Experimental Drug Shows Promise in Prostate Cancer Diagnosis, Treatment

Small molecule agent able to detect or destroy prostate cancer cells when combined with different radionuclides.

A new agent shows promise in not only diagnosing prostate cancer, but also treatment of the disease.

Prostate-specific membrane antigen (PSMA) is a surface protein typically found in healthy prostate cells, but has much higher levels on prostate cancer cells.

“Therefore, PSMA is an ideal target for diagnostic purposes as well as targeted therapies against prostate cancer," biotechnologist Dr. Matthias Eder, of the German Cancer Research Center, said in a press release.

A research team led by Dr. Eder developed a small molecule called PSMA-617, which can attach to PSMA and can be labeled with radionuclides. When bound to the radioactive diagnostic radionuclide gallium-68, PSMA-617 can be used to detect miniscule assemblies of prostate cancer cells in positron emission tomography scans.

"In this way, physicians are able to detect small secondary tumors in other organs or closely monitor response to therapy,” Dr. Eder said. “Diagnostic approaches that have been used in the clinic so far have not come close to this sensitivity.”

PSMA-617 can also bind to the therapeutic radionuclide lutetium-177, which is taken up by tumor cells carrying the PSMA target molecule to eradicate the cells from the inside. The researchers noted this process represents a promising treatment option, specifically in cases of hard-to-treat hormone-resistant prostate carcinoma.

"Other agents that target PSMA and can be coupled with strong or weak radiation emitters are already being developed," said Dr. Klaus Kopka, a chemist and departmental head at the German Cancer Research Center. "However, only a few of these agents have turned out to be ideal. Most of them are too unstable, accumulate insufficiently in cancer cells and wash out too slowly from healthy organs. By contrast, PSMA-617 accumulates in large quantities in tumors and metastases and is stored well in cancer cells. As a result, prostate cancer can be irradiated from the inside, so to speak."