Acolbifene - CAS 182167-02-8
Not Intended for Therapeutic Use. For research use only.
Product Name:
Catalog Number:
EM 652; EM-652; EM652; SCH57068; SCH-57068; SCH 57068.
CAS Number:
Acolbifene, also known as EM-652, or SCH-57068, is a selective estrogen receptor modulator (SERM). Acolbifene is currently being studied in the prevention of breast cancer in women at high risk of breast cancer. EM-652 is the compound having the highest affinity for the estrogen receptor, including estradiol. It has higher affinity for the ER than ICI 182780, hydroxytamoxifen, raloxifene, droloxifene and hydroxytoremifene. EM-652 was also the most potent inhibitor of the percentage of cycling cancer cells.
Current Developer:
EndoCeutics, Quebec City, Canada
Chemical Structure
CAS 182167-02-8 Acolbifene

Reference Reading

1.The combination of the rexinoid, LG100268, and a selective estrogen receptor modulator, either arzoxifene or acolbifene, synergizes in the prevention and treatment of mammary tumors in an estrogen receptor-negative model of breast cancer.
Liby K1, Rendi M, Suh N, Royce DB, Risingsong R, Williams CR, Lamph W, Labrie F, Krajewski S, Xu X, Kim H, Brown P, Sporn MB. Clin Cancer Res. 2006 Oct 1;12(19):5902-9.
PURPOSE: We tested whether a selective estrogen receptor modulator (SERM) and a rexinoid are active for prevention and treatment in the mouse mammary tumor virus-neu mouse model of estrogen receptor-negative breast cancer.
2.Effect of toremifene and ospemifene, compared to acolbifene, on estrogen-sensitive parameters in rat and human uterine tissues.
Labrie F, Martel C, Gauthier S, Pelletier G, Sancéau JY. Horm Mol Biol Clin Investig. 2010 Jan 1;1(3):139-46. doi: 10.1515/HMBCI.2010.016.
BACKGROUND: Although the first generation selective estrogen receptor modulator (SERM) tamoxifen (TAM) is well known for its uterotrophic activity, this study compares the stimulatory effect of the TAM derivatives toremifene (TORE) and ospemifene (OSPE) on estrogen-sensitive parameters in rat and human uterine tissues.
3.Clinical Trial of Acolbifene in Premenopausal Women at High Risk for Breast Cancer.
Fabian CJ1, Kimler BF2, Zalles CM3, Phillips TA1, Metheny T1, Petroff BK1, Havighurst TC4, Kim K4, Bailey HH5, Heckman-Stoddard BM6. Cancer Prev Res (Phila). 2015 Dec;8(12):1146-55. doi: 10.1158/1940-6207.CAPR-15-0109. Epub 2015 Sep 21.
The purpose of this study was to assess the feasibility of using the selective estrogen receptor modulator (SERM) acolbifene as a breast cancer prevention agent in premenopausal women. To do so, we assessed change in proliferation in benign breast tissue sampled by random periareolar fine-needle aspiration (RPFNA) as a primary endpoint, along with changes in other risk biomarkers and objective and subjective side effects as secondary endpoints. Twenty-five women with cytologic hyperplasia ± atypia and ≥2% of breast epithelial cells staining positive for Ki-67, received 20 mg acolbifene daily for 6-8 months, and then had benign breast tissue and blood risk biomarkers reassessed. Ki-67 decreased from a median of 4.6% [interquartile range (IQR), 3.1%-8.5%] at baseline to 1.4% (IQR, 0.6%-3.5%) after acolbifene (P < 0.001; Wilcoxon signed-rank test), despite increases in bioavailable estradiol. There were also significant decreases in expression (RT-qPCR) of estrogen-inducible genes that code for pS2, ERα, and progesterone receptor (P ≤ 0.