QOLP-23. PHASE II RANDOMISED PLACEBO-CONTROLLED DOUBLE-BLIND STUDY OF ACETAZOLAMIDE VERSUS PLACEBO FOR CEREBRAL OEDEMA IN RECURRENT AND/OR PROGRESSIVE HIGH-GRADE GLIOMA REQUIRING TREATMENT WITH DEXAMETHASONE

INTRODUCTION Symptoms of raised intracranial pressure (ICP) in recurrent or progressive high-grade glioma (HGG) generally require corticosteroid treatment, often causing toxicity with variable effects on reversing ICP symptoms. Acetazolamide reduces ICP in other clinical settings including case series in glioma. AIM To explore whether addition of oral acetazolamide enables safe dexamethasone dose reduction in management of raised ICP in recurrent and/or progressive HGG. METHODS Participants had recurrent, progressive and/or persistent residual HGG requiring recommencement of dexamethasone, dose increase or dexamethasone dependency; prior/current bevacizumab was an exclusion. Eligible participants were randomised 1:1 to acetazolamide 250mg twice daily or placebo for 8 weeks. Standardised protocols were used for dexamethasone dose changes in both arms, with planned dose decrease from day 5 once ICP symptoms were stable. The primary endpoint was a composite of dexamethasone dose reduction and stability of performance status. Secondary endpoints included toxicity and feasibility (accrual and compliance). RESULTS Thirty participants of a planned sample of 84 were enrolled (mean age 58 y (32-89)) from 7 Australian sites. The mean baseline dexamethasone dose was 6.2mg (4-16mg). Mean duration on treatment was 38 days (4-57) in placebo group and 31 days (3-60) in acetazolamide group, with 9 participants (30%) completing all study treatment (6 placebo, 3 acetazolamide). Study withdrawal was due to adverse events (n=6 (1 placebo, 5 acetazolamide)) and disease progression (n=6 (3 per arm)). Four participants (13%) (2 per arm) were stable responders meeting the primary endpoint criteria (≥50% corticosteroid dose reduction from baseline by 28 days maintained for 7 days, and no deterioration in performance status). Ten participants experienced a total of 13 serious adverse events (acetazolamide arm: 5 participants (33%), 6 events, 2 related). DISCUSSION The addition of acetazolamide did not facilitate dexamethasone reduction. The study closed early due to poor accrual and increasing availability of bevacizumab.