Final analysis of overall survival for the phase III CONFIRM trial fulvestrant 500 mg versus 250 mg

SUMMARY: Fulvestrant (FASOLODEX®) is an Estrogen Receptor (ER) antagonist and downregulates the cellular levels of ER in a dose-dependent manner. The CONFIRM trial is a phase III study in which postmenopausal women with estrogen receptor (ER) positive advanced breast cancer, who had progressed after prior endocrine therapy, were randomized to be treated with either FASLODEX® 500 mg (n=362) or FASLODEX® 250 mg (n=374) every 28 days. The primary end point for this study was Progression Free Survival (PFS). In the primary analysis, FASLODEX® 500 mg was associated with a statistically significant increase in PFS compared with FASLODEX® 250 mg. Even though there was a trend towards improved overall survival (OS) with the higher dose, this was not statistically significant. In the updated second survival analysis presented at this symposium, the median OS trend prevailed with FASLODEX® 500mg compared with FASLODEX® 250mg, given every 28 days (26.4 months vs 22.3 months, P=0.16). This translated into a 4 month increase in median overall survival and a 19% reduction in the risk of death. The authors concluded that the higher dose of FASLODEX® may indeed confer some survival benefit to this patient subsets. Di Leo A, Jerusalem G, Petruzelka L, et al. CTRC-AACR San Antonio Breast Cancer Symposium; 2012; Abstract S1-4.