DESTINY-Breast06
Moved Enhertu ahead of chemotherapy in hormone-positive breast cancer and extended it to 'ultralow' HER2.
PFS 13.2 vs 8.1 months (HR 0.62); similar benefit in HER2-ultralow. Approved 2025.
Setting
HR+ HER2-low/ultralow breast cancer after endocrine therapy, chemotherapy-naive: T-DXd vs chemotherapy
Phase
Phase 3
Sponsor
Daiichi Sankyo / AstraZeneca
Registry
Headline result
PFS HR 0.62.
Reported
2024
Enrolled
866
Replication
Replicates DESTINY-Breast04 in an earlier line and extends it to HER2-ultralow.
In plain words
What these results mean for people, not percentages
Progression-free survival, HER2-low (BICR)primarysurrogate endpoint
- Median 13.2 vs 8.1 months with Trastuzumab deruxtecan compared with Chemotherapy (TPC); about 5.1 months longer for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 38 percent lower chance of the event at any given time (hazard ratio 0.62, likely range 0.51 to 0.74).
- 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.
Progression-free survival, ITT (HER2-low + ultralow)surrogate endpoint
- Median 13.2 vs 8.1 months with Trastuzumab deruxtecan compared with Chemotherapy (TPC); about 5.1 months longer for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 37 percent lower chance of the event at any given time (hazard ratio 0.63, likely range 0.53 to 0.75).
- 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.
Objective response rate, HER2-lowresponse endpoint
- 56.5 vs 32.2 out of 100 had their tumour shrink with Trastuzumab deruxtecan compared with Chemotherapy (TPC); 24.3 more per 100.
- Roughly one extra person helped for every 4 treated. That is a rough figure taken from the two percentages, not a guarantee for any one person.
- A response rate counts how many people had their tumours shrink by a set amount; shrinking is encouraging but does not by itself show that people live longer or feel better.
Be careful
- These results apply to the people the trial enrolled: HR+ HER2-low/ultralow breast cancer after endocrine therapy, chemotherapy-naive: T-DXd vs chemotherapy. 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.
866 participants enrolled.
Progression-free survival, HER2-low (BICR)primary
HR 0.62 (0.51–0.74) · p <0.0001
Trastuzumab deruxtecan
13.2 mo
Chemotherapy (TPC)
8.1 mo
Progression-free survival, ITT (HER2-low + ultralow)
HR 0.63 (0.53–0.75)
Trastuzumab deruxtecan
13.2 mo
Chemotherapy (TPC)
8.1 mo
Objective response rate, HER2-low
Trastuzumab deruxtecan56.5 of 100
Chemotherapy (TPC)32.2 of 100
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival, HER2-low (BICR)primary | Trastuzumab deruxtecan | 359 | 13.2 months | 0.62 (0.51–0.74) | <0.0001 | link |
| Chemotherapy (TPC) | 354 | 8.1 months | ||||
| Progression-free survival, ITT (HER2-low + ultralow) | Trastuzumab deruxtecan | 436 | 13.2 months | 0.63 (0.53–0.75) | — | link |
| Chemotherapy (TPC) | 430 | 8.1 months | ||||
| Objective response rate, HER2-low | Trastuzumab deruxtecan | — | 56.5% | — | — | link |
| Chemotherapy (TPC) | — | 32.2% |
Replication
Replicates DESTINY-Breast04 in an earlier line and extends it to HER2-ultralow.