Session: MP40: Prostate Cancer: Detection & Screening I
MP40-13: 18F-rhPSMA-7.3 Detection Rates in Patients with Recurrence of Prostate Cancer Following Primary Treatment with Radiation Therapy: Results from the SPOTLIGHT Study
Introduction: 18F-rhPSMA-7.3 is a novel high affinity prostate specific membrane antigen-targeting positron emission tomography (PET) radiopharmaceutical with potential for low bladder activity. The SPOTLIGHT study (NCT04186845) evaluated 18F-rhPSMA-7.3 in men with prostate cancer recurrence. Here, we report the 18F-rhPSMA-7.3 detection rates among a subgroup of SPOTLIGHT patients who had undergone primary treatment with radiation therapy only. Methods: Men with prostate cancer recurrence underwent PET 50–70 minutes after IV administration of 296 MBq 18F-rhPSMA-7.3. Scans were evaluated by 3 blinded central readers, with data reported for the individual readers and for the majority read (agreement for =2 readers). Detection rates, including region level analyses, were stratified by the prior treatment. Results: In total, 389 men had an evaluable 18F-rhPSMA-7.3 scan. Of these, 76 (median [range] PSA, 4.405 [0.03-134.60] ng/mL) had previously been treated with radiation therapy only. In total, 75 (99%) of the 76 patients had a positive 18F-rhPSMA-7.3 scan, and only 32 had positive findings confined to the prostate with no further extraprostatic detection (majority read data). Conversely, 18F-rhPSMA-7.3-avid pelvic nodes were detected in 25% of patients, with distant lesions detected in 43%. Table 1 presents the overall and regional detection rates. Conclusions: High 18F-rhPSMA-7.3 detection rates were observed in this population of patients with intact prostates experiencing prostate cancer recurrence after radiation therapy. While 42% of patients experienced recurrence only in the prostate, the finding of 18F-rhPSMA-7.3-avid lesions in distant extrapelvic sites in up to half of patients has the potential to influence management, especially where definitive salvage therapy to the intact prostate is being considered. SOURCE OF Funding: Blue Earth Diagnostics
