Drug
Letrozole clinical trials
Also written Femara, CGS 20267 and FEM345.
Related medicines add 1 study
Counted the way a researcher would: Letrozole with its salts, dosage forms, brands and biosimilars. Looking for a trial to join? Including related medicines shows more you could take part in.
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How each study uses Letrozole is sorted by a rule, right about nine times in ten. Readers can ask us to read every study one by one.Ask us to read each study
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Approvals
The first approval found in each region, with its record
- United States
- 25 Jul 1997 · FEMARA · NDA 020726 (FDA, Drugs@FDA)
- European Union
- Not in EMA's list of EU-wide authorisations
From FDA's Drugs@FDA and Purple Book (through openFDA) and the European Medicines Agency, files of Sept 2026 and 27 Oct 2026. National approvals in Europe and other countries are not included. How this is worked out
How studies write it
Studies that test it under each name
Studies by the year they started
340 studies that test it; most in 2022 (21)
| Year | Studies |
|---|---|
| 1998 | 2 |
| 1999 | 1 |
| 2000 | 6 |
| 2001 | 2 |
| 2002 | 6 |
| 2003 | 8 |
| 2004 | 11 |
| 2005 | 15 |
| 2006 | 12 |
| 2007 | 13 |
| 2008 | 18 |
| 2009 | 12 |
| 2010 | 7 |
| 2011 | 8 |
| 2012 | 11 |
| 2013 | 9 |
| 2014 | 7 |
| 2015 | 15 |
| 2016 | 19 |
| 2017 | 15 |
| 2018 | 18 |
| 2019 | 16 |
| 2020 | 17 |
| 2021 | 15 |
| 2022 | 21 |
| 2023 | 19 |
| 2024 | 14 |
| 2025 | 12 |
| 2026 | 11 |
By phase
A phase 1/2 study counts in both.
What it is tested for
Each study’s main condition, where its own words name it, so a study counts once.
Who runs them
Industry 53 · Other 287
Novartis Pharmaceuticals (24) · M.D. Anderson Cancer Center (9) · Dana-Farber Cancer Institute (8) · Cairo University (8) · Assiut University (8) · University of California, San Francisco (6) · The University of Hong Kong (6) · Fudan University (5)
Often tested with
Tested in the same studies.
Tamoxifen (26) · Anastrozole (18) · Exemestane (14) · Palbociclib (14) · Everolimus (13) · Trastuzumab (12) · Abemaciclib (10) · Clomiphene (9)
Related medicines
As reviewed, each with the page that says it.
- One of Aromatase inhibitors source
Coming up
From the study records. Dates are the sponsors’ own estimates and often move.
Tested against it · 14 phase 3 studies under way
Letrozole is the comparator. A study of two new drugs counts under both.
- 3AZD9833 · AstraZeneca · next primary completion Apr 2027
- 2Palazestrant · Olema Pharmaceuticals, Inc. · next primary completion Dec 2028
- 2HRS-8080 · Shandong Suncadia Medicine Co., Ltd. · next primary completion Aug 2027
- 1Giredestrant · Hoffmann-La Roche
- 1Imlunestrant · Eli Lilly and Company · next primary completion Oct 2027
- 1Vepdegestrant · Pfizer · next primary completion Dec 2026
- 1RO5126766 · Verastem, Inc. · next primary completion Oct 2028
- 1Defactinib · Verastem, Inc. · next primary completion Oct 2028
Reaching primary completion within a year · 20, 3 in phase 3
Studies that test Letrozole, phase 3 first.
- Dec 2026Clinical Study on Adjuvant Therapy of TQB3616 Combined With Endocrine Therapy Compared With Placebo Combined With Endocrine Therapy in Patients With Breast CancerPhase 3 · Chia Tai Tianqing Pharmaceutical Group Co., Ltd.
- Feb 2027Letrozole With or Without Paclitaxel and Carboplatin in Treating Patients With Stage II-IV Ovarian, Fallopian Tube, or Primary Peritoneal CancerPhase 3 · NRG Oncology
- Jul 2027MAintenance Therapy With Aromatase Inhibitor in Epithelial Ovarian Cancer (MATAO)Phase 3 · Swiss GO Trial Group
- Dec 2026Abemaciclib and Letrozole to Treat Endometrial CancerPhase 2 · Gynecologic Oncology Group
- Dec 2026Pyrotinib Maleate, CDK4/6 Inhibitor and Letrozole in Combination for Stage II-III TPBC: a Phase II TrialPhase 2 · Shengjing Hospital
- Dec 2026Phase II Lenvatinib and Pembrolizumab in Endocrine Resistant Breast Cancer With LetrozolePhase 2 · National Cancer Centre, Singapore
- Dec 2026Dalpiciclib With or Without Entinostat and Letrozole in HR+/HER2- Early Breast CancerPhase 2 · Hebei Medical University Fourth Hospital
- Dec 2026Letrozole in Preventing Recurrence of Endometrioma Following Laparoscopic Ovarian CystectomyNot applicable · The University of Hong Kong
- Dec 2026Use of Letrozole for Ectopic PregnancyPhase 4 · Hospital de Clinicas de Porto Alegre
- Jan 2027Neoadjuvant Lenvatinib Combined With Letrozole in Hormone Receptor Positive Breast CancerPhase 1/2 · National University Hospital, Singapore
Studies
Open first, then newest update. How each study uses Letrozole is read from its arms, and is right about nine times in ten. Ask us to read each study. These are the studies that list it as an intervention; a search of ClinicalTrials.gov also finds studies that mention it only in a description, such as earlier treatment.
Testing it · 340
- A Study Evaluating the Efficacy and Safety of Multiple Treatment Combinations in Patients With Metastatic or Locally Advanced Breast CancerRecruitingPhase 1/2Hoffmann-La RocheNCT03424005Written as Letrozole
- Saruparib (AZD5305) Plus Camizestrant or Plus Endocrine Therapy, Compared With CDK4/6 Inhibitor Plus Endocrine Therapy or Plus Camizestrant in HR-Positive, HER2-Negative (IHC 0, 1+, 2+/ ISH Non-amplified), BRCA1, BRCA2, or PALB2m Advanced Breast CancerRecruitingPhase 3AstraZenecaNCT06380751Written as Letrozole
- A Study of Avutometinib, Defactinib, and Letrozole in People With Low-Grade Serous Ovarian CancerRecruitingPhase 2Memorial Sloan Kettering Cancer CenterNCT06394804Written as Letrozole
- ALPINE: Maintenance Letrozole/AbemaciclibRecruitingPhase 2Dana-Farber Cancer InstituteNCT06366347Written as Letrozole
- Phase 3 Study of Gedatolisib as First-Line Treatment for Patients With HR-Positive, HER2-Negative Advanced Breast Cancer (VIKTORIA-2)RecruitingPhase 3Celcuity IncNCT06757634Written as Arm C: Gedatolisib + Palbociclib + Letrozole
- De-EscaLaTion of Aromatase Inhibitor Therapy: A Randomized Phase II Study of De-escalated Letrozole in Hormone Receptor-Positive Early Breast CancerNot yet recruitingPhase 2Montefiore Medical CenterNCT07866430Written as Letrozole
- Prescription of Letrozole for Uterine MyomaRecruitingPhase 4University of California, San FranciscoNCT06143631Written as Letrozole 2.5mg
- A Study of MK-5684 in People With Certain Solid Tumors (MK-5684-015/OMAHA-015)RecruitingPhase 2Merck Sharp & Dohme LLCNCT06979596Written as Letrozole
- FET-LET-2x2: Clinical Pregnancy Rates After Frozen Embryo Transfer in Natural and Modified Natural CyclesRecruitingNot applicableUniversity of Novi SadNCT07425990Written as Letrozole (Aromatase Inhibitors)
- GnRHa + Letrozole in Non-obese Progestin-insensitive Endometrial Cancer and Atypical Hyperplasia PatientsRecruitingPhase 2/3Xiaojun ChenNCT05316935Written as Letrozole 2.5mg
- GnRHa + Letrozole in Obese Progestin-insensitive Endometrial Cancer PatientsRecruitingPhase 2/3Xiaojun ChenNCT06379113Written as Letrozole 2.5mg
- Study of Letrozole in Recurrent GliomasRecruitingEarly Phase 1University of CincinnatiNCT03122197Written as Letrozole Oral Tablet
- Letrozole in Uterine LeiomyosarcomaRecruitingPhase 2GOG FoundationNCT05649956Written as Letrozole
- Kumorixilib Plus Capecitabine and Letrozole for Neoadjuvant Treatment of HR-Positive HER2-Negative Breast CancerNot yet recruitingPhase 2Fujian Cancer HospitalNCT07691333Written as Letrozole 2.5mg
- Clinical Study of Local and Systemic Biological Impact of GLP1/GIP-Receptor Agonists in Patients With Breast Cancer: The CLARA TrialNot yet recruitingPhase 2Universitaire Ziekenhuizen KU LeuvenNCT07676331Written as Letrozole (Aromatase Inhibitors)
- RESOLVE: Abemaciclib + Letrozole +/- Metformin or Gedatolisib in Endometrial CancerRecruitingPhase 2Dana-Farber Cancer InstituteNCT03675893Written as Letrozole
- Single Cell Immune and Non-immune Correlates of Response to Neoadjuvant AbemaciclibRecruitingPhase 2University of Texas Southwestern Medical CenterNCT04614194Written as Letrozole
- Fertility Preservation Using Tamoxifen and Letrozole in Estrogen Sensitive Tumors TrialRecruitingPhase 3University of California, San FranciscoNCT03011684Written as Letrozole
- Letrozole Versus Methotrexate for Management of Undisturbed Ectopic PregnancyNot yet recruitingPhase 2Kafrelsheikh UniversityNCT07624903Written as Letrozole 2.5Mg Tab
- Fudan University Shanghai Cancer Center Breast Cancer Precision Platform Series Study- Neoadjuvant TherapyRecruitingPhase 2Fudan UniversityNCT05582499Written as Letrozole
See all 340 studies that test Letrozole →
Given beside what is tested · 203 — Letrozole is usual care or a partner of the new treatment
- A Study of Tersolisib (LY4064809) and Abemaciclib With Hormone Therapies in Participants With PIK3CA-Mutated Early Breast CancerNot yet recruitingPhase 2Eli Lilly and CompanyNCT07935317Written as Letrozole
- A Phase I Dose Escalation Study of CG-7321 Monotherapy or Combination Therapy in Advanced Solid TumorsRecruitingPhase 1Chengdu Cynogen Bio-pharmaceutical Tech. Co., Ltd.NCT07923214Written as Letrozole
- Study to Test the Safety and Tolerability of PF-07220060 in Participants With Advance Solid TumorsRecruitingPhase 2PfizerNCT04557449Written as Letrozole
- Testing Whether Hormone Therapy With Ribociclib is as Effective as Chemotherapy Followed by Hormone Therapy With Ribociclib for the Treatment of High Anatomic Stage Breast Cancer With Low Recurrence Risk, The RxFINE-Low TrialRecruitingPhase 3National Cancer Institute (NCI)NCT07391774Written as Letrozole
- A Study to Evaluate the Effects of GDC-4198 in Combination With Letrozole, Fulvestrant, or Giredestrant in Participants With Locally Advanced or Metastatic Hormone Receptor-Positive, HER2-Negatve Breast CancerNot yet recruitingPhase 1Genentech, Inc.NCT07867262Written as Letrozole
- A Study With NKT5097 for Adults With Advanced/Metastatic Solid TumorsRecruitingPhase 1NiKang Therapeutics, Inc.NCT07029399Written as Letrozole
- A Study Evaluating the Efficacy and Safety of Inavolisib Plus CDK4/6 Inhibitor and Letrozole vs Placebo + CDK4/6i and Letrozole in Participants With Endocrine-Sensitive PIK3CA-Mutated, Hormone Receptor-Positive, HER2-Negative Advanced Breast CancerRecruitingPhase 3Hoffmann-La RocheNCT06790693Written as Letrozole
- A Study of Tersolisib (LY4064809/STX-478) With Other Anti-Cancer Treatments in Participants With Advanced Breast Cancer With a Genetic Change (PIK3CA)RecruitingPhase 3Eli Lilly and CompanyNCT07174336Written as Letrozole
- Study of IEV407 as Single Agent or in Combination in Patients With Advanced HR+/HER2- Breast CancerRecruitingPhase 1Novartis PharmaceuticalsNCT07604571Written as Letrozole
- Study of GVV858 as a Single Agent or in Combination With Endocrine Therapy in Patients With HR+/HER2- Breast Cancer and Other Advanced Solid TumorsRecruitingPhase 1/2Novartis PharmaceuticalsNCT07288359Written as Letrozole
- A Study to Learn About the Study Medicine Called PF-08165784 in People With PIK3CA-Mutated Advanced or Metastatic Solid TumorsNot yet recruitingPhase 1PfizerNCT07897721Written as Letrozole
- A Prospective, Phase II, Exploratory Study Protocol of a Chemotherapy Sensitivity-based Culmerciclib Combination Regimen in Neoadjuvant Therapy for HR+/HER2- Breast Cancer.RecruitingPhase 2The First Affiliated Hospital with Nanjing Medical UniversityNCT07900516Written as Letrozole
- A Phase III Clinical Study of HRS-6209 Plus Letrozole as First-line Therapy in Patients With Advanced or Metastatic Breast CancerNot yet recruitingPhase 3Jiangsu HengRui Medicine Co., Ltd.NCT07894328Written as HRS-6209 + Letrozole
- A Study to Test Inavolisib Treatments in Participants With Early-Stage, PIK3CA-Mutated Breast CancerRecruitingPhase 2Hoffmann-La RocheNCT07054190Written as Letrozole
- BGB-43395 Plus Letrozole Versus CDK4/6i Plus Letrozole for Patients With Advanced or Metastatic HR+/HER2- Breast Cancer Who Have Not Received Prior Treatment for Advanced or Metastatic DiseaseRecruitingPhase 3BeOne MedicinesNCT07492641Written as Letrozole
- Safety Extension Study for Subjects With HR+, HER2- Breast Cancer for Subjects Who Have Completed the OVELIA StudyEnrolling by invitationPhase 3Tolmar Inc.NCT05645536Written as Letrozole tablets
- A Trial of HRS-6209 in Combination With Other Antitumor Therapies in Breast Cancer Patients or HRS-9813 as Monotherapy in Patients With Advanced Solid TumorsRecruitingPhase 1/2Jiangsu HengRui Medicine Co., Ltd.NCT06555068Written as HRS-6209 in Combination with Letrozole
- Study of PF-07248144 in Advanced or Metastatic Solid TumorsRecruitingPhase 2PfizerNCT04606446Written as Letrozole
- BGB-43395 Alone or as Part of Combination Therapies in Participants With Breast Cancer and Other Advanced Solid TumorsRecruitingPhase 1BeOne MedicinesNCT06120283Written as Letrozole
- Study of AVZO-021 in Patients With Advanced Solid TumorsRecruitingPhase 1/2Avenzo Therapeutics, Inc.NCT05867251Written as Letrozole
Showing 20 of 203.
As the comparator · 40 — what is tested is compared with Letrozole
- A Study of Avutometinib (VS-6766) + Defactinib (VS-6063) in Recurrent Low-Grade Serous Ovarian CancerRecruitingPhase 3Verastem, Inc.NCT06072781Written as Letrozole
- DCIS: RECAST Trial Ductal Carcinoma In Situ: Re-Evaluating Conditions for Active Surveillance Suitability as TreatmentRecruitingPhase 2QuantumLeap Healthcare CollaborativeNCT06075953Written as Letrozole
- A Study of Camizestrant in ER+/HER2- Early Breast Cancer After at Least 2 Years of Standard Adjuvant Endocrine TherapyRecruitingPhase 3AstraZenecaNCT05774951Written as Letrozole
- Elacestrant for Treating ER+/HER2- Breast Cancer Patients With ctDNA Relapse (TREAT ctDNA)RecruitingPhase 3European Organisation for Research and Treatment of Cancer - EORTCNCT05512364Written as Letrozole 2.5mg
- A Phase 3 Study of HRS-8080 Versus Treatment Chosen by Physicians in Locally Advanced and Metastatic Breast CancerRecruitingPhase 3Shandong Suncadia Medicine Co., Ltd.NCT07024173Written as Letrozole Tablets
- Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast CancerRecruitingPhase 3Olema Pharmaceuticals, Inc.NCT07085767Written as Letrozole
- Compare Adjuvant Monotherapy With Endocrine or Accelerated Partial Breast Irradiation After LumpectomyRecruitingPhase 2UNC Lineberger Comprehensive Cancer CenterNCT05472792Written as tamoxifen, anastrozole, exemestane, letrozole, fulvestrant, toremifene
- A Phase III Trial Comparing HRS-8080 With Standard Endocrine Therapy in Patients With Intermediate or High Risk Early Breast CancerRecruitingPhase 3Shandong Suncadia Medicine Co., Ltd.NCT07349069Written as Letrozole tablets
- Cabergoline & Letrozole Versus Letrozole in Ovulation Induction in PCOSRecruitingNot applicableMst.Sumyara KhatunNCT07255911Written as Letrozole 0.5mg
- Adjuvant Abemaciclib for Locoregional Recurrence of HR-positive, HER2-negative Breast Cancer (JCOG2313, AURA)RecruitingPhase 3Japanese Foundation for Cancer ResearchNCT07190443Written as Endocrine Therapy (ET): letrozole, anastrozole, exemestane, tamoxifen
- Trastuzumab Deruxtecan Versus Standard Neoadjuvant Treatment for HER2-positive Breast CancerRecruitingPhase 2Karolinska University HospitalNCT05900206Written as Letrozole
- A Trial of Early Detection of Molecular Relapse With Circulating Tumour DNA Tracking and Treatment With Palbociclib Plus Fulvestrant Versus Standard Endocrine Therapy in Patients With ER Positive HER2 Negative Breast CancerRecruitingPhase 2Royal Marsden NHS Foundation TrustNCT04985266Written as Letrozole
- A Study Evaluating the Efficacy and Safety of Giredestrant Combined With Palbociclib Compared With Letrozole Combined With Palbociclib in Participants With Estrogen Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer (persevERA Breast Cancer)Active, not recruitingPhase 3Hoffmann-La RocheNCT04546009Written as Letrozole
- ExclUsive endocRine Therapy Or Radiation theraPy for Women Aged ≥70 Years Early Stage Breast CancerActive, not recruitingPhase 3Azienda Ospedaliero-Universitaria CareggiNCT04134598Written as Endocrine Therapy (ET): letrozole, anastrozole, exemestane, tamoxifen
- Tailoring NEOadjuvant Therapy in Hormone Receptor Positive, HER2 Negative, Luminal Breast Cancer.Active, not recruitingPhase 2Borstkanker Onderzoek GroepNCT03283384Written as Letrozole
- Phase III Study to Assess AZD9833+ CDK4/6 Inhibitor in HR+/HER2-MBC With Detectable ESR1m Before Progression (SERENA-6)Active, not recruitingPhase 3AstraZenecaNCT04964934Written as Letrozole
- Study for Participants Continuing From Pfizer-sponsored Palbociclib (a Study Medicine) StudiesActive, not recruitingPhase 2PfizerNCT05226871Written as Letrozole
- Magnesium Oxide and Letrozole Versus Letrozole Alone on Ovarian Response in Insulin Resistant PCOSCompletedNot applicableBangladesh Medical UniversityNCT07766590Written as Letrozole 2.5mg
- OP-1250 (Palazestrant) vs. Standard of Care for the Treatment of ER+/HER2- Advanced Breast CancerActive, not recruitingPhase 3Olema Pharmaceuticals, Inc.NCT06016738Written as Letrozole
- An Adjuvant Endocrine-based Therapy Study of Camizestrant (AZD9833) in ER+/HER2- Early Breast Cancer (CAMBRIA-2)Active, not recruitingPhase 3AstraZenecaNCT05952557Written as Letrozole
Showing 20 of 40.
What changed recently
From the registry's own updates since Oct 15, 2026.
Results posted1
Codes
What other systems call Letrozole · ClinicalTrials.gg INT006690
- MeSH (NLM) D000077289LetrozoleConfirmed ClinicalTrials.gov, NLM, Wikidata
- UNII (FDA) 7LKK855W8ILETROZOLEConfirmed FDA, NLM, Wikidata
- RxNorm 72965Confirmed FDA, Wikidata
- Wikidata Q194974letrozoleConfirmed FDA, NLM, Wikidata
- NCI Thesaurus C1527LetrozoleOne source FDA
- DrugBank DB01006One source Wikidata
| System | Code | Name there | Checked by |
|---|---|---|---|
| MeSH (NLM) | D000077289 | Letrozole | Confirmed ClinicalTrials.gov, NLM, Wikidata |
| UNII (FDA) | 7LKK855W8I | LETROZOLE | Confirmed FDA, NLM, Wikidata |
| RxNorm | 72965 | — | Confirmed FDA, Wikidata |
| Wikidata | Q194974 | letrozole | Confirmed FDA, NLM, Wikidata |
| NCI Thesaurus | C1527 | Letrozole | One source FDA |
| DrugBank | DB01006 | — | One source Wikidata |
“Confirmed” means two independent publishers link the code to this drug; “one source”, one does and its name agrees.