Fulvestrant 250 mg versus anastrozole for Chinese patients with advanced breast cancer: results of a multicentre, double-blind, randomised phase III trial

Background and purpose Fulvestrant, an oestrogen receptor (ER) antagonist with no known agonist effects, has shown activity in postmenopausal patients with ER-positive advanced breast cancer recurring or progressing following prior endocrine therapy. This double-blind, double-dummy, randomised phase III study (NCT00327769) was designed to compare the efficacy and safety of fulvestrant versus anastrozole in advanced breast cancer of Chinese postmenopausal women whose disease has progressed following prior endocrine treatment. Materials and methods A total of 234 patients were randomised to fulvestrant 250 mg/month (n = 121) or 1 mg/day anastrozole (n = 113), together with matching placebo. The primary endpoint was time to progression (TTP). Secondary endpoints included objective response rate (ORR), duration of response (DoR), clinical benefit rate (CBR) and time to treatment failure (TTF). Results Baseline characteristics were similar, with the possible exception that a higher number of fulvestrant patients had received two prior chemotherapy regimens. Median TTP was 110 days in the fulvestrant group versus 159 days in the anastrozole group (hazard ratio [HR], 1.314; 95% confidence intervals [CI], 0.948, 1.822; P = 0.101). ORR was 10% in the fulvestrant group and 14% in the anastrozole group. Median DoR from randomisation to progression was 436 days versus 432 days for the fulvestrant and anastrozole groups, respectively. CBR for fulvestrant (36.1%) versus anastrozole (48.2%) was not statistically different between the groups. TTF (110 days versus 147 days for the fulvestrant and anastrozole groups, respectively) was not statistically different between the treatments (HR, 1.307; 95% CI, 0.961, 1.778; P = 0.088). Both treatments were well tolerated, with only two patients treated with fulvestrant and four patients treated with anastrozole withdrawn from study treatment due to adverse events. Conclusions These data demonstrate that fulvestrant 250 mg and anastrozole were similarly effective and well tolerated in the treatment of postmenopausal Chinese women with advanced breast cancer whose disease had progressed or recurred on prior endocrine treatment.