In the absence of clinically available biomarkers for CNS malignancies, the conventional method for disease monitoring in glioma patients is radiologic. While most cancers shed cell-free molecules of tumor-derived DNA into the circulation, brain tumors form the exception to this rule, rarely shedding detectable levels of tumor DNA into the bloodstream. Microbubble-enhanced focused ultrasound (MB-FUS) is a rapidly emerging clinical tool to safely open the blood-brain barrier (BBB) for enhanced neurotherapeutic delivery and liquid biopsy. Previous work demonstrated MB-FUS treatments in infiltrating gliomas using multi-transducer systems with embedded acoustic emissions (AEMs) monitoring. In this study, we analyzed serum samples from a Phase 1 clinical trial of combined MB-FUS BBB opening with adjuvant temozolomide treatment of the tumor-infiltrated brain regions surrounding the surgical resection cavity of patients with newly diagnosed glioblastoma. The analysis evaluated the technical and treatment parameters associated with BBB opening, circulating DNA levels, and other biomarkers of MB-FUS effects. We analyzed serum samples using Real-SeqS and ELISA to quantify biomarker levels in longitudinal serum fluid samples derived from 13 patients undergoing repeated cycles of MB-FUS plus temozolomide. Our work and others in the field establish the potential for MB-FUS-enabled, non-invasive biopsy of gliomas, which would fundamentally advance the diagnosis, monitoring, and management of brain tumors.