Positive prostate 68GaPSMA-PET/CT correlates with detection of CD45-/PSMA+ non-sperm epithelial cells obtained by liquid biopsy of seminal fluid in patients with prostate cancer (PCa).
Prostate Specific Membrane Antigen (PSMA) presents high expression in PCa cells and has been considered an attractive target for molecular imaging. 68GaPSMA-PET/CT showed high detection rate of nodal and bone metastases and, recently, was tested for diagnosis of primary PCa. Seminal fluid (SF) might contain prostate-derived PSMA positive tumour cells in men with PCa and serve as diagnosis. In order to investigate the clinical reliability of 68GaPSMA-PET/CT for identification of primary PCa we tested the hypothesis that it correlates with detection of CD45-/PSMA+ non-sperm epithelial cells obtained by liquid biopsy of SF in patients with PCa.
This is a nested analysis combining data from two observational, longitudinal, prospective studies. Patients with primary PCa detected by 68GaPSMA-PET/CT software assisted fusion biopsy (Protocol ICH/382/2016), who received an indication to radical prostatectomy (RP), had a sample of SF one month after the biopsy and just before the RP (Protocol ICH/1791/2017). The prostate-derived cells from semen (non sperm epithelial cells) were sorted using the fluorescence-activated cell sorting (FACSAria III - BD Biosciences, San Jose, USA) and the CD45 negative/PSMA positive (CD45-/PSMA+) served as markers of interest. The primary endpoint was to determine the relationship between 68GaPSMA-PET/CT results and detection of CD45-/PSMA+ non-sperm epithelial cells in SF.
Seven patients over 59, who had received a diagnosis of PCa by 68GaPSMA-PET/CT software assisted fusion biopsy and were scheduled for radical prostatectomy (RP), collected SF. The FACS procedure sorted non-sperm epithelial cells and CD45-/PSMA+ cell, as well, in SF of all the patients with positive imaging, but not in negative ones. Figure 1 presents the SF cytology of CD45-/PSMA+ sorted cells (arrow) and CD45+/PSMA- ones (*).
Our findings, by the first, showed a potential correlation between the 68GaPSMA-PET/CT, PCa and cancer-specific markers detected by SF liquid biopsy. These findings may represent the proof-of-concept to improve the role of 68GaPSMA-PET/CT for primary PCa diagnosis in a selected population and to further investigate the prostate cancer tumor elements by liquid biopsy of the SF.