Single-cell advances in the investigation of the pathogenesis and treatment of brain metastasis

Brain metastasis remains a significant cause of morbidity and mortality for cancer patients with limited treatment options. Single-cell RNA-seq has greatly expanded our ability to study cancer and metastasis, particularly in our assessment of tumor heterogeneity and the tumor microenvironment. In recent years, there have been several single-cell studies that have applied this technology to brain metastasis. These studies have described transcriptional characteristics of brain metastatic tumor cells and characterized immune cell changes as well as contributions of vascular and stromal cells to the brain metastatic microenvironment. This review article summarizes these studies, how they contribute to our knowledge of the molecular and cellular steps that occur in brain metastasis and in response to therapy, and how they suggest promise for future treatments.