Radiation Dosimetry of <sup>18</sup>F-Clofarabine, a PET Probe Targeting the Deoxyribonucleoside Salvage Pathway
AID  - 10.2967/jnumed.116.182394
DP  - 2017 Mar 01
TA  - Journal of Nuclear Medicine
PG  - 374--378
VI  - 58
IP  - 3
4099  - http://jnm.snmjournals.org/content/58/3/374.short
4100  - http://jnm.snmjournals.org/content/58/3/374.full
SO  - J Nucl Med2017 Mar 01; 58
AB  - 18F-clofarabine, a nucleotide purine analog, is a substrate for deoxycytidine kinase (dCK), a key enzyme in the deoxyribonucleoside salvage pathway. 18F-clofarabine might be used to measure dCK expression and thus serve as a predictive biomarker for tumor responses to dCK-dependent prodrugs or small-molecule dCK inhibitors, respectively. As a prerequisite for clinical translation, we determined the human whole-body and organ dosimetry of 18F-clofarabine. Methods: Five healthy volunteers were injected intravenously with 232.4 ± 1.5 MBq of 18F-clofarabine. Immediately after tracer injection, a dynamic scan of the entire chest was acquired for 30 min. This was followed by 3 static whole-body scans at 45, 90, and 135 min after tracer injection. Regions of interest were drawn around multiple organs on the CT scan and copied to the PET scans. Organ activity was determined and absorbed dose was estimated with OLINDA/EXM software. Results: The urinary bladder (critical organ), liver, kidney, and spleen exhibited the highest uptake. For an activity of 250 MBq, the absorbed doses in the bladder, liver, kidney, and spleen were 58.5, 6.6, 6.3, and 4.3 mGy, respectively. The average effective dose coefficient was 5.1 mSv. Conclusion: Our results hint that 18F-clofarabine can be used safely in humans to measure tissue dCK expression. Future studies will determine whether 18F-clofarabine may serve as a predictive biomarker for responses to dCK-dependent prodrugs or small-molecule dCK inhibitors.