Post Hoc Analysis of Rapid and Deep Prostate-specific Antigen Decline and Patient-reported Health-related Quality of Life in SPARTAN and TITAN Patients with Advanced Prostate Cancer

Background Adding apalutamide to androgen-deprivation therapy (ADT) resulted in a rapid (at 3- and 6-mo treatment) and deep prostate-specific antigen (PSA) decline (to ≤0.2 ng/ml or ≥90% from baseline), improved overall survival, reduced risk of disease progression, and prolonged health-related quality of life (HRQoL) in nonmetastatic castration-resistant prostate cancer (nmCRPC) in SPARTAN and metastatic castration-sensitive PC (mCSPC) in TITAN. Objective To evaluate the association of a rapid, deep PSA decline at 3 and 6 mo achieved with the addition of apalutamide to ADT with patient-reported outcomes (PROs) in SPARTAN and TITAN. Design, setting, and participants A post hoc analysis of SPARTAN and TITAN PRO data was performed. Intervention Apalutamide versus placebo plus concurrent ADT. Outcome measurements and statistical analysis PROs were assessed using Functional Assessment of Cancer Therapy-Prostate (FACT-P; SPARTAN and TITAN), Brief Pain Inventory—Short Form (BPI-SF; TITAN), and Brief Fatigue Inventory (BFI; TITAN) at baseline, prespecified cycles during treatment, and after progression for ≤1 yr. The association between a deep PSA decline at landmark 3 or 6 mo of apalutamide and the time to worsening of PROs was assessed using the Kaplan-Meier methodology and Cox proportional-hazard modeling. Results and limitations Among 806 SPARTAN and 525 TITAN apalutamide-treated patients, the median treatment duration was 32.9 and 39.3 mo, respectively. Patients achieving a deep PSA decline at 3 mo had longer time to worsening in FACT-P total, FACT-P physical well-being, BPI-SF worst pain intensity, or BFI worst fatigue intensity. The 6-mo PSA decline results were similar. Limitations of patient characteristics in clinical studies should be considered. Conclusions Attaining a deep and rapid PSA decline at 3 mo with apalutamide plus ADT was associated with longer preservation of overall HRQoL and physical well-being in nmCRPC and mCSPC. Patient summary Quality of life is maintained in individuals with advanced prostate cancer who achieve a deep prostate-specific antigen decline at 3 mo of apalutamide plus drugs that lower male sex hormones.