Molecular staging by RT-PCR analysis for PSA and PSMA in peripheral blood and bone marrow samples is an independent predictor of time to biochemical failure following radical prostatectomy for clinically localized prostate cancer

Abstract

Radical prostatectomy should ideally be curative for all patients with clinically localized prostate cancer (PrCa), yet a sizeable proportion of them eventually relapse. We examined in this setting the feasibility of pre-operative risk stratification for early post-operative relapse using reverse transcriptase polymerase chain reaction (RT-PCR) for prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) transcripts in preoperative bone marrow (BM) biopsies and peripheral blood (PBL) samples. Nested RT-PCR for PSA and PSMA transcripts were performed in RNA from BM biopsies and PBL samples prospectively obtained from 111 men newly diagnosed, by trans-rectal ultrasound (TRUS)-guided biopsy, with clinically localized PrCa and scheduled to undergo radical prostatectomy, according to their respective doctors' recommendation. Molecular analysis for each sample (PBL or BM) was considered positive only if both PSA and PSMA transcripts were detectable. Serial serum PSA level measurements served for biochemical follow-up and detection of biochemical failure (PSA >0.2 ng/ml). PBL and BM RT-PCR molecular staging delineated three groups of patients (a) PBL-BM- (72 patients, 65%), (b) PBL+BM+ (29 patients, 26%), and (c) PBL+BM- (10 patients, 9%). These three groups corresponded to low, high, and intermediate risk for early post-prostatectomy recurrence (median time to biochemical failure of >38, 8, and >28 months, respectively). Multivariate analysis confirmed that molecular staging status was independent predictor of disease-free survival, after adjusting for PSA levels and Gleason score. In clinically localized PrCa, combined PSA/PSMA RT-PCR in PBL and BM is an independent predictor of time to biochemical failure following radical prostatectomy.

Theranostic Agents for Photodynamic Therapy of Prostate Cancer by Targeting Prostate-Specific Membrane Antigen

“…Expression of PSMA correlates with the stage of disease and Gleason score (26). PSMA expression is also higher in prostate cancer cells from hormone-refractory patients, (26,27) and increased PSMA expression has been shown to be an independent marker of disease recurrence (27)(28)(29). In addition to being overexpressed in prostate cancer, PSMA is also expressed in the neovasculature of many solid tumors (30), making PSMA a promising target for both imaging (31)(32)(33) and treatment of prostate cancer (34)(35)(36).…”

Combined androgen blockade therapy can convert RT-PCR detection of prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) transcripts from positive to negative in the peripheral blood of patients with clinically localized prostate cancer and increase biochemical failure-free survival after curative therapy

“…We have previously shown that this protocol can stratify prostate cancer patients with either relative high (median bFFS 8 months) or relative low risk for biochemical failure (median bFFS )36 months) (24).…”

“…RNA extraction and molecular staging by nested RT-PCR for PSA and PSMA transcripts in PB samples were performed as previously described (11,20,24). Our RT-PCR protocol for PSA and PSMA mRNA detection was developed to minimize the adverse consequences of illegitimate transcription by defining as a positive detection only that which corresponded for positive detections of both PSA and PSMA transcripts at each individual PB sample.…”

“…Our RT-PCR protocol for PSA and PSMA mRNA detection was developed to minimize the adverse consequences of illegitimate transcription by defining as a positive detection only that which corresponded for positive detections of both PSA and PSMA transcripts at each individual PB sample. In addition, our protocol was developed so that its positive results correspond to clinically relevant levels of cell dissemination in PB (5-10 prostate cancer cells/mL of blood), thereby avoiding ultra-sensitive RT-PCR detection protocols, as previously published (20,24).…”

“…Therefore, by declaring as a positive detection only cases of a confirmed detection of both transcripts (PSA and PSMA mRNA) in the same PB sample (24), by optimizing the RT-PCR protocol so that its positive results correspond to clinically relevant level of microscopic prostate cancer burden (3-5 tumor cells/10 6 PB cells or 5-10 tumor cells/mL PB) (24)(25)(26) and by using -0.8 mg of RNA in a PCR test to avoid the detection of illegitimate transcription (23), we prevented ultra-sensitive detection by our molecular staging protocol (20,24). This clinically relevant RT-PCR detection protocol for the combined detection of PSA and PSMA transcripts in PB and in bone marrow biopsy samples, performed preoperatively, provides independent prognostic information for biochemical failure-free survival (bFFS) in patients with clinically localized prostate cancer (24). It can therefore be potentially used as a guide for the therapeutic management of these patients.…”