Autoimmunity and benefit from trastuzumab treatment in breast cancer: Results from the HERA trial

Background/Aim: This study sought to determine whether an autoimmune background could identify patients with HER2-positive early breast cancer (EBC) who derive differential benefit from primary adjuvant trastuzumab-based therapy. Patients and Methods: HERA is an international randomized trial of 5,102 women with HER2-positive EBC, who were enrolled to either receive adjuvant trastuzumab or not. In this exploratory analysis, the interaction between autoimmune history and the magnitude of trastuzumab benefit was evaluated. Results: A total of 5,099 patients were included in the current analysis. Among them, 325 patients (6.4%) had autoimmune disease history, 295 of whom had active disease. Patients were randomly assigned to trastuzumab or no-trastuzumab groups. Similar reductions in the risk of events in patients with and without autoimmune history were observed (interaction p=0.95 for disease-free survival, and p=0.62 for overall survival). Conclusion: No evidence of a differential benefit from trastuzumab in patients with a medical history of autoimmune disease was found.