Exemestane, sold under the brand name Aromasin, is a steroidal aromatase inhibitor. The FDA initially approved it for the treatment of advanced breast cancer in 1999. Later, it received approval for the adjuvant treatment of postmenopausal women with estrogen receptor-positive early breast cancer in 2005. Furthermore, it has been used in doping to enhance athletic performance, thus banned by the World Anti-Doping Agency (WADA). At Pinnacle Peptides, exemestane for sale is exclusively available for research and experimentation.

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
Synonyms: 107868-30-4, Aromasin
Molecular Formula: C20H24O2
Molecular Weight: 296.4 g/mol
CAS number: 107868-30-4
PubChem CID: 60198

Exemestane structurally resembles 4-androstenedione, a natural substrate of the aromatase enzyme. Research shows that exemestane competes with testosterone and androstenedione and binds to the active site of the enzyme through a covalent bond, resulting in irreversible inhibition of aromatase. Aromatase is responsible for the transformation of androgen into estrogen. Blocking of aromatase in postmenopausal women decreases the levels of estrogen and suppresses the proliferation of hormone-sensitive breast cancer cells.

1. Early Stage Breast Cancer

Tamoxifen as an adjuvant treatment has been shown to decrease the risk of recurrence by 47% when administered for five years post-surgery. However, breast cancer relapses despite tamoxifen treatment in certain cases. Research shows that alternative endocrine therapies might show improved efficacy in such scenarios.

The Intergroup Exemestane Study (IES) found that the patients who switched to exemestane, following 3 years of tamoxifen therapy, experienced a significant reduction in the risk of recurrence by 32%. Plus, the incidence of contralateral breast cancer was notably lower in the exemestane group compared to the tamoxifen group. The study concluded that exemestane improved the risk of disease-free survival as compared to tamoxifen [1].

Similarly, The Tamoxifen Exemestane Adjuvant Multinational (TEAM) Phase 3 trial was conducted to compare the long-term efficacy of exemestane monotherapy with sequential treatment. The results indicated similar disease-free survival rates in both groups after 5 years. Notably, the sequential treatment group exhibited a higher incidence of gynecological symptoms, venous thrombosis, and endometrial abnormalities, while the exemestane-only group experienced more musculoskeletal issues [2].

2. Breast Cancer in Premenopausal Women

The results from the SOFT and TEXT trial suggest that exemestane in combination with ovarian suppression significantly decreased the recurrence rates of breast cancer in premenopausal women as compared to those taking tamoxifen and ovarian suppression therapy [3].

3. Advanced Stage Breast Cancer

Research suggests that resistance to breast cancer treatment is associated with the interaction between estrogen receptor signaling and PI3/AKT/mTOR pathway. Thus, co-targeting these pathways might improve outcomes in patients with advanced-stage breast cancer.

The results of the BOLERO-2 trial support the efficacy of combination therapy, using exemestane plus everolimus, as first-line treatment for disease recurrence in patients who don’t respond to non-steroidal aromatase inhibitors. Furthermore, the study suggested the earlier introduction of combination treatment in estrogen receptor-positive advanced breast cancer [4].

Similarly, another study revealed that exemestane prolongs survival time and delays the progression of cancer as compared to megestrol acetate in patients with advanced-stage breast cancer who experienced failure of tamoxifen [5].

4. Breast Cancer Prevention

Exemestane has been shown to prevent the incidence of contralateral breast cancer among postmenopausal women. In a study involving 4560 postmenopausal women who were at high risk of breast cancer, exemestane decreased the risk of invasive breast cancer by 65% as compared to the control group. Furthermore, overall rates of both invasive and noninvasive breast cancers were lower in the exemestane group (0.35% vs. 0.77%) [6].

Exemestane is a steroidal aromatase inhibitor indicated for the treatment of breast cancer. It decreases the exposure of estrogen, thus reducing the proliferation of hormone-sensitive breast cancer cells. It has been shown to decrease the risk of breast cancer in women at high risk. Furthermore, it can reduce the incidence of cancer recurrence. It’s often abused by athletes to enhance performance. We don’t support its unwarranted use and offer exemestane purchase solely for research. Only buy exemestane if you are a qualified researcher.

1. 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.
2. 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.
3. Pagani, O., et al., Adjuvant Exemestane with Ovarian Suppression in Premenopausal Breast Cancer. New England Journal of Medicine, 2014. 371(2): p. 107-118.
4. 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.
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. Goss, P.E., et al., Exemestane for Breast-Cancer Prevention in Postmenopausal Women. New England Journal of Medicine, 2011. 364(25): p. 2381-2391.