Activity of fulvestrant 500 mg versus anastrozole 1 mg as first-line treatment for advanced breast cancer: results from the FIRST study.
OBJECTIVE
To compare the clinical activity of the pure antiestrogen fulvestrant at 500 mg/mo (double the approved dose) with the aromatase inhibitor anastrozole as first-line endocrine therapy for advanced hormone receptor-positive breast cancer in postmenopausal women.


METHODS
FIRST (Fulvestrant First-Line Study Comparing Endocrine Treatments) is a phase II, randomized, open-label, multicenter study of a fulvestrant high-dose (HD) regimen (500 mg/mo plus 500 mg on day 14 of month 1) versus anastrozole (1 mg/d). The primary efficacy end point was clinical benefit rate (CBR), defined as the proportion of patients experiencing an objective response (OR) or stable disease for > or = 24 weeks. The primary analysis was performed 6 months after the last patient was randomly assigned.


RESULTS
CBR was similar for fulvestrant HD (n = 102) and anastrozole (n = 103), 72.5% v 67.0%, respectively (odds ratio, 1.30; 95% CI, 0.72 to 2.38; P = .386). Objective response rate (ORR) was also similar between treatments: fulvestrant HD, 36.0%; anastrozole, 35.5%. Time to progression (TTP) was significantly longer for fulvestrant versus anastrozole (median TTP not reached for fulvestrant HD v 12.5 months for anastrozole; hazard ratio, 0.63; 95% CI, 0.39 to 1.00; P = .0496). Duration of OR and CB also numerically favored fulvestrant HD. Both treatments were well tolerated, with no significant differences in the incidence of prespecified adverse events.


CONCLUSIONS
First-line fulvestrant HD was at least as effective as anastrozole for CBR and ORR and was associated with significantly longer TTP. Fulvestrant HD was generally well tolerated, with a safety profile similar to that of anastrozole.
Robertson
John F R
JF
Division of Breast Surgery, University of Nottingham, Nottingham City Hospital, Hucknall Rd, Nottingham, NG5 1PB, United Kingdom. john.robertson@nottingham.ac.uk
Llombart-Cussac
Antonio
A
Rolski
Janusz
J
Feltl
David
D
Dewar
John
J
Macpherson
Euan
E
Lindemann
Justin
J
Ellis
Matthew J
MJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077384:Anastrozole; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000556:secondary; D004958:Estradiol / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D000077267:Fulvestrant; D006801:Humans; D008875:Middle Aged; D009570:Nitriles / Q000627:therapeutic use*; D017698:Postmenopause; D014230:Triazoles / Q000627:therapeutic use*
D000970:Antineoplastic Agents; D009570:Nitriles; D014230:Triazoles; D000077267:Fulvestrant; D000077384:Anastrozole; D004958:Estradiol