PSMA-PET/CT: New radiotracer pictures more prostate tumors

ST. LOUIS—Few options remain for patients with chemical-castration resistant prostate cancer and even effective imaging can be tough once advanced metastases take hold. However an emerging radiotracer homes in on prostate-specific anatomy and finds elusive lesions, according to a study presented this year at the Society of Nuclear Medicine and Molecular Imaging’s 2014 Annual Meeting.

The tracer is F-18 DCFBC, a small-molecule PET agent among a group of agents that bind to prostate-specific membrane antigen (PSMA). PSMA is present even in healthy cells, but in malignant cells increased uptake of radiotracer can indicate disease. This research looks particularly at the efficacy of the radiotracer when used with PET/CT for the imaging of both castration-sensitive and resistant prostate cancer.

“F-18 DCFBC is one of several emerging small molecule PET radiopharmaceuticals for prostate cancer that promise to bring functional imaging for prostate cancer into clinical reality in the near future,” said Steve Cho, MD, PhD, assistant professor of nuclear medicine and PET in the department of radiology at Johns Hopkins University School of Medicine in Baltimore. “F-18 DCFBC and other emerging PSMA and prostate cancer imaging agents will help greatly improve patient management and our understanding of prostate cancer beyond what is currently known.”

The research included imaging of 12 patients in an ongoing clinical trial. Seven of the prostate cancer patients had higher PSMA levels, which, with increased folate levels, were positively associated with associated castration-resistant status. F-18 DCFBC performed comparably to conventional imaging except in highly scarred bone metastases and was actually superior to the standard for the cervical spine or where there were signs of degeneration, and in lymph nodes that were smaller than a centimeter.

“PSMA-based functional imaging such as F-18 DCFBC PET promises to help patients with prostate cancer by the following: improving detection of both primary and metastatic prostate cancer and therapy response assessment and improving therapy development,” explained Cho. “Patients will be able to start treatment or switch to an appropriate treatment regimen by using functional imaging, in conjunction with other non-imaging biomarkers, to greatly improve their clinical management and quality of life while minimizing adverse effects.” 

This radiotracer is still under investigation and researchers are currently looking into standardizing radiochemistry and biodistribution in multicenter clinical trials.