Treatment With Tucatinib in Patients With an Isolated Brain Progression of a Metastatic Breast Cancer

The overall survival of patients with metastatic breast cancer has steadily improved over the past decades, mainly due to advances in systemic treatment. Despite these advances, the development of brain metastases remains a serious and devastating complication that decreases quality of life and increases morbidity and mortality. The HER2CLIMB randomized study demonstrated that adding the investigational drug tucatinib to the standard treatment trastuzumab and capecitabine improved both progression-free survival and overall survival in people diagnosed with human epidermal growth factor 2 (HER2)-positive metastatic breast cancer, previously treated with trastuzumab, pertuzumab, and T-DM1. In patients with brain metastases, the 1-year progression-free survival was 25% in the tucatinib group and 0% in the placebo group. These results suggest that tucatinib may be a new standard treatment for HER2-positive metastatic disease. The aim of the non-randomized phase II study, InTTercePT, is to evaluate the effectiveness of adding tucatinib to trastuzumab and pertuzumab in the event of cerebral progression, after the end of local treatment.