A new imaging agent detecting copper accumulation in tumors is better at detecting early prostate cancer relapse than the tracing molecules used currently, an Italian study shows.
Because the new agent is not excreted through the urine – and therefore does not accumulate in the bladder – it allows for a more thorough exploration of the pelvic and prostatic region than standard imaging agents. The molecule also is better at detecting the site of relapse in patients with low prostate-specific antigen (PSA) levels.
Copper is key for the activation of several molecules involved in cell proliferation. Its levels are increased in tumors, suggesting that copper concentration in cancer cells could be used as an imaging biomarker for positron emission tomography/computed tomography (PET/CT) scans.
Studies in mice and humans with prostate cancer already had shown that agent, copper-64 chloride (64CuCl2), accumulated in cancerous regions. But its ability to detect prostate cancer relapse following surgery or radiation therapy remained unknown.
So, researchers conducted a clinical trial comparing 64CuCl2 with the commonly used PET/CT tracer fluorine-18-choline (18F-choline) in 50 prostate cancer patients with biochemical relapse — deemed as patients with rising PSA levels — after first-line surgery or external radiation therapy.
Because standard imaging agents are excreted in the urine, their accumulation in the bladder may interfere with a thorough assessment of the pelvis and prostate. But 64CuCl2 is instead excreted through the liver, facilitating the assessment.
The maximum accumulation of the molecule was seen in less than one hour after injection, researchers found.
Interestingly, while the standard tracer only identified 56 percent of relapse cases, 64CuCl2 had a detection rate of 82 percent, a difference that is statistically significant. A higher detection rate also was seen in patients with low PSA levels (below 1 ng/ml).
In general, 64CuCl2 was more sensitive at detecting prostate cancer lesions, including metastasis in lymph-nodes and bones.
“This is the first time this novel agent has been compared with 18F-choline-PET/CT in a considerable number of prostate cancer patients with biochemical relapse,” Arnoldo Piccardo of E.O. Ospedali Galliera in Genoa, Italy, and lead author of the study, said in a press releaseof the Society of Nuclear Medicine and Molecular Imaging.
The findings demonstrate that 64CuCl2 is a more suitable tracer to evaluate the prostate and surrounding areas, and has greater detection power over the standard tracer, the researchers concluded.
Additional studies encompassing a larger number of patients are now warranted to fully explore and characterize the potential of this imaging agent in the management of prostate cancer, Piccardo said.
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