Piflufolastat F 18-PET/CT in patients with prostate cancer: An analysis of OSPREY (cohorts A and B) standardized uptake value (SUV) results stratified by PSA and Gleason score.

Abstract

5024 Background: The OSPREY clinical trial was a phase 2/3 prospective study of prostate specific membrane antigen (PSMA) PET/CT using piflufolastat F 18. Piflufolastat F 18 (aka 18F-DCFPyL or PyL) is a novel PSMA-targeting radiopharmaceutical approved for imaging of PCa pts both at initial staging and for disease recurrence. Here we describe SUV results by biopsy status, baseline PSA levels, and Gleason score (GS). Methods: Piflufolastat F 18-PET/CT was evaluated in men with NCCN high-risk PCa scheduled to undergo radical prostatectomy with pelvic lymphadenectomy (RP-PLND) (Cohort A) and men with radiologically suspected recurrent/metastatic PCa (Cohort B). A single IV dose of 9 mCi (333 MBq) of piflufolastat F 18 was administered followed by PET/CT acquisition 1-2 hours later. Piflufolastat F 18 uptake in various lesion locations as defined by maximum and peak SUV (SUVmax, SUVpeak) were determined by three blinded, independent central readers for each tissue (e.g., bone, lymph nodes (LN), soft tissue). To measure SUVs, the reader placed a volume of interest (VOI) on each identified lesion. SUVmax was defined as the maximum single-voxel SUV within the VOI. SUVpeak within the VOI was defined as the average SUV within a fixed-sized VOI (1 cm diameter sphere), representing the cluster with the highest average SUV. Results: 345 men underwent piflufolastat F 18-PET/CT. Cohort B (n = 93evaluable) SUVmax and SUVpeak were significantly higher for biopsy positive (+)(one biopsy lesion/pt) when compared to biopsy negative (-) lesions from bone and LN. SUVpeak for biopsied bone and LN (Cohort B) appeared to increase with rising baseline PSA. In high-risk PCa pts, SUVpeak for prostate (Cohort A; n = 252 evaluable) increased with baseline PSA and were highest for GS 9-10 (Table). Conclusions: Piflufolastat F 18-PET/CT uptake was significantly higher in biopsy + lesions and increased with baseline PSA. Prostate SUVpeak was highest for GS 9-10. Clinical trial information: NCT02981368. [Table: see text]