Exemestane 25 mg administered once daily was evaluated in a randomized double-blind, multicenter, multinational comparative study and in two multicenter single-arm studies of postmenopausal women with advanced breast cancer who had disease progression after treatment with tamoxifen for metastatic disease or as adjuvant therapy. Some patients also have received prior cytotoxic therapy, either as adjuvant treatment or for metastatic disease.
The primary purpose of the three studies was evaluation of objective response rate (complete response [CR] and partial response [PR]). Time to tumor progression and overall survival were also assessed in the comparative trial. Response rates were assessed based on World Health Organization (WHO) criteria, and in the comparative study, were submitted to an external review committee that was blinded to patient treatment. In the comparative study, 769 patients were randomized to receive exemestane tablets 25 mg once daily (N = 366) or megestrol acetate 40 mg four times daily (N = 403). Demographics and baseline characteristics are presented in Table 9.
(N = 366)
(N = 403)
Median Age (Range)
65 (35 to 89)
65 (30 to 91)
ECOG Performance Status
Site of Metastasis
Prior Tamoxifen Therapy
The efficacy results from the comparative study are shown in Table 10. The objective response rates observed in the two treatment arms showed that exemestane was not different from megestrol acetate. Response rates for exemestane from the two single-arm trials were 23.4% and 28.1%.
Exemestane (N = 366)
Megestrol Acetate (N = 403)
Objective Response Rate = CR + PR (%)
Median Duration of Response (Weeks)
Median TTP (Weeks)
Abbreviations: CR = complete response, PR = partial response, SD = stable disease (no change), TTP = time to tumor progression, C.I. = confidence interval, MA = megestrol acetate, EX = exemestane
There were too few deaths occurring across treatment groups to draw conclusions on overall survival differences. The Kaplan-Meier curve for time to tumor progression in the comparative study is shown in Figure 2.
Figure 2. Time to Tumor Progression in the Comparative Study of Postmenopausal Women with Advanced Breast Cancer Whose Disease Had Progressed After Tamoxifen Therapy
25 mg tablet is supplied as a round, white film coated, biconvex tablets, debossed with product identification “54 571” on one side and plain on the other side.
NDC 0054-0080-13: Bottle of 30 Tablets
Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.]
Dispense in a tight, child-resistant container as defined in the USP/NF.
Advise the patient to read the FDA-approved patient labeling (Patient Information).
Advise patients that exemestane lowers the level of estrogen in the body. This may lead to reduction in bone mineral density (BMD) over time. The lower the BMD, the greater the risk of osteoporosis and fracture [see Warnings and Precautions (5.1)].
Other Estrogen-Containing Agents
Advise patients that they should not take estrogen-containing agents while they are taking exemestane as these could interfere with its pharmacologic action [see Warnings and Precautions (5.3)].
Use in Premenopausal Women
Advise patients that exemestane is not for use for the treatment of breast cancer in premenopausal women [see Warnings and Precautions (5.5)].
Advise pregnant women and females of reproductive potential that exposure during pregnancy or within 1 month prior to conception can result in fetal harm. Advise females to inform their healthcare provider of a known or suspected pregnancy [see Warnings and Precautions (5.6) and Use in Specific Populations (8.1)].
Advise females of reproductive potential to use effective contraception while taking exemestane and for 1 month after the last dose [see Use in Specific Poplulations (8.3)].
Advise women not to breastfeed during treatment with exemestane and for 1 month after the last dose [see Use in Specific Populations (8.2)].
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