SABCS 2018: Adjuvant Therapies for HER2-Positive Breast Cancer Compared in KATHERINE Trial
Posted: Wednesday, December 19, 2018
Substituting ado-trastuzumab emtansine (T-DM1) for trastuzumab as adjuvant therapy “substantially improved” invasive disease–free survival for certain patients with HER2-positive early breast cancer that had progressed, according to data from the phase III KATHERINE trial. Charles E. Geyer, Jr, MD, of the Virginia Commonwealth University Massey Cancer Center, Richmond, and colleagues presented these results at the 2018 San Antonio Breast Cancer Symposium (SABCS; Abstract GS1-10) with publication in The New England Journal of Medicine.
This open-label, global phase III study focused on 1,486 patients with HER2-positive breast cancer who had residual invasive disease after completing neoadjuvant therapy plus HER2-targeted therapy. The investigators found that adjuvant T-DM1 improved invasive disease–free survival, the study’s primary endpoint. The risk of developing an invasive recurrence was reduced by 50% (P < .0001). Patients were randomly assigned 1:1 to receive treatment with T-DM1 or trastuzumab every 3 weeks for 14 cycles.
“After review of the prespecified interim analysis, the independent data monitoring committee recommended full analysis and disclosure of the results,” noted Dr. Geyer and colleagues. “Invasive disease–free survival events occurred in 91 patients (12.2%) in the T-DM1 arm compared with 165 patients (22.2 %) in the trastuzumab arm.” T-DM1 treatment increased the estimated 3-year invasive disease–free survival rates (88.3% vs. 77.0% with trastuzumab), yet the overall survival analysis remains immature (hazard ratio = 0.70, P = .085). Safety data were consistent with T-DM1’s known profile.
