The FDA approves T-DXd (fam-trastuzumab deruxtecan-nxki; Enhertu) for two separate indications in adults with HER2-positive early-stage breast cancer, marking a major expansion of the drug into curative-intent disease. The first approval is for neoadjuvant treatment in patients with Stage II or III HER2-positive disease, using T-DXd for four cycles followed by taxane, trastuzumab, and pertuzumab. The second is for adjuvant treatment in patients who still have residual invasive disease after neoadjuvant HER2-directed therapy. The agency also approved two companion diagnostics to identify eligible HER2-positive patients, consistent with the labeled IHC 3+ or ISH+ requirement.
A New Neoadjuvant Option Based on DESTINY-Breast11
The neoadjuvant approval was supported by DESTINY-Breast11, a randomized phase 3 trial that enrolled 927 adults with high-risk, HER2-positive early-stage breast cancer. In the key comparison, patients treated with four cycles of T-DXd followed by four cycles of THP achieved a centrally assessed pathologic complete response rate of 67.3%, compared with 56.3% for the anthracycline-containing ddAC-THP regimen. That difference was statistically significant, with a reported p value of 0.003.
This is an important result because it places T-DXd much earlier in the treatment pathway and supports a strategy designed to intensify biologic HER2 targeting before surgery. At the same time, the FDA noted an important limitation: the secondary endpoints of event-free survival and overall survival in DESTINY-Breast11 were not statistically controlled or powered. In other words, the neoadjuvant approval rests primarily on the pathologic complete response advantage, with supportive context coming from the separate adjuvant DESTINY-Breast05 trial.
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DESTINY-Breast05 Strengthens the Post-Neoadjuvant Case
The adjuvant approval is arguably even more practice-shaping because it addresses one of the highest-risk HER2-positive early breast cancer populations: patients with residual invasive disease after neoadjuvant therapy. DESTINY-Breast05 randomized 1,635 adults to receive either T-DXd or T-DM1 for up to 14 cycles. At three years, invasive disease-free survival was 92.4% with T-DXd versus 83.7% with T-DM1, corresponding to a hazard ratio of 0.47. Disease-free survival results were almost identical, again with a hazard ratio of 0.47 and a highly significant p value below 0.0001.
These data are clinically meaningful because T-DM1 has been the established post-neoadjuvant standard after residual disease since KATHERINE. A hazard ratio of 0.47 suggests a substantial reduction in invasive recurrence or death, and this degree of benefit is exactly why the FDA granted priority review and previously recognized the adjuvant indication with breakthrough therapy designation. Overall survival data remain immature, with 47 deaths reported across both study arms at the time of the invasive disease-free survival analysis, so long-term follow-up will still matter.
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What This Means for HER2-Positive Early Breast Cancer
Taken together, these two approvals move T-DXd into two of the most clinically important decision points in early HER2-positive breast cancer. First, it now has an FDA-approved neoadjuvant role in Stage II or III disease before standard THP. Second, it has an approved adjuvant role for patients with residual invasive disease after neoadjuvant HER2-targeted treatment. That creates a much broader early-stage footprint for a drug that had already become central in metastatic HER2-positive breast cancer.
The bigger clinical implication is that T-DXd is no longer being used only as a later-line rescue strategy. It is now being used earlier, in settings where cure is still the goal. That shift matters because it reflects growing confidence in the drug’s activity, but it also raises important future questions about sequencing, long-term toxicity, and how best to individualize therapy across the neoadjuvant and post-neoadjuvant continuum. Those questions will become even more relevant as clinicians interpret pCR-based benefit in one setting and invasive disease-free survival benefit in another.
Safety Still Requires Close Attention
The approval does not change the need for careful monitoring. The prescribing information includes a boxed warning for interstitial lung disease and pneumonitis, along with warnings for neutropenia and left ventricular dysfunction. In the neoadjuvant setting, the recommended dose is 5.4 mg/kg every three weeks for four cycles followed by THP for four cycles. In the adjuvant setting, the recommended dose is 5.4 mg/kg every three weeks for up to 14 cycles unless recurrence or unacceptable toxicity occurs.
That safety profile remains central to real-world adoption. T-DXd is highly active, but it is not a low-intensity drug, and its use in patients being treated with curative intent requires a different level of caution than in the metastatic setting. The benefit is clearly compelling, especially after residual disease, but multidisciplinary teams will need to be thoughtful about pulmonary monitoring, cardiac assessment, and overall treatment tolerance.
Why This Approval Stands Out
FDA Approves T-DXd in a decision that matters not only because it broadens access to the drug, but because it highlights how rapidly HER2-positive early breast cancer treatment is evolving. The neoadjuvant approval reflects growing confidence in the depth of response achieved with T-DXd-based therapy, while the adjuvant approval offers clinicians a stronger option than T-DM1 for patients with residual invasive disease after preoperative treatment. For HER2-positive early-stage breast cancer, May 15, 2026 may stand out as one of the most consequential recent approval dates.
Read About All DESTINY-Breast Trials on OncoDaily