Targeting free prostate-specific antigen for in vivo imaging of prostate cancer using a monoclonal antibody specific for unique epitopes accessible on free prostate-specific antigen alone

Susan Evans-Axelsson, David Ulmert, Anders Örbom, Pernilla Peterson, Olle Nilsson, Johan Wennerberg, Joanna Strand, Karin Wingårdh, Tomas Olsson, Zandra Hagman, Vladimir Tolmachev, Anders Bjartell, Hans Lilja, Sven Erik Strand

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

This study investigated the feasibility of targeting the free, unbound forms of prostate-specific antigen (fPSA) for in vivo imaging of prostate adenocarcinomas (PCa), as PSA is produced and secreted at abundance during every clinical stage and grade of PCa, including castration-resistant disease. We injected 125I-labeled monoclonal antibody PSA30 (specific for an epitope uniquely accessible on fPSA alone) intravenously in male nude mice carrying subcutaneous xenografts of LNCaP tumors (n=36). Mice were sacrificed over a time course from 4 hours to 13 days after injecting 125I- labeled PSA30. Tissue uptake of 125I-PSA30 at 48 and 168 hours after intravenous injection was compared with two clinically used positron emission tomography radiopharmaceuticals, 18F-fluoro-deoxy-glucose ( 18F-FDG) or 18F-choline, in cryosections using Digital AutoRadiography (DAR) and also compared with immunohistochemical staining of PSA and histopathology. On DAR, the areas with high 125I-PSA30 uptake corresponded mainly to morphologically intact and PSA-producing LNCaP cells, but did not associate with the areas of high uptake of either 18F-FDG or 18F-choline. Biodistribution of 125I-PSA30 measured in dissected organs ex vivo during 4 to 312 hours after intravenous injection demonstrated maximum selective tumor uptake 24-48 hours after antibody injection. Our data showed selective uptake in vivo of a monoclonal antibody highly specific for fPSA in LNCaP cells. Hence, in vivo imaging of fPSA may be feasible with putative usefulness in disseminated PCa.

Original languageEnglish
Pages (from-to)243-251
Number of pages9
JournalCancer Biotherapy and Radiopharmaceuticals
Volume27
Issue number4
DOIs
Publication statusPublished - 1 May 2012
Externally publishedYes

Keywords

  • digital autoradiography
  • dual isotope imaging
  • free PSA
  • prostate cancer
  • prostate-specific antigen
  • Radioimmunodetection

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Pharmacology
  • Cancer Research

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