Jane S. Ricciuti, RPh, MS


September 20, 2002

In This Article

Antineoplastic Agents

(anastrozole) Oral Tablets

Manufacturer: AstraZeneca

Drug Approval Classification: Supplemental New Drug Application (Approval Date: 9/5/02)

New Indication: This supplemental approval includes the following new indication.

Arimidex is indicated for adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer.

The effectiveness of Arimidex in early breast cancer is based on an analysis of recurrence-free survival in patients treated for a median of 31 months. Further follow-up of study patients will be required to determine long-term outcomes.

Dosing: The dosage of Arimidex is one 1-mg tablet taken once a day.

For adjuvant treatment of early breast cancer in postmenopausal women, the optimal duration of therapy is unknown. The median duration of therapy at the time of data analysis was 31 months; the ongoing Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial is planned for 5 years of treatment.

Clinical Summary: ATAC is a multicenter, double-blind trial of 9366 postmenopausal women with operable breast cancer randomized to adjuvant treatment with Arimidex 1 mg daily, tamoxifen 20 mg daily, or a combination of the 2 treatments for 5 years or until disease recurrence. At the time of the efficacy analysis, women had received a median of 31 months of treatment and had been followed for recurrence-free survival for a median of 33 months. The primary end point of the trial is recurrence-free survival, ie, time to occurrence of a distant or local recurrence, or contralateral breast primary tumor, or death from any cause.

Trial results show 318 of 3125 women in the Arimidex group had a relapse of their breast cancer or died, compared with 379 of 3116 women in the tamoxifen group (hazard ratio = 0.83; P = .0144), representing a statistically significant 17% relative reduction in the risk of disease recurrence with Arimidex. The relative reduction in the risk of recurrence was 22% in women with confirmed hormone-sensitive tumors with Arimidex treatment (217 of 2617 women) compared with tamoxifen (272 of 2598 women; hazard ratio = 0.78).

Tamoxifen should not be administered with Arimidex. Estrogen-containing therapies should not be used with Arimidex because they may diminish its pharmacologic action.

Adverse Effects: ATAC trial adverse events are summarized in the Table 1 below.

Arimidex (anastrozole) Labeling

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