# MONARCH 3

Source: https://onco.cc/trials/monarch-3/  
OnCo record `monarch-3` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Abemaciclib roughly doubled the time to progression when added to an aromatase inhibitor; the survival gain of about 13 months narrowly missed statistical significance.

## Summary

MONARCH 3, trial NCT02246621 sponsored by Eli Lilly and reported in 2017, showed that abemaciclib roughly doubled the time to progression when added to a non-steroidal aromatase inhibitor as first-line treatment for postmenopausal HR-positive, HER2-negative advanced breast cancer. It randomised 493 women and met its primary progression-free survival endpoint, and the final overall survival analysis showed a numerical gain of about thirteen months that narrowly missed statistical significance at the prespecified threshold. OnCo links it to CDK4/6 as a target, abemaciclib, aromatase inhibitors, Matthew P. Goetz and the bottleneck of wrong doses, and MONARCH 2, which tested abemaciclib with fulvestrant after endocrine progression, did show a significant survival benefit. Whether a large numerical survival gain that misses significance should count is the question the trial leaves open.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-07
- Registry id: NCT02246621
- Phase: 3
- Setting: First-line postmenopausal HR+/HER2- advanced breast cancer: abemaciclib + NSAI vs placebo + NSAI
- Sponsor: Eli Lilly
- Enrolled: 493
- Result: PFS HR 0.54; OS 66.8 vs 53.7 months, HR 0.80 (NS).
- Outcomes: Progression-free survival: Abemaciclib + NSAI 28.2 months vs Placebo + NSAI 14.8 months, HR 0.54; Overall survival: Abemaciclib + NSAI 66.8 months vs Placebo + NSAI 53.7 months, HR 0.8
- Replication: MONARCH 2 (abemaciclib + fulvestrant after endocrine progression) did show a significant OS benefit (HR 0.76).

## Sources

- ClinicalTrials.gov NCT02246621: https://clinicaltrials.gov/study/NCT02246621

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- technologies: [CDK4/6 inhibitors](https://onco.cc/technologies/cdk46-inhibitor/)
- targets: [CDK4/6](https://onco.cc/targets/cdk4-6/)
- drugs: [Abemaciclib](https://onco.cc/drugs/abemaciclib/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/)
- companies: [Eli Lilly (incl. Loxo)](https://onco.cc/companies/eli-lilly/)
- people: [Matthew P. Goetz](https://onco.cc/people/matthew-goetz/)
- bottlenecks: [Wrong doses](https://onco.cc/bottlenecks/b-dose-optimisation/)
- roadmaps: [Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test](https://onco.cc/roadmaps/hormonal-therapy-roadmap/)

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JSON: https://onco.cc/api/v1/entities/monarch-3.json