INNV-25. POST-OPERATIVE LOW DOSE VERSUS STANDARD DOSE DEXAMETHASONE FOR MANAGEMENT OF CEREBRAL EDEMA: A RANDOMIZED, DOUBLE-BLINDED FEASIBILITY STUDY IN PATIENTS WITH PRIMARY OR METASTATIC BRAIN TUMORS UNDERGOING CRANIOTOMY FOR TUMOR RESECTION

Abstract INTRODUCTION Although dexamethasone is effective for controlling cerebral edema during the peri-operative period, its immunosuppressive properties can inhibit responses to immunotherapy. We hypothesized that patients with mild to moderate cerebral edema could be safely managed post-operatively with lower doses of dexamethasone. METHODS Eligible patients with brain tumors who had less than 10 mm of midline shift on their pre-operative brain MRIs were randomized 1:1 to the standard or low dose dexamethasone arm, each tapering double blinded through post-op day 8. The double blind was maintained using equivalent volumes for IV doses and capsules containing dexamethasone or placebo. By post-op day 9, participants received the same dose of dexamethasone and continued tapering to off by day 14. Additional doses of dexamethasone were allowed if needed, based on specified symptom criteria. Lack of feasibility was defined as a participant requiring 18 mg or more of dexamethasone in addition to the planned total dose of dexamethasone (low dose: 49 mg; standard dose: 112 mg). Brain MRIs were performed on post-operative days 1, 3, and 8 to evaluate changes in cerebral edema. Manual segmentation and computer-assisted techniques were used to quantitatively measure cerebral edema volume. RESULTS Twenty-six patients were randomized and treated within tumor type strata (primary versus metastatic), of which 25 were evaluable. None of the participants on the low dose dexamethasone arm met the criteria for lack of feasibility. The quantitative assessment of differences in cerebral edema between the arms is ongoing and will be presented. CONCLUSIONS Administration of lower doses of dexamethasone post-operatively to brain tumor patients with mild to moderate cerebral edema is feasible. Treatment with lower doses of dexamethasone post-operatively should be considered in this patient population when peri-operative administration of immunotherapy is planned.