monarchE
The first CDK4/6 inhibitor to reduce recurrence after surgery in high-risk hormone-positive breast cancer.
iDFS HR 0.68 at 5 years (absolute benefit 7.6%); OS trend favourable, not yet significant.
- 92.2 vs 88.7 out of 100 alive without the cancer coming back at 2 years with Abemaciclib + endocrine therapy compared with Endocrine therapy alone; 3.5 more per 100.
- Roughly one extra person helped for every 29 treated. That is a rough figure taken from the two percentages, not a guarantee for any one person.
- Put another way, the treated group had about 25 percent lower chance of the event at any given time (hazard ratio 0.75, likely range 0.6 to 0.93).
- 83.6 vs 76 out of 100 alive without the cancer coming back at 5 years with Abemaciclib + endocrine therapy compared with Endocrine therapy alone; 7.6 more per 100.
- Roughly one extra person helped for every 13 treated. That is a rough figure taken from the two percentages, not a guarantee for any one person.
- Put another way, the treated group had about 32 percent lower chance of the event at any given time (hazard ratio 0.68, likely range 0.6 to 0.77).
- 86 vs 79.2 out of 100 alive without the cancer coming back at 5 years with Abemaciclib + endocrine therapy compared with Endocrine therapy alone; 6.8 more per 100.
- Roughly one extra person helped for every 15 treated. That is a rough figure taken from the two percentages, not a guarantee for any one person.
- Put another way, the treated group had about 32 percent lower chance of the event at any given time (hazard ratio 0.675).
- This is a surrogate endpoint: it measures the cancer being controlled or absent on scans and tests, which often, but not always, translates into living longer.
- These results apply to the people the trial enrolled: Adjuvant abemaciclib 2 years + endocrine therapy in high-risk node-positive HR+/HER2- breast cancer. People in a different situation may not see the same effect.
- The trial selected people by a biomarker (HER2); the result should not be assumed for people whose cancer does not have it.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
5,637 participants enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Invasive disease-free survival at 2 yearsprimary | Abemaciclib + endocrine therapy | 2,808 | 92.2% | 0.75 (0.6–0.93) | 0.01 | link |
| Endocrine therapy alone | 2,829 | 88.7% | ||||
| Invasive disease-free survival at 5 years | Abemaciclib + endocrine therapy | — | 83.6% | 0.68 (0.6–0.77) | — | link |
| Endocrine therapy alone | — | 76% | ||||
| Distant relapse-free survival at 5 years | Abemaciclib + endocrine therapy | — | 86% | 0.675 | — | link |
| Endocrine therapy alone | — | 79.2% |
Ribociclib is a second adjuvant CDK4/6 option, and the only one with data in node-negative stage II disease. Roughly 3 in 100 patients avoid a relapse or death at three years, so the decision depends heavily on individual risk, tolerance of a three-year oral drug, and cost. Whether the benefit persists after treatment ends, as it did with abemaciclib, needs longer follow-up.
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.