The European Union has approved Enhertu for some people with an early, high-risk form of breast cancer, to be given after surgery. It is the drug’s first EU approval in early breast cancer, where the goal of treatment is cure, according to the companies that make it1.
The decision covers adults with HER2-positive breast cancer who had drug treatment before their operation, but who still had invasive cancer left in the tissue removed at surgery1. HER2 is a growth-promoting protein on the surface of cells. When cancer cells make too much of it, the disease is often more aggressive2. In the UK, around one in five breast cancer cases is HER2-positive3.
What happened
The European Commission granted the approval on the advice of the European Medicines Agency’s committee for human medicines, which had given a positive opinion1. Enhertu (trastuzumab deruxtecan) is approved as a monotherapy, meaning it is given on its own, in the “adjuvant” setting: treatment after surgery meant to lower the chance the cancer comes back1.
To qualify, patients must have had earlier “neoadjuvant” treatment, given before surgery to shrink the tumor, that included a taxane chemotherapy and a HER2-targeted drug1. The companies said this is the third EU approval for Enhertu in four months1.
Enhertu is an antibody-drug conjugate: an antibody aimed at HER2, joined to a second drug component. It was discovered by Daiichi Sankyo and is developed and sold jointly by Daiichi Sankyo and AstraZeneca1.
The evidence: a head-to-head trial
The approval rests on a trial called DESTINY-Breast05. It was a Phase 3 study, the large final stage of testing before approval, presented at the European Society for Medical Oncology meeting in 2025 and then published in The New England Journal of Medicine1.
The trial did not compare Enhertu with a dummy treatment. It compared it with trastuzumab emtansine, known as T-DM1, an older drug already used in this situation1. That matters: the result shows how Enhertu did against an existing option, not against nothing.
The companies reported these main results1:
- Enhertu lowered the risk of invasive cancer coming back, or death, by 53% compared with T-DM1. In statistical terms the hazard ratio was 0.47, with a range of likely values from 0.34 to 0.66.
- At three years, 92.4% of people on Enhertu were alive and free of invasive cancer, against 83.7% on T-DM1.
- A broader measure that also counted non-invasive returns of disease gave almost the same picture: 92.3% against 83.5% at three years, again a 53% lower risk.
Put simply, out of every 100 people, about 92 on Enhertu and about 84 on the older drug had no invasive cancer return and were alive three years on, by the trial’s figures1.
Sibylle Loibl of the German Breast Group and Goethe University Medicine Frankfurt, the trial’s lead investigator, said in the companies’ announcement:
“For patients with HER2 positive early breast cancer and residual invasive disease after neoadjuvant therapy, reducing the risk of disease recurrence is critical for sustained long-term outcomes.”1
Side effects
The companies said the safety profile in DESTINY-Breast05 matched what was already known about Enhertu, with no new safety concerns1. The announcement did not give side-effect rates from this trial alone. Instead it gave pooled figures from 4,146 patients who received the drug at the same dose across many cancer types1.
In that pooled group, the most common severe side effects were low levels of a type of white blood cell (18.7%), low red blood cells (8.2%) and fatigue (7.4%), followed by other drops in blood counts, nausea, changes in liver tests, diarrhea and vomiting1. Side effects that led to death occurred in 0.9% of patients, including lung inflammation, called interstitial lung disease or pneumonitis, in 0.8%1.
What it does not show yet
The main results cover about three years after treatment1. The approval announcement did not report whether Enhertu helps people live longer overall than T-DM1, so that question remains open in these sources.
The announcement also did not give the number of people in the trial. Its side-effect numbers come from patients with many kinds of cancer, not only from this group of early breast cancer patients1. And the result applies to a specific situation: people who still had cancer at surgery after earlier treatment. It does not speak to everyone with HER2-positive breast cancer.
Who is behind it
The results and the quoted comments come from the companies’ announcement. Besides Loibl, the statement quoted Ken Keller, Daiichi Sankyo’s global head of oncology business, and Dave Fredrickson, who leads AstraZeneca’s oncology hematology business unit1. Fredrickson said the approval had “the potential to establish a new benchmark” in this setting1.
There is money attached. The EU approval triggers a $75 million milestone payment from AstraZeneca to Daiichi Sankyo1. The two companies have worked together on the drug since March 2019; they share it worldwide except in Japan, where Daiichi Sankyo holds exclusive rights, and Daiichi Sankyo handles manufacturing4.
How it fits with earlier approvals
Enhertu was first approved for advanced breast cancer that had spread. The UK, for example, gave it a conditional approval in 2021 for people whose HER2-positive cancer had spread and who had already had two or more HER2 treatments3. It is now approved in nearly 100 countries for HER2-positive breast cancer that has spread5.
Over the past year it has moved earlier in treatment. In March 2026, China gave a conditional approval for Enhertu before surgery, followed by other drugs, based on a separate trial called DESTINY-Breast114. In May 2026, the US Food and Drug Administration approved it both before surgery and after surgery, based on DESTINY-Breast11 and DESTINY-Breast055. Those US approvals came with $155 million in milestone payments to Daiichi Sankyo5. At that time, AstraZeneca’s Fredrickson said that “up to 1 in 4 patients still experience disease recurrence” in HER2-positive early breast cancer5.
The companies now say Enhertu is approved in more than 35 countries and regions for use after surgery in this group, based on DESTINY-Breast051.
Europe is also weighing other uses. In May 2026, the EU medicines committee recommended Enhertu for HER2-positive tumors of many types that had spread, and AstraZeneca said the DESTINY-Breast05 filing was then under EU review2. In July 2026, the committee recommended Enhertu with pertuzumab as a first treatment for HER2-positive breast cancer that has spread, based on a trial showing a 44% lower risk of the disease worsening or death6.
Biohack recently covered another drug of the same broad type in a different cancer: a targeted drug that cut death risk 32% in advanced womb cancer.
What to watch next
- Longer follow-up from DESTINY-Breast05, including whether the gap in cancer returning holds and whether it affects overall survival.
- Decisions on access in individual European countries, which approval alone does not settle.
- Use before surgery in Europe, after the US and China approved Enhertu in that earlier step based on DESTINY-Breast1154.
- Copies of the drug: Samsung Bioepis said in January 2026 it was adding a biosimilar, a close copy, of trastuzumab deruxtecan to its pipeline, at an early stage before lab testing in animals4.
