Fulvestrant Versus Anastrozole in Endocrine Therapy–Naïve Women With Hormone Receptor–Positive Advanced Breast Cancer: Final Overall Survival in the Phase III FALCON Trial

Abstract

The randomized phase III FALCON trial demonstrated significant improvement in progression-free survival (PFS) with fulvestrant versus anastrozole in postmenopausal women with endocrine therapy–naïve, hormone receptor–positive/human epidermal growth factor receptor 2–negative advanced breast cancer. Herein, the prespecified final overall survival (OS) analysis is reported. After the primary PFS analysis, data were collected on survival, serious adverse events, and health-related quality of life. The final OS analysis was triggered at ≥65% maturity and ≥8 years since the last patient was enrolled. Analyses were descriptive with nominal P values (one-sided α threshold .01845). At the data cutoff (July 11, 2022), 314 (68.0%) of 462 patients had died (fulvestrant, 157/230 [68.3%], anastrozole, 157/232 [67.7%]). The final OS analysis of FALCON demonstrated no significant difference between fulvestrant and anastrozole (medians, 44.8 and 42.7 months, respectively; hazard ratio [HR], 0.97 [95% CI, 0.77 to 1.21]; P = .7579). Among patients with nonvisceral disease (n = 208), a trend showed a 15% reduction in the relative risk of death with fulvestrant versus anastrozole (median OS, 65.2 v 47.8 months; HR, 0.85 [95% CI, 0.60 to 1.20]). Data from FALCON are consistent with published evidence of long-term clinical benefit with fulvestrant and other endocrine therapies in the subset of patients with nonvisceral disease.