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An oral SERD that works alone in ESR1-mutant tumours and, combined with abemaciclib, doubles progression-free time in everyone regardless of mutation.
Three arms (imlunestrant n=331; standard ET n=330; imlunestrant + abemaciclib n=213). In ESR1-mutant tumours imlunestrant alone: PFS 5.5 vs 3.8 months (HR 0.62). Imlunestrant + abemaciclib vs imlunestrant: PFS 9.4 vs 5.5 months (HR 0.57; updated 10.9 vs 5.5, HR 0.59), with benefit irrespective of ESR1 status. Updated analysis (SABCS 2025): ESR1-mutant OS 34.5 vs 23.1 months for monotherapy vs standard ET. FDA approved imlunestrant (Inluriyo) 25 September 2025 for ESR1-mutant disease.
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.
874 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival, ESR1-mutant (imlunestrant vs standard ET)primary | Imlunestrant | - | 5.5 months | 0.62 (0.46 to 0.82) | <0.001 | link |
| Standard endocrine therapy | - | 3.8 months | ||||
| Progression-free survival (imlunestrant + abemaciclib vs imlunestrant)primary | Imlunestrant + abemaciclib | 213 | 10.9 months | 0.59 (0.46 to 0.75) | <0.001 | link |
| Imlunestrant | 213 | 5.5 months | ||||
| Overall survival, ESR1-mutant (imlunestrant vs standard ET), updated | Imlunestrant | - | 34.5 months | - | - | link |
| Standard endocrine therapy | - | 23.1 months |
Shares HR-positive metastatic breast cancer after CDK4/6 inhibitors, Abemaciclib, CDK4/6, Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test.
Shares ESR1 mutation, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Estrogen receptor (ERα), Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test.
Shares Imlunestrant, ESR1 mutation, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Estrogen receptor (ERα).
Shares Oral SERD, Oral SERD + CDK4/6 inhibitor after ESR1 emergence, ESR1 mutation, HR-positive metastatic breast cancer after CDK4/6 inhibitors.
Shares HR-positive metastatic breast cancer after CDK4/6 inhibitors, Estrogen receptor (ERα), Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test, Endocrine therapy (SERMs, AIs, SERDs).
Shares Abemaciclib, CDK4/6, Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test, Eli Lilly (incl. Loxo).
Shares Imlunestrant, Eli Lilly (incl. Loxo), Endocrine therapy (SERMs, AIs, SERDs), HR-positive / HER2-negative breast cancer.
Shares Abemaciclib, CDK4/6, Estrogen receptor (ERα), Endocrine therapy (SERMs, AIs, SERDs).