BIOM-56. A FEASIBILITY STUDY UTILIZING SEQUENTIAL CEREBROSPINAL FLUID (CSF) - BASED LIQUID BIOPSY AND AMIDE PROTON TRANSFER (APT) MRI TO DIFFERENTIATE DISEASE PROGRESSION FROM RADIATION NECROSIS IN PATIENTS WITH BRAIN METASTASIS FROM SOLID TUMORS

Abstract BACKGROUND Brain metastases affect 30–40% of patients with solid tumors, and as systemic therapies improve survival, intracranial recurrences are more common. Radiation therapy is standard of care treatment but can frequently lead to radiation necrosis, which can mimic tumor progression on imaging. The lack of reliable and validated, non-invasive diagnostic methods to distinguish both can lead to diagnostic uncertainty, which can negatively impact treatment decisions and patient outcomes. Methyl-SaferSeqS is a digital next-generation sequencing approach which provides a comprehensive view of DNA alterations and is used to evaluate tumor-derived DNA in CSF. APT MRI is a newly emerging molecular imaging technique that generates image contrast based predominantly on the amide protons in mobile cellular proteins and peptides that are endogenous in tissue, with promising potentials for identifying radiation necrosis. METHODS We hypothesize that sequential CSF-based liquid biopsy, using Methyl-SaferSeqS, and APT MRI are both feasible and acceptable exams that can distinguish tumor progression from radiation necrosis in patients undergoing radiation therapy for brain metastases. Patients with newly diagnosed brain metastases requiring radiation therapy are enrolled. CSF-based liquid biopsy and APT MRI are performed prior to treatment, at the time of clinical/imaging suspicious findings for progression or radiation necrosis and subsequently until stabilization or definite diagnosis. Primary endpoints are acceptability and feasibility. We anticipate accrual of a total of 12 patients over 24 months. CONCLUSIONS We built an innovative multi-disciplinary collaboration clinical study investigating the acceptability and feasibility of sequential CSF-based liquid biopsy and APT MRI to differentiate disease progression from radiation necrosis in patients with brain metastases from solid tumors.