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The first trial to change treatment because of a blood test rather than a scan: switching to camizestrant when an ESR1 mutation appeared in the blood delayed progression by seven months.
3,256 patients screened by serial ctDNA; 315 with an emergent ESR1 mutation randomised. PFS 16.0 vs 9.2 months (HR 0.44, P<0.0001). OS immature; no crossover. FDA ODAC voted 6-3 against (30 April 2026), questioning the clinical meaning of acting on ctDNA before progression; the FDA nonetheless granted accelerated approval on 4 September 2026 (Etcamah), the first ctDNA-triggered switch indication.
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.
315 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survivalprimary | Switch to camizestrant + CDK4/6 | 157 | 16 months | 0.44 (0.31 to 0.6) | <0.0001 | link |
| Continue AI + CDK4/6 | 158 | 9.2 months |
Shares Selective oestrogen receptor degrader (SERD), ESR1 mutation, Camizestrant, HR-positive metastatic breast cancer after CDK4/6 inhibitors.
Shares Selective oestrogen receptor degrader (SERD), ESR1 mutation, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Estrogen receptor (ERα).
Shares Oral SERD + CDK4/6 inhibitor after ESR1 emergence, ESR1 mutation, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Estrogen receptor (ERα).
Shares Oral SERD + CDK4/6 inhibitor after ESR1 emergence, ESR1 mutation, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Estrogen receptor (ERα).
Shares Camizestrant, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test, AstraZeneca.
Shares Molecular-progression switching beyond ESR1, Tumour heterogeneity and clonal evolution, Acquired resistance to every therapy, Circulating tumour DNA (ctDNA).
Shares Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test, Tumour heterogeneity and clonal evolution, Targeted therapy roadmap: imatinib → designed for resistance → the undruggable drivers fall, Acquired resistance to every therapy.
Shares Nicholas Turner, HR-positive metastatic breast cancer after CDK4/6 inhibitors, Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test, AstraZeneca.