Abstract C160: Baseline characteristics, safety, and efficacy of Radium-223 in metastatic castration resistant prostate cancer by race: Insights from the REASSURE US subset
Authors: Conti Peter S. , Sartor Oliver , Taplin Mary-Ellen , Song Daniel Y. , George Saby , Tomaszewski Jeffrey , Sylvester John , Mantz Constantine , Given Robert W. , Brookland Robert , Meltzer Jeff , Korn Matthew J. , Andres Richard , Babajanyan Svetlana , Higano Celestia 
Published: September 2024

Abstract
Background: REASSURE (NCT02141438) is a global, prospective, single-arm, observational study of Ra-223 use in patients with mCRPC with bone metastases within routine clinical settings. Using data from the second planned interim analysis, we compared baseline characteristics, survival, and safety outcomes among White, Black, and Asian patients treated with Ra-223 in the US subset of REASSURE. Methods: In this descriptive analysis (data collection 8-20-2014 to 3-20-2019), we examined baseline characteristics, OS, and safety outcomes for the US subset enrolled into REASSURE stratified by race (White, Black, Asian). Results: Of the 498 men in the US subset, 414 (83.1%) reported as White, 58 (11.7%) as Black, and 10 (2.0%) as Asian; race was not reported for 16 (3.2%) patients. Median age at study entry was 74.0, 69.5, and 71.0 years for White, Black, and Asian men, respectively. The proportion of patients whose prostate cancer was American Joint Committee on Cancer (AJCC) 7th edition stage III or IV at initial diagnosis was 45.2%, 58.6%, and 60.0% for White, Black, and Asian patients, respectively. The proportion of patients who completed 6 Ra-223 injections was similar across groups. Median duration of observation from the start of Ra-223 treatment was 11.3 months (range 0.4-41.3 months) for White patients, 14.9 months (range 0.7-39.1 months) for Black patients, and 20.5 months (range 4-27.7 months) for Asian patients. Median OS for White, Black, and Asian patients was 17.3 months (95% CI, 15.2-19.2 months), 19.5 months (95% CI, 12.9-27.1 months), and 21.8 months (95% CI, 3.58 months-not applicable), respectively. Any treatment-emergent drug related AE, treatment-emergent SAE, or drug-related SAE occurred in 45.2%, 41.4%, and 10.0% of White, Black, and Asian patients, respectively. Any-grade and grade ≥3 drug-related hematological TEAEs occurred in 8.4% and 5.3% of White patients, respectively, 15.5% and 12.1% of Black patients, respectively, and were not observed in Asian patients. Incidence of bone fractures was 4.1%, 3.4%, and 0% in White, Black and Asian patients respectively. Conclusions: This descriptive analysis of REASSURE found that Black patients were younger and presented with later-stage disease at diagnosis compared with White patients. A trend toward longer OS was seen in Black and Asian patients compared with White patients. AEs occurred at similar rates among groups. Drug-related hematological TEAEs, which have been reported with Ra-223 treatment, were more common in Black patients compared with White and Asian patients. Given the very small number of Asian patients enrolled in REASSURE, comparisons with this group should be interpreted with caution.
Citation Format: Peter S. Conti, Oliver Sartor, Mary-Ellen Taplin, Daniel Y. Song, Saby George, Jeffrey Tomaszewski, John Sylvester, Constantine Mantz, Robert W. Given, Robert Brookland, Jeff Meltzer, Matthew J. Korn, Richard Andres, Svetlana Babajanyan, Celestia Higano. Baseline characteristics, safety, and efficacy of Radium-223 in metastatic castration resistant prostate cancer by race: Insights from the REASSURE US subset [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C160.