COPENHAGEN, Denmark — Fulvestrant significantly prolonged PFS compared with anastrozole among women with hormone receptor–positive advanced breast cancer, according to randomized phase 3 study results presented at the European Society for Medical Oncology Congress.
Women with less aggressive, lower-volume disease derived the greatest benefit.
Matthew J. Ellis
“For patients with nonvisceral disease whose life isn’t immediately threatened by breast cancer — a group for whom physicians would typically choose endocrine therapy as a first approach — it looks like fulvestrant could be a new standard of care,” Matthew J. Ellis, MB, BChir, BSc, PhD, FRCP, director of the Lester and Sue Smith Breast Center at Baylor College of Medicine, said in a press release.
Fulvestrant, a selective estrogen receptor degrader, targets the function of the hormone receptor. It does not interfere with estrogen levels, unlike aromatase inhibitors such as anastrozole.
In the double blind, multicenter FALCON trial, Ellis and colleagues compared fulvestrant with anastrozole in 462 patients with ER–positive or PR–positive locally advanced or metastatic breast cancer who had not undergone hormonal therapy.
Researchers randomly assigned patients 230 patients to 500 mg fulvestrant via intramuscular administration on days 0, 14 and 28, then every 28 days. The other 232 patients received 1 mg daily anastrozole
PFS served as the primary endpoint. Secondary endpoints included OS, objective response rate — defined as complete response or partial response — response duration, clinical benefit rate — comprised of complete response, partial response, and stable disease at 24 weeks or beyond — duration of clinical benefit, health-related quality of life and safety.
Patients assigned fulvestrant achieved significantly longer median PFS (16.6 months vs. 13.8 months; HR = 0.79; 95% CI, 0.63-0.99). Fulvestrant-treated patients also achieved a higher response rate (46.1% vs. 44.9%; OR = 1.07; 95% I, 0.72-1.61) and a higher clinical benefit rate (78.3% vs. 74.1%; OR = 1.25; 95% CI, 0.82-1.93), but the differences did not reach statistical significance.
Researchers reported longer median duration of response (20 months vs. 13.2 months) and longer median duration of clinical benefit (22.1 months vs. 19.1 months) in the fulvestrant group.
The effect of treatment on health-related quality of life appeared comparable between treatment groups. Patients assigned fulvestrant experienced slightly higher rates of arthralgia (16.7% vs. 10.3%) and hot flushes (11.4% vs. 10.3%).
“[Fulvestrant is] tolerated as well as anastrozole, and better than other drugs that could potentially be used in this setting, such as chemotherapy or CDK4 inhibitors,” Ellis said. “In patients for whom you are looking for a low-toxicity approach, such as older patients or those with low-volume disease, it looks like a good option.” – by Mark Leiser
For more information: Ellis MJ, et al. LBA14_PR. Presented at: European Society for Medical Oncology Congress; Oct. 7-11, 2016; Copenhagen, Denmark.
AstraZeneca provided funding for this study. Ellis reports employment or leadership positions with; stock or other ownership in; and patents, royalties or intellectual property with Bioclassifier LLC. He reports consultant or advisory roles with AstraZeneca, Celgene, Novartis and Pfizer. Please see the abstract for a list of all other researchers’ relevant financial disclosures.