Approximately 15-to-30 percent of patients with metastatic breast cancer have brain metastasis (BM), with basal-like breast cancer (BLBC) metastasizing to the brain most frequently. The prognosis for BLBC-BM patients is poor, as the blood-brain barrier prevents most therapeutics from reaching the brain. Testing candidate therapies in clinical trials is also challenging because animal models that mimic BM are limited. In a new study, researchers from Brigham and Women’s Hospital and collaborators engineered a bimodal tumor-suppressing and killing molecule that can be delivered to the brain by stem cells. They tested the therapy in three new mouse models of BLBC-BM that imitate human cancers and found that it successfully prolonged the lifespan of the mice. Findings are published in Science Advances.