Letrozole clinical trials
Letrozole is named as an intervention in 106 current clinical trials in our China, USA, Spain, France, South Korea, Italy, Germany, Australia, Canada, Mexico, UK, Israel, Brazil, Taiwan, Japan, Belgium, Turkey, Portugal, Poland, Netherlands, Singapore, Austria, Czechia, Ireland, Switzerland, India, Egypt, Denmark, Sweden and Norway registers. 52 are recruiting patients now. The most common phase is Phase 3. The sponsor with the most trials is Eli Lilly and Company (7). The most-studied condition is Breast Cancer. The EU clinical trials register (CTIS) separately lists 7 authorised or ongoing trials.
Where Letrozole is approved
All regulators →Of the three regulators tracked here, the first to approve Letrozole was Canada, on 21 May 1997. It is approved in 2 of the 3 regulators tracked here.
From the regulators' own registers: FDA Drugs@FDA, the EMA medicines list and Health Canada's Notice of Compliance database. Dates are the first listed approval of a product containing only this substance; combination products and nationally authorised EU medicines are not counted.
What health systems spend on Letrozole
All medicines →From NHSBSA Prescription Cost Analysis (Open Government Licence v3.0) and CMS State Drug Utilization Data. Both are gross amounts: neither system publishes its discounts or rebates per drug. Products combining several substances are not counted here.
How Letrozole works
All drug targets →- Cytochrome P450 19A1 inhibitor InhibitorTarget: CYP19A1 cytochrome P450 family 19 subfamily A member 1✓ In ChEMBL and the Guide to Pharmacology
- AzoospermiaPhase 3
- InfertilityPhase 3
- AnovulationPhase 3
- Breast adenocarcinomaPhase 3
- Estrogen-receptor negative breast cancerPhase 3
- Estrogen-receptor positive breast cancerPhase 3
- Fallopian tube cancerPhase 3
- Gender identity disorderPhase 3
- HypogonadismPhase 3
- Hypogonadotropic hypogonadismPhase 3
Mechanisms and diseases from ChEMBL via the Open Targets Platform (release 26.09), ChEMBL record CHEMBL1444, CC BY-SA 3.0. Targets checked against the IUPHAR/BPS Guide to PHARMACOLOGY (2026.3.1), ligand 5209, CC BY-SA 4.0. Trial phases are not approvals: approved uses are shown from the regulators' own records where we hold them.
NICE appraisals of Letrozole
All NICE appraisals →NICE, which decides whether the NHS in England should fund new medicines, has published 1 technology appraisal of Letrozole. 1 is current, and 1 of it recommends it for at least some patients.
| Appraisal | NICE recommendation | Published | Status |
|---|---|---|---|
| Hormonal therapies for the adjuvant treatment of early oestrogen-receptor-positive breast cancer NICE TA112 | Recommended | 22 Nov 2006 | Current |
NICE decisions apply to the NHS in England. In Ireland the HSE decides on reimbursement, advised by the National Centre for Pharmacoeconomics. Titles, categories and dates link to the guidance on nice.org.uk. © NICE 2026 technology appraisal guidance. Available from www.nice.org.uk/guidance. All rights reserved. Subject to Notice of rights. NICE guidance is prepared for the National Health Service in England. All NICE guidance is subject to regular review and may be updated or withdrawn. NICE accepts no responsibility for the use of its content in this product/publication.
Patient leaflets for Letrozole
The package leaflet is the official guide for patients that comes with every medicine. These links go to the regulators that publish it.
- IEIreland: 10 products on the HPRA listEach product record links to the HPRA, which publishes the leaflet and SmPC.
- UKUnited Kingdom: Search MHRA ProductsPatient information leaflets and SmPCs for UK-licensed products.
- USUnited States: Search DailyMedFDA-approved labels, including patient and medication guides.
Leaflets differ between brands and countries; always read the one that comes with your own medicine. This is regulatory information, not medical advice.
Reference identifiers for Letrozole
- ATC code
- L02BG04
- ChEMBL
- CHEMBL1444
- DrugBank
- DB01006
- PubChem CID
- 3902
- CAS number
- 112809-51-5
- FDA UNII
- 7LKK855W8I
- Wikidata
- Q194974
- Wikipedia
- Letrozole
Codes that identify this medicine in other databases, from Wikidata (CC0), matched by its ChEMBL ID. The ATC code is the WHO classification of what the medicine is used for.
Trials by status
Trials by phase
Clinical trials of Letrozole
106 trialsRegisters list studies that are recruiting, about to open, active but closed to enrolment, or enrolling by invitation. The UK and USA registers cover industry-sponsored studies only. Trial titles and statuses are copied from the registry as published.
Letrozole in the EU trials register (CTIS)
7 trialsAuthorised or ongoing trials in the EU Clinical Trials Information System that list a product containing Letrozole. Many trials are registered in both CTIS and ClinicalTrials.gov, so these are shown separately rather than added to the count above. Trials with a site in Ireland are listed first.
Letrozole across our data
Ireland · EU · USThe same active substance in our other registers, matched by its exact name. Each entry links to the register record it comes from.
Licensed in Ireland (HPRA)
10 single-substance products containing Letrozole on the HPRA medicines list.
- Letrozole 2.5 mg film-coated tabletsClonmel Healthcare Ltd · PA0126/198/001 · Marketed
- Letrozole 2.5 mg film-coated tabletsAccord Healthcare Ireland Ltd. · PA2315/109/001 · Marketed
- Letrozole Bluefish 2.5 mg film-coated tabletsBluefish Pharmaceuticals AB · PA1436/013/001 · Marketed
- Letrozole Teva 2.5 mg film-coated tabletsTeva Pharma B.V. · PA0749/085/001 · Marketed
- Letzo 2.5 mg film-coated tabletsRowex Limited, · PA0711/190/001 · Marketed
Supply shortages
No entry for Letrozole in the EMA, FDA or German BfArM shortage lists we track.
Conditions studied with Letrozole
108 conditionsAll 108 conditions
| Condition (as registered) | Trials |
|---|---|
| Breast Cancer | 44 |
| Metastatic Breast Cancer | 6 |
| Breast Neoplasms | 5 |
| HR+/HER2- Breast Cancer | 4 |
| HER2-negative Breast Cancer | 3 |
| Advanced Breast Cancer | 3 |
| Atypical Endometrial Hyperplasia | 3 |
| Progesterone Resistance | 3 |
| Breast Cancer, Early Breast Cancer | 2 |
| ER Positive Breast Cancer | 2 |
| Ovarian Cancer | 2 |
| Locally Advanced Breast Cancer | 2 |
| HR+, HER2-, Advanced Breast Cancer | 2 |
| Advanced HR+/HER2- Breast Cancer | 2 |
| Early Breast Cancer | 2 |
| Advanced Solid Tumor | 2 |
| Endometrial Neoplasms | 2 |
| Obesity | 2 |
| Early-stage Breast Cancer | 2 |
| HER2-positive Breast Cancer | 2 |
| Ectopic Pregnancy | 2 |
| Endometrial Cancer | 2 |
| PCOS (Polycystic Ovary Syndrome) of Bilateral Ovaries | 2 |
| Low Grade Fallopian Tube Serous Adenocarcinoma | 1 |
| Ovarian Low Grade Serous Adenocarcinoma | 1 |
| Primary Peritoneal Low Grade Serous Adenocarcinoma | 1 |
| Stage II Fallopian Tube Cancer AJCC v8 | 1 |
| Breast Ductal Carcinoma In Situ | 1 |
| Invasive Breast Carcinoma | 1 |
| Multicentric Breast Carcinoma | 1 |
| Multifocal Breast Carcinoma | 1 |
| ER-positive Breast Cancer | 1 |
| Stage IIB Breast Cancer | 1 |
| Stage III Breast Cancer | 1 |
| Neoplasm Metastasis | 1 |
| Low Grade Serous Ovarian Cancer | 1 |
| Solid Tumors, Adult | 1 |
| Breast Adenocarcinoma | 1 |
| Hormone Receptor Positive | 1 |
| Stage IA Breast Cancer AJCC v7 | 1 |
| Stage IB Breast Cancer AJCC v7 | 1 |
| Malignant Neoplasm | 1 |
| Solid Tumor | 1 |
| Estrogen Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer | 1 |
| ER-Positive HER2-Negative Breast Cancer | 1 |
| Locally Advanced or Metastatic ER+ HER2- Breast Cancer | 1 |
| Locally Advanced or Metastatic Castration-resistant Prostate Cancer | 1 |
| Locally Advanced or Metastatic Non-small Cell Lung Cancer | 1 |
| Small Cell Lung Cancer | 1 |
| CCNE1 Amplification | 1 |
| Advanced CCNE1-amplified Solid Tumors | 1 |
| Metastatic Castration-resistant Prostate Cancer | 1 |
| Head and Neck Cancer | 1 |
| Hormone-receptor-positive Breast Cancer | 1 |
| HR+ Breast Cancer | 1 |
| Triple Negative Breast Cancer (TNBC) | 1 |
| CCNE1 Amplified Advanced Solid Tumors | 1 |
| HR+ HER2- Breast Cancer | 1 |
| HR+/HER2- Advanced/Metastatic Breast Cancer | 1 |
| Tubular Breast Cancer | 1 |
| Mucinous Breast Cancer | 1 |
| Invasive Ductal Breast Cancer | 1 |
| Inflammatory Breast Cancer | 1 |
| HR Positive HER2 Negative Advanced Breast Cancer | 1 |
| Letrozole | 1 |
| Infertility, Female | 1 |
| Breast Neoplasm | 1 |
| Breast Tumors | 1 |
| Triple-Negative Breast Cancer (TNBC) | 1 |
| HR Positive, HER2 Positive Breast Cancer | 1 |
| Advanced Unresectable or Metastatic Breast Cancer of Adults | 1 |
| Endometrial Neoplasm Malignant Stage I | 1 |
| Advanced Unresectable or Metastatic Breast Cancer | 1 |
| Advanced Solid Tumors | 1 |
| HER-2 Positive Breast Cancer | 1 |
| Estrogen Receptor Positive Breast Cancer | 1 |
| Ovarian Neoplasm Epithelial | 1 |
| Fallopian Tube Neoplasms | 1 |
| Peritoneal Neoplasms | 1 |
| High-grade Serous Ovarian Carcinoma (HGSOC) | 1 |
| Low Grade Serous Ovarian Carcinoma | 1 |
| Adult Type Granulosa Cell Tumor | 1 |
| Cancer Metastatic | 1 |
| ER+ Breast Cancer | 1 |
| Low Grade Endometrial Stromal Sarcoma | 1 |
| Adenomyosis of Uterus | 1 |
| Infertility Assisted Reproductive Technology | 1 |
| Carcinoma, Ovarian Epithelial | 1 |
| Low Grade Serous Adenocarcinoma of Ovary | 1 |
| Breast Neoplasm Female | 1 |
| Anatomic Stage II Breast Cancer AJCC v8 | 1 |
| Anatomic Stage IIIA Breast Cancer AJCC v8 | 1 |
| Anatomic Stage IIIC Breast Cancer AJCC v8 | 1 |
| Estrogen Receptor-Positive Breast Carcinoma | 1 |
| Uterine Leiomyosarcoma | 1 |
| Locoregional Recurrence | 1 |
| Hormone Receptor-positive Breast Cancer | 1 |
| Low Grade Serous Carcinoma | 1 |
| Hormone Receptor-Positive HER2-Negative Advanced Breast Cancer | 1 |
| Abortion in First Trimester | 1 |
| High Risk Breast Carcinoma | 1 |
| Invasive Carcinoma of the Breast | 1 |
| Node Negative Breast Cancer | 1 |
| Recurrent Endometrial Cancer | 1 |
| TP53 | 1 |
| Subclinical Hypothyroidism | 1 |
| Female Infertility | 1 |
| Miscarriage | 1 |
Sponsors
lead sponsor per trial+ 49 more sponsors in the trial list above.
By country register
A trial with sites in more than one country appears in each of those registers. CTIS does not publish a recruiting flag; its trials may also appear in the registers above.
Related compounds
Questions about Letrozole trials
How many clinical trials are testing Letrozole?
106 current trials in our China, USA, Spain, France, South Korea, Italy, Germany, Australia, Canada, Mexico, UK, Israel, Brazil, Taiwan, Japan, Belgium, Turkey, Portugal, Poland, Netherlands, Singapore, Austria, Czechia, Ireland, Switzerland, India, Egypt, Denmark, Sweden and Norway registers name Letrozole (also registered as CGS 20267) as a drug or biological intervention, as of the registry sync on 9 November 2026. Completed and withdrawn studies are not counted.
Are Letrozole trials recruiting patients?
Yes. 52 of the 106 trials are recruiting: 24 with sites in China, 19 with sites in USA, 15 with sites in Spain, 17 with sites in France, 13 with sites in South Korea, 13 with sites in Italy, 14 with sites in Germany, 12 with sites in Australia, 10 with sites in Canada, 6 with sites in Mexico, 10 with sites in UK, 7 with sites in Israel, 9 with sites in Brazil, 10 with sites in Taiwan, 11 with sites in Japan, 8 with sites in Belgium, 7 with sites in Turkey, 5 with sites in Portugal, 7 with sites in Poland, 7 with sites in Netherlands, 7 with sites in Singapore, 4 with sites in Austria, 5 with sites in Czechia, 4 with sites in Ireland, 3 with sites in Switzerland, 2 with sites in India, 4 with sites in Egypt, 3 with sites in Denmark and 2 with sites in Sweden. Eligibility and site contacts are on each trial's record. Only the study team can confirm whether a patient is eligible.
Who sponsors Letrozole clinical trials?
Eli Lilly and Company (7), Pfizer (5), Novartis Pharmaceuticals (5) and Hoffmann-La Roche (5), among 64 lead sponsors in total. The number in brackets is how many trials each organisation leads.
Are there Letrozole clinical trials in Ireland?
Yes. 10 trials in our Ireland register (ClinicalTrials.gov). Some may be the same study registered in both. See the Irish clinical trials register for sites and contacts.
Is Letrozole licensed in Ireland?
Yes. The HPRA medicines list includes 10 single-substance products containing Letrozole, for example Letrozole 2.5 mg film-coated tablets (Clonmel Healthcare Ltd). A licence does not mean a product is currently marketed or reimbursed; see each product's record.
Is there a Letrozole shortage?
Not in the lists we track: Letrozole has no entry in the EMA, FDA or German BfArM shortage registers as of their latest sync.
Where does this information come from?
Every trial, status, phase and sponsor on this page is copied from public ClinicalTrials.gov records by a daily sync. Nothing here describes how Letrozole works or whether it is effective, and it is not medical advice.
How this page is built
Everything on this page is copied from public ClinicalTrials.gov registry records — it is not written from memory, and nothing here describes how Letrozole works or whether it is effective. Each trial links to its own record so you can check it yourself.
- ClinicalTrials.gov (U.S. National Library of Medicine) ↗ Trial IDs, titles, intervention names and synonyms, phase, overall status, lead sponsor and conditions for every trial on this page
This page is built automatically: a daily sync job reads the registry records behind our country trial registers, collects every trial that lists Letrozole (or a registered synonym) as a drug or biological intervention, and tabulates the registry fields directly. Placebos and generic comparators are excluded. There is no AI drafting and no per-compound editorial pass, and the page has not been clinically reviewed. The “last verified” date above is the timestamp of that sync, not a review date. Our general editorial approach is described in our editorial standards and corrections policy. The ClinicalTrials.gov data on this page was last retrieved on 9 Nov 2026. How every register is built: methodology · fixes we have made: corrections log.