The Prognostic Value of ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT in Metastatic Castration-Resistant Prostate Cancer Treated with...

We aimed to explore the value of prostate-specific membrane antigen (PSMA) and ¹⁸F-FDG PET/CT in efficacy evaluation and prognosis analysis for patients with metastatic castration-resistant prostate cancer (mCRPC) who underwent Lutetium-177-labeled Evans blue-modified PSMA (¹⁷⁷Lu-EB-PSMA) therapy.

This study retrospectively enrolled 35 mCRPC patients who received ¹⁷⁷Lu-EB-PSMA therapy between January 2019 and April 2022, with follow-up data until December 2024. The correlation and predictive value of parameters derived from ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT with prostate-specific antigen (PSA) response rate, PSA progression-free survival (PSA-PFS), and overall survival (OS) were explored.

Among the 35 patients, 27 and 15 received 2 and 3 cycles of ¹⁷⁷Lu-EB-PSMA therapy, respectively. The best PSA response rate was 54.3% (19/35 patients), the median PSA-PFS was 4.8 months (95% confidence interval [CI] 4.2-7.2), and the median OS was 13.9 months (95% CI 11.5-17.3). Multivariable analysis demonstrated that baseline PSMA-positive tumor volume (hazard ratio [HR], 1.223 [95% CI, 1.065-1.404]; P = 0.011) was an independent prognostic factors of PSA-PFS and higher baseline total lesion PSMA for OS (HR, 1.180 [95% CI, 1.065-1.390]; P = 0.015). The newly emerged lesions after the first cycle of therapy on ⁶⁸Ga-PSMA PET/CT (NELs_1-PSMA) were identified as an early on-treatment progression indicator associated with worse outcomes in exploratory analyses (For PSA-PFS, HR, 6.419 [95% CI, 1.880-19.437]; P = 0.001; For OS, HR, 3.976 [95% CI, 2.015-9.433]; P = 0.001) .

⁶⁸Ga-PSMA PET/CT may provide valuable information for predicting long-term outcomes in patients undergoing ¹⁷⁷Lu-EB-PSMA therapy. These findings are hypothesis-generating; the potential role warrants prospective validation in larger, independent cohorts.

ClinicalTrials.gov, NCT03780075, Registered 19 December 2019, retrospectively registered, https://clinicaltrials.gov/study/NCT03780075.