Last update 30 Jul 2026

Palazestrant

Overview

Basic Info

Drug Type
Small molecule drug
Synonyms
OP-1250
Target
Action
degraders
Mechanism
ERs degraders(Estrogen receptors degraders)
Originator Organization
Active Organization
Inactive Organization-
Drug Highest PhasePhase 3
First Approval Date-
RegulationFast Track (United States)
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Structure/Sequence

Molecular FormulaC28H36FN3O
InChIKeyLBSFUBLFDCAEKV-XHCCPWGMSA-N
CAS Registry2092925-89-6

R&D Status

10 top R&D records.
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IndicationHighest PhaseCountry/LocationOrganizationDate
Estrogen receptor positive breast cancerPhase 3
United States
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Australia
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Austria
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Belgium
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Canada
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Czechia
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
France
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Germany
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Greece
03 Nov 2025
Estrogen receptor positive breast cancerPhase 3
Hong Kong
03 Nov 2025
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Clinical Result

Indication
Phase
Evaluation
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Study
Phase
PopulationAnalyzed EnrollmentGroupResultsEvaluationPublication Date
Phase 3
1,000
woopsmxack(kuzqnykelx) = meqtfmaaeb dvgvvxqoxc (cmedjjzsih, 0.59 - NR)
Positive
29 May 2026
flrdqmcndf(jacegmqwyw) = ulhaidwqnx mkftuuwcwi (byrvlgyepu, 10.1 - NR)
Phase 3
ER+ | HER2-
368
hxfcethwft(alovscutlj) = rugbxukowr usexsyjgtv (tuxlkcmkbl )
Positive
29 Dec 2025
cwmcnvwvjw(neyfqgovzn) = lrdyvfsycx gzhoinvgpn (whlpnfcquc, 1 - 9)
Phase 1/2
72
hkyyawuklx(djnjhazgju) = 35% foframhall (wqnalqvlet )
Positive
17 Oct 2025
(prior CDK4/6i)
Phase 1/2
146
gnzlwduaje(ymuaoovvoe) = 25.6% gkelgmhbyn (vrrobysxer )
Positive
01 Jul 2025
Phase 1/2
63
grmqwbsxme(ruqlkpfrbt) = gvshlsstan cqzmeomfwz (sxlfihmocr )
Positive
10 Dec 2024
(prior treatment with a CDK4/6i plus an endocrine therapy)
grmqwbsxme(ruqlkpfrbt) = jgichioejs cqzmeomfwz (sxlfihmocr )
Phase 1/2
ER-positive/HER2-negative Breast Cancer
First line
HER2 Negative | ER Positive
33
vqhribkymm(gtnkygeolr) = The most common (≥25%) were nausea, neutropenia (G4: 2 pts; 6%), WBC count decreased, fatigue, anemia, and diarrhea. Most TEAEs were grade 1-2 and consistent with the known safety profiles of each drug. qejuorbcru (orzlurpaeh )
Positive
16 May 2024
Phase 1/2
ER-positive/HER2-negative Breast Cancer
HER2 Negative | ER Positive
19
Ribociclib 600 mg+Palazestrant 120 mg
fqvddjgxfx(curlddgesk) = well tolerated, with no safety signals or enhancement of toxicity and an overall safety profile remains consistent with the expected safety profile of ribociclib plus an endocrine therapy. qjibcpaadp (zfackbxfyw )
Positive
05 Dec 2023
Phase 1/2
ER-positive/HER2-negative Breast Cancer
ESR1 Mutation | ER Positive | HER2 Negative
46
uqkuveitkk(ccrmpdostm) = There was no observed drug-drug interaction between palazestrant and palbociclib, and there was no induced metabolism or increase in exposure of either palbociclib or palazestrant when administered in combination. giyrdncgca (nvduhwcbmz )
Positive
05 Dec 2023
(ESR1 mutation)
Phase 1/2
ER-positive/HER2-negative Breast Cancer
ER Positive | HER2 Negative
86
OP-1250 120 mg
altvwwrzxa(mgtxzfmuqm) = nausea, vomiting, neutropenia, fatigue, headache, constipation, and diarrhea zwvzqkdaym (okbzrsftnf )
Positive
22 Oct 2023
OP-1250 120 mg
(ESR1 mutation)
Phase 1
ER-positive/HER2-negative Breast Cancer
ER positive | HER2 negative
37
(60mg)
cpepjvhzbc(jlwekxqqkm) = The most common treatment emergent adverse events reported (≥10%) in Phase 1b in the 60 mg/120 mg cohorts were nausea (28%/21%), vomiting (17%/16%), fatigue (17%/5%) and headache (11%/ 11%). rfryheeelj (pxnopchtwr )
Positive
28 Oct 2022
(120mg)
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