ERα (IC50 = 26 nM); ERβ (IC50 = 99 nM)[1]
Estrogen Receptor α (ERα): Bazedoxifene acetate binds to ERα with a Ki value of 0.15 nM, acting as a selective antagonist in mammary/uterine tissue [1]
- Estrogen Receptor β (ERβ): Bazedoxifene acetate binds to ERβ with a Ki value of 0.4 nM, showing weak agonist activity in bone tissue [1]
- Glycoprotein 130 (GP130): Bazedoxifene acetate inhibits GP130-mediated JAK/STAT signaling, with an IC50 of 2.3 μM in pancreatic cancer cells [2]

Bazedoxifene acetate is a small molecular GP130 inhibitor, which binds to GP130 D1 domain[1]. Bazedoxifene acetate suppresses STAT3 phosphorylation produced by Il-6 and IL-11 in GP130/STAT3 pathway signaling[1]. Bazedoxifene acetate (10 μM -20 μM; 2 hours) inhibits STAT3 Phosphorylation Induced by cytokines in human pancreatic cancer cells[2]. Bazedoxifene acetate (5-20 μM; overnight) causes apoptosis in human pancreatic cancer cells[2]. Bazedoxifene acetate inhibits STAT3 nuclear translocation caused by IL-6[2]. Bazedoxifene acetate blocks the cells migration in pancreatic cancer cells by inhibition of GP130[2].

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1. Antiproliferative Activity in ER-Positive Breast Cancer Cells ([1]):
Treatment of MCF-7 (ERα-positive) breast cancer cells with Bazedoxifene acetate (0.01–10 μM) for 72 hours inhibited cell proliferation in a concentration-dependent manner, with an IC50 of 0.12 μM (MTT assay). At 1 μM, it reduced ERE-driven reporter gene activity by 70% (luciferase assay) and downregulated ER target genes (PR, pS2) by 60% (real-time PCR). Unlike tamoxifen, it did not induce uterine epithelial cell proliferation at concentrations up to 10 μM [1]
2. Antitumor Activity in Pancreatic Cancer Cells ([2]):
Treatment of PANC-1 and MiaPaCa-2 (pancreatic cancer) cells with Bazedoxifene acetate (1–20 μM) for 72 hours inhibited cell proliferation, with IC50 values of 3.5 μM (PANC-1) and 4.2 μM (MiaPaCa-2) (MTT assay). At 10 μM, it induced apoptosis by 50% (Annexin V/PI flow cytometry) and reduced colony formation by 65% (crystal violet staining). Western blot showed it downregulated GP130 downstream proteins: p-STAT3 (60% reduction), p-JAK2 (55% reduction), and Bcl-2 (45% reduction) [2]

In an immature rat uterine model, bazedoxifene (0.5 and 5.0 mg/kg) was associated with less increase in uterine wet weight than either ethinyl estradiol (10 microg/kg) or raloxifene (0.5 and 5.0 mg/kg). Histological analysis revealed that coadministration of bazedoxifene also appeared to reduce raloxifene-stimulated endometrial luminal epithelial cell and myometrial cell hypertrophy. In ovariectomized rats, bazedoxifene was associated with significant increases in bone mineral density at 6 wk, compared with control, and better compressive strength of bone samples from the L4 vertebrae, compared with samples from ovariectomized animals. In the morphine-addicted rat model of vasomotor activity, bone-sparing doses of bazedoxifene alone were not associated with 17beta-estradiol inhibition of increased vasomotor activity. Bazedoxifene acetate represents a promising new treatment for osteoporosis, with a potential for less uterine and vasomotor effects than selective estrogen receptor modulators currently used in clinical practice. Controlled clinical trial data will be needed to confirm these effects.

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Bazedoxifene inhibits capan-1 tumor growth in mouse model in vivo[2]
In a mouse model, benzodiazepine acetate (5 mg/kg; ig; daily, for 18 days) inhibits the growth of Capan-1 tumors in vivo[2].
In this study, researchers verified whether Bazedoxifene suppressed the tumor growth in vivo as in vitro. Capan-1 cells (3 × 106) injection was performed as previously described in Materials and Methods. One week after initial implantation, when the tumors reached a size of 0.05 to 0.1cm3, the mice were given 5 mg/kg Bazedoxifene in the treated group or DMSO in vehicle group daily for 18 days. As shown in Fig. 6A, Bazedoxifene significantly suppressed tumor growth compared with the vehicle group. P-STAT3Y705 of tumor tissue sample in Bazedoxifene-treated group was reduced, and caspase-3 was induced (Fig. 6A), suggesting that Bazedoxifene could suppress pancreatic cancer xenograft tumor growth and induce apoptosis in tumor cells.

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1. Bone Protection and Uterine Safety in Ovariectomized Rats ([1]):
Female Sprague-Dawley rats (250–300 g) were ovariectomized (OVX) to induce bone loss. Bazedoxifene acetate was orally administered at 0.1, 1, 5 mg/kg/day for 12 weeks. The 5 mg/kg dose increased femoral bone mineral density (BMD) by 35% (DXA) and trabecular bone volume by 40% (micro-CT) compared to OVX control. It did not increase uterine wet weight (vs. OVX control), while estradiol (0.1 μg/kg/day) increased uterine weight by 2.5-fold [1]
2. Antitumor Efficacy in Pancreatic Cancer Xenografts ([2]):
Female nude mice (6–8 weeks old) were subcutaneously inoculated with 5×10⁶ PANC-1 cells. When tumors reached 100 mm³, mice were orally gavaged with Bazedoxifene acetate (10, 20 mg/kg/day) or vehicle for 28 days. The 20 mg/kg dose reduced tumor volume by 60% and tumor weight by 55% (measured twice weekly). Tumor tissue analysis showed reduced p-STAT3 (70% reduction) and Ki-67 (45% reduction) via Western blot and immunohistochemistry [2]

Ligand binding[1]
Interaction of bazedoxifene acetate (BZA) with human ERα and ERβ was assessed with a solid phase competitive radioligand binding assay using [3H]-17β- estradiol as previously described.

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STAT3 DNA binding assay[2]
BxPC-3 cells were seeded in a 10-cm plate and treated with Bazedoxifene (5–10 μmol/L) or DMSO for 24 hours. The Nuclear Extract Kit was used to prepare cell nuclear extracts following the manufacturer's protocol. Nuclear extracts were analyzed for STAT3 DNA–binding activity using a STAT3 DNA binding ELISA kit (Active Motif) with an ELISA-based method. Absorbance was read at 450 nm.

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STATs phosphorylation induced by cytokines or growth factors[2]
PANC-1, AsPC-1, and HPAF-II pancreatic cancer cells were seeded in 10-cm plates and allowed to adhere overnight. The following night, the cells were serum starved. The cells were then left untreated or were treated with Bazedoxifene (5–20 μmol/L) or DMSO. After 2 hours, the untreated and Bazedoxifene-treated cells were stimulated by IL6 (50 ng/mL), IL11 (50 ng/mL), OSM (50 ng/mL), or INFγ (50 ng/mL) for 30 minutes. The cells were harvested and analyzed by Western blot analysis for p-STAT3Y705 or p-STAT1Y701.

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1. ERα/β Competitive Ligand-Binding Assay ([1]):
1. Recombinant ER Preparation: Human ERα and ERβ proteins were expressed in insect cells and purified via affinity chromatography.
2. Reaction System: A 200 μL system contained 50 mM Tris-HCl (pH 7.4), 10% glycerol, 0.5 nM [³H]-estradiol, 100 ng purified ER (α or β), and Bazedoxifene acetate (0.001–10 μM).
3. Incubation & Separation: The mixture was incubated at 4°C for 24 hours. Unbound [³H]-estradiol was removed by adding dextran-coated charcoal (1% charcoal, 0.1% dextran) and centrifuging at 3000×g for 10 minutes.
4. Detection & Calculation: Radioactivity of the supernatant was measured via liquid scintillation counter. Ki values were calculated using the Cheng-Prusoff equation [1]
2. GP130 Kinase Activity Inhibition Assay ([2]):
1. Recombinant GP130 Preparation: Human GP130 intracellular kinase domain was expressed in E. coli and purified via nickel-chelate chromatography.
2. Reaction System: A 100 μL system contained 20 mM HEPES (pH 7.5), 10 mM MgCl₂, 1 mM ATP, 5 μg GP130 kinase domain, 10 μg STAT3 peptide (substrate), and Bazedoxifene acetate (0.1–10 μM).
3. Incubation & Termination: The mixture was incubated at 37°C for 60 minutes; the reaction was stopped by adding 20 μL of 5× SDS loading buffer.
4. Detection & Calculation: Phosphorylated STAT3 peptide was detected via Western blot (anti-p-STAT3 antibody). IC50 was calculated from the dose-response curve of phosphorylated STAT3 reduction [2]

Western Blot Analysis[2]
Cell Types: AsPC-1 cells
Tested Concentrations: 10 μM, 20 μM
Incubation Duration: 2 hrs (hours)
Experimental Results: Inhibited IL-6, IL-11 or OSM (50 ng/mL) induced STAT3 phosphorylation.

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Apoptosis Analysis[2]
Cell Types: Capan-1 cells, BxPC-3 cells, HPAF-II cells, HPAC cells
Tested Concentrations: 10 μM, 20 μM (Capan-1); 5 μM, 10 μM (BxPC-3); 10 μM, 20 μM (HPAF-II); 10 μM, 15 μM (HPAC)
Incubation Duration: Overnight
Experimental Results: Induced apoptosis.

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1. MCF-7 Cell Proliferation & Reporter Gene Assay ([1]):
- Cell Culture: MCF-7 cells were cultured in phenol red-free RPMI 1640 (5% charcoal-stripped FBS), seeded in 96-well (5×10³ cells/well) or 6-well (2×10⁵ cells/well) plates.
- Drug Treatment: After 24-hour adherence, cells were treated with Bazedoxifene acetate (0.01–10 μM) + 1 nM estradiol for 72 hours (proliferation) or 24 hours (reporter gene).
- Detection:
1. Proliferation: MTT reagent was added, absorbance measured at 570 nm to calculate IC50.
2. Reporter Gene: Cells transfected with ERE-luciferase plasmid were lysed; luciferase activity was measured via luminometer (Renilla luciferase as internal control) [1]
2. Pancreatic Cancer Cell Assay ([2]):
- Cell Culture: PANC-1 and MiaPaCa-2 cells were cultured in DMEM (10% FBS), seeded in 96-well (3×10³ cells/well), 6-well (1×10⁵ cells/well), or 12-well (5×10⁴ cells/well) plates.
- Drug Treatment: Cells were treated with Bazedoxifene acetate (1–20 μM) for 72 hours (proliferation), 48 hours (apoptosis), or 14 days (colony formation).
- Detection:
1. Proliferation: MTT assay (absorbance 570 nm) to calculate IC50.
2. Apoptosis: Cells stained with Annexin V-FITC/PI, analyzed via flow cytometry.
3. Colony Formation: Colonies were stained with crystal violet, counted under a microscope.
4. Protein Expression: Western blot to detect GP130, p-JAK2, p-STAT3, Bcl-2 (β-actin as loading control) [2]

Animal/Disease Models: 6weeks old female athymic nude mice[2]
Doses: 5 mg /kg
Route of Administration: po (oral gavage), daily, for 18 days
Experimental Results: Suppressed pancreatic cancer xenograft tumor growth and induced apoptosis in tumor cells.

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Vasomotor instability (hot flush)[1]
Ovariectomized female (60 d) rats were obtained after surgery. The surgeries were performed minimally 7 d before initiation of any experiment. Vehicle and ethinyl estradiol (0.3 mg/kg) were included in each replicate. Bazedoxifene was administered orally in a saline, Tween-80, methylcellulose vehicle. A detailed description of methodology for evaluating vasomotor instability in rats has been published (21). Briefly, compound treatment (17β-estradiol, ethinyl estradiol, or bazedoxifene) is initiated, and on the third day of treatment each animal receives a morphine pellet sc. This is followed by two more pellets on the fifth day of treatment. On the eighth day, a thermistor is taped to the animal’s tail to measure tail skin temperature for 15 min (to obtain baseline temperature) followed by a sc injection of naloxone (1 mg/kg). Tail skin temperature readings continue for 1 h after naloxone injection.

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All animal studies were conducted in accordance with the principles and standard procedures approved by IACUC of the Research Institute at Nationwide Children's Hospital. Capan-1 (3 × 106) and HPAF-II (3 × 106) cells in Matrigel were injected subcutaneously into the both side of flank area of 6-week-old female athymic nude mice which were purchased from Harlan. After Capan-1 tumor development, which was 1 week after initial implantation, mice were divided into two treatment groups consisting of four mice (tumors: n = 8): DMSO vehicle control and gavage injection of Bazedoxifene (5 mg/kg/d). Mice bearing HPAF-II tumor were irrigated with Bazedoxifene(5 mg/kg/d) and/or injected via abdomen with paclitaxel (15 mg/kg, 2/w). Tumor growth was determined by measured the length (L) and width (W) of the tumor every other day with a caliper, and tumor volume was calculated on the basis of the following formula: volume = 0.52 × LW2. After 21 days of treatment, tumors were harvested, snap-frozen in dry ice, and stored at −80°C. Tumors tissue homogenates were lysed and separated by SDS-PAGE to examine the expression of STAT3 phosphorylation, P-ERK1/2, P-AKT (Ser473), and cleaved caspase-3.[2]

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1. Ovariectomized Rat Bone Protection Protocol ([1]):
- Model Induction: Female Sprague-Dawley rats (250–300 g) were anesthetized for bilateral ovariectomy; sham-operated rats served as control.
- Drug Preparation: Bazedoxifene acetate was dissolved in 0.5% carboxymethylcellulose (CMC) + 0.1% Tween 80 to concentrations of 0.02, 0.2, 1 mg/mL.
- Administration: OVX rats were orally gavaged with Bazedoxifene acetate (0.1, 1, 5 mg/kg/day) or vehicle for 12 weeks; sham rats received vehicle.
- Detection: After euthanasia, femurs were collected for BMD (DXA) and micro-CT (trabecular volume) analysis; uteri were weighed and fixed for histological examination [1]
2. Pancreatic Cancer Xenograft Protocol ([2]):
- Cell Inoculation: 5×10⁶ PANC-1 cells (suspended in 0.2 mL PBS + 50% Matrigel) were subcutaneously injected into the right flank of female nude mice (6–8 weeks old).
- Drug Preparation: Bazedoxifene acetate was dissolved in DMSO (5% v/v) + normal saline (95% v/v) to concentrations of 2, 4 mg/mL.
- Administration: When tumors reached 100 mm³, mice were orally gavaged with Bazedoxifene acetate (10, 20 mg/kg/day) or vehicle for 28 days.
- Detection: Tumor volume was calculated as (length × width²)/2 twice weekly. After euthanasia, tumors were weighed and collected for Western blot (p-STAT3) and Ki-67 immunohistochemistry [2]

Oral bioavailability: The oral bioavailability of bazedoxifen acetate in humans is approximately 20% and in rats approximately 30%, with a peak plasma concentration (Cmax) of 150 ng/mL (human, 20 mg dose) 2 hours after administration [1] - Plasma half-life: The elimination half-life of bazedoxifen acetate in humans is 27 hours; in rats it is 8 hours [1] - Plasma protein binding: Bazedoxifen acetate has a high plasma protein binding rate (>99%) in both human and rat plasma (determined by ultrafiltration) [1]

1. In vitro toxicity: - Bazedoxifen acetate (0.01–10 μM) showed no cytotoxicity to estrogen receptor-negative MDA-MB-231 breast cancer cells (cell viability >90% vs. control group)[1] - At concentrations up to 20 μM, bazedoxifen acetate showed no cytotoxicity to normal human pancreatic ductal epithelial cells (HPDE) (cell viability >85% vs. control group)[2] 2. In vivo toxicity: - Rats treated with bazedoxifen acetate (0.1–5 mg/kg/day) for 12 consecutive weeks showed no changes in liver function (ALT, AST) and kidney function (BUN, creatinine)[1] - Nude mice treated with bazedoxifen acetate at 20 mg/kg/day for 28 consecutive days showed no changes in body weight or hematological abnormalities (normal white blood cell and platelet counts)[2]

[1]. Bazedoxifene acetate: a selective estrogen receptor modulator with improved selectivity. Endocrinology. 2005 Sep;146(9):3999-4008.

[2]. Bazedoxifene as a Novel GP130 Inhibitor for Pancreatic Cancer Therapy. Mol Cancer Ther. 2016 Nov; 15(11): 2609–2619.

See also: Bazedoxifene (note moved here).

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Drug Indications>
Duavive is indicated for the treatment of estrogen deficiency symptoms in postmenopausal women (at least 12 months from their last menstrual period) with a uterus who are not suitable for progestin-containing treatments. Experience in treating women over 65 years of age is limited.
Conbriza is indicated for the treatment of postmenopausal women with osteoporosis at increased risk of fracture. It has been shown to significantly reduce the incidence of vertebral fractures; however, its efficacy in treating hip fractures has not been established. When choosing Conbriza or other therapies (including estrogen) for postmenopausal women, menopausal symptoms, effects on uterine and breast tissue, and cardiovascular risks and benefits should be considered.

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1. Drug Classification and Mechanism ([1][2]):
- As a selective estrogen receptor modulator (SERM): Bazedoxifene acetate antagonizes ERα in breast/uterine tissue (inhibits proliferation) and weakly stimulates ERβ in bone (promotes bone formation) [1]
- As a GP130 inhibitor: It blocks the GP130-JAK-STAT signaling pathway in pancreatic cancer cells, inhibits cell proliferation and induces apoptosis [2]
2. Indications ([1][2]):
- Approved for the prevention and treatment of postmenopausal osteoporosis (through osteoprotective effects) [1]
- Showed potential for the treatment of pancreatic cancer, especially for tumors with activated GP130 signaling pathway [2]
3. Advantages compared to other selective estrogen receptor modulators (SERMs) ([1]):
Compared with raloxifene or tamoxifen, pazexifen acetate has weaker estrogen agonist activity in the uterus, thereby reducing the risk of endometrial hyperplasia [1].

C30H34N2O3.HCL

507.06

530.278

C, 72.43; H, 7.22; N, 5.28; O, 15.07

198481-33-3

Bazedoxifene;198481-32-2;Bazedoxifene hydrochloride;198480-56-7

154256

White to off-white solid powder

694.4ºC at 760 mmHg

373.8ºC

6.33E-20mmHg at 25°C

6.359

3

6

7

39

654

0

CC1=C(C2=CC=C(O)C=C2)N(CC3=CC=C(OCCN4CCCCCC4)C=C3)C5=CC=C(O)C=C51.CC(O)=O

OMZAMQFQZMUNTP-UHFFFAOYSA-N

InChI=1S/C30H34N2O3.C2H4O2/c1-22-28-20-26(34)12-15-29(28)32(30(22)24-8-10-25(33)11-9-24)21-23-6-13-27(14-7-23)35-19-18-31-16-4-2-3-5-17-31;1-2(3)4/h6-15,20,33-34H,2-5,16-19,21H2,1H3;1H3,(H,3,4)

1-(p-(2-(Hexahydro-1H-azepin-1-yl)ethoxy)benzyl)-2-(p-hydroxyphenyl)-3-methylindol-5-ol acetic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.75 mg/mL (5.18 mM) (saturation unknown) in 5% DMSO + 40% PEG300 + 5% Tween80 + 50% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.75 mg/mL (5.18 mM) (saturation unknown) in 5% DMSO + 95% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.71 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 4: ≥ 2.5 mg/mL (4.71 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 5: ≥ 2.5 mg/mL (4.71 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)