The radioactive imaging agent, fluciclovine F18 (Axumin), was approved by the FDA for use in positron emission tomography (PET) scans in men with suspected recurrence of prostate cancer whose prostate-specific antigen (PSA) levels rise following prior treatment.
Clinicians now hope to be able to better determine the location of the recurrence in the prostate, as this defines optimal choice of therapy. There is a low diagnostic accuracy with standard imaging tests used to determine identification of sites of recurrence, which is the reason why more accurate techniques are needed.
“When the PSA is at very low levels, imaging tests are not able to determine the location of the recurrent prostate cancer,” said Libero Marzella, MD, PhD, of the FDA’s Center for Drug Evaluation and Research and director of the Division of Medical Imaging Products, in a statement. “Axumin is shown to provide another accurate imaging approach for these patients.”
Experts estimate that up to one-third of patients who receive curative treatment after a diagnosis of primary prostate cancer will experience recurrence within 10 to 15 years following primary treatment.
PET scans are a well-established non-invasive imaging technique that uses the radiotracer [18F]flouro 2-deoxyglucose (FDG) for many tumor types. However, this agent is not widely used in imaging prostate cancer because of poor uptake and high urinary excretion limiting imaging quality.
The other PET radiotracer that is available, C11 choline, has been shown to improve detection in men with biochemical recurrent prostate cancer, but its 20-minute half-life limits use to medical centers with specialized on-site C11 production capability.
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.