monarchE: two years of abemaciclib after surgery in high-risk, hormone-receptor-positive early breast cancer
Adding two years of the CDK4/6 inhibitor abemaciclib to standard hormone therapy after surgery cut the risk of the cancer coming back by a quarter in women with node-positive, high-risk disease.
Open-label phase 3 trial of 5,637 patients with hormone-receptor-positive, HER2-negative early breast cancer at high risk of recurrence (four or more positive nodes, or one to three nodes with grade 3, tumour 5 cm or more, or high Ki-67), randomised to standard endocrine therapy with or without two years of abemaciclib. Primary endpoint was invasive disease-free survival (iDFS).
At the pre-planned interim analysis, iDFS was improved (HR 0.75; 2-year iDFS 92.2% vs 88.7%). The benefit widened with time: at five years iDFS was 83.6% vs 76.0%, a 7.6-point absolute difference (HR 0.68), well after abemaciclib had stopped. It was the first adjuvant CDK4/6 inhibitor to succeed after palbociclib failed in PALLAS and PENELOPE-B.
- Invasive disease-free survival HR 0.75 (95% CI 0.60-0.93) at the interim analysis; 2-year iDFS 92.2% vs 88.7%.
- Five-year update (2024): iDFS 83.6% vs 76.0% (HR 0.68) and distant relapse-free survival 86.0% vs 79.2%, with the curves continuing to separate after treatment ended.
- Diarrhoea occurred in over 80% of abemaciclib patients (mostly grade 1-2) and roughly one in six discontinued because of adverse events.
- Ki-67 of 20% or more identified a higher-risk group but did not predict a larger relative benefit, so the label was later broadened to all high-risk node-positive patients.
- Overall survival data remain immature.
Women with hormone-receptor-positive, HER2-negative breast cancer that has spread to lymph nodes and has other high-risk features can now be offered two years of abemaciclib alongside their hormone therapy, with a durable reduction in relapse. It does not apply to node-negative or low-risk disease, and the diarrhoea and cost are real trade-offs to discuss.
- No overall survival benefit has yet been shown.
- Open-label design with an endpoint (iDFS) that includes second primary cancers.
- The contrast with the negative PALLAS trial (palbociclib) is not fully explained: differences in drug, dose intensity, or population selection are all possible.
- Two years of a costly oral drug for a 7-8 point absolute gain raises access questions in many health systems.
Pages like this
not linked directly; found by shared links- Key paperNATALEE: three years of ribociclib after surgery in a broad population of hormone-receptor-positive early breast cancer
Shares monarchE, NATALEE, Miguel Martín, CDK4/6 inhibitors.
- IdeaUse residual disease tests to decide who needs ten years of hormone therapy
Shares monarchE, Endocrine therapy (SERMs, AIs, SERDs), Dormant cells and minimal residual disease, Toxicity and quality of life are undervalued.
- PathwayThe cell-cycle engine (cyclins & CDKs)
Shares Abemaciclib, CDK4/6 inhibitors, CDK4/6, Estrogen receptor (ERα).
- PersonMatthew P. Goetz
Shares Abemaciclib, CDK4/6, Estrogen receptor (ERα), HR-positive / HER2-negative breast cancer.
- PairingCDK4/6 inhibitor + endocrine therapy
Shares Abemaciclib, CDK4/6 inhibitors, Endocrine therapy (SERMs, AIs, SERDs), HR-positive / HER2-negative breast cancer.
- TrialEMBER-3
Shares Abemaciclib, CDK4/6, Estrogen receptor (ERα), HR-positive / HER2-negative breast cancer.
- PathwayOestrogen receptor signalling
Shares Abemaciclib, CDK4/6 inhibitors, CDK4/6, Estrogen receptor (ERα).
- ProductImlunestrant
Shares Eli Lilly (incl. Loxo), Estrogen receptor (ERα), Endocrine therapy (SERMs, AIs, SERDs), HR-positive / HER2-negative breast cancer.