Head-to-head evidence
Anastrozole vs Letrozole
Same mechanism, same race: design-graded trial evidence for both assets, with the grading rationale shown. Grades describe the quality of the evidence, never the merits of either security.
HR+/HER2- Metastatic Breast Cancer
Shared mechanism: Aromatase · full HR+/HER2- Metastatic Breast Cancer pipeline
Anastrozole
Marketed by AstraZeneca and partners
NCT00291759 · Phase 3 · completed
The trial was large and randomized, with an active tamoxifen comparator, but it was open-label rather than blinded. Registry results were not posted at the time of grading; the key result shown was recovered from the cited external source.
Next expected readout: November 2026 · NCT04906395 (registry estimate)
Letrozole
Marketed by Novartis
NCT00004205 · Phase 3 · completed
The study randomly assigned 8,028 participants and used quadruple blinding with active tamoxifen-based comparator groups. Its primary endpoint was the hard clinical outcome of disease-free survival, but the registry provides no results showing whether the comparison was met or missed.
Next expected readout: November 2026 · NCT04906395 (registry estimate)
The full competitive landscape for each asset (every same-race competitor with aligned evidence, sortable) is on the asset pages: Anastrozole's landscape · Letrozole's landscape