The Clinical Utility of 18F-Fluciclovine PET/CT in Biochemically Recurrent Prostate Cancer: an Academic Center Experience Post FDA Approval - Beyond the Abstract

18F-Fluciclovine (18F-FACBC, anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid, Axumin®) was approved by the US Food and Drug Administration (FDA) in 2016. Although studies prior to FDA approval have shown the usefulness and limitations of 18F-fluciclovine PET/CT, it is important to evaluate its performance in real-world clinical scenarios. Here, we retrospectively analyzed data from 165 patients with biochemical recurrence (BCR) of prostate cancer who had 18F-fluciclovine PET/CT at our institution post-FDA approval.

Seventy (42.4%) patients had at least one other concurrent conventional imaging study (CT, MRI, and bone scan) within 3 months before or after the 18F-fluciclovine PET scan: abdomen-pelvis CT (n = 31), pelvic MRI (n = 31), and bone scan (n = 26). The detection rate of 18F-fluciclovine PET (54.8 %, 17/31) was significantly higher than that of CT (25.8 %, 8/31) (P < 0.05). The detection rate of 18F-fluciclovine PET (83.9%, 26/31) was significantly higher than that of (64.5%, 20/31) (P < 0.05). There were no patients with negative 18F-fluciclovine PET who had lesions identified on CT or MRI in our cohort. Our results confirm the superiority of 18F-fluciclovine PET in lesion detection over CT and MR at biochemical recurrence. The main advantage of 18F-fluciclovine PET over conventional CT or MR is that 18F -fluciclovine PET often detects subcentimeter lesions with increased uptake. For dedicated bone imaging, 25/26 (96.2%) bone scans were congruent with 18F-fluciclovine PET, while 1/26 (3.8%) patients with negative bone scans had an osseous lesion identified on 18F-fluciclovine PET.

One hundred and two patients (62%) had changes in clinical management based on 18F-fluciclovine PET findings. Twelve of these patients (12%) had lesion localization on 18F-fluciclovine PET, despite negative conventional imaging. On the other hand, treatment plans of 14 patients with negative 18F-fluciclovine PET (the median prostate-specific antigen [PSA] was 2.3 ng/mL) were changed based on additional PET imaging with a different radiopharmaceutical including prostate-specific membrane antigen (PSMA)-based PET. Our results provide additional evidence that the relatively lower detection rate of 18F-fluciclovine PET in patients with low PSA levels is one of its drawbacks and argue for the usefulness of PSMA-based PET, which contributed to a change in treatment strategy in 11 of 14 patients.

It is without a doubt that PSMA-based PET radiopharmaceuticals will largely replace 18F-Fluciclovine in the future; however, there will be a lag in commercial availability in the United States and perhaps in other countries. Therefore, we believe 18F-Fluciclovine will continue to play an important role in the management of prostate cancer patients and it is important for physicians to know the benefits and limitations of 18F-Fluciclovine in a real clinical setting.

Written by: Ryusuke Nakamoto, MD, PhD, Postdoctoral Research Fellow, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University Medical Center, Stanford, California

Andrei H. Iagaru, MD, FACNM, Professor of Radiology - Nuclear Medicine, Chief, Division of Nuclear Medicine and Molecular Imaging, Director, Nuclear Medicine Residency Program, Co-Director, PET-MRI Research Program, Stanford University, Stanford, California

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