Exemestane (Page 6 of 7)

1 4.2 Treatment of Advanced Breast Cancer

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.

Table 9. Demographics and Baseline Characteristics from the Comparative Study of Postmenopausal Women with Advanced Breast Cancer Whose Disease Had Progressed after Tamoxifen Therapy
Parameter Exemestane (N = 366) Megestrol Acetate (N = 403)
Median Age (range) 65 (35–89) 65 (30–91)
ECOG Performance Status
0 167 (46%) 187 (46%)
1 162 (44%) 172 (43%)
2 34 (9%) 42 (10%)
Receptor Status
ER and/or PgR + 246 (67%) 274 (68%)
ER and PgR unknown 116 (32%) 128 (32%)
Responders to prior tamoxifen 68 (19%) 85 (21%)
NE for response to prior tamoxifen 46 (13%) 41 (10%)
Site of Metastasis
Visceral ± other sites 207 (57%) 239 (59%)
Bone only 61 (17%) 73 (18%)
Soft tissue only 54 (15%) 51 (13%)
Bone & soft tissue 43 (12%) 38 (9%)
Measurable Disease 287 (78%) 314 (78%)
Prior Tamoxifen Therapy
Adjuvant or Neoadjuvant 145 (40%) 152 (38%)
Advanced Disease, Outcome
CR, PR or SD ≥ 6 months 179 (49%) 210 (52%)
SD < 6 months, PD or NE 42 (12%) 41 (10%)
Prior Chemotherapy
For advanced disease ± adjuvant 58 (16%) 67 (17%)
Adjuvant only 104 (28%) 108 (27%)
No chemotherapy 203 (56%) 226 (56%)

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 tablets were not different from megestrol acetate. Response rates for exemestane tablets from the two single-arm trials were 23.4% and 28.1%.

Table 10. Efficacy Results from the Comparative Study of Postmenopausal Women with Advanced Breast Cancer Whose Disease Had Progressed after Tamoxifen Therapy
Response Characteristics Exemestane (N=366) Megestrol Acetate (N=403)
Objective Response Rate = CR + PR (%) 15 12.4
Difference in Response Rate (AR-MA) 2.6
95% C. I. 7.5, -2.3
CR (%) 2.2 1.2
PR (%) 12.8 11.2
SD ≥ 24 Weeks (%) 21.3 21.1
Median Duration of Response (weeks) 76.1 71
Median TTP (weeks) 20.3 16.6
Hazard Ratio (AR-MA) 0.84
Abbreviations: CR = complete response, PR = partial response, SD = stable disease (no change), TTP = time to tumor progression, C.I. = confidence interval, MA = megestrol acetate, AR = 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.

(click image for full-size original)


Product: 50090-5193

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Advise the patient to read the FDA-approved patient labeling (Patient Information).

Bone Effects
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)].

Embryo-Fetal Toxicity
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 Populations (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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