18F-Flotufolastat (18F-rhPSMA-7.3) is a newly approved prostate-specific membrane antigen targeting radiopharmaceutical for diagnostic imaging of prostate cancer (PCa). SPOTLIGHT (National Clinical Trials 04186845) evaluated 18F-flotufolastat in men with suspected PCa recurrence. Here, we present results of predefined exploratory endpoints from SPOTLIGHT to evaluate the impact of clinical factors on 18F-flotufolastat detection rates (DR).
The impact of baseline prostate-specific antigen (PSA), PSA doubling time (PSAdt), and International Society of Urologic Pathology Grade Group (GG) on 18F-flotufolastat DR was evaluated among all SPOTLIGHT patients with an evaluable scan, with DR stratified according to the patients' prior treatment (radical prostatectomy ± radiation therapy [RP] or radiation therapy only [RT]). The patients underwent positron emission tomography 50 to 70 minutes after receiving 18F-flotufolastat (296 MBq IV), and scans were read by 3 blinded central readers, with the majority read representing agreement between ≥2 readers.
In total, 389 men (median PSA: 1.10 ng/mL) were evaluable. By majority read, 18F-flotufolastat identified distant lesions in 39% and 43% of patients treated with prior RP or RT, respectively. The overall DR broadly increased with increasing PSA (<0.2 ng/mL: 33%; ≥10 ng/mL: 100%). Among patients with PSA <1 ng/mL, 68% had positive scans, and 27% had extrapelvic findings. PSAdt was available for 145/389 (37%) patients. PSAdt did not appear to influence 18F-flotufolastat DR (77%-90% across all PSAdt categories). Among patients with prior RP, DR ranged from 70% to 83% across PSAdt categories, and 100% DR was reported for all post-RT patients. In total, 362/389 (93%) patients had baseline GG data. Overall DRs were uniformly high (75%‒95%) across all GG. When stratified by prior treatment, DRs across all GG were 69% to 89% in patients with prior RP and ≥96% in patients with prior RT.
18F-Flotufolastat-positron emission tomography enabled the accurate detection of recurrent PCa lesions across a wide range of PSA, PSAdt, and International Society of Urologic Pathology GG, thus supporting its clinical utility for a broad range of patients with recurrent PCa.
Advances in radiation oncology. 2024 May 01*** epublish ***
Benjamin H Lowentritt, Ashesh B Jani, Brian T Helfand, Edward M Uchio, Michael A Morris, Jeff M Michalski, Albert Chau, Phillip Davis, Brian F Chapin, David M Schuster, SPOTLIGHT Study Group
Chesapeake Urology Research Associates, Towson, Maryland., Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, Georgia., NorthShore University Health System, Evanston, Illinois., University of California Irvine Medical Center, Irvine, California., Advanced Molecular Imaging and Therapy, Glen Burnie, Maryland., Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri., Blue Earth Diagnostics Ltd, Oxford, United Kingdom., Blue Earth Diagnostics, Monroe Township, New Jersey., Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, Texas., Division of Nuclear Medicine and Molecular Imaging, Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia.