Letrozole

Generic Name: Letrozole

Brand Names: Femara, Kisqali Femara Co-pack

Drug Type: Small Molecule

Chemical Formula: C_₁₇H_₁₁N_₅

CAS Number: 112809-51-5

Unique Ingredient Identifier: 7LKK855W8I

Background: Letrozole, or CGS 20267, is an oral non-steroidal type II aromatase inhibitor first described in the literature in 1990. It is a third generation aromatase inhibitor like exemestane and anastrozole, meaning it does not significantly affect cortisol, aldosterone, and thyroxine.

Letrozole was granted FDA approval on 25 July 1997.

Indication: Letrozole is indicated to treat postmenopausal women with hormone receptor (HR) positive early breast cancer, postmenopausal women with early breast cancer who have periviously been treated with tamoxifen, and postmenopausal women with HR+ or unknown advanced breast cancer. Letrozole, given with ribociclib, is indicated to treat pre, peri, and postmenopausal women with HR+ and human epidermal growth factor 2 (HER2) negative advanced or metastatic breast cancer.

Associated Conditions: Advanced Breast Cancer, Anovulatory cycle, Epithelial Ovarian Cancer, HR+, HER2-, Advanced Breast Cancer, Stage I Breast Cancer, Metastatic HR + HER2 - breast cancer

Clinical Trials

BGB-43395 Alone or as Part of Combination Therapies in Chinese Participants With HR+/HER2- Breast Cancer and Other Advanced Solid Tumors

Phase 1

Active, not recruiting

Conditions: Advanced Solid Tumor
Metastatic Solid Tumor
Hormone-receptor-positive Breast Cancer
Breast Cancer
Metastatic Breast Cancer
Hormone Receptor Positive Malignant Neoplasm of Breast
HER2-negative Breast Cancer

Interventions: Drug: BGB-43395
Drug: Fulvestrant
Drug: Letrozole

First Posted Date: 2024-02-12

Last Posted Date: 2025-05-20

Lead Sponsor: BeiGene

Target Recruit Count: 33

Registration Number: NCT06253195

Locations: 🇨🇳
Beijing Cancer Hospital, Beijing, Beijing, China
🇨🇳
Guangxi Medical University Cancer Hospital, Nanning, Guangxi, China
🇨🇳
Fujian Cancer Hospital, Fuzhou, Fujian, China

and more 4 locations

Effects of Letrozole During the Luteal Phase After Controlled Ovarian Stimulation in Oocyte Donors.

Phase 3

Recruiting

Conditions: Luteinised Follicular Cyst

Interventions: Drug: Administration of letrozole

First Posted Date: 2024-02-06

Last Posted Date: 2025-05-21

Lead Sponsor: IVI Madrid

Target Recruit Count: 152

Registration Number: NCT06244745

Locations: 🇪🇸
IVI-Madrid, Madrid, Spain

Optimizing Extended Adjuvant Endocrine Therapy in Patients With Breast Cancer

Phase 3

Not yet recruiting

Conditions: Breast Cancer

Interventions: Drug: Letrozole
Drug: Tamoxifen
Drug: Anastrozole
Drug: Exemestane

First Posted Date: 2024-01-25

Last Posted Date: 2025-04-20

Lead Sponsor: Region Örebro County

Target Recruit Count: 3832

Registration Number: NCT06223698

Locations: 🇸🇪
Visby Hospital, Visby, Gotland, Sweden
🇸🇪
Gävle Hospital, Gävle, Sweden
🇸🇪
Kalmar Hospital, Kalmar, Sweden

and more 12 locations

Endometrial Preparation in Frozen Embryo Transfer Cycles

Phase 4

Recruiting

Conditions: IVF

Interventions: Drug: estradiol valerate and letrozole
Drug: letrozole 2,5 mg tablet

First Posted Date: 2023-12-26

Last Posted Date: 2024-02-26

Lead Sponsor: Rahem Fertility Center

Target Recruit Count: 210

Registration Number: NCT06181305

Locations: 🇪🇬
Rahem fertility center, Zagazig, Egypt

Functional Imaging in Prediction of Response to Abemaciclib for Advanced Hormone Receptor-Positive, HER2-Negative Breast Cancer

Phase 2

Recruiting

Conditions: Locally Advanced Unresectable HER2-Negative Breast Carcinoma
Metastatic HER2-Negative Breast Carcinoma
Anatomic Stage IV Breast Cancer AJCC v8
Anatomic Stage III Breast Cancer AJCC v8
Locally Advanced Unresectable Hormone Receptor-Positive Breast Carcinoma
Metastatic Hormone Receptor-Positive Breast Carcinoma

Interventions: Drug: Abemaciclib
Drug: Anastrozole
Procedure: Biospecimen Collection
Procedure: Computed Tomography
Procedure: Diagnostic Imaging
Drug: Exemestane
Other: Fludeoxyglucose F-18
Drug: Fluorine F 18 Fluoro Furanyl Norprogesterone
Drug: Fulvestrant
Biological: Gonadotropin-releasing Hormone Analog
Drug: Letrozole
Procedure: Positron Emission Tomography
Drug: Tamoxifen
Drug: Therapeutic Estradiol

First Posted Date: 2023-12-21

Last Posted Date: 2025-03-12

Lead Sponsor: University of Washington

Target Recruit Count: 60

Registration Number: NCT06179303

Locations: 🇺🇸
Siteman Cancer Center at Washington University, Saint Louis, Missouri, United States
🇺🇸
Fred Hutch/University of Washington Cancer Consortium, Seattle, Washington, United States

Prescription of Letrozole for Uterine Myoma

Phase 4

Recruiting

Conditions: Leiomyoma
Fibroid Uterus
Fibroid
Leiomyoma, Uterine

Interventions: Drug: Letrozole 2.5mg
Other: Placebo

First Posted Date: 2023-11-22

Last Posted Date: 2024-10-24

Lead Sponsor: University of California, San Francisco

Target Recruit Count: 140

Registration Number: NCT06143631

Locations: 🇺🇸
University of Mississippi Medical Center, Jackson, Mississippi, United States
🇺🇸
University of California, San Francisco, San Francisco, California, United States

RADIANT: Pre-op Radiation With Abemaciclib and Letrozole

Phase 1

Recruiting

Conditions: Breast Cancer

Interventions: Drug: Abemaciclib
Drug: Letrozole

First Posted Date: 2023-11-18

Last Posted Date: 2024-04-03

Lead Sponsor: Mridula George, MD

Target Recruit Count: 15

Registration Number: NCT06139107

Locations: 🇺🇸
Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey, United States

BGB-43395 Alone or as Part of Combination Therapies in Participants With Breast Cancer and Other Advanced Solid Tumors

Phase 1

Recruiting

Conditions: Advanced Solid Tumor
Hormone Receptor Positive Malignant Neoplasm of Breast
Advanced Breast Cancer
Metastatic Breast Cancer
Hormone-receptor-positive Breast Cancer
HER2-negative Breast Cancer
Hormone Receptor Positive HER-2 Negative Breast Cancer
Non-small Cell Lung Cancer
Hormone Receptor Positive Breast Carcinoma

Interventions: Drug: BGB-43395
Drug: Fulvestrant
Drug: Letrozole

First Posted Date: 2023-11-07

Last Posted Date: 2025-05-09

Lead Sponsor: BeiGene

Target Recruit Count: 79

Registration Number: NCT06120283

Locations: 🇧🇷
Fundacao Universidade de Caxias Do Sul Instituto de Pesquisas Em Saude, Petropolis, Brazil
🇧🇷
Hospital Sao Lucas Da Pucrs Uniao Brasileira de Educacao E Assistencia, Porto Algre, Brazil
🇺🇸
Sarah Cannon Research Institute (Scri) At Health One, Denver, Colorado, United States

and more 124 locations

DCIS: RECAST Trial Ductal Carcinoma In Situ: Re-Evaluating Conditions for Active Surveillance Suitability as Treatment

Phase 2

Recruiting

Conditions: Ductal Carcinoma in Situ

Interventions: Drug: Testosterone + Anastrazole
Drug: Z-endoxifen
Drug: Tamoxifen
Drug: Elacestrant
Drug: Exemestane
Drug: Letrozole
Drug: Anastrazole

First Posted Date: 2023-10-10

Last Posted Date: 2025-04-29

Lead Sponsor: QuantumLeap Healthcare Collaborative

Target Recruit Count: 400

Registration Number: NCT06075953

Locations: 🇺🇸
Berkeley Outpatient Center, Berkeley, California, United States
🇺🇸
UCSF, San Francisco, California, United States
🇺🇸
Atrium Health Wake Forest Baptist Comprehensive Cancer Center, Winston-Salem, North Carolina, United States

and more 5 locations

A Study of Avutometinib (VS-6766) + Defactinib (VS-6063) in Recurrent Low-Grade Serous Ovarian Cancer

Phase 3

Recruiting

Conditions: Low Grade Serous Ovarian Cancer

Interventions: Drug: avutometinib
Drug: Pegylated liposomal doxorubicin
Drug: Defactinib
Drug: Paclitaxel
Drug: Letrozole
Drug: Anastrozole

First Posted Date: 2023-10-10

Last Posted Date: 2025-05-21

Lead Sponsor: Verastem, Inc.

Target Recruit Count: 270

Registration Number: NCT06072781

Locations: 🇺🇸
HonorHealth, Phoenix, Arizona, United States
🇺🇸
University of Arkansas, Little Rock, Arkansas, United States
🇺🇸
UCLA Health, Los Angeles, California, United States

and more 88 locations

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