Real-world survival of men with metastatic castration-sensitive prostate cancer (mCSPC) initiated on apalutamide (APA) or enzalutamide (ENZ) in an oncology database: ROME Study.

Abstract

57 Background: Androgen receptor signaling inhibitors (ARSIs), including APA and ENZ, have demonstrated progression-free and overall survival benefits for men with mCSPC in the clinical trial setting, but data evaluating real-world treatment effectiveness remains limited. The aim of this study was to describe real-world survival among men with mCSPC who initiated APA or ENZ in the United States (US). Methods: In this retrospective longitudinal cohort study, clinical data from the Flatiron Metastatic Prostate Cancer (PC) Core Registry Electronic DataMart (1/1/2013–05/31/2023) were used. Patients with chart-confirmed metastasis and without castration resistance were classified into two treatment cohorts based on earliest initiation of APA or ENZ on/after 12/16/2019 (index date). Patients had ≥12 months of clinical data pre-index and were followed from the index date until the earliest of 24 months post-index, end of clinical activity, or end of data availability. Patients’ date of death was obtained from electronic medical records, Social Security Death Index, or other confirmed sources. Using an intention-to-treat approach, Kaplan-Meier analysis was used to describe the proportion of patients surviving by 24 months post-index. An unadjusted Cox proportional hazards model was used to describe crude differences in survival rates between patients initiating APA and ENZ. Results: There were 234 APA (mean age: 73.2 years; 59.8% White, 13.7% Black) and 527 ENZ (mean age: 73.9 years; 55.2% White, 13.1% Black) patients included in this study (Table). APA median time on-treatment was 10.9 months over a median observation period of 13.3 months, while ENZ median time on-treatment was 11.1 months over a median 14.8 months observation period. By 24 months, a higher proportion of patients in the APA cohort survived than in the ENZ cohort (85.4% vs 73.9%; unadjusted hazard ratio=0.59, 95% confidence interval: 0.39, 0.95; p=0.030; Table). Conclusions: In this real-world analysis of patients with mCSPC, more patients treated with APA survived by 24 months following treatment initiation as compared to treatment with ENZ. While the current study reports unadjusted analyses, future studies adjusting for potential confounding variables should be conducted to confirm these findings in order to inform clinicians on treatment selection for patients with mCSPC. [Table: see text]