Fulvestrant 500 mg vs 250 mg in postmenopausal women with estrogen receptor-positive advanced breast cancer: a randomized, double-blind registrational trial in China

// Qingyuan Zhang 1 , Zhimin Shao 2 , Kunwei Shen 3 , Li Li 4 , Jifeng Feng 5 , Zhongsheng Tong 6 , Kangsheng Gu 7 , Xiaojia Wang 8 , Binghe Xu 9 , Guofang Sun 10 , Huifang Chen 10 , Yuri Rukazenkov 11 , Zefei Jiang 12 1 Harbin Medical University Cancer Hospital, Harbin, Heilongjiang, China 2 Fudan University Shanghai Cancer Center, Shanghai, China 3 Shanghai Ruijin Hospital, Shanghai, China 4 The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China 5 Jiangsu Cancer Hospital, Nanjing, Jiangsu, China 6 Tianjin Cancer Hospital, Tianjin, China 7 The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China 8 Zhejiang Cancer Hospital, Hangzhou, Zhejiang, China 9 Cancer Hospital and Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China 10 AstraZeneca, Shanghai, China 11 AstraZeneca, Macclesfield, UK 12 307 Hospital of Chinese People’s Liberation Army, Beijing, China Correspondence to: Zefei Jiang, email: jiangzf@hotmail.com Keywords: advanced breast cancer, fulvestrant, endocrine therapy, hormone receptor-positive breast cancer Received: February 15, 2016      Accepted: May 28, 2016      Published: June 23, 2016 ABSTRACT The international CONFIRM study showed that fulvestrant 500 mg improved progression-free survival (PFS) vs fulvestrant 250 mg in postmenopausal women with estrogen receptor (ER)-positive locally advanced/metastatic breast cancer (LA/MBC). In this randomized, double-blind study, postmenopausal Chinese women with ER-positive LA/MBC and progression after endocrine therapy received fulvestrant 500 mg (days 0, 14, 28, and every 28 days thereafter) or fulvestrant 250 mg (every 28 days). Consistency with the international study was assumed if the hazard ratio (HR) for comparison of PFS (primary endpoint) was < 1 (stratified log-rank test). The study was not powered to assess between-group differences. In total, 221 patients were randomized (fulvestrant 500 mg: n = 111; fulvestrant 250 mg: n = 110). Baseline characteristics were balanced. Median PFS was 8.0 months with fulvestrant 500 mg vs 4.0 months with 250 mg (HR = 0.75; 95% confidence interval [CI] 0.54−1.03; P = 0.078). PFS (HR; 95% CI) favored fulvestrant 500 mg in post-antiestrogen (0.86; 0.54−1.37) and post-aromatase inhibitor (0.65; 0.42−1.03) settings. No new safety considerations were observed. These results are consistent with the international CONFIRM study, supporting the superior clinical benefit of fulvestrant 500 mg in women with ER-positive LA/MBC experiencing progression following prior endocrine therapy.