Among patients with advanced, hormone receptor-positive breast cancer who had not been treated previously for advanced disease, those who took fulvestrant lived longer than those who took anastrozole, according to data from the phase II FIRST trial presented at the 2014 San Antonio Breast Cancer Symposium.
“We found fulvestrant to be significantly better for women with advanced breast cancer than a third-generation aromatase inhibitor [anastrozole], which has been the most potent endocrine therapy thus far in the first-line setting for advanced disease,” said John Robertson, MD, professor of surgery at Graduate Entry Medical School at the University of Nottingham, Royal Derby Hospital, in the United Kingdom.
“Preliminary analysis from the FIRST phase II trial, which was reported previously, showed longer disease control with 500 mg fulvestrant during the treatment phase compared with anastrozole. The new data we report here translate our previous finding into improved overall survival,” Robertson added.
“Despite the improved disease control on treatment and improved overall survival seen in the FIRST study, we do not expect this to change the standard of care at this point since it was a phase II study,” Robertson explained. “A phase III [FALCON] study has been initiated to support the regulatory approval for fulvestrant as a first-line agent in this setting, which would be practice-changing.”
The FIRST trial, initiated in 2006, was a randomized, open-label study, to which 205 women with advanced, hormone receptor-positive disease were enrolled from 62 centers in nine countries. Patients were assigned to either 500 mg fulvestrant (102 patients) or anastrozole (103 patients) as first-line therapy. As of July 2014, information on 170 patients was available: 33 patients were alive and 137 have died.
Median overall survival, calculated when 67% of the study participants died, was 54.1 months for women who took fulvestrant, versus 48.4 months for those who took anastrozole.
Patients who took fulvestrant were 30% less likely to die of their disease compared with those who took anastrozole. Adverse events were similar in both groups.
“This is an exciting and a promising finding given that CONFIRM, our earlier phase III trial to test 500 mg fulvestrant in a second-line setting, also showed a survival advantage over anastrozole,” Robertson said.
This study was funded by AstraZeneca. Robertson’s institution has received research grant funding from AstraZeneca for the work on fulvestrant. Robertson has received travel expenses and honoraria for speaking at AstraZeneca meetings or being a member of advisory boards for AstraZeneca, Pfizer, Novartis, Bayer, and Amgen.