[18F]NaF PET/CT imaging biomarkers of progression-free survival in metastatic prostate cancer.

277 Background: 18F-Sodium Fluoride (NaF) PET/CT has been shown to be superior to 99mTc-MDP SPECT in detection of bone metastases and shows great promise to reliably measure functional changes in bone. This study assesses the relationship of Progression Free Survival (PFS) with NaF PET/CT measures in patients with metastatic Castration-Resistant Prostate Cancer (CRPC). Methods: 55 CRPC patients had NaF PET/CT scans performed at baseline, which was repeated at week 9 if receiving taxane-based therapy (N = 16) or week 12 if receiving androgen-signaling pathway (AR) inhibitors (N = 39). Bone lesions were identified using a novel technique allowing for extraction and tracking of PET metrics from individual lesions at every timepoint. Cox proportional hazard regression analyses were conducted to evaluate associations between imaging metrics and PFS. Results: Median PFS was 8.3 months (range 1.0-30.3+). The strongest predictor of PFS in univariate analysis was total functional burden (SUVtotal) (P < 0.0001) dur...