Abstract D084: Overall survival (OS) of African-American (AA) and Caucasian (CAU) men who received sipuleucel-T for metastatic castration-resistant prostate cancer (mCRPC)—final PROCEED analysis
Authors: Sartor Oliver , Armstrong Andrew J , Ahaghotu Chiledum , McLeod David G , Cooperberg Matthew R , Penson David F , Kantoff Philip W , Vogelzang Nicholas J , Hussain Arif , Pieczonka Christopher. M , Shore Neal D , Quinn David I , Heath Elisabeth I , Tutrone Ronald F , Schellhammer Paul F , Harmon Matthew , Chang Nancy N , Freedland Stephen J , Higano Celestia S 
Published: September 2020

Abstract
BACKGROUND: Prostate cancer risk and mortality are higher in AAs versus CAUs. Post-hoc analyses of pooled Phase 3 data (n = 737) suggested substantial OS benefit for AA men receiving sipuleucel-T (n=33) vs placebo (n = 10) (McLeod 2012). Compared with pooled placebo patients (n = 249), number needed to treat for OS benefit at 3 years was 3 for AAs and 8 for all sipuleucel-T-treated patients (n = 488) (Moses 2017). Herein we analyzed PROCEED (NCT01306890), a large real-world registry, in which all patients received sipuleucel-T. Previously presented at ASCO Annual Meeting 2019 (Sartor 2019).METHODS: In PROCEED, 1902 mCRPC patients received 1 or more sipuleucel-T infusions. OS of all AA (n=221) and CAU (n=1649) men were compared. Baseline prostate-specific antigen (PSA), the most important prognostic variable for OS after sipuleucel-T (Schellhammer 2013), substantially differed by race. Thus, OS for a PSA-matched cohort (n=219 AA; n=438 CAU) was compared and univariable/multivariable analyses were performed. Post-sipuleucel-T use of OS-prolonging anticancer interventions was also assessed. RESULTS: After a median follow-up of 46.6 mo, median OS was 35.2 (all sipuleucel-T-treated AAs) and 29.9 mo (all sipuleucel-T-treated CAUs): HR 0.81, 95% CI 0.68–0.97; P=0.03. In the PSA-matched cohort, median OS was 35.3 and 25.8 mo, respectively (HR 0.70, 95% CI 0.57–0.86; p&lt;0.001). Sipuleucel-T-treated AAs with lower baseline PSA had markedly longer median OS vs sipuleucel-T-treated CAUs. Among those with PSA less than or equal to median baseline PSA (29.48 ng/ml), median OS was 54.3 mo (AA) vs. 33.4 (CAUs); HR 0.52, 95% CI 0.37–0.72; p&lt;0.001. Along with other known prognostic factors, AA race was independently associated with prolonged OS on detailed multivariable analyses (HR 0.60, 95% CI 0.48–0.74; p&lt;0.001) and confirmed on sensitivity analyses. Post-sipuleucel-T life-prolonging anti-cancer therapies were balanced between groups. CONCLUSIONS: Sipuleucel-T-treated AAs had significantly improved OS vs sipuleucel-T-treated CAUs. This analysis marks the largest known racial difference in OS in response to any therapy for mCRPC, a finding with implications for both prostate cancer pathophysiology and cancer immunotherapy. REFERENCES: Sartor 2012 (DOI: 10.1200/JCO.2019.37.15_suppl.5035); McLeod 2012 (DOI: 10.1016/j.juro.2012.02.1051); Moses KA et al 2017 (DOI: 10.1016/j.urology.2016.07.045); Schellhammer 2013 (DOI: 10.1016/j.urology.2013.01.061)
Citation Format: Oliver Sartor, Andrew J Armstrong, Chiledum Ahaghotu, David G McLeod, Matthew R Cooperberg, David F Penson, Philip W Kantoff, Nicholas J Vogelzang, Arif Hussain, Christopher. M Pieczonka, Neal D Shore, David I Quinn, Elisabeth I Heath, Ronald F Tutrone, Paul F Schellhammer, Matthew Harmon, Nancy N Chang, Stephen J Freedland, Celestia S Higano. Overall survival (OS) of African-American (AA) and Caucasian (CAU) men who received sipuleucel-T for metastatic castration-resistant prostate cancer (mCRPC)—final PROCEED analysis [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D084.