Adjuvant Trastuzumab Emtansine Improves Overall Survival in HER2+ Breast Cancer

THURSDAY, Jan. 16, 2025 (HealthDay News) — For patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer, adjuvant trastuzumab emtansine (T-DM1) improves overall survival more than trastuzumab alone, according to a study published in the Jan. 16 issue of the New England Journal of Medicine.

Charles E. Geyer Jr., M.D., from the National Surgical Adjuvant Breast and Bowel Project Foundation in Pittsburgh, and colleagues randomly assigned patients 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 14 cycles of T-DM1 or trastuzumab (743 individuals in each treatment group).

With a median follow-up of 8.4 years, the researchers found that T-DM1 sustained the improvement in invasive disease-free survival over trastuzumab (unstratified hazard ratio for invasive disease or death, 0.54; 95 percent confidence interval, 0.44 to 0.66). Seven-year invasive disease-free survival was 80.8 and 67.1 percent with T-DM1 and trastuzumab, respectively. A significantly lower risk for death was seen with T-DM1 versus trastuzumab (unstratified hazard ratio, 0.66; 95 percent confidence interval, 0.51 to 0.87; P = 0.003). Seven-year overall survival was 89.1 and 84.4 percent, respectively, with T-DM1 and trastuzumab. In 26.1 and 15.7 percent of patients in the T-DM1 and trastuzumab groups, respectively, adverse events of grade 3 or higher were noted.

“This prespecified long-term follow-up analysis provides additional support for the neoadjuvant therapy paradigm by showing that adjuvant T-DM1 also provided a significant improvement in overall survival and no evidence of long-term safety issues,” the authors write.

The study was funded by F. Hoffmann-La Roche/Genentech, the manufacturer of trastuzumab emtansine.

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