Advertisment
Trastuzumab emtansine improves outcomes in HER2-positive breast cancer

Researchers report that adjuvant (post-surgical) trastuzumab emtansine (T-DM1) treatment of women with high-risk HER2-positive breast cancer has reduced their long-term risk of death or invasive disease by 46% and improved survival compared to trastuzumab monotherapy.
The final results of the phase 3 KATHERINE clinical trial were published on January 15, 2025 in the New England Journal of Medicine (NEJM).
“KATHERINE is a landmark clinical trial that found T-DM1 had such improved activity relative to trastuzumab that the results were reported earlier than had been anticipated when the study was originally designed. The results changed the standard of care globally for patients with HER2-positive early breast cancer,” said lead author Charles E. Geyer Jr., M.D., professor in the Division of Malignant Hematology and Medical Oncology at the University of Pittsburgh/Pitt School of Medicine, UPMC (University of Pittsburgh Medical Center) Hillman and UPMC Magee-Women’s Hospital. “We continued to follow patients to understand the full magnitude of the benefit, and we now show that T-DM1 leads to stable long-term improvements in invasive disease-free survival and improves overall survival.”
As background, the authors noted that T-DM1 combines trastuzumab and the chemotherapy agent emtansine. When trastuzumab attaches to the HER2 receptor on cancer cells, it opens the way for emtansine to more effectively attateck the cancer cells and to eliminate them.
The investigators enrolled and randomly assigned 1,486 subjects with HER2-positive early breast cancer with residual invasive disease in the breast or axilla after neoadjuvant systemic treatment with taxane-based chemotherapy and trastuzumab to receive either T-DM1 or trastuzumab for 14 cycles.
At 7-years follow up, they found that invasive disease-free survival was 80.8% for the adjuvant T-DM1 cohort and 67.1% for the trastuzumab monotherapy cohort.
Overall survival was 89.1% with T-DM1 and 84.4% with trastuzumab monotherapy.
Adverse events were higher in the T-DM1 cohort (26.1%) compared to the trastuzumab monotherapy cohort (15.7%). But the overall safety of T-DM1 was deemed to be acceptable.
The authors concluded, “As compared with trastuzumab, T-DM1 improved overall survival with sustained improvement in invasive disease–free survival among patients with HER2-positive early breast cancer with residual invasive disease after neoadjuvant therapy.”