Phase II, randomized, double-blind study of two dose levels of arzoxifene in patients with locally advanced or metastatic breast cancer.
OBJECTIVE
To select a daily dose of arzoxifene (LY353381), a selective estrogen receptor modulator, for use in future studies in women with locally advanced or metastatic breast cancer who are either potentially tamoxifen sensitive (TS) or tamoxifen refractory (TR).


METHODS
This trial was a randomized, double-blind, phase II study of arzoxifene 20 mg (n = 55) and 50 mg (n = 57) in women with advanced or metastatic breast cancer. Patients were randomly assigned to balance for number of metastatic disease sites, prior tamoxifen therapy, and estrogen receptor status. The primary end point was tumor response rate (RR). Secondary end points included clinical benefit rate (CBR), time to progression (TTP), and toxicity.


RESULTS
Forty-nine patients were TS and 63 were TR. According to independent review, among TS patients, RR was higher in the 20-mg arm than the 50-mg arm (26.1% v 8.0%), with a longer TTP (8.3 v 3.2 months; P >.05). Among the TR patients, response rate was the same in the 20-mg and 50-mg arms (10.3%) with similar TTP (2.7 and 2.8 months, respectively; P >.05). CBR was higher in the 20-mg arm than in the 50-mg arm among TS patients (39.1% v 20.0%) and TR patients (13.8% v 10.3%). Arzoxifene was well tolerated. Dose-dependent toxicity was not demonstrated. There were no deaths during study.


CONCLUSIONS
Arzoxifene is effective in the treatment of TS and TR patients with advanced or metastatic breast cancer at the 20-mg and 50-mg dose levels. Toxicities are minimal, and the therapy is tolerated. The 20-mg dose seems to be at least as effective as the 50-mg dose. Accordingly, arzoxifene 20 mg/d was selected for further study in patients with breast cancer.
Buzdar
Aman
A
M.D. Anderson Cancer Center and US Oncology Research, Houston, and Baylor-Sammons Cancer Center and Texas Oncology, Dallas, TX. 77030, USA. abuzdar@mdanderson.org
O'Shaughnessy
Joyce A
JA
Booser
Daniel J
DJ
Pippen
John E
JE
Jones
Stephen E
SE
Munster
Pamela N
PN
Peterson
Patrick
P
Melemed
Allen S
AS
Winer
Eric
E
Hudis
Clifford
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D014408:Biomarkers, Tumor / Q000097:blood; D001943:Breast Neoplasms / Q000097:blood / Q000737:chemistry / Q000188:drug therapy* / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D019008:Drug Resistance, Neoplasm; D004717:Endometrium / Q000187:drug effects; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D005260:Female; D006801:Humans; D008875:Middle Aged; D018579:Patient Selection; D010880:Piperidines / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D011960:Receptors, Estrogen / Q000032:analysis; D016019:Survival Analysis; D013629:Tamoxifen / Q000494:pharmacology; D013876:Thiophenes / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D020847:Estrogen Receptor Modulators; D010880:Piperidines; D011960:Receptors, Estrogen; D013876:Thiophenes; D013629:Tamoxifen; C115121:LY 353381