In a new article published today in the Proceedings of the National Academies of Sciences, we have found that certain types of immunotherapy can increase cerebral edema (brain swelling) in patients and mice with glioblastoma tumors. The widely prescribed antihypertensive agent losartan overcomes this immune-related adverse event, enhances the immune response against the tumor, and conveys survival benefits that are associated with predictive biomarker signatures from the tumor prior to treatment.