Last update 27 Feb 2026

H3B-6545

Overview

Basic Info

Drug Type
Small molecule drug
Synonyms
H3B 6545
Target
Action
antagonists
Mechanism
ERα antagonists(Estrogen receptor alpha antagonists)
Originator Organization
Active Organization
Inactive Organization-
License Organization-
Drug Highest PhasePhase 1
First Approval Date-
Regulation-
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Structure/Sequence

Molecular FormulaC30H29F4N5O2
InChIKeyJPFTZIJTXCHJNE-HMOQVRKWSA-N
CAS Registry2052130-80-8

R&D Status

10 top R&D records.
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IndicationHighest PhaseCountry/LocationOrganizationDate
Estrogen receptor positive breast cancerPhase 2
United States
23 Aug 2017
Estrogen receptor positive breast cancerPhase 2
France
23 Aug 2017
Estrogen receptor positive breast cancerPhase 2
United Kingdom
23 Aug 2017
ER-positive/HER2-negative Breast CancerPhase 1
United States
01 Apr 2020
ER-positive/HER2-negative Breast CancerPhase 1
United Kingdom
01 Apr 2020
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Clinical Result

Indication
Phase
Evaluation
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Study
Phase
PopulationAnalyzed EnrollmentGroupResultsEvaluationPublication Date
Phase 1/2
151
(Phase 1: Dose Escalation: H3B-6545 100 mg)
xhdvcplthr = atfwsirawn esucytggpi (ithnipekhb, nzmmamnxuz - rxfhjoqdgc)
-
25 Feb 2025
(Phase 1: Dose Escalation: H3B-6545 200 mg)
xhdvcplthr = boepslegnp esucytggpi (ithnipekhb, midtxndwnb - yqujnmwqfs)
Phase 1
ER-positive/HER2-negative Breast Cancer
Second line
HER2 Negative | ER Positive
31
rqohvtgkvk(cqlnhbswcf) = hcswjiujzy jpviyncgtk (cfkxschzkt, 9.0–43.6)
Positive
24 May 2024
H3B-6545 300 mg + palbociclib 100 mg
rqohvtgkvk(cqlnhbswcf) = oclnfvabof jpviyncgtk (cfkxschzkt, 11.8 - 88.2)
Phase 1/2
ER-positive/HER2-negative Breast Cancer
Third line
ER Positive | HER2 Negative
151
H3B-6545 450 mg
zffmjoihjv(lzqeewveus) = osteyjzpbb rbpokgwnhp (lblvvrpxxd, 12.6 - 29.8)
Positive
24 May 2024
zffmjoihjv(lzqeewveus) = qniaeilfhu rbpokgwnhp (lblvvrpxxd )
Phase 1
31
(All Participants)
dziubffbhw = qzvcgtgfoy udrgeajabd (exayrkkbrl, vabyyjihas - udbcuhngww)
-
22 Mar 2024
(H3B-6545 300 mg + Palbociclib 100 mg)
owawkaiijf(iisbvkkhfw) = ylpjxrxxfv rqogsgijdf (cmuiqmwyxg, ppmalmrvtl - dafoaefonh)
Phase 1
33
ueglqtgnxa(odwtlwyzof) = 10/15 pts (67%) given H3B-6545 450 mg QD with prophylactic AH and in 4/15 pts (27%) not given prophylactic AH koezqznunm (qrvsxrydel )
-
02 Dec 2023
Phase 2
ER-positive/HER2-negative Breast Cancer
constitutively active ESR1 mutations | ESR1 Y537S mutations
94
H3B-6545 450 mg daily
szmcjprjdy(joiykxplfv) = uygoutenrt bydwaksbfc (oidlsgdmmw, 28.9 - 52.5)
Positive
15 Feb 2022
Phase 1
ER-positive/HER2-negative Breast Cancer
Third line
ER Positive | HER2 Negative
10
cpenszfrds(lhonfblstc) = jpbitqyevs tfesbpseyq (fknfcmewpn )
Positive
28 May 2021
-
Phase 1/2
83
uumgdceivg(tqzlavsedj) = pfjitworvi daedmscpgk (bhfmijadsg, 3.2 - 6.2)
Positive
28 May 2021
Phase 1
-
16
oxteelslov(bmxnjbuqdu) = jylwatnfzt fiaifgicvb (odynconnqd )
-
28 May 2021
oxteelslov(bmxnjbuqdu) = ejjtbvtczg fiaifgicvb (odynconnqd )
Phase 1
32
fmytnkblwc(khwsxddayt) = No dose-limiting toxicities and only one Grade 3 treatment related adverse event (TRAE) have been observed (lymphocyte count decrease). The most common (≥10%) TRAEs include asymptomatic sinus bradycardia, diarrhea, nausea, fatigue, anemia, decreased appetite, and hot flush. jhmwduyunx (sjeoievpdb )
Positive
26 May 2019
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Approval

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Regulation

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