Predictive value of metastatic distribution patterns on [⁶⁸Ga]Ga-PSMA PET/CT for [¹⁷⁷Lu]Lu-PSMA therapy

This study aimed to assess the predictive value of metastatic distribution patterns on ⁶⁸Ga-PSMA-11 PET/CT in patients with chemotherapy- and castration-resistant prostate cancer undergoing ¹⁷⁷Lu-PSMA-617 radioligand therapy.

A retrospective analysis was conducted on 48 patients who received ¹⁷⁷Lu-PSMA-617 therapy between April 2019 and August 2023. Demographic, clinical, and laboratory data, along with pre- and post-treatment ⁶⁸Ga-PSMA-11 PET/CT images, were evaluated for associations with molecular response and progression. Whole-body PET/CT segmentation was performed using METAVOL software. Treatment response was classified using RECIP 1.0 criteria, and predictive values were analyzed using SPSS 22.0, with statistical significance set at p < 0.05.

Based on RECIP 1.0 criteria, 58.3% (n = 28) responded to therapy, while 41.7% (n = 20) did not. Disease progression was observed in 29.2% (n = 14), and 70.8% (n = 34) showed no progression. Molecular response was significantly associated with parotid SUVmean (OR = 1.137, p = 0.047) and highest miM1 stage (OR = 0.241, p = 0.046). Molecular progression was significantly associated with lymph node metastasis (OR = 0.144, p = 0.006), bone-only metastasis (OR = 4.333, p = 0.030), ln/metTL-PSMA ratio (OR = 0.070, p = 0.042), b/metTL-PSMA ratio (OR = 13.085, p = 0.040), and TL-PSMA-based lymph node dominance over bone metastases (OR = 0.385, p = 0.044).

This study highlights the predictive value of metastatic burden distribution on ⁶⁸Ga-PSMA PET/CT in determining treatment outcomes of ¹⁷⁷Lu-PSMA therapy.