1. Others
  2. Estrogen Receptor/ERR


Cat. No.: HY-112596
Handling Instructions

H3B-6545 is an oral, selective estrogen receptor covalent antagonist (SERCA).

For research use only. We do not sell to patients.

H3B-6545 Chemical Structure

H3B-6545 Chemical Structure

CAS No. : 2052130-80-8

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Other Forms of H3B-6545:

  • Biological Activity

  • Technical Information

  • Purity & Documentation

  • References


H3B-6545 is an oral, selective estrogen receptor covalent antagonist (SERCA).

IC50 & Target

Estrogen receptor[1]

In Vitro

H3B-6545 is a highly selective small molecule that potently antagonizes wild-type and mutant ERα in biochemical and cell based assays. In vitro comparisons with standard of care and other experimental agents confirm increased cell potency of H3B-6545 under continuous as well as washout treatment conditions[1]. H3B-6545, a member of a novel class of ERα antagonists refer to as selective ER covalent antagonist (SERCA), which inactivates both wild-type and mutant ERα by targeting C530 and enforcing a unique antagonist conformation. H3B-6545 is a first-in-class selective ER covalent antagonist (SERCA). H3B-6545 inhibits ERαWT activity and growth of ERαWT -positive breast cancer lines. H3B-6545 potently inhibits ERαWT activity and suppresses proliferation of ERαWT -positive breast cancer lines. With GI50s of 0.3-0.4, 1.0, 0.5, 5.2, and 0.2 nM for MCF7, HCC1428, BT483, T47D and CAMA-1 cell lines[1].

In Vivo

In vivo, once daily oral dosing of H3B-6545 shows potent activity and superior efficacy to fulvestrant in the MCF-7 xenograft model with maximal antitumor activity at doses >10x below the maximum tolerated dose in mice. In addition, H3B-6545 shows superior antitumor activity to Tamoxifen and Fulvestrant in patient derived xenograft models of estrogen receptor positive breast cancer including models carrying ERα mutations in rat and monkeys, H3B-6545 is well tolerated across a broad dose range and at exposures that significantly exceed those required for efficacy in mouse xenograft models[1].

Clinical Trial
Solvent & Solubility
In Vitro: 

10 mM in DMSO

Stock Solutions
Concentration Solvent Mass 1 mg 5 mg 10 mg
1 mM 1.7619 mL 8.8093 mL 17.6187 mL
5 mM 0.3524 mL 1.7619 mL 3.5237 mL
10 mM 0.1762 mL 0.8809 mL 1.7619 mL
*Please refer to the solubility information to select the appropriate solvent.
Molecular Weight









Please store the product under the recommended conditions in the Certificate of Analysis.


Room temperature in continental US; may vary elsewhere

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Cat. No.: HY-112596