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Moved Enhertu ahead of chemotherapy in hormone-positive breast cancer and extended it to 'ultralow' HER2.
DESTINY-Breast06, trial NCT04494425 sponsored by Daiichi Sankyo and AstraZeneca and published in the New England Journal of Medicine in 2024, moved trastuzumab deruxtecan ahead of chemotherapy in HR-positive, HER2-low breast cancer after endocrine therapy and extended it to HER2-ultralow tumours. It randomised 866 chemotherapy-naive patients to trastuzumab deruxtecan or chemotherapy, met its primary progression-free survival endpoint in HER2-low disease with a similar benefit in the ultralow group and a much higher response rate, and was approved in 2025. It replicates DESTINY-Breast04 in an earlier line, and whether any HER2 expression threshold matters at all is the open question.
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.
866 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival, HER2-low (BICR)primary | Trastuzumab deruxtecan | 359 | 13.2 months | 0.62 (0.51 to 0.74) | <0.0001 | link |
| Chemotherapy (TPC) | 354 | 8.1 months | ||||
| Progression-free survival, ITT (HER2-low + ultralow) | Trastuzumab deruxtecan | 436 | 13.2 months | 0.63 (0.53 to 0.75) | - | link |
| Chemotherapy (TPC) | 430 | 8.1 months | ||||
| Objective response rate, HER2-low | Trastuzumab deruxtecan | - | 56.5% | - | - | link |
| Chemotherapy (TPC) | - | 32.2% |
Shares HER2-low scoring → T-DXd, Calibrated reference slides so every lab scores HER2-low the same way, AI quantification of HER2-low and HER2-ultralow, HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH).
Shares AI quantification of HER2-low and HER2-ultralow, HER2-low and HER2-ultralow metastatic breast cancer, Daiichi Sankyo, Trastuzumab deruxtecan.
Shares HER2-low and HER2-ultralow metastatic breast cancer, HER2-low and HER2-ultralow, Daiichi Sankyo, Trastuzumab deruxtecan.
Shares HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2-low and HER2-ultralow metastatic breast cancer, HER2-low and HER2-ultralow, Trastuzumab deruxtecan.
Shares HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2-low and HER2-ultralow metastatic breast cancer, HER2-low and HER2-ultralow, Trastuzumab deruxtecan.
Shares HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2-low and HER2-ultralow metastatic breast cancer, HER2-low and HER2-ultralow, Trastuzumab deruxtecan.
Shares HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2-low and HER2-ultralow metastatic breast cancer, HER2-low and HER2-ultralow, Trastuzumab deruxtecan.
Shares Daiichi Sankyo, Trastuzumab deruxtecan, Topoisomerase-I inhibitors (and ADC payloads), AstraZeneca.