title: Prostate extracellular vesicles in patient plasma as a liquid biopsy platform for prostate cancer using nanoscale flow cytometry.
abstract: BACKGROUND
  Extracellular vesicles released by prostate cancer present in seminal fluid, urine, and blood may represent a non-invasive means to identify and prioritize patients with intermediate risk and high risk of prostate cancer. We hypothesize that enumeration of circulating prostate microparticles (PMPs), a type of extracellular vesicle (EV), can identify patients with Gleason Score≥4+4 prostate cancer (PCa) in a manner independent of PSA.
  
  
  METHODS
  Plasmas from healthy volunteers, benign prostatic hyperplasia patients, and PCa patients with various Gleason score patterns were analyzed for PMPs. We used nanoscale flow cytometry to enumerate PMPs which were defined as submicron events (100-1000nm) immunoreactive to anti-PSMA mAb when compared to isotype control labeled samples. Levels of PMPs (counts/µL of plasma) were also compared to CellSearch CTC Subclasses in various PCa metastatic disease subtypes (treatment naïve, castration resistant prostate cancer) and in serially collected plasma sets from patients undergoing radical prostatectomy.
  
  
  RESULTS
  PMP levels in plasma as enumerated by nanoscale flow cytometry are effective in distinguishing PCa patients with Gleason Score≥8 disease, a high-risk prognostic factor, from patients with Gleason Score≤7 PCa, which carries an intermediate risk of PCa recurrence. PMP levels were independent of PSA and significantly decreased after surgical resection of the prostate, demonstrating its prognostic potential for clinical follow-up. CTC subclasses did not decrease after prostatectomy and were not effective in distinguishing localized PCa patients from metastatic PCa patients.
  
  
  CONCLUSIONS
  PMP enumeration was able to identify patients with Gleason Score ≥8 PCa but not patients with Gleason Score 4+3 PCa, but offers greater confidence than CTC counts in identifying patients with metastatic prostate cancer. CTC Subclass analysis was also not effective for post-prostatectomy follow up and for distinguishing metastatic PCa and localized PCa patients. Nanoscale flow cytometry of PMPs presents an emerging biomarker platform for various stages of prostate cancer.
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Colleen N
authors.initials: CN
authors.lastname: Biggs
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Khurram M
authors.initials: KM
authors.lastname: Siddiqui
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.|Department of Urology, University of Dammam, Dammam, Saudi Arabia.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Al-Zahrani
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Siddika
authors.initials: S
authors.lastname: Pardhan
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Sabine I
authors.initials: SI
authors.lastname: Brett
authors.affiliation: Department of Mechanical and Materials Engineering, Western University, London, Canada.
authors.forename: Qiu Q
authors.initials: QQ
authors.lastname: Guo
authors.affiliation: Department of Mechanical and Materials Engineering, Western University, London, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Urology, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Wolf
authors.affiliation: Department of Surgery, Western University, London, Canada.|Department of Oncology, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Power
authors.affiliation: Sandia National Laboratories, Albuquerque, NM, USA.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Durfee
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Connor D
authors.initials: CD
authors.lastname: MacMillan
authors.affiliation: Sandia National Laboratories, Albuquerque, NM, USA.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Townson
authors.affiliation: Sandia National Laboratories, Albuquerque, NM, USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Brinker
authors.affiliation: University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Fleshner
authors.affiliation: Department of Surgery, Western University, London, Canada.|Department of Oncology, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Izawa
authors.affiliation: Department of Oncology, Western University, London, Canada.
authors.forename: Ann F
authors.initials: AF
authors.lastname: Chambers
authors.affiliation: Department of Surgery, Western University, London, Canada.|Department of Oncology, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Chin
authors.affiliation: Department of Surgery, Western University, London, Canada.|Translational Prostate Cancer Research Laboratory, Lawson Health Research Institute, London, Canada.
authors.forename: Hon S
authors.initials: HS
authors.lastname: Leong
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D001706:Biopsy; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000378:metabolism / Q000473:pathology*; D000067128:Extracellular Vesicles / Q000378:metabolism / Q000473:pathology*; D005434:Flow Cytometry / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D011467:Prostate / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011470:Prostatic Hyperplasia / Q000097:blood / Q000473:pathology / Q000601:surgery; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000601:surgery; D064129:Prostatic Neoplasms, Castration-Resistant / Q000097:blood / Q000473:pathology / Q000601:surgery; D046988:Proteasome Endopeptidase Complex / Q000276:immunology; D012189:Retrospective Studies; D014407:Tumor Cells, Cultured; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D017430:Prostate-Specific Antigen; C000589188:PSMA1 protein, human; D046988:Proteasome Endopeptidase Complex
keywords: extracellular vesicles; liquid biopsy; nanoscale flow cytometry; prostate cancer; prostate microparticles
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