PET/CT Study with Fluciclovin (18F) in Recurrent Prostate Cancer Following a Normal PSMA-PET/CT Scan

Prostate cancer develops in the prostate gland, a gland located below the bladder in men that surrounds the urethra. By far the most common form is adenocarcinoma, which originates in the glandular tissue of the prostate. Prostate cancer confined to the prostate is generally treated with the goal of a cure; surgical removal of the prostate (radical prostatectomy) and radiation therapy are among the most important treatment options, and both can be supplemented with hormone deprivation therapy. If the PSA level in the blood rises again after curative treatment, this is referred to as a biochemical recurrence (a return of the disease that is initially detectable only in the laboratory). Often, no focal lesions can yet be detected on imaging at this stage. To determine where the disease has returned, a PSMA-PET/CT scan is frequently performed. PSMA is a protein that is typically found in higher concentrations on prostate cancer cells than on healthy tissue. The test uses a weakly radioactive tracer that binds to PSMA. Positron emission tomography (PET) makes it possible to visualize where this tracer accumulates in the body. The computed tomography (CT) scan, performed simultaneously, shows the exact location of these areas within the body. How well a recurrence of prostate cancer can be detected depends, among other factors, on the PSA level and on how much PSMA the tumor cells produce. Especially with low PSA levels, the examination may yield inconclusive results. Therefore, not every recurrence can be detected with a PSMA-PET/CT scan. The new tracer fluciclovin (18F) could represent a new option for early diagnosis. This is a synthetically produced, radioactively labeled amino acid that, like natural amino acids, is taken up into cells via specific transporters in the cell membrane. Since these transporters are often present in greater quantities in tumor cells, the substance can accumulate there more strongly and become visible during the scan. Fluciclovin (18F) is administered through a vein (intravenously). A PET/CT scan is then performed to visualize where the tracer accumulates in the body.

The aim of this observational study is to investigate whether a PET/CT scan using the tracer fluciclovin (18F) can visualize foci of recurrent prostate cancer. The examination takes place as part of routine clinical care, so there is no assignment to different study groups and no control group (uncontrolled). The images are stored pseudonymized and evaluated by three independent nuclear medicine specialists who are not aware of the findings at the time of evaluation. Patients are then followed for twelve months. After one month, a questionnaire is sent to the referring physicians to determine whether the planned course of treatment has changed. After twelve months, additional test results—such as further imaging, PSA levels, the course of treatment, and, where available, tissue biopsies—are used to review the PET/CT findings.

Eligible participants are male patients aged 18 and older with prostate cancer (prostate adenocarcinoma) that was previously treated with the intent to cure, whose PSA level has risen again (suspected biochemical recurrence) and whose subsequent PSMA-PET/CT was negative or inconclusive. Patients currently undergoing or who have recently completed hormone deprivation therapy are ineligible to participate.