Real-world outcomes among patients with metastatic castration-resistant prostate cancer (mCRPC) receiving guideline-recommended therapies after treatment with ¹⁷⁷ Lu-PSMA-617: A real-world prostate cancer disease observation (PRECISION) da

61 Background: 177 Lu-PSMA-617 was approved in March 2022 for patients with mCRPC pretreated with an androgen receptor pathway inhibitor (ARPI) and a taxane. There are limited data on the effectiveness of treatments post- 177 Lu-PSMA-617. The aim of this study was to describe prostate-specific antigen (PSA) responses among patients with mCRPC receiving a guideline-recommended therapy as the next therapy after 177 Lu-PSMA-617 treatment. Methods: This retrospective, observational study used real-world data from the PRECISION data platform, a proprietary dataset developed by Novartis, comprised of patient-level electronic health record and claims data that represent the US advanced prostate cancer population in the community, academic, urology, and medical oncology settings. Patients with mCRPC who received any guideline-recommended therapy at least 14 days after treatment with 177 Lu-PSMA-617 between March 23, 2022 and July 31, 2024 were included. Guideline-recommended therapies included abiraterone, enzalutamide, darolutamide, apalutamide, cabazitaxel, docetaxel, pembrolizumab, sipuleucel-T, niraparib, olaparib, talazoparib, rucaparib, and radium-223. Patients’ PSA values while on 177 Lu-PSMA-617 treatment were compared with their PSA values during the subsequent therapy course. Proportions of patients achieving reductions in PSA levels ≥50% (PSA50) and ≥80% (PSA80) were estimated. All analyses were descriptive. Results: A total of 152 patients receiving any subsequent guideline-recommended therapy after 177 Lu-PSMA-617 were identified. Mean age was 72.1 years. Most patients received an ARPI (n=93, 61.2%) – abiraterone (n=38), enzalutamide (n=37), darolutamide (n=10), or apalutamide (n=8) – as their subsequent therapy. Of patients who received a taxane (n=42, 27.6%), 24 received cabazitaxel and 18 received docetaxel. Median time to initiation of subsequent therapy was 206 days (interquartile range [IQR] 101–301 days) from 177 Lu-PSMA-617 initiation and 44 days (IQR 17–119 days) from 177 Lu-PSMA-617 discontinuation. Overall, among patients with sufficient information for PSA evaluation (n=30), 46.7% achieved PSA50 and 40.0% PSA80 post- 177 Lu-PSMA-617. Among patients receiving an ARPI, PSA50 was observed in 11/18 (61.1%) and PSA80 in 10/18 (55.6%). Among patients receiving a taxane, PSA50 and PSA80 were seen in 3/12 (25.0%) and 2/12 (16.7%), respectively. Conclusions: In this real-world analysis, the majority of patients who received guideline-recommended therapies after 177 Lu-PSMA-617 achieved at least a PSA50 response, suggesting that 177 Lu-PSMA-617 treatment does not preclude response to other subsequent therapies.