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Clinical data
Synonyms LY-353381
Routes of
By mouth
Drug class Selective estrogen receptor modulator
CAS Number
PubChem CID
Chemical and physical data
Formula C28H29NO4S
Molar mass 475.60 g/mol
3D model (JSmol)
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Arzoxifene (INN; developmental code name LY-353381) is a selective estrogen receptor modulator (SERM) of the benzothiophene group which was never marketed.[1] It is a potent estrogen antagonist in mammary and uterine tissue while acting as an estrogen agonist to maintain bone density and lower serum cholesterol. Arzoxifene is a highly effective agent for prevention of mammary cancer induced in the rat by the carcinogen nitrosomethylurea and is significantly more potent than raloxifene in this regard. Arzoxifene is devoid of the uterotrophic effects of tamoxifen, suggesting that, in contrast to tamoxifen, it is unlikely that the clinical use of arzoxifene will increase the risk of developing endometrial carcinoma.


In a phase 3 clinical study in postmenopausal women, arzoxifene was shown to increase bone spine and hip mineral density and had no effect on the uterus and endometrium.[2]

Lilly announced in August 2009 that preliminary results from a five-year clinical study showed that arzoxifene met its primary endpoints of reduction in vertebral fractures and breast cancer in postmenopausal women. However arzoxifene failed to meet secondary endpoints of reduction in non-vertebral fractures and cardiovascular events and improvements in cognitive function. Based on these results, Lilly announced they are discontinuing further development of the drug and would not seek regulatory approval.[3]

A 2015 network meta-analysis found that arzoxifene significantly reduced the risk of breast cancer (RR = 0.415) and to a greater extent than raloxifene (RR = 0.572) or tamoxifen (RR = 0.708).[4]


  1. ^ Overk CR, Peng KW, Asghodom RT, et al. (2007). "Structure-activity relationships for a family of benzothiophene selective estrogen receptor modulators including raloxifene and arzoxifene". ChemMedChem. 2 (10): 1520–6. doi:10.1002/cmdc.200700104. PMID 17654759. 
  2. ^ Bolognese M, Krege JH, Utian WH, Feldman R, Broy S, Meats DL, Alam J, Lakshmanan M, Omizo M (July 2009). "Effects of arzoxifene on bone mineral density and endometrium in postmenopausal women with normal or low bone mass". J. Clin. Endocrinol. Metab. 94 (7): 2284–9. doi:10.1210/jc.2008-2143. PMID 19351734. 
  3. ^ "Lilly Reports on Outcome of Phase III Study of Arzoxifene". Press Release. Eli Lilly and Company. 2009-08-18. Retrieved 2009-08-24. 
  4. ^ Mocellin S, Pilati P, Briarava M, Nitti D (2016). "Breast Cancer Chemoprevention: A Network Meta-Analysis of Randomized Controlled Trials". J. Natl. Cancer Inst. 108 (2). doi:10.1093/jnci/djv318. PMID 26582062. 

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