Fulvestrant

Biological Activity

Fulvestrant (Faslodex) is a new estrogen receptor (ER) antagonist for the treatment of advanced breast cancer. It binds competitively to the oestrogen receptor (ER), with high affinity, and downregulates ER by functional blockade and increased turnover. Fulvestrant is a potent inhibitor of the growth of human breast cancer cells in vitro and in vivo. It has demonstrated pure anti-estrogenic activity in animal systems. Fulvestrant is an estrogen receptor antagonist with no agonist effects, which works both by down-regulating and by degrading the estrogen receptor. Because of a different mode of action to that of other hormonal agents, fulvestrant is effective in the treatment of tamoxifen-resistant disease and, unlike tamoxifen, has no known estrogen agonist effects.

Product Citations

• 

  Int J Biol Sci. 2018 Oct 3;14(12):1755-1768.

  Inhibition of Estrogen Signaling Reduces the Incidence of BRCA1-associated Mammary Tumor Formation.
  Fulvestrant purchased from AbMole

• 

  Oncotarget. 2016 Dec 20;7(51):83893-83906.

  Arctigenin functions as a selective agonist of estrogen receptor β to restrict mTORC1 activation and consequent Th17 differentiation
  Fulvestrant purchased from AbMole

• 

  Breast Cancer Res Treat. 2015 Jan;149(1):69-79.

  The PI3K/mTOR dual inhibitor P7170 demonstrates potent activity against endocrine-sensitive and endocrine-resistant ER+ breast cancer.
  Fulvestrant purchased from AbMole

Customer Product Validations & Biological Datas

	Source	Int J Biol Sci (2018 Oct). Figure 6. Fulvestrant (Abmole Bioscience, Houston, USA)
	Method	subcutaneously
	Cell Lines	Conditional Brca1-knockout and MMTV-Cre transgenic mice
	Concentrations	250 mg/kg
	Incubation Time	-
	Results	The chemotherapeutic efficacy of fulvestrant was examined in 18 sets of allograft mice produced from tumors from 18 individuals.

	Source	Int J Biol Sci (2018 Oct). Figure 5. Fulvestrant (Abmole Bioscience, Houston, USA)
	Method	subcutaneously
	Cell Lines	Conditional Brca1-knockout and MMTV-Cre transgenic mice
	Concentrations	250 mg/kg
	Incubation Time	-
	Results	In addition, histological analyses revealed that the number and size of lobular and ductal tubes were reduced in fulvestrant-treated mammary glands and their structure showed evidence of degeneration and shrinkage.

	Source	Int J Biol Sci (2018 Oct). Figure 4. Fulvestrant (Abmole Bioscience, Houston, USA)
	Method	subcutaneously
	Cell Lines	Conditional Brca1-knockout and MMTV-Cre transgenic mice
	Concentrations	250 mg/kg
	Incubation Time	-
	Results	In addition, fulvestrant-treated tumors displayed large necrotic areas with a lower level of the proliferation marker, and higher levels of cleaved caspase-3 and positive TUNEL staining compared with untreated tumor tissues (Fig. 4C), suggesting that estrogen signaling contributes to altered aggressiveness of Brca1-mutant tumors.

	Source	Oncotarget (2016). Figure 5. ICI-182780 (Abmole Bioscience Kowloon, Hong Kong).
	Method
	Cell Lines	CD4+CD62L+ T Cell
	Concentrations	0.1 μM
	Incubation Time	3 d
	Results	As shown in Figure 5A and 5B, neither MPP nor G15 showed noticeable effect on the decreased percentage of Th17 (IL-17A+CD4+ T) cells induced by arctigenin. Both ICI and PHTPP themselves did not affect the Th17 differentiation, but they markedly diminished the inhibitory effect of arctigenin. As expected, E2 could effectively decrease the percentage of Th17 cells. An addition of ICI also diminished the inhibitory effect of E2 on Th17 differentiation. Arctigenin markedly increased the expressions of ERβ target genes CAV1 and ENPP2, but showed no obvious effect on the expression of ERβ during Th17 differentiation (Figure 5C), which coincided well with the fact that arctigenin specifically promoted the expression of ERβ target genes in EL4 cells.

	Source	Breast Cancer Res Treat (2015). Figure 4.Fulvestrant was obtained either in the clinical formulation (Astrazeneca) or in the powder form (Abmole),
	Method	tumor volume, Ki67 staining, western bolt
	Cell Lines	T47D/FR
	Concentrations	5 mg/week s.c. in 100 µL
	Incubation Time	3 days(wb) or 8 weeks
	Results	"P7170 (in the context of a fulvestrant backbone) significantly decreased cell proliferation in T47D/FR tumors, but did not significantly increase apoptosis."

	Source	Breast Cancer Res Treat (2015). Figure 3.Fulvestrant was obtained either in the clinical formulation (Astrazeneca) or in the powder form (Abmole),
	Method	tumor volume, western blot, H&E staining, Ki67 staining, TUNEL test
	Cell Lines	MCF-7
	Concentrations	5 mg/week s.c. in 100 µL
	Incubation Time	3 days(wb) or 4-6 weeks
	Results	The addition of 5 mg/kg/day P7170 to fulvestrant significantly decreased tumor volumes compared to fulvestrant alone after 3–4.5 weeks of treatment (p<0.05)

	Source	Breast Cancer Res Treat (2015). Figure 2.Fulvestrant was obtained either in the clinical formulation (Astrazeneca) or in the powder form (Abmole),
	Method	flow cytometry
	Cell Lines	MCF-7, MCF-7/FR, MCF-7/LTED, HCC-1428, T47D, T47D/FR
	Concentrations	1 µM
	Incubation Time	3-4 days
	Results	In MCF-7, MCF-7/LTED, T47D, and T47D/FR cells, the combination of P7170 and fulvestrant significantly increased apoptosis compared to either drug alone.

Protocol

Cell Experiment
Cell lines	MCF-7
Preparation method	MCF-7 cells were plated at 10 000 cells/well in 96-well culture plates in MEM with 10% fetal bovine serum, and they were allowed to adhere for 48 h. Thereafter, the cultures were washed with serum-free MEM and incubated in 100 μl serum-free MEM. After 72 h, the medium was removed and replaced with 2% charcoal-stripped FBS–MEM containing 10 pmol/l E2 with either RAD1901 or additional E2 at concentrations ranging from 10−15 to 10−6 mol/l. The medium was removed after 48 h of incubation and the cells were lysed by adding 100 μl of CellTiter Glo (Promega, Madison, Wisconsin, USA), diluted 1 : 1 in water, per well. The plates were gently mixed on a plate shaker for 10 min before the luminescent signal was measured on a luminometer. The EC50 and IC50 of the test compound were defined as the concentrations that resulted in half-maximum shift.
Concentrations	Ranging from 10−15 to 10−6 mol/l
Incubation time	48 h

Animal Experiment
Animal models	MCF-7 xenograft models: Female athymic nude mice [Crl:NU(NCr)-Foxn1nu]
Formulation	Formulated for use as a homogenous suspension in 0.5% (w/v) methylcellulose in deionized water
Dosages	0.5 mg/animal daily
Administration	subcutaneous injection

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

Species	Mouse	Rat	Rabbit	Guinea pig	Hamster	Dog
Weight (kg)	0.02	0.15	1.8	0.4	0.08	10
Body Surface Area (m2)	0.007	0.025	0.15	0.05	0.02	0.5
Km factor	3	6	12	8	5	20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by	Animal B Km
	Animal A Km

For example, to modify the dose of Compound A used for a mouse (20 mg/kg) to a dose based on the BSA for a rat, multiply 20 mg/kg by the K_m factor for a mouse and then divide by the K_m factor for a rat. This calculation results in a rat equivalent dose for Compound A of 10 mg/kg.

Chemical Information

References

Fulvestrant - a novel endocrine therapy for breast cancer.
Johnston SJ, et al. Curr Med Chem. 2010;17(10):902-14. PMID: 20156170.

Comparison of fulvestrant versus tamoxifen for the treatment of advanced breast cancer in postmenopausal women previously untreated with endocrine therapy: a multinational, double-blind, randomized trial.
Howell A, et al. J Clin Oncol. 2004 May 1;22(9):1605-13. PMID: 15117982.