Progression-free survival results in postmenopausal Asian women: subgroup analysis from a phase III randomized trial of fulvestrant 500 mg vs anastrozole 1 mg for hormone receptor-positive advanced breast cancer (FALCON)
The international, phase III FALCON study (NCT01602380) in postmenopausal patients with hormone receptor-positive, locally advanced/metastatic breast cancer (LA/MBC) who had not received prior endocrine therapy, demonstrated statistically significant improvement in progression-free survival (PFS) for patients who received fulvestrant 500 mg vs anastrozole 1 mg. This subgroup analysis evaluated PFS in Asian (randomized in China, Japan, or Taiwan) and non-Asian patients from the FALCON study.
Eligible patients (estrogen receptor- and/or progesterone receptor-positive LA/MBC; World Health Organization performance status 0–2; ≥ 1 measurable/non-measurable lesion[s]) were randomized. PFS was assessed via Response Evaluation Criteria in Solid Tumours version 1.1, surgery/radiotherapy for disease worsening, or death (any cause). Secondary endpoints included: objective response rate, clinical benefit rate, duration of response, and duration of clinical benefit. Consistency of effect across subgroups was assessed via hazard ratios and 95% confidence intervals (CIs) using a log-rank test. Adverse events (AEs) were evaluated.
Of the 462 randomized patients, the Asian and non-Asian subgroups comprised 67 and 395 patients, respectively. In the Asian subgroup, median PFS was 16.6 and 15.9 months with fulvestrant and anastrozole, respectively (hazard ratio 0.81; 95% CI 0.44–1.50). In the non-Asian subgroup, median PFS was 16.5 and 13.8 months, respectively (hazard ratio 0.79; 95% CI 0.62–1.01). Secondary outcomes were numerically improved with fulvestrant vs anastrozole in both subgroups. AE profiles were generally consistent between Asian and non-Asian subgroups.
Results of this subgroup analysis suggest that treatment effects in the Asian patient subgroup are broadly consistent with the non-Asian population.
KeywordsAsian Anastrozole Fulvestrant Progression-free survival Safety
The authors wish to thank Lynda M. Grinsted for her contribution to the statistical analysis of these data. Medical writing support, funded by AstraZeneca, was provided by Laura Fullerton-Batten of Complete Medical Communications.
Compliance with ethical standards
The study was conducted in accordance with the Declaration of Helsinki, the International Conference on Harmonisation, and Good Clinical Practice Guidelines. An ethics committee or institutional review board approved the final protocol at each study site.
All patients provided written, informed consent.
Conflict of interest
Shinzaburo Noguchi has been an advisor for Taiho, and has received research funding from AstraZeneca, Novartis, Chugai, Daiichi-Sankyo, Takeda, Pfizer, Ono, Taiho, and Eisai, and honoraria from AstraZeneca, Novartis, and Chugai. Matthew J. Ellis holds stock and has a leadership position with Bioclassifier LLC, which derives royalties and other income from a sublicense to Nanostring LLC for PAM50-based diagnostics, including Prosigna; he has been an ad hoc consultant for, and received honoraria and research funding from, AstraZeneca, and has also been a consultant for Pfizer, Puma and Novartis. John F. R. Robertson has been a consultant for, and has received honoraria from, AstraZeneca and Bayer AG, has received research funding from AstraZeneca, Bayer AG, and Novartis, has provided expert testimony for AstraZeneca, holds stocks or other ownership with Oncimmune, and holds stock options with Carrick Therapeutics. Jackie Thirlwell is an employee of JMT Statistics Ltd, and is under contract to provide statistical support to AstraZeneca. Mehdi Fazal is an employee of AstraZeneca. Zhimin Shao has no conflicts of interest to disclose.
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