Tucatinib, Trastuzumab, and Capecitabine for the Treatment of HER2+ LMD

The purpose of this study is to evaluate a new treatment for patients with HER2+ metastatic breast cancer (MBC) with leptomeningeal disease (LMD). This is a rare and fast-growing form of cancer. Leptomeningeal disease refers to the seeding of tumor cells to the leptomeninges and dissemination in the cerebrospinal fluid. Currently, there are is no standard of care treatment for LMD. However, we think the combination therapy will be safe and well-tolerated and may also improve survival. Blood and spinal fluid samples will be collected to evaluate the effects on the body and the cancer, which will help provide greater understanding to therapy response in patients. The study has a two-stage design with the first stage including 15 subjects from up to ten institutions nationwide. If it advances to the second stage based on the number of successes, another 15 subjects will be enrolled.