Sipuleucel-T (sip-T) and oral androgen axis inhibitors in black men being treated for metastatic castration-resistance prostate cancer (mCRPC): Observations from the Medicare Fee for Service (FFS) population.

Abstract

e17589 Background: Black men historically have been underrepresented in clinical trials, contributing to poor understanding of potential race-based differences in prostate cancer care and biology. This retrospective, real world analysis examines survival outcomes in black men who received sip-T or oral agents like abiraterone or enzalutamide for mCRPC. Methods: Using Medicare Fee for Service Identifiable Research data, we identified racially black men with a qualifying prostate cancer diagnosis (ICD-9 185, ICD-10 C-61) and an initial drug claim for treatment (abiraterone acetate, cabazitaxel, docetaxel, enzalutamide, radium-223, or sip-T) in 2014 or 2015. Continuous Part A, B, and D eligibility and no HMO enrollment were required for 24 months or until death per Social Security Death Index. We compared outcomes in black patients who received sip-T at any time vs those who received an oral agent in any line and no sip-T. Survival was estimated using the Kaplan-Meier method (unadjusted) and hazard ratios using Cox proportional hazards regression. Results: Of 14,456 patients identified in 2014 and 2015, 1603 were racially black. Among eligible men, 140 received sip-T and 1266 received an oral agent. At 24 months, 76% of men who received sip-T were still alive compared with 49% of those who received the oral agents (Table). Median OS was not estimable in men who received sip-T but was 23.1 months (95% CI: 21.6, NE) in those who received oral agents (Table). In a univariate model, use of sip-T resulted in a 63% reduction in risk of death compared to never receiving sip-T (HR, 0.37 [95% CI, 0.26, 0.52], P < 0.0001). Conclusions: In this real world analysis of black mCRPC patients, sip-T at any point was associated with longer OS over those receiving the oral agents without ever receiving sip-T. Development of a multivariate model is planned. [Table: see text]