T-DM1 for HER2-Positive Disease That Doesn’t Fully Respond to Neoadjuvant Chemotherapy

HER2-positive early breast cancer patients who have cancer remaining in their breast or lymph nodes after neoadjuvant (before surgery) chemotherapy plus HER2-targeted therapy have a high risk of recurrence and death. KATHERINE is a phase III clinical trial that randomized node-positive patients of all stages who did not fully respond to chemotherapy before surgery to receive T-DM1 (Kadcyla) or trastuzumab (Herceptin) for 14 cycles after surgery. They sought to answer the question of whether substituting T-DM1 for trastuzumab would improve outcomes. T-DM1 is an antibody drug conjugate that consists of the HER2 antibody joined with the chemotherapy drug, maytansinoid DM1. When T-DM1 interacts with HER2 receptors on the surface of cancer cells, it gets taken up by the cells and the chemotherapy drug is released into the cell. Analysis of the KATHERINE trial data showed that giving T-DM1 after surgery instead of trastuzumab resulted in a clinically meaningful improvement in invasive disease-free survival (IDFS). Three-year IDFS improved from 77% to 88.3% with T-DM1. This benefit was seen regardless of hormone receptor (ER/PR) status and the extent of disease that remained after chemotherapy. More follow-up is pending to evaluate the effect of T-DM1 on overall survival; however, T-DM1 is likely an essential part of the new standard of care for this patient population.
(Abstract GS1-10) Highlights from the 2018 San Antonio Breast Cancer Symposium
By Anh Diep, VMD, PhD Candidate, and Erika Bell, PhD, Manager of Medical Information, Bay Area Cancer Connections
​In early December 2018, thousands of researchers from across the world convened in San Antonio, Texas, for the 41st Annual San Antonio Breast Cancer Symposium. This five-day symposium brought together experts in basic, translational, and clinical research; clinicians; and patient advocates to present and discuss advances in breast cancer research and treatment. As progress in breast cancer continues, the challenges remain: to personalize treatment based on characteristics of the cancer, to minimize over- and under-treatment, and to maximize quality of life. This article highlights several of the talks from the 2018 symposium that are most likely to have a direct impact on the clinical care of breast cancer patients. For access to complete symposium resources, including abstracts, posters, and presentations, visit sabcs.org.