Because treatment for prostate cancer is highly individualized, molecular imaging technologies are helping to improve the ways in which prostate cancer is diagnosed and treated. Molecular imaging, a field where a radiotracer is used as the imaging agent, is a useful tool for both detecting and treating prostate cancer. There are several radiotracers that are used to image patients with prostate cancer. These include fluorodeoxyglucose (FDG), sodium fluoride (NaF), fluciclovine, choline and agents that target prostate-specific membrane antigen (PSMA).
PSMA is a transmembrane protein that’s overexpressed in prostate cancer. Because of its external location on the surface of prostate cells, it is easily accessible to researchers targeting it with molecules for the purpose of prostate imaging or delivery therapies. The goal of a PSMA (positron-emission tomography) PET is to locate and determine the extent of prostate cancer.
PSMA compounds have been developed by a number of groups and companies over the last ten years. Thomas Hope, MD, associate professor and director of molecular therapy in the UC San Francisco Department of Radiology and Biomedical Imaging, is interested in novel imaging agents and therapies for prostate cancer and neuroendocrine tumors. “One of the biggest unmet needs in prostate cancer treatment is for patients with a biomedical recurrence of their cancer,” says Dr. Hope. “This means that after a patient undergoes definitive therapy, such as prostatectomy or radiation therapy, their prostate-specific antigen (PSA) level rises and it is not clear where the patient’s disease is.”
“Up until recently, common imaging methods used were fluciclovine PET, or NaF PET and bone scans, but these modalities are not sensitive enough to detect disease in patients with low PSA levels,” continues Dr. Hope. He says that a number of agents have been developed, but a lot of work still needs to be done. UCSF and UCLA are two major institutions that are working collaboratively on PSMA studies, and hope to jointly obtain FDA approval for the first PSMA-targeted PET agent. Overall, centers like UCSF and UCLA are running clinical trials and will continue to publish results as we learn more about the role PSMA PET impacts the care of patients with prostate cancer.