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Femara (letrozole)
Third-generation aromatase inhibitor that blocks estrogen biosynthesis by inhibiting the aromatase enzyme (CYP19A1).
Letrozole (Femara) is a third-generation aromatase inhibitor developed by Novartis, approved in 1997. First-line adjuvant therapy for postmenopausal ER-positive breast cancer. Also widely used for fertility treatment. Available generically.
At a glance
| Generic name | letrozole |
|---|---|
| Also known as | Femara |
| Sponsor | Novartis AG |
| Drug class | Aromatase Inhibitor [EPC] |
| Target | Cytochrome P450 11B2, mitochondrial, Aromatase, Cytochrome P450 11B1, mitochondrial |
| Modality | Small molecule |
| Therapeutic area | Oncology |
| Phase | FDA-approved |
| First approval | 1997-07-25 (United States) |
Mechanism of action
Letrozole is a non-steroidal aromatase inhibitor that blocks the conversion of androgens to estrogens, reducing circulating estrogen levels by >95% in postmenopausal women. It has largely replaced tamoxifen as first-line adjuvant therapy for postmenopausal ER-positive breast cancer. Also widely used off-label for ovulation induction in infertility treatment.
Approved indications
- Controlled ovarian stimulation
- Early Breast Cancer Hormone Receptor Positive and Postmenopausal
- Hormone receptor positive malignant neoplasm of breast
- Induction of ovulation in polycystic ovarian syndrome
- Induction of ovulation in unexplained infertility
Common side effects
- Arthralgia
- Hot flashes
- Flushing
- Asthenia
- Edema
- Headache
- Dizziness
- Hypercholesterolemia
- Increased sweating
- Bone pain
- Musculoskeletal pain
- Fractures
Serious adverse events
- Myocardial infarction
- Thromboembolic events
- Fractures (long-term follow-up)
Key clinical trials
- Clinical Outcomes of Letrozole-induced Endometrial Preparation Regimens Versus Conventional Endometrial Preparation Regimens Including Natural Cycle, Hormone Replacement Regimens in FET, a Randomized (NA)
- A Randomized Phase III Trial Comparing 16 to 18 Weeks of Neoadjuvant Exemestane (25 mg Daily), Letrozole (2.5 mg), or Anastrozole (1 mg) in Postmenopausal Women With Clinical Stage II and III Estrogen (Phase 3)
- A Multicenter, Open-label, Phase 2 Basket Study of MK-5684 in Participants With Selected Solid Tumors (OMAHA-015) (Phase 2)
- A Phase 1/2, First-in-human Study to Assess the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Antitumor Activity of AVZO-023 as a Single Agent, and in Combination With AVZO-021 and/or (Phase 1)
- A Phase II Non-randomized, Parallel Group Study of Goserelin or Leuprorelin Plus Letrozole in Premenopausal Patients Versus Letrozole Alone in Postmenopausal Patients With Metastatic Breast Cancer (Phase 2)
- Intrauterine Insemination With Letrozole Versus Intrauterine Insemination in Natural Cycle. A Muticenter Randomized Controlled Trial (NA)
- An Open Label Phase II Study of the Efficacy and Safety of Abemaciclib, a Cyclin Dependent Kinase (CDK4/6) Inhibitor in Selected Patients With Recurrent Ovarian or Endometrial Cancer (Phase 2)
- A PHASE 1/2A STUDY EVALUATING THE SAFETY, TOLERABILITY, PHARMACOKINETICS, PHARMACODYNAMICS, AND ANTI-TUMOR ACTIVITY OF PF-07220060 AS A SINGLE AGENT AND AS PART OF COMBINATION THERAPY IN PARTICIPANTS (Phase 2)
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| FDA label | Mechanism, indications, dosing, boxed warnings, drug interactions |
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
Competitive intelligence
For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:
- Femara CI brief — competitive landscape report
- Femara updates RSS · CI watch RSS
- Novartis AG portfolio CI