Trial Demonstrates High Efficacy of Antibody-Drug Conjugate in Preventing Early-Stage Breast Cancer Recurrence

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.

The findings were published in the Journal of Clinical Oncology.

Trastuzumab Emtansine (T-DM1), known as an antibody-drug conjugate, is currently approved for post-surgical, or adjuvant, treatment of patients with HER2-positive breast cancer which remains after pre-surgical treatment and is also approved for patients with metastatic HER2-positive breast cancer.

The new study, a randomized phase II trial dubbed ATEMPT, involved patients with a stage 1 HER2-positive cancer, meaning it was small and without lymph node involvement.

Researchers also investigated biomarkers to predict cancer recurrence despite T-DM1 treatment. They utilised the HER2DX test, which evaluates clinical factors and the activity of four genes within tumour tissue. The findings indicated that patients with high scores on the HER2DX test had a greater risk of cancer recurrence.

The trial enrolled 512 patients across cancer centers with 384 participants receiving T-DM1 and 128 receiving chemotherapy and trastuzumab. Five years post-treatment, the T-DM1 group showed a 97% rate of no cancer recurrence. Additionally, the study highlighted that the rate of clinically relevant toxicities was similar in both groups. However, patient-reported outcomes revealed that those treated with T-DM1 experienced a better quality of life, reporting less neuropathy, less hair loss, and improved work productivity compared to those who received chemotherapy and trastuzumab.

Overall, the study underscored the potential of T-DM1 as an effective and well-tolerated treatment option for patients with early-stage HER2-positive breast cancer, particularly those at higher risk of 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.

Reference: Paolo Tarantino et al., Adjuvant Trastuzumab Emtansine Versus Paclitaxel Plus Trastuzumab for Stage I Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer: 5-Year Results and Correlative Analyses From ATEMPT. JCO 0, JCO.23.02170; DOI:10.1200/JCO.23.02170