Endoxifen HCl targets the estrogen receptor (ER). It acts as a selective estrogen receptor antagonist. It shows anti-estrogenic effects in breast cancer cells expressing ERα. It decreases E2-induced PR expression in MCF-7 cells. By blocking the estrogen receptor, it inhibits estrogen-driven breast cancer cell growth. It is the most important active metabolite of tamoxifen.

Endoxifen shows anti-estrogenic effects, and decreases the E2-induced PR expression in MCF-7 cells. Endoxifen also blocks ER-alpha transcriptional activity and inhibits estrogen-induced breast cancer cell proliferation. In MCF7, HS 578T, and BT-549 cells, Endoxifen significantly inhibits cell proliferation. Endoxifen also exhibits four-fold higher inhibition on PKC activity compared to tamoxifen. Endoxifen inhibits the hERG current by preferentially interacting with the activated states of cloned hERG potassium channels with IC50 of 1.6 μM
Cell Assay: MCF7 and Ishikawa cells are grown in 10% triple charcoal-stripped serum-containing medium for 3 d. The cells are then plated at a density of 2,000 cells per well in 96-well tissue culture plates and treated as indicated every 48 h. Cell proliferation assays are conducted 8 days after the first treatment using a CellTiter-Glo Luminescent Cell Viability kit according to the manufacturers protocol.

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In MCF-7 human breast cancer cells, Endoxifen (10^-9 to 10^-6 M) dose-dependently inhibited E2 (10^-10 M)-induced progesterone receptor (PR) mRNA expression, with near-complete suppression at 10^-7 M (100 nM), a concentration close to therapeutic plasma levels (8-75 nM). Endoxifen alone (in the absence of E2) did not alter PR mRNA expression. The anti-estrogenic potency of Endoxifen was similar to that of 4-hydroxy-tamoxifen, and combination of both metabolites at 10^-7 M each did not show additive or antagonistic effects. No significant interconversion between Endoxifen and 4-hydroxy-tamoxifen was detected in the culture medium after 24 h.[1]
In vitro, Endoxifen HCl shows anti-estrogenic effects and decreases E2-induced PR expression in MCF-7 cells. It inhibits hERG in a concentration-dependent manner with an IC50 of 1.6 μM. It is a potent and selective estrogen receptor antagonist. These in vitro studies confirm its mechanism as an estrogen receptor antagonist and its anti-proliferative effects on breast cancer cells. It is a valuable tool for studying estrogen receptor signaling in breast cancer.

In vivo, Endoxifen (8 mg/kg, ) inhibits growth of MCF-7 human mammary tumor xenografts in mice, showing more potency than Tamoxifen.
In vivo, Endoxifen HCl is the active metabolite of tamoxifen, contributing to its therapeutic effects in breast cancer. It has reached Phase 2 clinical trials. Its efficacy in inhibiting breast cancer growth has been demonstrated in clinical studies. As a SERM, it has both estrogenic and anti-estrogenic effects depending on the tissue. It is a research compound and a drug metabolite.

Non-cellular receptor binding assays for Endoxifen HCl typically involve measuring its affinity for the estrogen receptor. These assays use purified receptor or cytosolic preparations and measure the displacement of a labeled ligand. Its binding affinity and potency as an estrogen receptor antagonist can be characterized. These experiments are essential for characterizing its receptor binding properties.

MCF-7 cells (estrogen receptor-positive human breast carcinoma cell line) were maintained at 37°C in 5% CO2 humidified atmosphere in improved minimum essential medium (IMEM) supplemented with 10% fetal bovine serum. Prior to experiments, cells were preconditioned in charcoal-stripped calf serum for 3 days to remove estrogens. Cells were treated with vehicle (0.1% ethanol), various doses of E2 (10^-13 to 10^-7 M), Endoxifen (10^-10 to 10^-6 M), 4-OH-Tam, or combinations for 24 h in IMEM with 10% charcoal-stripped calf serum. Total RNA was extracted from approximately 2.5×10^5 cells using an RNeasy Mini Kit, followed by DNase treatment. RNA concentration was measured by A260 and quality assessed by Agilent 2100 Bioanalyzer. cDNA was synthesized from DNase-treated total RNA using reverse transcription system. Real-time quantitative PCR (TaqMan) was performed using cDNA equivalent to 50 ng total RNA in an iCycler real-time PCR machine. PR and GAPDH were multiplexed. Primer and probe sequences for PR: forward 5'-GAG CAC TGG ATG CTG TTG CT-3', reverse 5'-GGC TTA GGG CTT GGC TTT C-3', probe 5'-FAM-TCC CAC AGC CAT TGG GCG TTC-BHQ1-3'. GAPDH: forward 5'-GAA GGT GAA GGT CGG AGT C-3', reverse 5'-GAA GAT GGT GAT GGG ATT TC-3', probe 5'-TxRed-CAA GCT TCC CGT TCT CAG CC-BHQ2-3'. Thermal cycling: 50°C for 2 min, 95°C for 2 min, then 42 cycles of 95°C for 15 s and 60°C for 1 min. Quantitative values from threshold cycle (Ct). Standard curve of PR single-stranded DNA showed good linear correlation. For measurement of metabolite interconversion, culture media were collected and concentrations of Endoxifen and 4-OH-Tam (Z- and E-isomers) were determined by HPLC with on-line derivatization and column switching. MCF-7 cells were treated with Endoxifen (10^-7 M), 4-OH-Tam (10^-7 M), or combination for 24 h in presence of E2 (10^-10 M), then media were analyzed.[1]
In vitro cell-based assays for Endoxifen HCl are conducted using breast cancer cell lines, such as MCF-7 cells, to assess its anti-estrogenic effects. Cells are treated with the compound, and its effects on cell proliferation and estrogen-responsive gene expression (e.g., PR) are measured. Its effects on hERG channel activity can also be assessed. These experiments are crucial for confirming its mechanism of action.

Dissolved in water; 8 mg/kg; Oral gavage Mice bearing MCF-7 human mammary tumor xenografts

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In vivo animal studies for Endoxifen HCl are typically conducted in mouse xenograft models of breast cancer to evaluate its antitumor efficacy. Tumor-bearing mice are treated with the compound, and tumor growth is monitored. However, specific detailed protocols are not extensively documented in standard summaries. Its efficacy in preclinical models supports its potential as a therapeutic agent.

In breast cancer patients receiving chronic tamoxifen (20 mg/day), average plasma concentration of Endoxifen is more than six-fold higher than that of 4-hydroxy-tamoxifen. Endoxifen plasma concentrations are highly variable and dependent on CYP2D6 genotype, with extensive metabolizers having up to 14-fold higher Endoxifen levels than 4-OH-Tam. The therapeutic plasma concentration range of Endoxifen in patients is approximately 8-75 nM. Endoxifen is formed from N-desmethyl-tamoxifen by CYP2D6, and its production is affected by CYP2D6 inhibitors and genetic polymorphisms.[1]
Endoxifen HCl has a molecular weight of 409.95 g/mol and a molecular formula of C25H28ClNO2. It is the active metabolite of tamoxifen. As a research compound, its pharmacokinetic properties have been studied in clinical trials. It is typically administered orally. Its half-life and other pharmacokinetic parameters are available from clinical studies. It is a research compound that has reached Phase 2 clinical trials.

The safety profile of Endoxifen HCl has been evaluated in clinical trials. Common side effects may include those similar to tamoxifen, such as hot flashes, nausea, and fatigue. It can also cause hERG-related cardiac effects. Comprehensive toxicological data are available from its clinical development program. Endoxifen HCl is not an approved drug and is available as a research compound.

Cancer Chemother Pharmacol.2005 May;55(5):471-8;Breast Cancer Res Treat.2010Jul;122(2):579-84.

Endoxifen hydrochloride is the hydrochloride salt of endocifine and its cis (z-) stereoisomer, possessing potential antitumor activity. Endocifine is the active metabolite of tamoxifen, competitively inhibiting the binding of estradiol to estrogen receptors, thereby preventing the receptors from binding to estrogen-responsive elements on DNA and reducing DNA synthesis. However, unlike tamoxifen, which relies on CYP2D6 enzyme activity to convert to its active metabolite endocifine, directly administered endocifine bypasses the CYP2D6 pathway. Due to the significant inter-individual variability in CYP2D6 gene activity caused by CYP2D6 gene polymorphism, theoretically, endocifine is more potent and has more uniform bioavailability across different patient populations.

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Endoxifen is an active metabolite of tamoxifen with anti-estrogenic properties. It is equipotent to 4-hydroxy-tamoxifen in suppressing E2-induced PR gene expression in breast cancer cells. Due to its higher plasma concentrations and comparable potency, Endoxifen is suggested to be more important than 4-hydroxy-tamoxifen for the anti-estrogenic action of tamoxifen in vivo. PR levels are routinely measured in breast cancer patients to guide tamoxifen therapy, and further clinical studies are needed to test the effects of CYP2D6 genetic variants on tamoxifen effectiveness related to Endoxifen concentrations.[1]
Endoxifen HCl is the active metabolite of tamoxifen and a potent and selective estrogen receptor antagonist. It shows anti-estrogenic effects and decreases E2-induced PR expression in MCF-7 cells. It has reached Phase 2 clinical trials for breast cancer. Endoxifen HCl is not an approved drug and is available as a research compound.

C25H28CLNO2

409.95

409.18

1032008-74-4

Endoxifen (Z-isomer);112093-28-4;Endoxifen hydrochloride;1197194-41-4;Endoxifen (E-isomer);114828-90-9;Endoxifen;110025-28-0;Endoxifen E-isomer hydrochloride;1197194-61-8

54613017

White to off-white solid powder

6.552

3

3

8

29

467

0

CC/C(=C(\C1=CC=C(C=C1)O)/C2=CC=C(C=C2)OCCNC)/C3=CC=CC=C3.Cl

RPFIMPDXTABYCN-BJFQDICYSA-

InChI=1S/C25H27NO2.ClH/c1-3-24(19-7-5-4-6-8-19)25(20-9-13-22(27)14-10-20)21-11-15-23(16-12-21)28-18-17-26-2;/h4-16,26-27H,3,17-18H2,1-2H3;1H/b25-24-

(Z)-4-(1-(4-(2-(methylamino)ethoxy)phenyl)-2-phenylbut-1-en-1-yl)phenol hydrochloride

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, avoid exposure to moisture.

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: 2.5 mg/mL (6.10 mM) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication.
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 2: 2.5 mg/mL (6.10 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
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 3: ≥ 1.25 mg/mL (3.05 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 12.5 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.)