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Drug

Letrozole

Established medicine
ClassCytochrome P450 19A1 inhibitorResearchActive indication expansion

Also known as Femara, Letrozol.

10
Research papers
46
Active clinical trials
Aromatase
Primary target
3
Regulatory events
Latest activity
beta

Recent clinical, regulatory, research and industry developments relating to this drug.

Elacestrant for Treating ER+/HER2- Breast Cancer Patients With ctDNA Relapse

Clinical trial2026-10-07Results expected Q4 2032 · ClinicalTrials.gov

Clinical considerations of the role of palbociclib in the management of advanced breast cancer patients with and without visceral metastases.

Research2018-03-01Annals of oncology : official journal of the European Society for Medical Oncology

Profile

Identifiers & mechanism

Canonical identifiers, marketed brand names and mechanism, resolved across RxNorm, ChEMBL and ATC.

Canonical name
Letrozole
Aliases & brands
FemaraLetrozol
RxNorm CUI
72965
ChEMBL ID
CHEMBL1444
ATC codes
L02BG04
UNII
7LKK855W8I
Primary mechanism
Cytochrome P450 19A1 inhibitor
Regulatory jurisdictions
fda

Pharmacology & targets

1 target

Known molecular targets and mechanisms supported by curated pharmacology databases.

Aromatase
CYP19A1 · P11511
INHIBITORCytochrome P450 19A1 inhibitor

Regulatory timeline

3 events

The complete regulatory record, grouped by authority — approvals, safety advisories and label changes. Each authority shows its most recent events; expand one to read its full history.

Earliest approval on record (generic/biosimilar)
2011-07-13
Latest approval
2026-09-14
Authorities
FDA
Total events
3
fdaU.S. Food and Drug Administration· 3 events
2026-09-15Label change
Label change: LETROZOLE (ANDA090292)
Evidence ↗
2026-09-14Generic approvalMarket
Generic approval: LETROZOLE (ANDA220438)
Evidence ↗
2011-07-13Generic approvalMarket
Generic approval: LETROZOLE (ANDA090292)
Evidence ↗

Data from the U.S. Food and Drug Administration (U.S. Food and Drug Administration), public domain (CC0).

Clinical trials

195 trials

The current development programme across all trial phases — status mix, phase distribution and the late-stage studies shaping the evidence base.

Development programme
CLINICALTRIALS.GOV · LIVE REGISTRY
195
registered trials across all phases
LATEST COMPLETION 2026
46
Active studies
32
Recruiting
88
Late-stage (III+)
88
Completed
61
Discontinued
PHASE DISTRIBUTIONn = 195
Early Phase 19Phase 116Phase 1 / 27Phase 275Phase 2 / 312Phase 336Phase 416Phase N / A24

Late-stage studies

Phase III+ trials still open or recently active — where late-stage evidence is being generated.

Recent completions

Trials that read out recently, adding to the completed evidence base.

Research activity

10 papers

Key research shaping understanding of this drug, combining the latest publications with the most influential evidence.

Publications over time
2007–2024
Most influential

Palbociclib and Letrozole in Advanced Breast Cancer.

The New England journal of medicine · 2016 · 2,179 cites

Ribociclib as First-Line Therapy for HR-Positive, Advanced Breast Cancer.

The New England journal of medicine · 2016 · 1,477 cites

Extending Aromatase-Inhibitor Adjuvant Therapy to 10 Years.

The New England journal of medicine · 2016 · 466 cites

Letrozole versus clomiphene for infertility in the polycystic ovary syndrome.

The New England journal of medicine · 2014 · 371 cites

Abemaciclib plus a nonsteroidal aromatase inhibitor as initial therapy for HR+, HER2- advanced breast cancer: final overall survival results of MONARCH 3.

Annals of oncology : official journal of the European Society for Medical Oncology · 2024 · 161 cites

Clinical considerations of the role of palbociclib in the management of advanced breast cancer patients with and without visceral metastases.

Annals of oncology : official journal of the European Society for Medical Oncology · 2018 · 73 cites
Recent papers
Major research themes8
Aromatase Inhibitors2Breast Neoplasms2Letrozole2Aminopyridines1Antineoplastic Combined Chemotherapy Protocols1Benzimidazoles1Neuronal Plasticity1Ovariectomy1
Journals, researchers & institutions
Top journals
  • The New England journal of medicine4
  • Annals of oncology : official journal of the European Society for Medical Oncology2
  • Annals of the American Thoracic Society1
  • Breast cancer research and treatment1
  • eNeuro1
  • Journal for immunotherapy of cancer1
Leading researchers
  • Campone M2
  • Diéras V2
  • Finn RS2
  • Gelmon K2
  • Im SA2
  • Iwata H2
  • Lu DR2
  • Martin M2
Leading institutions
free-text, unnormalised
  • Mayo Clinic2
  • 3 Swedish Medical Center1
  • 9 Stanford University1
  • Abramson Cancer Center1
  • Advanced Cancer Translational Research Institute1
  • Aichi Cancer Center1

Related diseases

1 conditions

Regulator-approved indications and conditions co-mentioned with this drug across the research literature. Number shows shared papers.

Active research areas

Related drugs

6 matches

Drugs sharing diseases, protein targets and literature with this one. Ranked by graph evidence (shared targets + diseases weighted above co-mentions).

Acts on the same molecular target as Letrozole, with an overlapping disease area.

Shared target1 shared disease1 shared paper

Studied across 2 of the same disease areas as Letrozole in the shared literature.

2 shared diseases1 shared paper

Studied across the same disease area as Letrozole in the shared literature.

1 shared disease2 shared papers

Studied across the same disease area as Letrozole in the shared literature.

1 shared disease2 shared papers

Studied across the same disease area as Letrozole in the shared literature.

1 shared disease1 shared paper

Studied across the same disease area as Letrozole in the shared literature.

1 shared disease1 shared paper
References & data sources
  • RxNorm (U.S. National Library of Medicine) — drug identity
  • ChEMBL (EMBL-EBI) & UniProt — pharmacology and targets
  • Europe PMC — research literature
  • ClinicalTrials.gov — clinical trials
  • Regulatory event sources are credited in the Regulatory Timeline above.