New treatment option for HER2-positive early-stage breast cancer: What to know

If you’ve been diagnosed with HER2-positive early-stage breast cancer, you may have questions about what your HER2 status means and whether recent treatment advances could affect your care.

In May 2026, the U.S. Food and Drug Administration (FDA) approved trastuzumab deruxtecan, or T-DXd (Enhertu), for two uses in HER2-positive early-stage breast cancer: before surgery for certain people with stage II or III disease and after surgery for people who have residual invasive disease following treatment before surgery.

These approvals are an important development because they bring a newer type of HER2-targeted treatment into earlier stages of breast cancer, when the goal is to eliminate cancer and reduce the risk of recurrence.

What is T-DXd?

T-DXd is a type of treatment called an antibody-drug conjugate (ADC).

An ADC combines a targeted antibody with a chemotherapy drug. The idea is to use the antibody to help deliver the chemotherapy directly to cancer cells.

Medical oncologist Dr. Sara Hurvitz describes this process as being similar to a “Trojan horse.” The antibody portion of T-DXd recognizes HER2 on the cancer cell, attaches to it, and is taken inside the cell. Once inside, the chemotherapy payload is released.

As Dr. Hurvitz explains, “the antibody goes and finds the cells with overexpression of HER2 on the cell surface, binds to the HER2, and is taken up into the cell, and the bomb goes off.”

Its chemotherapy payload can also affect nearby cancer cells, including some that may have lower levels of HER2. Dr. Hurvitz explains that the “bomb itself is able to leave the cancer cell that it’s killed and kill neighboring tumor cells that may not have HER2 expression [or] high expression.”

What did the FDA approve in 2026?

The FDA recently approved T-DXd for two different situations in HER2-positive early-stage breast cancer.

Before surgery

For adults with HER2-positive stage II or stage III breast cancer, T-DXd followed by a taxane, trastuzumab, and pertuzumab (THP) is now FDA-approved as neoadjuvant treatment, meaning treatment given before surgery.

The approval was based on results from the phase III DESTINY-Breast11 trial, which included 927 adults with high-risk, early-stage HER2-positive breast cancer.

Researchers found that 67.3% of patients who received T-DXd followed by THP had a pathologic complete response (pCR), compared with 56.3% of patients who received dose-dense doxorubicin and cyclophosphamide followed by THP.

A pCR means that no invasive cancer could be found in the breast or nearby lymph nodes at the time of surgery. A pCR is an encouraging sign and is associated with better outcomes for many people with early-stage breast cancer. 

After surgery when cancer remains

The FDA also approved T-DXd as adjuvant treatment, which is treatment given after surgery, for adults with HER2-positive breast cancer who have residual invasive disease.

This is important because sometimes cancer treatment given before surgery doesn’t completely eliminate invasive cancer. Finding residual disease at surgery can indicate a higher risk of recurrence.

The approval was based on the phase III DESTINY-Breast05 trial, which compared T-DXd with trastuzumab emtansine, or T-DM1, in people with residual invasive HER2-positive breast cancer after neoadjuvant treatment.

For these patients, additional treatment after surgery provides another opportunity to reduce the risk of the cancer returning.

Why does treatment before surgery matter?

One of the important changes in early-stage breast cancer treatment is the increasing use of neoadjuvant therapy, or treatment before surgery.

Treating breast cancer before surgery can attack cancer cells throughout the body while also shrinking or eliminating the tumor in the breast. It also gives doctors an opportunity to see how the cancer responds.

If no invasive cancer remains at surgery, this response can provide important information about prognosis. If cancer remains, that information can help doctors determine whether additional treatment after surgery may be beneficial.

The new approvals provide another treatment option at both of these important points in care.

What should you ask your oncologist?

If you have HER2-positive early-stage breast cancer, consider asking your care team:

• What is my exact HER2 test result?
• Is treatment before surgery recommended for me?
• Could T-DXd be an option in my treatment plan?
• How will we know whether my cancer is responding to treatment?
• If cancer remains after surgery, what additional treatment might I need?
• How does my hormone receptor status affect my treatment plan?
• What side effects should I watch for, and how can they be managed?

If you’ve recently been diagnosed with HER2-positive early-stage breast cancer, talk with your oncology team about how the latest treatment options may fit into your individual treatment plan.

Disclaimer: The information provided in this article is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Outcomes4Me is not acting as your caregiver, and any suggestions or guidance offered should not replace the advice of your healthcare provider or qualified medical professional. Always seek the guidance of your physician or other qualified health provider with any questions you may have regarding a medical condition.