Erika Hamilton, Chair, Executive Committee, Breast and Breast Program Lead at Sarah Cannon Research Institute, shared a post on LinkedIn:
“FDA Approval of T-DXd in 1st Line HER2-Positive Breast Cancer!
Today, the FDA has approved trastuzumab deruxtecan (T-DXd) in combination with pertuzumab as a first-line treatment for patients with unresectable or metastatic HER2-positive breast cancer — a potential new standard of care in this setting.
This approval is grounded in the phase III DESTINY-Breast09 trial, which marked a major advancement in first-line therapy for HER2-positive disease.
In DESTINY-Breast09, the combination of T-DXd and pertuzumab:
- Reduced the risk of disease progression or death by ~44% compared with the established THP regimen (trastuzumab + pertuzumab + taxane).
- Delivered a median progression-free survival (PFS) of 40.7 months vs 26.9 months with standard THP.
- Showed a high confirmed objective response rate (~85.1%), with 15.1% complete responses.
Importantly, the safety profile was consistent with what we know for each agent, with no new safety signals identified in this first-line setting.
This milestone represents the first meaningful improvement in first-line induction therapy HER2-positive metastatic disease in more than a decade and underscores the impact of antibody-drug conjugate strategies.
Immense congratulations to the clinical investigators, patients and families who selflessly helped develop this drug through trials, and collaborative teams whose work made this possible. This advancement will meaningfully change how we treat patients with HER2-positive metastatic breast cancer.
What now?
Well – last SABCS 2024 we saw data from PATINA adding palbociclib to ET + HP once induction taxane had stopped. Significant improvement of PFS. This SABCS2025 we saw HER2CLIMB05 as a maintenence regimen for HR+ or HR- patients again once taxane was dropped showing a PFS benefit of adding tucatinib to HP maintenance.
We anticipate approvals in these maintenance regimens.
Important to note: DB-09 did NOT include a maintenence regimen, this trial continued T-DXd to progression. But with breast cancer being fast moving, I suspect we will all extrapolate this data and think to use maintenence therapy for most patients we treat.
The benefits in QoL of being off cytotoxic therapy for 2+ years is just too good to pass up for many. Will be important, particularly for T-DXd in a data-free zone, ‘how’ we go about doing that and I would suggest to at least treat to maximal radiologic response.”
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