1392P - Lutetium-177-prostate-specific membrane antigen therapy (177Lu-PSMA) in patients (Pts) with prior radium-223 (223Ra): Safety and effectiveness outcomes

Background

Previous studies suggest feasibility of using ¹⁷⁷Lu-PSMA after ²³³Ra with an acceptable safety profile. Here, we investigate the safety and effectiveness of ¹⁷⁷Lu-PSMA in pts with metastatic castration-resistant prostate cancer (mCRPC) and prior ²²³Ra in the RALU study.

Methods

Pt data were retrospectively collected in German nuclear medicine centres from 2021 to 2022. Safety and effectiveness were evaluated in all pts and by the treatment sequence (²²³Ra then chemotherapy [Ct] then ¹⁷⁷Lu-PSMA [Ra-Ct-Lu] and Ct then ²²³Ra then ¹⁷⁷Lu-PSMA [Ct-Ra-Lu]).

Results

Overall, 133 pts were evaluated. Before starting ¹⁷⁷Lu-PSMA, the proportion of pts with an Eastern Cooperative Oncology Group performance status of 0, 1 or 2 was 0%, 62% and 38%, respectively. Median prostate-specific antigen (PSA) was 285.5 ng/ml and median alkaline phosphatase (ALP) was 146.0 U/L. 56% of pts had received ≥4 life prolonging therapies, including abiraterone (71%), enzalutamide (70%), docetaxel (74%) and cabazitaxel (23%). 71% of pts had received 6 ²²³Ra injections. All pts had bone metastases; 27% had visceral metastases. 73% of pts received 1–4 ¹⁷⁷Lu-PSMA cycles and 27% received ≥5 cycles. Safety is shown in the table. During ¹⁷⁷Lu-PSMA treatment, PSA50 response occurred in 42% of all pts, 46% of the Ra-Ct-Lu pts and 36% of the Ct-Ra-Lu pts. ALP30 response occurred in 19% of all pts and was similar in the Ra-Ct-Lu and Ct-Ra-Lu groups (13% vs 11%, respectively). Median overall survival (OS) from the start of ¹⁷⁷Lu-PSMA treatment was 13 (95% CI 11–16), 12 (9–15) and 14 (9–17) months in the all pts, Ra-Ct-Lu and Ct-Ra-Lu groups, respectively. Table: 1392P

ASAT, aspartate aminotransferase; N, number of pts per group; n, number of pts with specified event; TEAE, treatment-emergent adverse events^a13 pts with multiple Cts were included in both groups^bFrom starting ¹⁷⁷Lu-PSMA to the end of 30-day follow-up^cUp to 90 days after last ¹⁷⁷Lu-PSMA dose^dNo grade 5 toxicities occurred

Conclusions

In this real-world setting, ¹⁷⁷Lu-PSMA therapy in pts with prior ²²³Ra had an acceptable safety profile and effectiveness was similar to other findings with ¹⁷⁷Lu-PSMA, indicating no cross-resistance. ²²³Ra and Ct order prior to ¹¹⁷Lu-PSMA did not alter the safety profile nor OS from the start of ¹⁷⁷Lu-PSMA.

Clinical trial identification

Editorial acknowledgement

Dr Chris Guise of Cancer Communications and Consultancy Ltd., Cheshire, UK, provided medical writing assistance, which was funded by Bayer. Dr Lila Adnane (Bayer) provided editorial assistance.

Legal entity responsible for the study

Bayer AG.

Funding

Bayer AG.

Disclosure

K. Rahbar: Financial Interests, Personal, Other, Honoraria: Advanced Accelerator Applications, Bayer; Financial Interests, Personal, Advisory Role: ABX GmbH, ABX-CRO, Bayer, Advanced Accelerator Applications. M. Essler: Financial Interests, Personal, Advisory Role: Advanced Accelerator Applications, Bayer, Ipsen; Financial Interests, Personal, Other, Travel/accommodation: Ipsen. M. Eiber: Financial Interests, Personal, Other, Patent application: rhPSMA; Financial Interests, Personal, Stocks/Shares: Novartis, Telix Pharmaceuticals; Financial Interests, Personal, Advisory Role: ABX, Advanced biochemical compounds, Blue Earth Diagnostics, Janssen Oncology, Telix Pharmaceuticals; Financial Interests, Personal, Research Grant: ABX, Advanced biochemical compounds; Financial Interests, Personal, Other, Travel/accommodation: Bayer Schering Pharma; Financial Interests, Institutional, Advisory Role: Novartis; Financial Interests, Institutional, Research Grant: Bayer, Blue Earth Diagnostics. C. la Fougère: Financial Interests, Personal, Advisory Role: EUSA-Pharma, Novartis, Ipsen, Oncodesign, Sirtex Medical; Financial Interests, Institutional, Research Grant: Oncovision. V. Prasad: Financial Interests, Personal, Other, Honoraria: Advanced Accelerator Applications; Financial Interests, Personal, Advisory Role: Bayer; Financial Interests, Personal, Research Grant: Ipsen. W.P. Fendler: Financial Interests, Personal, Advisory Role: Janssen, Calyx; Financial Interests, Personal, Speaker’s Bureau: Janssen, Bayer; Financial Interests, Personal, Other, Honoraria: Parexel; Financial Interests, Personal, Research Grant: SOFIE. P. Rassek: Financial Interests, Personal, Other, Employment of immediate family member: Porterhouse Group AG Paracelsus Kliniken. R.A. Bundschuh: Financial Interests, Personal, Other, Honoraria: Eisai AG; Financial Interests, Personal, Advisory Role: Bayer. M. Kurtinecz, A. Schmall, F. Verholen: Financial Interests, Personal, Full or part-time Employment: Bayer. O. Sartor: Financial Interests, Personal, Advisory Role: Bayer, Sanofi, AstraZeneca, Dendreon, Constellation Pharmaceuticals, Advanced Accelerator Applications, Pfizer, Bristol Myers Squibb, Bavarian Nordic, EMD Serono, Astellas Pharma, Progenics, Blue Earth Diagnostics, Myovant Sciences, Myriad Genetics, Novartis, Clarity Pharmaceuticals, Fusion Pharmaceuticals, Isotopen Technologien, Janssen, Noxopharm, Clovis Oncology, Noria Therapeutics, Point Biopharma, TeneoBio, Telix Pharmaceuticals, Theragnostics; Financial Interests, Personal, Other, Travel/accommodation: Bayer, Johnson & Johnson, Sanofi, AstraZeneca, Progenics; Financial Interests, Personal, Expert Testimony: Sanofi; Financial Interests, Personal, Research Grant: SOTIO, Janssen; Financial Interests, Personal, Stocks/Shares: Lilly, GlaxoSmithKline, AbbVie, Cardinal Health, United Health Group, PSMA Therapeutics, Clarity Pharmaceuticals, Noria Therapeutics, Clovis Oncology; Financial Interests, Institutional, Research Grant: Bayer, Sanofi, Endocyte, Merck, InVitae, Constellation Pharmaceuticals, Advanced Accelerator Applications, AstraZeneca, Dendreon. All other authors have declared no conflicts of interest.