June 2024- A year of treatment with a medicine made of an antibody and chemotherapy drug has proven highly effective in preventing stage 1 HER2-positive breast cancer from recurring in patients, a team led by Dana-Farber Cancer Institute researchers has found.

In a clinical trial involving 512 patients with the earliest stage of breast cancer that tested positive for the HER2 protein, 97% of those treated with trastuzumab emtansine (T-DM1) after surgery were alive and free of invasive cancer five years after treatment. The results, published online today in the Journal of Clinical Oncology, suggest that T-DM1 is a reasonable treatment approach for this stage 1 population, the study authors say.

Moreover, In conjunction with the trial, researchers looked for biomarkers of whether the cancer was likely to recur even after treatment with T-DM1. They found that patients with high scores on the HER2DX test – which weighs clinical factors and the activity of four genes within tumor tissue – had a greater risk of recurrence.

“Patients with stage 1 HER2-positive breast cancer have recurrence rates of 5 to 30%. Post-surgical treatment with chemotherapy and the antibody trastuzumab, which binds to HER2, can significantly reduce the risk of recurrence in these patients. But the side effects can have a detrimental impact on patients’ quality of life,” says study lead author Paolo Tarantino, MD, of Dana-Farber and the University of Milan (Italy). “In this study, we evaluated T-DM1, which links trastuzumab to a powerful chemotherapy agent, for effectiveness and toxicity in this group of patients.”

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Researchers enrolled 512 patients at cancer centers across the U.S., treating 384 with T-DM1 and 128 with chemotherapy and trastuzumab. Investigators found that, five years after treatment, 97% of patients receiving T-DM1 had no evidence of cancer recurrence. The rate of clinically relevant toxicities was similar in the T-DM1 group and the chemotherapy-and-trastuzumab group. However, patient-reported outcomes from this study shower better quality of life with T-DM1, that was associated with less neuropathy, less hair loss and better work productivity than chemotherapy and trastuzumab.

HER2DX testing showed that patients with a risk score above an established threshold had a significantly higher chance of cancer recurrence.

“The ATEMPT trial has taught us that one year of T-DM1 after surgery for patients with a stage 1 HER2-positive cancer leads to outstanding long term outcomes, making it a reasonable treatment approach for select patients,” says senior author Sara Tolaney, MD, MPH, Chief, Division of Breast Oncology, Dana-Farber Cancer Institute.

Genentech, Gloria Spivak Faculty Advancement Fund, and Susan G. Komen supported the trial.