Anastrozole (Page 5 of 8)

14.2 First-Line Therapy in Postmenopausal Women with Advanced Breast Cancer

Two double-blind, controlled clinical studies of similar design (0030, a North American study and 0027, a predominately European study) were conducted to assess the efficacy of anastrozole compared with tamoxifen as first-line therapy for hormone receptor positive or hormone receptor unknown locally advanced or metastatic breast cancer in postmenopausal women. A total of 1021 patients between the ages of 30 and 92 years old were randomized to receive trial treatment. Patients were randomized to receive 1 mg of anastrozole once daily or 20 mg of tamoxifen once daily. The primary endpoints for both trials were time to tumor progression, objective tumor response rate, and safety.

Demographics and other baseline characteristics, including patients who had measurable and no measurable disease, patients who were given previous adjuvant therapy, the site of metastatic disease and ethnic origin were similar for the two treatment groups for both trials. The following table summarizes the hormone receptor status at entry for all randomized patients in trials 0030 and 0027.

Table 11 – Demographic and Other Baseline Characteristics

Number (%) of subjects

Trial 0030

Trial 0027

Receptor status

Anastrozole 1 mg

Tamoxifen 20 mg

Anastrozole 1 mg

Tamoxifen 20 mg

(N=171)

(N=182)

(N=340)

(N=328)

ER* and/or PgR†

151 (88.3)

162 (89.0)

154 (45.3)

144 (43.9)

ER* unknown, PgR† unknown

19 (11.1)

20 (11.0)

185 (54.4)

183 (55.8)

* ER = Estrogen receptor

† PgR = Progesterone receptor

For the primary endpoints, trial 0030 showed that anastrozole had a statistically significant advantage over tamoxifen (p=0.006) for time to tumor progression; objective tumor response rates were similar for anastrozole and tamoxifen. Trial 0027 showed that anastrozole and tamoxifen had similar objective tumor response rates and time to tumor progression (see Table 12 and Figures 5 and 6).

Table 12 below summarizes the results of trial 0030 and trial 0027 for the primary efficacy endpoints.

Table 12 – Efficacy Results of First-line Treatment

Endpoint

Trial 0030

Trial 0027

Anastrozole

1 mg

(N=171)

Tamoxifen

20 mg

(N=182)

Anastrozole

1 mg

(N=340)

Tamoxifen

20 mg

(N=328)

Time to progression (TTP)

Median TTP (months)

11.1

5.6

8.2

8.3

Number (%) of subjects who progressed

114 (67%)

138 (76%)

249 (73%)

247 (75%)

Hazard ratio (LCL*)†

1.42 (1.15)

1.01 (0.87)

2 sided 95% CI‡

(1.11, 1.82)

(0.85, 1.20)

p-value§

0.006

0.920

Best objective response rate

Number (%) of subjects with CR¶+ PR#

36 (21.1%)

31 (17.0%)

112 (32.9%)

107 (32.6%)

Odds Ratio (LCL*)♠

1.30 (0.83)

1.01 (0.77)

* LCL = Lower Confidence Limit

† Tamoxifen:Anastrozole

‡ CI = Confidence Interval

§ Two-sided Log Rank

¶ CR = Complete Response

# PR = Partial Response

♠ Anastrozole:Tamoxifen

Figure 5 -- Kaplan-Meier Probability of Time to Disease Progression for All Randomized Patients (Intent-to-Treat) in Trial 0030
(click image for full-size original)

Figure 5 — Kaplan-Meier probability of time to disease progression for all randomized patients (intent-to-treat) in Trial 0030

Figure 6 -- Kaplan-Meier Probability of Time to Progression for All Randomized Patients (Intent-to-Treat) in Trial 0027
(click image for full-size original)

Figure 6 — Kaplan-Meier probability of time to progression for all randomized patients (intent-to-treat) in Trial 0027

Results from the secondary endpoints were supportive of the results of the primary efficacy endpoints. There were too few deaths occurring across treatment groups of both trials to draw conclusions on overall survival differences.

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