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Exemestane Becomes the First And Only Aromatase Inhibitor for Adjuvant Sequential Therapy in Early-Stage Breast Cancer

New indication supported by landmark international study demonstrating consistent disease-free survival benefit versus tamoxifen

MONTREAL, CANADA -- May 17, 2006 -- Pfizer Canada today announced that Aromasin (exemestane tablets), has been granted a Notice of Compliance with Conditions (NOC/c) by Health Canada making it the first and only aromatase inhibitor approved for adjuvant sequential therapy for breast cancer after 2-3 years of treatment with tamoxifen.

The indication is for sequential adjuvant (after surgery) treatment of postmenopausal women with estrogen-receptor positive early breast cancer who have received 2 to 3 years of initial adjuvant tamoxifen therapy.

"People must not underestimate the importance of a switch option in adjuvant endocrine treatment -- it is a critical therapeutic step," says Dr. Kathleen Pritchard, Professor in the Department of Medicine, Faculty of Medicine at the University of Toronto. "Any time we can talk about improvements in disease-free survival, we know we are making important strides in the battle against breast cancer."

The new indication is based on strong efficacy results from the landmark Intergroup Exemestane Study (IES) study, which evaluates the switch from tamoxifen to Aromasin for adjuvant breast cancer therapy. The initial results of this study were published in the New England Journal of Medicine on March 11, 2004.(1)


The IES study showed the following:
- Postmenopausal women with early-stage breast cancer who switched to Aromasin after 2 to 3 years of tamoxifen for a combined total of 5 years of adjuvant hormonal therapy had 31 percent more protection from cancer recurrence than those who remained on 5 years of tamoxifen therapy.
- Postmenopausal women with early-stage breast cancer who switched to Aromasin after 2-3 years of tamoxifen for a combined total of 5 years of adjuvant hormonal therapy had a 68 percent reduced risk of cancer in the other breast compared to 5 years of tamoxifen alone. Overall, the spread of cancer to the other breast was rare in both study groups.

The IES study also demonstrated that taking Aromasin after 2-3 years of tamoxifen for a combined total of five years of adjuvant hormonal therapy can give more women a greater chance for a cancer-free future compared to five years of tamoxifen alone.
Until now, in Canada, Aromasin has been indicated for hormonal treatment of advanced breast cancer in women with natural or artificially-induced post-menopausal status whose disease has progressed following antiestrogen therapy.

"Most importantly, women need to be discussing these treatment options with their physician," says Dr. Pritchard. "In general, the higher the risk of recurrence, the more appropriate adjuvant treatment with Aromasin may be."

About the Intergroup Exemestane Study (IES) Study
The Intergroup Exemestane Study (IES) involved 4,724 post-menopausal women in 37 countries with breast cancer who were followed for an average of 35 months. IES was the largest study reported in the switch setting. The IES study demonstrated that patients who switched to Aromasin after two or three years of taking tamoxifen were more likely to remain cancer free than those who continued on tamoxifen.

In the double-blind trial, after 2-to-3 years of adjuvant tamoxifen therapy, patients were randomized to receive either Aromasin (25 mg) or to continue on tamoxifen (20 mg) daily. Patients receiving Aromasin experienced a 31 percent reduction in the risk of recurrence of the disease at three years, as compared to those continuing on tamoxifen. This reduction includes fewer local and distant tumours as well as new cancer in the other breast.

Consistent benefits were observed in the following subgroups of patients:
- Both node negative or positive women
- Both chemotherapy-treated or naive women
- Breast hormone receptors positive women

Aromasin was generally well tolerated. The most commonly reported adverse events included hot flashes, fatigue, bone/joint and muscle pain, headache, insomnia, increased sweating, hypertension, dizziness, pain in limb, back pain, nausea, depression, osteoarthritis, and visual disturbances.(2) Continuation of tamoxifen therapy was associated with a greater incidence of endometrial cancer, blood clots, hot flashes, vaginal bleeding, and muscle cramps.(2) The International Collaborative Cancer Group under the auspices of the Breast International Group coordinated the IES study, which was supported by Pfizer.


REFERENCES:
1. Coombes RC, Hall E, et al for the Intergroup Exemestane Study. A Randomized Trial of Exemestane after Two to Three Years of Tamoxifen Therapy in Postmenopausal Women with Primary Breast Cancer. New England Journal of Medicine. 2004. 350 (11): 1081-1092.
2. Aromasin (exemestane) Product Monograph, April 26, 2006, p. 10


SOURCE: Pfizer Canada Inc.

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