A Step Forward in the Treatment of HER2-Positive Breast Cancer

A major breakthrough in the treatment of high-risk HER2-positive breast cancer: adjuvant therapy with trastuzumab emtansine (T-DM1) has been shown to significantly improve survival, paving the way for increasingly effective and personalized therapies to enhance the lives of patients worldwide.

According to the final results of the phase 3 KATHERINE clinical trial, conducted by researchers from the University of Pittsburgh and the UPMC Hillman Cancer Center oncology network, T-DM1 reduced the risk of death or disease progression by 46% compared to standard treatment with trastuzumab.

Significant Long-Term Improvements

Published in the New England Journal of Medicine, the results confirm that treatment with T-DM1 improves invasive disease-free survival (iDFS) and overall survival (OS). After seven years of follow-up, the iDFS rate was 80.8% in patients treated with T-DM1, compared to 67.1% in those who received trastuzumab alone. Overall survival was also higher: 89.1% with T-DM1 versus 84.4%.

"These results have changed the global standard of care for HER2-positive breast cancer," said lead author Dr. Charles E. Geyer Jr., professor in the Division of Malignant Hematology and Medical Oncology at the University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, and UPMC Magee-Womens Hospital. "We have shown that T-DM1 not only reduces the risk of recurrence but provides stable and lasting survival benefits."

How T-DM1 Works

T-DM1 is an antibody-drug conjugate that combines trastuzumab with a chemotherapeutic agent, emtansine. This innovative approach works like a "Trojan horse": trastuzumab binds to the HER2 receptor on cancer cells, allowing emtansine to penetrate the malignant cells and destroy them from within.

Uniform Benefits Across All Subgroups

A key element of the study was the consistent benefit of T-DM1 across all patient subgroups, regardless of factors such as disease extent, hormone receptor status, or ethnicity. This result underscores the universal efficacy of T-DM1 as an adjuvant treatment for HER2-positive breast cancer.

Toward New Milestones

Despite significant progress, Dr. Geyer emphasizes that the work is not yet complete. The research team is currently investigating a new antibody-drug conjugate, trastuzumab deruxtecan (T-DXd), for patients with low levels of HER2 expression.

"We won't stop until we achieve 100% disease-free survival for all patients," said Dr. Geyer.

The KATHERINE clinical trial was funded by Hoffmann-La Roche/Genentech.

Read the press release: Trastuzumab Emtansine Improves Overall Survival in HER2 Breast Cancer