Quality metrics analysis in patients who received Lutetium-177 PSMA-617 (177Lu–PSMA) therapy in a real-world practice setting.

Abstract

e17049 Background: 177Lu–PSMA is a radiolabeled small molecule that delivers β radiation to cells expressing prostate-specific membrane antigen (PSMA). It has been approved for use in metastatic castration-resistant prostate cancer (mCPRC) in 3/2022, based on VISION study. The Food and Drug Administration (FDA) label for 177Lu–PSMA requires prior therapy with an androgen receptor pathway inhibitor (ARPI) and taxane-based chemotherapy as well as presence of at least one PSMA-positive tumor with uptake greater than normal liver and no PSMA-negative lesions on a PSMA positron emission tomography (PET) scan. In the VISION study, PSMA PET was performed within 4 weeks of therapy start. Further, patient received either 177Lu–PSMA plus protocol permitted standard of care (SOC), including ARPI, or SOC alone. Given the relatively recent approval of this therapy, real-world familiarity with administration of this agent may not be optimal. Methods: A retrospective analysis of 25 patients with mCRPC who received 177Lu–PSMA therapy since 3/2022 at the University of California Irvine (24/25) and Hoag Hospital (1/25) was performed. Multiple variables were analyzed and compared to the FDA label for this agent as well as design of the VISION study. Results: All patients in this study had received an ARPI and at least one taxane chemotherapy prior to 177Lu–PSMA. A PSMA-PET scan was obtained prior to 177Lu–PSMA therapy in all patients. The timing of the scan was within 4 weeks of starting 177Lu–PSMA therapy in only 5/25 (20.0%) patients. The average time from PSMA PET scan to 177Lu–PSMA therapy start was 66 days [range: 18 - 326 days]. None of the PSMA PET scan reports included a baseline liver standardized uptake value (SUV) or mentioned whether any lesions were non PSMA-avid. All reports provided SUV values for some, but not all, PSMA-avid lesions. The average maximum SUV of the most PSMA-avid lesion noted on the reports was 34.7. All PSMA PET scans were retrospectively reviewed by a nuclear medicine specialist and the average maximum SUV of the most PSMA-avid lesion on re-review was 42.0 (p <0.05). During 177Lu–PSMA therapy, co-administration of ARPI occurred in 10/24 (23.8%) of patients. Conclusions: This study highlights the differences in quality metrics between patients who received 177Lu–PSMA therapy in a real-world practice setting compared to the FDA label for this agent and VISION study design. Differences included lack of uniform PSMA PET scan reporting, timing of obtaining pre-treatment PSMA PET imaging, and co-administration of ARPI. Development of institutional algorithms around administration of 177Lu–PSMA therapy may be needed.