Clinical outcomes and safety of enzalutamide (ENZA) plus androgen-deprivation therapy (ADT) in metastatic hormone-sensitive prostate cancer (mHSPC) in patients aged < 75 and ≥ 75 years: ARCHES post hoc analysis.

Abstract

5069 Background: Patients with metastatic prostate cancer aged ≥75 years have a poorer prognosis compared with younger patients. In ARCHES (NCT02677896), ENZA + ADT improved radiographic progression-free survival (rPFS), overall survival (OS), and other key secondary endpoints vs. placebo (PBO) + ADT in patients with mHSPC. Final OS results confirmed a long-term survival benefit with ENZA + ADT. This post hoc analysis of ARCHES data investigated OS and other clinical outcomes in patients aged <75 and ≥75 years. Methods: Patients with mHSPC (n=1150) were randomized 1:1 to ENZA (160 mg/day) + ADT or PBO + ADT, stratified by disease volume and prior docetaxel use. Subgroup analysis was performed in patients aged <75 and ≥75 years. Efficacy and safety outcomes were compared across treatment arms. Results: Of the ARCHES population, 339 patients (29.5%) were aged ≥75 years (ENZA + ADT, n=170; PBO + ADT, n=169); PBO patients crossing over to ENZA were aged: <75 years, n=133; ≥75 years, n=47. Some differences in baseline characteristics were observed between age groups, such as higher prior docetaxel use in patients aged <75 years (ENZA + ADT, 21.0%; PBO + ADT, 20.4%) vs. those aged ≥75 years (ENZA + ADT, 10.6%; PBO + ADT, 11.2%). When compared to PBO + ADT, ENZA + ADT improved OS and other secondary efficacy endpoints in both age groups without evidence of statistical heterogeneity (Table); however, 95% confidence intervals for OS and rPFS hazard ratios spanned 1 in the older age group. The safety profile of treatment arms was generally similar in both age groups, with a higher incidence of falls, cognitive impairment, and cardiovascular events among elderly patients receiving ENZA + ADT vs. PBO + ADT. Conclusions: This post hoc analysis of ARCHES data demonstrated that ENZA + ADT provides clinical benefit and is generally well-tolerated in patients with mHSPC aged ≥75 years, supporting the therapeutic role of ENZA in these patients. Clinical trial information: NCT02677896. [Table: see text]