Across a number of institutions, the authors recruited men aged 18 years and older with rising PSA after definitive therapy and negative or equivocal standard of care imaging (e.g., CT/MRI, bone scintigraphy, or F-18 fluciclovine). The authors undertook by PyL-PET/CT using s single 9 mCi (333 MBq) ± 20% dose of PyL, followed by PET/CT 1-2 hours later. Patients with positive 18F-DCFPyL-PET/CT scans based on local interpretation were scheduled for follow up within 60 days to verify suspected lesion(s) using a composite SOT.
As their primary outcome of interest, the authors assessed the correct localization rate (CLR), defined as the percentage of pts with a 1:1 correspondence between at least one lesion identified by PyL-PET/CT and the composite standard of truth: pathology, correlative imaging, or PSA response, in descending order of priority. The trial was successful if the lower bound of the 95% confidence interval for CLR exceeded 20% for at least two of three independent, blinded central 18F-DCFPyL-PET/CT reviewers.
The authors accrued 208 men who met inclusion criteria. Median PSA in this cohort was 0.8 [0.2 - 98.4] ng/mL. Using their defined primary outcome of correct localization rate, the authors demonstrated that PyL-PET/CT correctly localized lesions in 84.8-87.0% of cases among the three readers (lower bound of 95% CI: 77.8%-80.4%), against the composite SOT. The performance of 18F-DCFPyL-PET/CT by CLR (≥1 lesion co-localized) and PPV (≥1 lesion confirmed) was maintained through all 3 SOT categories:
1. histopathology (N=31): 78.6-82.8% and 92.9-93.3% for CLR and PPV, respectively;
2. correlative imaging (N=100): 86.1-88.6% and 87.0-89.5% for CLR and PPV, respectively;
3. PSA response (N=1): 100% for both CLR and PPV.
Additionally, CLR remained high regardless of which correlative imaging modality was used including 18F-fluciclovine-PET/CT (N=71; CLR 86.8-90.9%), MRI (N=23; CLR 80.0-86.7%) and CT (n=6; CLR 80.0-100%).
Thus, the authors conclude that PSMA-targeted 18F-DCFPyL-PET/CT detected and localized metastatic lesions with high CLR and PPV in men with BCR who had negative or equivocal conventional imaging studies.
Presented by: Frederic Pouliot, M.D., Ph.D., FRCSC Assistant professor Department of Surgery Faculty of Medicine, Université Laval Centre De Recherche in Quebec Canada
Co-Authors: Michael A. Gorin, Steven P. Rowe, Lawrence Saperstein, David Josephson, Peter R. Carroll, Jeffrey Y.C. Wong, Austin R. Pantel, Steve Y. Cho, Kenneth L. Gage, Morand Piert, Andrei Iagaru, Janet H. Pollard, Vivien Wong, Jessica Jensen, Nancy Stambler, Michael J. Morris, Barry A. Siegel
Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center Twitter @WallisCJD during the 2021 ASCO Genitourinary Cancers Symposium (ASCO GU), February 11th to 13th, 2021