“Lighting up” Prostate Cancer

Prostate cancer is notoriously difficult to image. In fact, traditional imaging technologies like CT (computerized tomography) and ultrasound are useless for clinically-localized disease (cancer still in the prostate). These technologies can find the prostate, but cannot reliably distinguish cancer from normal prostate gland. Recently, improvements in MRI (magnetic resonance imaging) have made this technology more useful for the diagnosis of localized prostate cancer. While the role of MRI in localized prostate cancer is being determined, the only useful imaging technologies are for patients with advanced and metastatic disease. For instance, CT scan (or MRI) can detect enlarged lymph nodes and nuclear medicine (bone) scans can find cancer that has spread to bones.

Even PET (positron emission tomography) imaging – which can detect many other cancers – is useless in prostate cancer. PET imaging makes use of a labelled glucose molecule that is taken up by rapidly dividing and growing cancer cells. Unfortunately prostate cancer is slow growing and does not pick up the glucose molecule to make it detectable.

Martin Pomper, MD, PhD

Researchers at the Brady Urological Institute and Johns Hopkins may be onto a new way to image prostate cancer using molecular genetics and PET imaging. Martin Pomper, MD, PhD, works with nanoparticle imaging technologies that preferentially bind to prostate cancer cells and emit a signal that can be detected. Instead of using a glucose pathway, Dr. Pomper has developed a nanoparticle that binds to PSMA (prostate specific membrane antigen), a protein overexpressed on prostate cancer cells. The nanoparticle sensor "only becomes activated when it encounters malignant cells, but not normal tissue, so that cancer and its metastases can be detected anywhere in the body."

PSMA-based PET imaging of a mouse model with prostate cancer tumor (yellow arrow) implanted
in the forearm of the mouse. The urinary system (kidneys, kid; bladder, bl) are also visualized in the
early imaging as the molecule is filtered by the urine. From Chen et al. [1]

Over several years, Dr. Pomper has worked to refine the molecule and technology used to image prostate cancer in the prostate and around the body. His work has been published in Nature Medicine and Cancer Research. Stay tuned as in human studies are in progress.

 
Portions of this story were extracted from "Molecular-Genetic Imaging Shows Individual Prostate Cancer Cells" in Discovery: Volume XI, Winter 2015 by the Patrick C. Walsh Prostate Cancer Research Fund.


 

 
[1] Chen Y, Pullambhatla M, Foss CA, Byun Y, Nimmagadda S, Senthamizhchelvan S, Sgouros G, Mease RC, Pomper MG. 2-(3-{1-Carboxy-5-[(6-[18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid, [18F]DCFPyL, a PSMA-based PET imaging agent for prostate cancer. Clin Cancer Res. 2011 Dec 15;17(24):7645-53. doi: 10.1158/1078-0432.CCR-11-1357. Epub 2011 Oct 31.