Researchers Released Data from a Clinical Trial Investigating Fluorine 18 Fluciclovine PET/CT Use to Identify Targets for Site-Directed Therapy

Fluorine 18 fluciclovine (FACBC) is a synthetic radiolabeled amino acid that is upregulated by many cancer cells, including prostate cancer cells.¹ In 2016, FACBC positron emission tomography (PET) was approved by the US Food and Drug Administration for prostate cancer and found to be superior to other molecular imaging techniques for this cancer type.¹ Recurrent disease occurs in up to one-third of patients with prostate cancer who undergo treatment and is typically found by an increase in prostate-specific antigen (PSA) levels.¹ Conventional imaging is limited in determining the extent and location of recurrence.¹ FACBC PET has the advantage of detecting recurrence of prostate cancer in patients posttreatment with low PSA levels.²

At the 2021 American Society of Clinical Oncology annual meeting, Wong and colleagues presented the results of an investigation of FACBC PET/CT use to identify potential targets for site-directed therapy and whether this approach leads to clinically relevant outcomes. Data were obtained from the Flu-BLAST-PC clinical trial, a prospective, interventional study that is enrolling men with prostate cancer and biochemical recurrence after they have had both radical prostatectomy and prostatic fossa adjuvant or salvage radiation. In addition, the participants were to have no evidence of metastasis by conventional computed tomography (CT) or bone imaging, a PSA ≥0.5 ng/mL to <10 ng/mL, and a PSA-doubling time >3 months and <18 months. After participants received FACBC PET/CT imaging, they were divided into 3 groups.²

Group 1 includes participants with no prostate cancer metastases who undergo observation. FACBC PET/CT is performed when PSA thresholds reach >2 ng/mL and >5 ng/mL. If their PSA increases to ≥10 ng/mL with the FACBC PET/CT remaining negative, they will no longer be eligible for the trial. Group 2 participants are defined as those with 1 to 3 prostate cancer lesions detected on FACBC PET/CT.² These participants will have site-directed surgery and/or radiation along with 6 months of androgen deprivation therapy (ADT) and abiraterone acetate with prednisone. The planned enrollment for this group is 65 participants. The primary study end point is undetectable PSA (<0.2 ng/mL) for group 2 participants 2 years after study treatment.² Group 3 consists of those participants with ≥4 prostate cancer lesions detected at the initial FACBC PET/CT. They are treated with 6 months of ADT and abiraterone acetate with prednisone only; no site-directed surgery is performed. If participants in group 1 are found to have prostate cancer metastasis, they are placed into group 2 or group 3 based on the number of lesions. Secondary end points are undetectable PSA for group 3 participants 2 years following study treatment, an undetectable PSA rate in groups 2 and 3 after testosterone recovery after ADT therapy, time elapse after ADT therapy is reinitiated, overall survival, tolerability, and safety.

References

1. Gusman M, Aminsharifi JA, Peacock JG, et al. Review of ¹⁸F-fluciclovine PET for detection of recurrent prostate cancer. Radiographics. 2019;39:822-841.
2. Wong RL, Holt SK, Zeng J, et al. The fluciclovine (FACBC) PET/CT site-directed therapy of oligometastatic prostate cancer (Flu-BLAST-PC) trial. J Clin Oncol. 2021;39:15_suppl.