MP20-14: Positive prostate 68GaPSMA-PET/CT correlates wit ... al fluid in patients with prostate cancer (PCa).

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).

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INTRODUCTION

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.

METHODS

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.

RESULTS

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 (*).

CONCLUSION

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.

Funding: None