FDA expands Enhertu use in early HER2-positive breast cancer

The FDA approved Enhertu, also called fam-trastuzumab deruxtecan-nxki, on May 15, 2026, for two separate uses in adults with HER2-positive early-stage breast cancer. One use is before surgery for stage II or III disease. The other is after surgery for people who still have invasive cancer left after earlier neoadjuvant treatment.

For patients and families, the big takeaway is that this is a treatment update, not a screening change. It may matter only for people whose tumor tests HER2-positive and whose cancer stage and treatment history match the new label.

What the FDA approved

According to the FDA, the first indication is Enhertu followed by a taxane, trastuzumab, and pertuzumab for neoadjuvant treatment of adults with HER2-positive stage II or III breast cancer, as determined by an FDA-authorized test. The second indication is Enhertu for adjuvant treatment in adults with HER2-positive breast cancer who have residual invasive disease after neoadjuvant treatment with trastuzumab, with or without pertuzumab, and a taxane-based regimen.

The agency also approved companion diagnostic tests used to identify HER2-positive patients for treatment decisions. In plain terms, the drug is not for every breast cancer diagnosis; the tumor has to meet the HER2 criteria in the label.

Who may qualify

The FDA’s language points to adults with HER2-positive breast cancer, defined in this approval as IHC 3+ or ISH+, and to specific clinical situations. The neoadjuvant use is for stage II or III disease before surgery. The adjuvant use is for people who still have invasive disease after prior neoadjuvant treatment.

That means a person’s stage, pathology report, and treatment history all matter. A HER2 test result alone is not enough to know whether this approval applies.

What DESTINY-Breast11 showed

The FDA says the neoadjuvant approval was based on DESTINY-Breast11, a randomized, three-arm, open-label trial that enrolled 927 adults with HER2-positive, high-risk, early-stage breast cancer. In the main analysis, the arm that received Enhertu followed by the trastuzumab/pertuzumab-based regimen had a higher pathologic complete response rate than the doxorubicin/cyclophosphamide plus trastuzumab/pertuzumab arm.

Pathologic complete response, or pCR, means no invasive cancer was found in the breast or axillary lymph nodes at surgery. That is an important short-term marker, but it is not the same as proving longer survival benefits on its own. The FDA notes that event-free survival and overall survival were not statistically controlled or powered in that study, so the neoadjuvant result should be read as meaningful but not final.

What DESTINY-Breast05 adds

The adjuvant approval was supported by DESTINY-Breast05, a randomized trial of 1,635 adults with residual invasive disease after neoadjuvant therapy. In that study, Enhertu was compared with trastuzumab emtansine, often called T-DM1.

At three years, the invasive disease-free survival rate was higher in the Enhertu group than in the T-DM1 group. That makes the adjuvant data especially important because it looks beyond an early response measure and into recurrence-related outcomes. Even so, the broader question of how much this improves long-term survival over more years of follow-up will still matter.

Safety issues to watch

The FDA says Enhertu’s prescribing information includes a boxed warning for interstitial lung disease and pneumonitis. It also includes warnings and precautions for neutropenia and left ventricular dysfunction. Those are not rare details to skim over; they are part of why patients need close monitoring during treatment.

In practical terms, people taking a therapy like this should know that new cough, shortness of breath, fever, or other breathing changes deserve prompt attention. Oncology teams also monitor blood counts and heart function because treatment can affect both.

Why this is not a screening or prevention update

This approval changes treatment options after a diagnosis is made. It does not change who should get screened for breast cancer, when mammograms should start, or how to prevent breast cancer in the general population.

HER2 is a tumor biomarker used to guide treatment. It is not a general population screening test.

What patients and caregivers can ask

People navigating a new HER2-positive diagnosis may want to ask:

What did my HER2 test show, and was it IHC 3+ or ISH+?
What is my stage, and does this approval apply to my situation?
Was surgery already done, and is there residual invasive disease?
How does Enhertu compare with the treatment already planned for me?
What side effects should I watch for, and how will you monitor my heart and lungs?

For anyone having new or worsening breathing symptoms during cancer treatment, the safest next step is to contact the oncology team promptly. Sudden or severe shortness of breath, chest pain, or trouble breathing should be treated as urgent.

For readers following the research, the American Cancer Society notes that HER2-positive disease is one of the main breast cancer subtypes and that targeted therapies have improved outcomes over time. This new approval fits that larger pattern, but it is still a specific treatment decision for a specific group of patients.

Sources

Editorial note: Weence articles are researched from cited public-health, medical, regulatory, journal, and reputable news sources and may be drafted with AI assistance. They are checked for source support, clarity, and safety guardrails before publication.

This article is for general informational purposes only and is not medical advice. Research findings can be early or incomplete, and health guidance can change. Always talk with a qualified healthcare professional about personal symptoms, diagnosis, medications, vaccines, screenings, or treatment decisions. If you think you may have a medical emergency, call emergency services right away.