Real-world prostate-specific antigen (PSA) response and disease progression among patients with non-metastatic castration-resistant prostate cancer (nmCRPC) initiated on apalutamide (APA).

Abstract

69 Background: For patients with nmCRPC, APA with androgen deprivation therapy is an important therapeutic option with demonstrated efficacy in improving metastasis-free survival (MFS), and other clinical outcomes. However, there is limited real-world information on these outcomes among patients with nmCRPC treated with APA. This study describes PSA response and MFS among patients with nmCRPC treated with APA in the United States as compared to the SPARTAN registrational trial. Methods: Clinical data from 2/2017 to 4/2022 collected from 77 community-based urology practices were used to evaluate patients with nmCRPC who received ≥1 APA dispensation (index date being the date of first dispensation). Patients were excluded if they had previously used another next-generation antiandrogen or had <12 months of pre-index clinical activity. PSA response was evaluated while on treatment and was defined as a post-index ≥90% decline (PSA90) in PSA from baseline (using the closest PSA value within 13 weeks prior to or on the index date) and was reported in patients with ≥1 post-index PSA test result by 3 months, 6 months, 12 months and overall. Disease progression was evaluated as MFS and defined as the time from index date to the occurrence of metastasis or death, whichever occurred first. Disease progression was described using Kaplan-Meier (KM) analysis by 6-month increments up to 24 months post-index. Results: A total of 406 patients with nmCRPC (mean age 78.8 years, 73% white, mean baseline PSA 9.0 ng/mL) were identified. Among 96 patients with available data, the mean (median) baseline PSA doubling time was 9.9 (7.5) months. The mean (median) treatment duration was 434 (305) days. PSA90 rates were 40% by 3 months, 51% by 6 months, 56% by 12 months, and 58% overall. KM rates for MFS were 95% at 6 months, 90% at 12 months, 82% at 18 months, and 75% at 24 months. PSA response and MFS for real-world patients were consistent with those observed from the SPARTAN trial. Conclusions: This real-world study of patients with nmCRPC demonstrates that APA treatment resulted in early, deep PSA responses, consistent with the SPARTAN trial. Moreover, MFS observed in the real-world was similar to that of the SPARTAN trial. [Table: see text]