Efficacy outcomes by baseline prostate-specific antigen quartile in the AFFIRM trial

Area of Science:

• Oncology
• Clinical Trials
• Prostate Cancer Research

Background:

• Metastatic castration-resistant prostate cancer (PCa) treatment often involves agents like enzalutamide.
• Prostate-specific antigen (PSA) is a key biomarker for monitoring PCa disease burden.
• Understanding the impact of baseline PSA on treatment efficacy is clinically significant.

Purpose of the Study:

• To conduct an exploratory analysis of the AFFIRM trial data.
• To evaluate differences in patient characteristics and efficacy outcomes based on baseline PSA levels.
• To assess the consistency of enzalutamide's benefits across different baseline PSA strata.

Main Methods:

• A post hoc subanalysis of 1199 patients from the randomized, double-blind, placebo-controlled AFFIRM trial.
• Patients received either oral enzalutamide (160 mg/d) or placebo.
• Efficacy endpoints included overall survival (OS), radiographic progression-free survival (rPFS), and time to PSA progression (TTPP), analyzed by baseline PSA quartiles.

Main Results:

• Enzalutamide demonstrated consistent improvements in OS, rPFS, and TTPP compared to placebo across all baseline PSA quartiles.
• Hazard ratios for OS improvements indicated significant benefits irrespective of baseline PSA levels.
• The analysis was not powered to statistically confirm the relationship between baseline PSA and efficacy outcomes.

Conclusions:

• Enzalutamide provides consistent survival benefits in metastatic castration-resistant prostate cancer patients.
• Treatment efficacy is maintained across varying baseline disease severity, as indicated by PSA levels.
• These findings support the use of enzalutamide regardless of baseline PSA in this patient population.