Clinical characteristics and outcomes of trial-ineligible patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) receiving androgen receptor targeted (ART) therapy.

Abstract

118 Background: mCRPC pts with significant comorbidities or poor performance status (PS) are often excluded from clinical trials for ART. These cohorts may not be representative of or comparable to real-world pts. We aimed to determine whether (1) baseline characteristics or (2) survival outcomes differed in pts with mCRPC categorized as eligible or ineligible for ART clinical trials. Methods: We screened for pts with mCRPC treated with abiraterone (abi-) or enzalutamide (enza-) at our institution between 2010 and 2021. Baseline characteristics were reviewed at treatment start and ART course recorded. We applied the inclusion/exclusion criteria from clinical trials, COU-AA-301, COU-AA-302, PREVAIL, and AFFIRM, to categorize pts as ineligible or eligible. Fischer’s exact was used to evaluate pt characteristics. Cox proportional hazards model was used to compare survival outcomes. Results: We identified 150 pts with mCRPC who initiated abi- or enza-. 54.7% of pts were deemed trial ineligible. Among pts on abi-, 48 of 86 (55.8%) pts were ineligible. Among those on enza-, 34 of 64 (53.1%) were ineligible. Common reasons for ineligibility included poor PS, radiation during treatment, and trial specific comorbidities. Among ineligible pts, 11% were post-chemotherapy compared to 20.6% of eligible pts (p = .162). Notably, trial ineligible pts were more likely to be non-Hispanic black when compared to trial eligible pts (29.3% vs. 17.6%, p = 0.036). Median OS was 30.2 for ineligible pts and 37.1 for eligible pts p = 0.46). for the ineligible pts and eligible pts respectively and there was no significant difference on univariate or multivariate analyses (HR: 0.84 [0.54, 1.32;]. Conclusions: Pts classified as trial ineligible had comparable survival outcomes when compared to trial eligible pts. Consistent with prior research on systemic racism in clinical trials, ineligible pts were more likely to identify as Black compared to eligible pts. Further research is warranted to confirm safety of ART in ineligible pts and identify strategies for reducing racial disparity gaps in cancer clinical trials.