Our objectives were to assess the prognostic value of posttherapy [177Lu]Lu-PSMA (LuPSMA) SPECT/CT by visual evaluation using RECIP 1.0 during LuPSMA therapy and develop an evidence-based clinical protocol to monitor the efficacy of LuPSMA. Methods: Patients with metastatic castration-resistant prostate cancer who received at least 2 LuPSMA cycles between April 2019 and November 2023 were retrospectively included in this study. Pairs of baseline and interim LuPSMA SPECT/CT (SPECT) and PSMA PET/CT (PET) images after 2 therapy cycles were analyzed per visual RECIP 1.0. Changes in prostate-specific antigen (PSA) levels at 12 wk were categorized by Prostate Cancer Working Group Criteria 3 guidelines and combined with RECIP 1.0 reads to determine disease progression using a composite classification method (PSA + RECIP). The primary outcome was the prognostic value of posttherapeutic SPECT by RECIP 1.0 for overall survival (OS). The clinical protocol was developed on the basis of the prognostic accuracy (Harrell concordance index, or C-index) of SPECT versus PET and the combination of SPECT plus PSA (SPECT + PSA) versus the combination of PET plus PSA (PET + PSA). Results: Data from 105 patients were evaluated. Progressive disease determined by SPECT was associated with shorter OS compared with stable disease (hazard ratio, 2.5; 95% CI, 1.2-5.3; P = 0.015) and with partial response (hazard ratio, 6.5; 95% CI, 2.7-15.7; P < 0.001). Of the 73 patients who underwent PET after 2 cycles, 7 (10%), 30 (41%), 22 (30%), and 30 (41%) had tumor progression shown by SPECT, PET, SPECT + PSA, and PET + PSA, respectively. The C-index for SPECT was inferior compared with that for PET (0.54 vs. 0.66; P < 0.001), whereas the C-indices for SPECT + PSA and PET + PSA did not differ significantly (0.62 vs. 0.66, respectively; P = 0.07). Conclusion: Posttherapeutic LuPSMA SPECT/CT per RECIP 1.0 after 2 therapy cycles was prognostic for OS. LuPSMA SPECT/CT identified significantly fewer patients with RECIP-classified progressive disease; however, SPECT + PSA achieved similar prognostic accuracy to PET + PSA for LuPSMA response evaluation.
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2025 Apr 24 [Epub ahead of print]
Lena M Unterrainer, Nicolas De Leiris, Marcus Unterrainer, Astrid Delker, Linus Hempel, Zachary Ells, Sophie C Kunte, Josef Zahner, Adrien Holzgreve, Mathias J Zacherl, Gabriel T Sheikh, Jozefina Casuscelli, Julien Leenhardt, Kenneth J Pienta, Emmanuelle Jacquet, Mathieu Laramas, Jerome Long, Marine Faure, Ghislaine Reboulet, Channing J Paller, Alexis Mercier, Lilja B Solnes, Kevin Kiraz, Harun Ilhan, Andrei Gafita, Loïc Djaileb
Department of Nuclear Medicine, University Hospital LMU Munich, Munich, Germany., Nuclear Medicine Department, University Grenoble Alpes, INSERM, CHU Grenoble Alpes, LRB, Grenoble, France., Department of Urology, University Hospital LMU Munich, Munich, Germany., Department of Urology, James Buchanan Brady Urological Institute, Johns Hopkins University, Baltimore, Maryland., Medical Oncology Department, University Grenoble Alpes, INSERM, CHU Grenoble Alpes, LRB, Grenoble, France., Institut Daniel Hollard, Mutualist Hospital Group, Grenoble, France., Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland., Division of Nuclear Medicine and Molecular Imaging; The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland; and., Nuclear Medicine Department, University Grenoble Alpes, INSERM, CHU Grenoble Alpes, LRB, Grenoble, France; .