ERBB2 and breast cancer: No late-phase studies have been done on patients with BrM, however, a phase I trial study is currently recruiting to investigate the side effects and best dose of HER2-CAR T cells injected intra-ventricularly in treating patients with brain or leptomeningeal metastases from HER2+ breast cancer (https://clinicaltrials.gov/ct2/show/NCT03696030).