Introduction of ARIMIDEX: a highly selective aromatase inhibitor

Aromatase inhibitors have been available for the treatment of breast cancer in postmenopausal women since the late 1970s.1,2 Despite the proven efficacy of aminoglutethimide, its use was limited by toxicity and lack of selectivity for the aromatase enzyme. This poor selectivity necessitated concomitant corticosteroid supplementation1; thus a search began for more effective, less toxic aromatase inhibitors.

In 1995, this search was realised with the introduction of the non-steroidal aromatase inhibitor ARIMIDEX (anastrozole), a highly selective aromatase inhibitor.3 After the launch of ARIMIDEX, other selective aromatase inhibitors became available in clinical practice—the non-steroidal aromatase inhibitor letrozole4 and the steroidal aromatase inhibitor exemestane.5

ARIMIDEX today: efficacy, evidence and experience 

Since its introduction in 1995, ARIMIDEX has grown to become a standard treatment for postmenopausal, hormone receptor-positive early breast cancer. ARIMIDEX (anastrozole 1 mg tablets) delivers6:

• Data with 10 years of follow-up6
• Demonstrated efficacy in disease-free survival (DFS), time to recurrence (TTR) and time to distant recurrence (TTDR)6
• Early and long-term benefits demonstrated beyond treatment completion6

The superiority of ARIMIDEX over tamoxifen in the adjuvant treatment of postmenopausal early breast cancer was first established on the 33 month analysis of the ATAC trial.6 With 68 months median follow up, patients have not been followed up for sufficient time after 5 years of treatment, to enable a long term post treatment effect for comparison.7 However, with the 10 years' follow up of the ATAC trial confirms that ARIMIDEX provides both early and long-term benefits that extend beyond the completion of active treatment.6 The recommended duration of treatment for early disease is 5 years.7

References

1. Santen RJ et al. Endocrine treatment of breast cancer in women. Endocr Rev 1990; 11(2): 221–65.
2. Holder WD. General surgery-important advances in clinical medicine: adrenalectomy for metastatic breast cancer: surgical versus medical treatment. West J Med 1983; 138(2): 252–3.
3. Buzdar A et al. Anastrozole, a potent and selective aromatase inhibitor, versus megestrol acetate in postmenopausal women with advanced breast cancer: results of overview analysis of two phase III trials. J Clin Oncol 1996; 14(7): 2000–11.
4. Dombernowsky P et al. Letrozole, a new oral aromatase inhibitor for advanced breast cancer: double-blind randomized trial showing a dose effect and improved efficacy and tolerability compared with megestrol acetate. J Clin Oncol 1998; 16(2): 453–61.
5. Kaufmann M et al. Exemestane is superior to megestrol acetate after tamoxifen failure in postmenopausal women with advanced breast cancer: results of a phase III randomized double-blind trial. J Clin Oncol 2000; 18(7): 1399–1411.
6. Cuzick J et al. Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 10-year analysis of the ATAC trial. Lancet Oncol 2010; doi:10.1016/S1470-2045(10)70257-6.
7. ARIMIDEX UK SmPC. Last updated 7^th Oct 2011. http://www.medicines.org.uk/emc/medicine/3845/SPC/Arimidex+1mg+Film-Coated+Tablet/

   As there may be local variations in the approved label, please consult the local ARIMIDEX prescribing information before use.