Enhertu Shows Real-World Success for HER2-Low Metastatic Breast Cancer

While Enhertu (trastuzumab deruxtecan, T-DXd) is an established treatment for patients with HER2-low metastatic breast cancer (mBC), there has been limited information about how well it works for patients treated in everyday community cancer clinics.

To address this, researchers conducted a study reviewing medical records from community oncology patients to understand who is receiving Enhertu and how they are doing after starting the medicine, with findings presented this week at the 43^rd Annual Miami Breast Cancer Conference, held March 5 to 8.

Understanding the Real-World Patient Population

The study looked at 300 randomly sampled adult patients with HER2-low mBC. This real-world group appeared to be older, frailer and more heavily pretreated than typical patients found in clinical trials. The average age was 63.5 years, and most patients were age 65 or older. About 22.7% of patients had an impaired performance status, meaning they had more difficulty with daily activities, and 39.3% had at least one other health problem or comorbidity.

Regarding the type of cancer, 77% of the patients had hormone receptor-positive (HR+) disease, while 23% had hormone receptor-negative (HR–-) disease. About one-fourth (24.7%) of the patients were diagnosed with metastatic disease from the very beginning.

Treatment Patterns and Sequencing

Most patients (87.3%) received Enhertu as a single therapy rather than in combination with other drugs. There were notable differences in when patients started Enhertu based on their hormone receptor status. For those with HR+ disease, 88.7% received Enhertu as their third line of treatment or later. In contrast, only 53.6% of HR–- patients received it that late in their treatment journey.

Clinical Effectiveness and Survival

Overall, Enhertu showed favorable effectiveness in this diverse community setting. On average, patients went more than seven months before their cancer worsened, and more than half of the patients saw their tumors shrink.

The study measured "real-world progression-free survival," which is the time from starting the drug until the cancer grows or the patient passes away. For the whole group, this was 7.4 months. When broken down by hormone receptor status, it was 7.7 months for HR+ patients and 4.9 months for HR–- patients. Additionally, about 62% of all patients were alive one year after starting the treatment.

Specific Findings for Subgroups

The research found that certain groups of patients had particularly positive results:

• Patients with HR+ disease who had not received prior chemotherapy for their metastatic cancer did especially well. These "chemo-naive" patients had a longer time before their cancer worsened (10.2 months) compared to those who had received prior chemotherapy (7.4 months).
• Among the chemo-naive HR+ patients, 74% were alive at the one-year mark, and 71% saw their tumors shrink.
• The treatment worked similarly for patients whether or not the cancer had spread to the brain. Patients with brain metastases had a progression-free survival of 6.3 months, which was numerically similar to the 7.5 months seen in patients without brain metastases.

Implications for Care

These findings support using Enhertu across a wide range of real-world patients in community cancer settings. Even though the patients in this study were often older or had more health problems than those in highly controlled clinical trials, the medicine still demonstrated favorable effectiveness. This suggests that the benefits of Enhertu extend to the diverse types of patients seen in everyday medical practice.

Reference:

1. “Trastuzumab deruxtecan in HER2-low metastatic breast cancer: real-world treatment patterns and outcomes from community oncology settings” by Marvin Nguyen et al., poster presented at 43rd Annual Miami Breast Cancer Conference; March 2026; Miami, FL.

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