Exemestane belongs to the class of steroidal aromatase inhibitors and is structurally related to the natural substrate androstenedione. Estrogen is primarily produced by the modification of androgen through aromatase in postmenopausal women and blocking its production is an effective way to control hormone-sensitive breast cancer. Exemestane binds irreversibly to the active site of aromatase and causes its inactivation, sometimes referred to as suicidal inactivation.

Exemestane doesn’t affect adrenal biosynthesis, progestogenic action and estrogenic activity. It slightly raises serum FSH and LH levels. FDA first approved it in 1999 and it was marketed under the brand name Aromasin. At Element Sarms, the option to buy liquid Exemestane is restricted to educational and research purposes.

From Pubchem

IUPAC Name:(8R,9S,10R,13S,14S)-10,13-dimethyl-6-methylidene-7,8,9,11,12,14,15,16-octahydrocyclopenta[a]phenanthrene-3,17-dione
Synonym: 107868-30-4, Aromasin
Molecular Formula: C20H24O2
Molecular Weight: 296.4 g/mol
CAS Number: 107868-30-4
PubChem CID: 60198

1. Exemestane and Breast Cancer Prevention

Exemestane has been shown to prevent contralateral breast cancer in postmenopausal women. A randomized double-blind placebo-controlled trial was designed to check the efficacy of exemestane in preventing breast cancer. 4560 postmenopausal women who were at high risk of breast cancer were randomly assigned to receive exemestane or placebo. After 35 months, exemestane showed a 65% relative reduction in invasive breast cancer incidence, also lowering overall invasive and noninvasive breast cancer rates (0.35% vs. 0.77%). Adverse events occurred in 88% of the treatment group and 85% of the placebo group, with no significant differences in fractures, cardiovascular events, other cancers, or treatment-related deaths [1].

2. Exemestane and Adjuvant Treatment in Early-stage Breast Cancer

In cases of estrogen-dependent breast cancers, blocking estrogen production by removing ovaries can effectively decrease its progression. Tamoxifen decreases the risk of recurrence by 47% when given after surgery for 5 years. Alternative endocrine therapies can be effective in cases of breast cancer relapse even after tamoxifen treatment.

The intergroup exemestane study (IES) was designed to evaluate whether postmenopausal women, after 2-3 years of tamoxifen for breast cancer, would benefit more by switching to exemestane versus continuing tamoxifen. Participants were randomly assigned to switch to exemestane or to continue to receive tamoxifen. After 2.5 years, exemestane showed a 32% risk reduction vs. tamoxifen, with a 4.7% absolute benefit in 3-year disease-free survival. Further, researchers found that contralateral breast cancer occurred in 20 patients in the tamoxifen group and 9 in the exemestane group [2].

The Tamoxifen Exemestane Adjuvant Multinational (TEAM) Phase 3 trial was conducted to compare the long-term efficacy of exemestane monotherapy as compared to sequential treatment. The findings indicated that both groups had similar disease-free survival after 5 years. The sequential group had more gynecological symptoms, venous thrombosis, and endometrial abnormalities, while the exemestane-only group had more musculoskeletal issues [3].

3. Exemestane and Breast Cancer in Premenopausal Women

Tamoxifen is the standard treatment of care for breast cancer adjuvant therapy in premenopausal women. SOFT and TEXT trial was conducted to examine whether exemestane is effective for premenopausal women with ovarian function suppression. Researchers randomly assigned participants with hormone receptor-positive breast cancer to receive exemestane plus ovarian suppression and tamoxifen plus ovarian suppression for a period of 5 years. The results found that the exemestane significantly reduced recurrence as compared to the tamoxifen group [4].

4. Exemestane and Advanced Stage Breast Cancer

Research shows that exemestane has superior efficacy over megestrol acetate for the treatment of advanced-stage breast cancer in postmenopausal women who didn’t respond to tamoxifen [5].

Increased PI3K/AKT/mTOR signaling is associated with resistance to endocrine-targeted therapies. Based on the results reported in the BOLERO-2 trial, exemestane along with everolimus (inhibitor of mTOR) has been approved for advanced-stage breast cancer patients who previously progressed on nonsteroidal aromatase inhibitors [6].

5. Current Status of Exemestane

Exemestane is an irreversible steroidal aromatase inhibitor primarily used for the treatment of breast cancer in postmenopausal women. It has also been shown to decrease the risk of cancer in premenopausal women. It is an FDA-approved drug for the adjuvant treatment in estrogen receptor-positive early-stage breast cancer and advanced-stage breast cancer in postmenopausal women. Many clinical trials are ongoing to explore its efficacy in combination with other drugs for HR-positive and HER2-negative premenopausal breast cancer patients. At Element Sarms, Aromasin for sale is solely available for research and educational purchases. Only buy exemestane for approved research.

1. Goss, P.E., et al., Exemestane for Breast-Cancer Prevention in Postmenopausal Women. New England Journal of Medicine, 2011. 364(25): p. 2381-2391.
2. Coombes, R.C., et al., 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): p. 1081-1092.
3. van de Velde, C.J., et al., Adjuvant tamoxifen and exemestane in early breast cancer (TEAM): a randomised phase 3 trial. Lancet, 2011. 377(9762): p. 321-31.
4. Pagani, O., et al., Adjuvant Exemestane with Ovarian Suppression in Premenopausal Breast Cancer. New England Journal of Medicine, 2014. 371(2): p. 107-118.
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. The Exemestane Study Group. J Clin Oncol, 2000. 18(7): p. 1399-411.
6. Beck, J.T., et al., Everolimus plus exemestane as first-line therapy in HR+, HER2− advanced breast cancer in BOLERO-2. Breast Cancer Research and Treatment, 2014. 143(3): p. 459-467.