City of Hope scientists have co-led research that characterizes extrachromosomal DNA (ecDNA) in brain tumors, linking these structures to oncogene activity and hypoxic tumor microenvironments. The study, published in Nature Communications, offers foundational data connecting ecDNA prevalence with key cancer drivers such as EGFR and p53 mutations. The findings may inform precision medicine approaches by elucidating how ecDNA reshapes the tumor microenvironment, resistance mechanisms, and progression pathways, ultimately guiding personalized therapies for aggressive brain cancers.