Apalutamide in Metastatic Castration-sensitive Prostate Cancer: Results from the Multicenter Real-world ARON-3 Study

Background and objective: Apalutamide (APA) is a treatment for metastatic castration-sensitive prostate cancer (mCSPC). In the ARON-3 study we investigated real-world experiences with APA treatment for mCSPC. Methods: We retrospectively assessed real-world clinical outcomes for patients with mCSPC treated with APA in the ARON-3 study. Overall survival (OS) was calculated from APA initiation to death from any cause. PSA90 was defined as a prostate-specific antigen decline of ≥90% from baseline, and PSA0.2 as achievement of a PSA level ≤0.2 ng/ml. Data for adverse events were retrospectively collected from electronic and paper charts and categorized according to Common Terminology Criteria for Adverse Events v5.0. Key findings and limitations: We included 531 patients with mCSPC treated with APA. High-volume disease was reported for 214 patients (40%), and 56 (11%) had visceral metastases. Median OS was not reached. PSA90 was experienced by 461 patients (87%) and PSA0.2 by 368 (69%). Median OS was significantly longer for patients with PSA90 or PSA0.2 than for subjects without these responses (p < 0.001). The incidence of grade 3-4 fatigue was higher among elderly patients (≥80 yr) than among younger patients (19% vs 5%), but the incidence of other adverse events was comparable between the age groups. Conclusions and clinical implications: APA is an effective and tolerable treatment for mCSPC in the real-world setting. Patient summary: The ARON-3 project collects data for patients with prostate cancer treated in multiple centers worldwide to assess outcomes in the real-world setting. We analyzed data for patients with metastatic hormone-sensitive prostate cancer receiving apalutamide. Our results show that apalutamide is a safe and effective drug in the real-world setting as well as in clinical trials.