Clinical application of Cu-64 PSMA PET/CT in Theranostics of prostate cancer

Objectives Copper-64 (⁶⁴Cu, T_1/2 =12.7h; Eβ+ max = 0.65MeV (17.9%); Eβ− max = 0.57MeV (39%)) is suitable for in-vivo PET imaging. Prostate specific membrane antigen (PSMA) is significantly over-expressed in undifferentiated prostate cancer. We report the initial data of molecular imaging with ⁶⁴Cu-PSMA PET/CT in Theranostics of prostate cancer.

Methods Cyclotron-produced ⁶⁴Cu was labeled with PSMA and a mean of 259.8 MBq of ⁶⁴Cu-PSMA was administered. Whole-body PET/CT (Biograph mCT Flow 64) was performed in nine patients referred for restaging following elevation of PSA. All ⁶⁴Cu-PSMA-positive lesions were counted and the SUVmax recorded. Images were compared to relevant previous imaging, and disease restaging was performed according to RECIST/PERCIST.

Results Previous prostatectomy had been performed in 7/9 (77.7%) patients. 2/9 (22.2%) patients had uptake in the prostate bed, suggestive of local recurrent disease. 5/9 (55.5%) patients demonstrated pathological tracer uptake in lymph node metastases. Skeletal metastaes were detected in 4/9 (44.4%) patients. 2/9 (22.2%) patients demonstrated no pathological tracer uptake, compatible with bio-chemical recurrence post-prostatectomy. Three patients had stable disease (SD), despite PSA increase. Progressive disease (PD) was observed in 4/9 (44.4%) patients, of which three were recommended ¹⁷⁷Lu-PSMA radioligand therapy (PRLT). No adverse effects were observed in any patient.

Conclusions ^Cu64 PSMA was found safe for clinical use. The results of this study demonstrate a high Theranostics potential for molecular imaging using ⁶⁴Cu-PSMA PET/CT in prostate cancer. Excellent image quality was obtained with high target to non target ratios, and late imaging up to 17 hours post injection could be performed. ⁶⁴Cu-PSMA PET/CT could possibly be used instead of ⁶⁸Ga-PSMA PET/CT for disease staging and restaging, as well as for planning ¹⁷⁷Lu-PSMA radioligand therapy.