F-18 labelled PSMA-1007: biodistribution, radiation dosimetry and histopathological validation of tumor lesions in prostate cancer patients

PURPOSE: The prostate-specific membrane antigen (PSMA) targeted positron-emitting-tomography (PET) tracer (68)Ga-PSMA-11 shows great promise in the detection of prostate cancer. However, (68)Ga has several shortcomings as a radiolabel including short half-life and non-ideal energies, and this has motivated consideration of (18)F-labelled analogs. (18)F-PSMA-1007 was selected among several (18)F-PSMA-ligand candidate compounds because it demonstrated high labelling yields, outstanding tumor uptake and fast, non-urinary background clearance. Here, we describe the properties of (18)F-PSMA-1007 in human volunteers and patients. METHODS: Radiation dosimetry of (18)F-PSMA-1007 was determined in three healthy volunteers who underwent whole-body PET-scans and concomitant blood and urine sampling. Following this, ten patients with high-risk prostate cancer underwent (18)F-PSMA-1007 PET/CT (1 h and 3 h p.i.) and normal organ biodistribution and tumor uptakes were examined. Eight patients underwent prostatectomy with extended pelvic lymphadenectomy. Uptake in intra-prostatic lesions and lymph node metastases were correlated with final histopathology, including PSMA immunostaining. RESULTS: With an effective dose of approximately 4.4–5.5 mSv per 200–250 MBq examination, (18)F-PSMA-1007 behaves similar to other PSMA-PET agents as well as to other (18)F-labelled PET-tracers. In comparison to other PSMA-targeting PET-tracers, (18)F-PSMA-1007 has reduced urinary clearance enabling excellent assessment of the prostate. Similar to (18)F-DCFPyL and with slightly slower clearance kinetics than PSMA-11, favorable tumor-to-background ratios are observed 2–3 h after injection. In eight patients, diagnostic findings were successfully validated by histopathology. (18)F-PSMA-1007 PET/CT detected 18 of 19 lymph node metastases in the pelvis, including nodes as small as 1 mm in diameter. CONCLUSION: (18)F-PSMA-1007 performs at least comparably to (68)Ga-PSMA-11, but its longer half-life combined with its superior energy characteristics and non-urinary excretion overcomes some practical limitations of (68)Ga-labelled PSMA-targeted tracers. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00259-016-3573-4) contains supplementary material, which is available to authorized users.