The U.S. Food and Drug Administration (FDA) has approved a new diagnostic tool to help doctors pinpoint exactly where in the body prostate cancer recurs. Axumin is a radioactive diagnostic agent for injection used for positron emission tomography (PET) imaging in men with suspected prostate cancer recurrence based on elevated PSA levels following prior treatment. With the approval of the agent, clinicians hope to better determine the location of the recurrence in the prostate, as this defines optimal choice of therapy. Standard imaging tests used to determine identification of sites of recurrence have low diagnostic accuracy, so more accurate techniques are needed.
“Imaging tests are not able to determine the location of the recurrent prostate cancer when the PSA is at very low levels. Axumin is shown to provide another accurate imaging approach for these patients.”
-Libero Marzella, M.D., Ph.D., FDA’s director of the Division of Medical Imaging Products
Axumin is a synthetic amino acid that is actively transported into prostate cancer cells by amino acid transporters. It is not metabolized, nor is it incorporated into newly synthesized proteins. Imaging studies have demonstrated that Axumin is preferentially taken up into prostate cancer compared with surrounding normal tissue and visualization is not obscured by bladder uptake.
The FDA based their decision on results of two studies that evaluated the safety and efficacy of Axumin (Blue Earth Diagnostics). One study compared 105 Axumin scans to histopathology obtained by prostate biopsy and by biopsies of suspicious imaged lesions in men suspected of having prostate cancer recurrence. In the second study, researchers evaluated 96 Axumin scans with C11 choline scans in patients with a median PSA of 1.44 ng/mL. In both studies, on-site radiologists read the scans, followed by three independent radiologists who read the same scans in a blinded fashion.
“Image interpretation errors can occur with Axumin PET imaging. A negative image does not rule out the presence of recurrent prostate cancer and a positive image does not confirm the presence of recurrent prostate cancer. Clinical correlation, which may include histopathological evaluation of the suspected recurrence site, is recommended.”
-FDA News Release
Overall, results of the independent scan readings were consistent and confirmed the results of the on-site readings, thereby supporting the efficacy of Axumin for imaging prostate cancer. The most commonly reported adverse reactions in patients are injection site pain, redness, and a metallic taste in the mouth. Axumin is a radioactive drug and the agency advises that the agent should be handled with appropriate safety measures to minimize radiation exposure to patients and healthcare providers during administration. Axumin is marketed by Blue Earth Diagnostics, Ltd., Oxford, United Kingdom.