|ATC code||L02BA03 (WHO)|
|Biological half-life||40 days|
|Chemical and physical data|
|Molar mass||606.772 g/mol|
|3D model (Jmol)||Interactive image|
|(what is this?)|
Fulvestrant (trade name Faslodex, by AstraZeneca) is a drug treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression following anti-estrogen therapy. It is a complete estrogen receptor antagonist with no agonist effects, which in addition, accelerates the proteasomal degradation of the estrogen receptor. The drug has poor oral bioavailability, and is administered monthly via intramuscular injection.
Fulvestrant is a selective estrogen receptor degrader (SERD). It is indicated for the treatment of hormone receptor positive metastatic breast cancer in postmenopausal women with disease progression following anti-estrogen therapy.
Four clinical trials in this setting showed similar efficacy to the other hormonal agents (aromatase inhibitors and tamoxifen) with good tolerability profile. Fulvestrant had a lower incidence of joint disorders.
A Phase 2 clinical trial, investigates the use of fulvestrant administered through a microcatheter into the lactiferous duct as neoadjuvant treatment for ductal carcinoma in situ and invasive breast cancer.
The U.K. National Institute for Health and Clinical Excellence (NICE) said in 2011 that it found no evidence Faslodex was significantly better than existing treatments, so its widespread use would not be a good use of resources for the country's National Health Service. The first month's treatment of Faslodex, which starts with a loading dose, costs £1,044.82 ($1,666), and subsequent treatments cost £522.41 a month. In the 12 months ending June 2015, the UK price (excluding VAT) of a month's supply of anastrozole (Arimidex), which is off patent, cost 89 pence/day, and letrozole (Femara) cost £1.40/day.
The original patent for Faslodex expired in October 2004. Drugs subject to pre-marketing regulatory review are eligible for patent extension, and for this reason AstraZeneca got an extension of the patent to December 2011. AstraZeneca has filed later patents. There is no generic Faslodex available. A later patent for Faslodex expires in January 2021.
Interference with lab result
Due to the medication having a similar chemical structure to estrogen, it can interact with immunoassays for blood estradiol concentrations and show falsely elevated results. This could improperly lead to medication discontinuation.
- Scott SM, Brown M, Come SE (2011). "Emerging data on the efficacy and safety of fulvestrant, a unique antiestrogen therapy for advanced breast cancer". Expert Opin Drug Saf. 10 (5): 819–26. doi:10.1517/14740338.2011.595560. PMID 21699443.
- S. Eva Singletary; Geoffrey L. Robb; Gabriel N. Hortobagyi (1 January 2004). Advanced Therapy of Breast Disease. PMPH-USA. pp. 568–. ISBN 978-1-55009-262-2.
- Wardell SE, Marks JR, McDonnell DP (2011). "The turnover of estrogen receptor α by the selective estrogen receptor degrader (SERD) fulvestrant is a saturable process that is not required for antagonist efficacy.". Biochem Pharmacol. 82 (2). PMID 21501600.
- Croxtall JD, McKeage K (2011). "Fulvestrant: a review of its use in the management of hormone receptor-positive metastatic breast cancer in postmenopausal women". Drugs. 71 (3): 363–80. doi:10.2165/11204810-000000000-00000. PMID 21319872.
- Valachis A, Mauri D, Polyzos NP, Mavroudis D, Georgoulias V, Casazza G (2010). "Fulvestrant in the treatment of advanced breast cancer: a systematic review and meta-analysis of randomized controlled trials". Crit. Rev. Oncol. Hematol. 73 (3): 220–7. doi:10.1016/j.critrevonc.2009.03.006. PMID 19369092.
- Flemming J, Madarnas Y, Franek JA (2009). "Fulvestrant for systemic therapy of locally advanced or metastatic breast cancer in postmenopausal women: a systematic review". Breast Cancer Res. Treat. 115 (2): 255–68. doi:10.1007/s10549-008-0137-8. PMID 18683044.
- "PK Study of Pre-Surgical Intramuscular and Intraductal Fulvestrant in Women With Invasive Breast Cancer or DCIS Undergoing Mastectomy". Clinicaltrials.gov. 28 August 2015.
- UK Department of Health Commercial Medicines Unit Electronic Medicines Information Tool, London, 2015
- UK’s NICE says no to AstraZeneca breast cancer drug Faslodex, The Pharma Letter, 10 November 2011
- National Institute for Health and Clinical Excellence Guidance Breast cancer (metastatic) - fulvestrant
- Patent Term Extensions The United States Patent and Trademark Office.
- Determination of Regulatory Review Period for Purposes of Patent Extension; FASLODEX A Notice by the Food and Drug Administration on 04/17/2003
- Generic Faslodex Availability, Drugs.COM
- Pink Ribbon Blues: How Breast Cancer Culture Undermines Women's Health By Gayle A. Sulik, Oxford University Press (Oct. 2010)
- Estradiol immunoassays – interference from the drug fulvestrant (Faslodex) may cause falsely elevated estradiol results. HMGov, UK.