Prostate-specific antigen response among Black and non-Black patients with advanced prostate cancer treated with apalutamide in a urology setting.

Abstract

124 Background: Apalutamide (APA) is approved to treat patients with non-metastatic castration-resistant prostate cancer (nmCRPC) or metastatic castration-sensitive prostate cancer (mCSPC) in the United States (US) but low enrollment of Black patients in clinical trials has led to limited clinical data about APA for this population. This study describes prostate-specific antigen (PSA) responses among Black and non-Black patients with nmCRPC or mCSPC treated with APA in a real-world community urology setting. Methods: Clinical data from 2/2018 to 3/2021 collected at 69 US urology practices were used to evaluate nmCRPC or mCSPC patients who received ≥1 APA prescription fill (index date). Baseline PSA was reported based with the most recent baseline PSA value and PSA doubling time (PSADT) in months (mo) was calculated in patients with at least 2 PSA tests before APA initiation. PSA response defined as the proportion of patients achieving either a reduction of 50% (PSA50) or 90% (PSA90) from baseline and was evaluated in patients with a PSA test result 8 weeks or later after initiating APA. Among patients with a response, the time from the index date to the response was also evaluated. Study results for Black and non-Black cohorts were summarized separately. Results: Data from 289 nmCRPC (19% Black) and 237 mCSPC (19% Black) patients were identified. Median baseline PSA, median baseline PSADT and post-index PSA responses are shown in Table. A PSA50 response was attained by numerically similar proportions of Black and non-Black patients with nmCRPC or mCSPC. A PSA90 response was observed in a numerically higher proportion of Black than non-Black nmCRPC patients. Median time to PSA50 and PSA90 was also similar between groups. Conclusions: This real-world study of nmCRPC and mCSPC patients demonstrates that PSA50 and PSA90 responses are achieved by high proportions of both Black and non-Black patients. Moreover, the PSA50 and PSA90 responses observed in this study are highly consistent with those observed in APA’s Phase 3 registrational trials for nmCRPC (SPARTAN)1 and for mCSPC (TITAN)2.