> Trialight public data. Index of pages: https://trialight.com/llms.txt
> Web page: https://trialight.com/data/asset/palazestrant-0fc00556-5838-4030-9ac2-6dbc12179acb
> Record changed: 2026-10-13

# Palazestrant

Highest phase reached

Phase 3

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

Drug type

Small molecule

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

## Development status

**Listing at source**

Listed

**Highest phase reached**

Phase 3

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

## Names and chemistry

**Drug type**

Small molecule

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

**Drug name**

Palazestrant

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

**Molecular weight**

449.61

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

**Structure (SMILES)**

CCCN1CC(Oc2ccc(\[C@@H\]3c4\[nH\]c5ccccc5c4C\[C@@H\](C)N3CC(C)(C)F)cc2)C1

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

### Other names (11)

- op 1250
- Op-1250
- OP-1250
- palazestrant
- Palazestrant
- palazestrant \[INN\]
- PALAZESTRANT \[USAN\]
- Palazestrant \[WHO-DD\]
- palazestrant inn
- palazestrant usan
- palazestrant who dd

## Identifiers

**CAS registry numbers**

- 2092925-89-6

**ChEMBL ID**

CHEMBL5314475

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

**InChIKey**

LBSFUBLFDCAEKV-XHCCPWGMSA-N

Source: [www.ebi.ac.uk](https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL5314475)

**PubChem compound IDs**

- 135351887

**FDA ingredient codes (UNII)**

- VU35KM56Q4

## Regulatory information

### Other regulatory facts

**First in class**

No

**Orphan designation**

No

## Pharmacology

### Drug classification

**Drug name stem**

\-estr-; -estrant

### Investigated indications (3)

- **Condition**  
Breast Neoplasms

**Highest recorded phase**  
1

**Condition identifier**  
EFO:0000305

**Subject identifier**  
D001943
- **Condition**  
Neoplasms

**Highest recorded phase**  
2

**Condition identifier**  
EFO:0000616

**Subject identifier**  
D009369
- **Condition**  
Breast Neoplasms

**Highest recorded phase**  
1

**Condition identifier**  
MONDO:0007254

**Subject identifier**  
D001943

### Open Targets indications (7)

- **Condition identifier**  
EFO\_0000616
- **Condition identifier**  
MONDO\_0004992

**Highest recorded phase**  
3
- **Condition identifier**  
MONDO\_0005070
- **Condition identifier**  
MONDO\_0005233

**Highest recorded phase**  
1
- **Condition identifier**  
MONDO\_0007254
- **Condition identifier**  
MONDO\_0007254

**Highest recorded phase**  
3
- **Condition identifier**  
MONDO\_0008315

**Highest recorded phase**  
1

### Trial references (3)

- NCT04505826  
Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT04505826)
- NCT05266105  
Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05266105)
- NCT05508906  
Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05508906)

## Chemical properties

**Hydrogen bond acceptors**

3

**Hydrogen bond donors**

1

**Polar surface area**

31.5

**Calculated partition coefficient (ALogP)**

5.73

**Calculated partition coefficient (XLogP)**

5.8

**Prodrug**

No

**Chirality**

Single enantiomer

**Inorganic**

No

**Rule-of-five violations**

1

**Rotatable bonds**

7

**Heavy atoms**

33

**Molecular formula**

C28H36FN3O

**Monoisotopic mass**

449.28424094

**Natural product**

No

## Evidence counts

**Recorded assays**

2

**Active assays**

2

### Active assay types

- Confirmatory

## Related records

### Trials (6)

- A Dose Escalation/Expansion Study of Oral OP-1250 in Subjects With Advanced and/or Metastatic HR+, HER2- Breast Cancer
- A Phase 1 Study of Oral OP-1250 in Combination With Palbociclib in HR+/HER2- Breast Cancer Patients
- OP-1250 (Palazestrant) vs. Standard of Care for the Treatment of ER+/HER2- Advanced Breast Cancer
- Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast Cancer
- [Phase 1 Study of OP-3136 in Advanced or Metastatic Solid Tumors](https://trialight.com/data/trial/phase-1-study-of-op-3136-in-advanced-or-metastatic-solid-218c8821-0b8f-4181-bc96-716a49f472d7.md)
- [Phase 1b Study of OP-1250 (Palazestrant) in Combination With Ribociclib, Alpelisib, Everolimus, or Atirmociclib in ER+, HER2- Breast Cancer](https://trialight.com/data/trial/phase-1b-study-of-op-1250-palazestrant-in-combination-with-746c22ad-90a4-44fb-89ce-ea1783413128.md)

### In development for (3)

- [Breast cancer](https://trialight.com/data/condition/breast-cancer-8ac10da3-93bd-54c5-a93b-265bc6699689.md) Phase 1
- Breast carcinoma Phase 1
- Neoplasm Phase 2

---

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