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Trade namesOrserdu
Other namesRAD-1901; ER-306323
  • (6R)-6-{2-[Ethyl({4-[2-(ethylamino)ethyl]phenyl}methyl)amino]-4-methoxyphenyl}-5,6,7,8-tetrahydronaphthalen-2-ol
Clinical data
Main usesBreast cancer[1]
Side effectsMusculoskeletal pain, nausea, increased cholesterol, elevated liver enzymes, increased triglycerides, tiredness, decreased hemoglobin, decreased sodium, kidney problems, diarrhea, headache, constipation, abdominal pain, hot flashes, upset stomach[1]
Routes of
By mouth
Typical dose345 mg OD[1]
License data
Legal status
Protein binding>99%[1]
MetabolismLiver (major: CYP3A4, minor: CYP2A6, CYP2C9)[1]
Elimination half-life30–50 hours[1]
ExcretionFeces (82%), urine (7.5%)[1]
Chemical and physical data
Molar mass458.646 g·mol−1
3D model (JSmol)
  • InChI=1S/C30H38N2O2/c1-4-31-17-16-22-6-8-23(9-7-22)21-32(5-2)30-20-28(34-3)14-15-29(30)26-11-10-25-19-27(33)13-12-24(25)18-26/h6-9,12-15,19-20,26,31,33H,4-5,10-11,16-18,21H2,1-3H3/t26-/m1/s1

Elacestrant, sold under the brand name Orserdu, is a medication used to treat breast cancer.[1] Specifically it is used for ER-positive, HER2-negative, ESR1-mutated advanced disease that has failed other treatment.[1] It is used in women after menopause or in men.[1] It is taken by mouth.[1]

Common side effects include musculoskeletal pain, nausea, increased cholesterol, elevated liver enzymes, increased triglycerides, tiredness, decreased hemoglobin, decreased sodium, kidney problems, diarrhea, headache, constipation, abdominal pain, hot flashes, and upset stomach.[1] Use in pregnancy may harm the baby.[1] It may interact with medications that affect CYP3A4.[1] It works by blocking the action of estrogens.[1]

Elacestrant was approved for medical use in the United States in 2023.[1] In the United States it costs about 22,500 USD per month.[3]

Medical uses

Elacestrant is used for the treatment of postmenopausal women or adult men with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression following at least one line of endocrine therapy.[2]


The typical dose is 345 mg once per day.[1]



Elacestrant is an antiestrogen, or an antagonist of the estrogen receptors, the biological targets of endogenous estrogens like estradiol.[1] It is specifically an antagonist of the estrogen receptor alpha (ERα).[1] Elacestrant is also a selective estrogen receptor degrader (SERD), in that it induces degradation of the ERα.[1][4]


The oral bioavailability of elacestrant is approximately 10%.[1] Its plasma protein binding is greater than 99% and is independent of concentration.[1] Elacestrant is metabolized in the liver, primarily by the cytochrome P450 enzyme CYP3A4 and to a lesser extent by CYP2A6 and CYP2C9.[1] The elimination half-life of elacestrant is 30 to 50 hours.[1] It is excreted 82% in feces and 7.5% in urine.[1]


Efficacy was evaluated in EMERALD (NCT03778931), a randomized, open-label, active-controlled, multicenter trial that enrolled 478 postmenopausal women and men with ER-positive, HER2-negative advanced or metastatic breast cancer of which 228 participants had ESR1 mutations.[2] Participants were required to have disease progression on one or two prior lines of endocrine therapy, including one line containing a CDK4/6 inhibitor.[2] Eligible participants could have received up to one prior line of chemotherapy in the advanced or metastatic setting.[2] Participants were randomized (1:1) to receive elacestrant 345 mg orally once daily (n=239) or investigator’s choice of endocrine therapy (n=239), which included fulvestrant (n=166) or an aromatase inhibitor (n=73).[2] Randomization was stratified by ESR1 mutation status (detected vs. not detected), prior treatment with fulvestrant (yes vs. no), and visceral metastasis (yes vs. no).[2] ESR1 mutational status was determined by blood circulating tumor deoxyribonucleic acid (ctDNA) using the Guardant360 CDx assay and was limited to ESR1 missense mutations in the ligand binding domain.[2]

The FDA granted the application for elacestrant priority review and fast track designations.[2]


It is a nonsteroidal combined selective estrogen receptor modulator (SERM) and selective estrogen receptor degrader (SERD) (described as a "SERM/SERD hybrid (SSH)") that was discovered by Eisai and is under development by Radius Health and Takeda for the treatment estrogen receptor (ER)-positive advanced breast cancer.[5] Elacestrant has dose-dependent, tissue-selective estrogenic and antiestrogenic activities, with biphasic weak partial agonist activity at the ER at low doses and antagonist activity at higher doses.[6] It shows agonistic activity on bone and antagonistic activity on breast and uterine tissues.[7] Unlike the SERD fulvestrant, elacestrant is able to readily cross the blood-brain-barrier into the central nervous system, where it can target breast cancer metastases in the brain,[6][7] and is orally bioavailable and does not require intramuscular injection.[6][7]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 "Orserdu- elacestrant tablet, film coated". DailyMed. 8 February 2023. Archived from the original on 11 February 2023. Retrieved 11 February 2023.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 "FDA approves elacestrant for ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer". U.S. Food and Drug Administration (FDA). 27 January 2023. Archived from the original on 2 February 2023. Retrieved 1 February 2023. Public Domain This article incorporates text from this source, which is in the public domain.
  3. "Orserdu Prices, Coupons, Copay & Patient Assistance". Drugs.com. Archived from the original on 1 July 2023. Retrieved 14 May 2023.
  4. Lloyd MR, Wander SA, Hamilton E, Razavi P, Bardia A (2022). "Next-generation selective estrogen receptor degraders and other novel endocrine therapies for management of metastatic hormone receptor-positive breast cancer: current and emerging role". Ther Adv Med Oncol. 14: 17588359221113694. doi:10.1177/17588359221113694. PMC 9340905. PMID 35923930.
  5. Clinical trial number NCT03778931 for "Phase 3 Trial of Elacestrant vs. Standard of Care for the Treatment of Patients With ER+/HER2- Advanced Breast Cancer" at ClinicalTrials.gov
  6. 6.0 6.1 6.2 Wardell SE, Nelson ER, Chao CA, Alley HM, McDonnell DP (October 2015). "Evaluation of the pharmacological activities of RAD1901, a selective estrogen receptor degrader". Endocrine-Related Cancer. 22 (5): 713–24. doi:10.1530/ERC-15-0287. PMC 4545300. PMID 26162914.
  7. 7.0 7.1 7.2 Garner F, Shomali M, Paquin D, Lyttle CR, Hattersley G (October 2015). "RAD1901: a novel, orally bioavailable selective estrogen receptor degrader that demonstrates antitumor activity in breast cancer xenograft models". Anti-Cancer Drugs. 26 (9): 948–56. doi:10.1097/CAD.0000000000000271. PMC 4560273. PMID 26164151.

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