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EPID-24. TRANSCRIPT: A cenTRAl NERVOUS SYSTEM CANCER CLINICAL tRIals PostmorTem


 
 
 Despite the growing number of neuro-oncology clinical trials, there have been limited advances in the treatment of malignant primary central nervous system tumors. We surveyed the landscape of past, ongoing, and planned trials to assess trends in their interventions, outcomes, and design considerations to guide future studies.
 
 
 
 Data on interventional trials on ClinicalTrials.gov were accessed programmatically using AACT and R. Neuro-oncology trials were isolated using primary malignant brain tumor classification terms. Instrument names from PROQOLID were used to identify clinical outcome assessment (COA) use. Linear regression was used to assess chronological trends; power analyses utilized CBTRUS survival rates among trials investigating overall survival.
 
 
 
 We identified 3039 interventional brain tumor trials that started between 1966 and 2025. Trials were most frequently phase II (43%), completed (40%), non-blinded (92%), single-group assignment (65%), non-randomized (51%) studies targeting glioblastoma (45%). Planned outcomes were reported by 93% of trials; this included adverse event or toxicity (54%), overall/x-year survival (44%), progression free survival (43%), maximum tolerated dose (16%), and objective response rate (14%). Evaluating the anticipated and actual trial enrollment, we estimate that only 10% and 8% of trial arms, respectively, were sufficiently powered to assess overall survival endpoints. 21% of trials mentioned the use of a COA (first trial initiated in 1992), majority of which were patient-reported outcomes. Among these, 25% and 58% reported COA as a primary or secondary outcome, respectively. The rate of COA use increased linearly over time at 1.1%/year but remained less than 5 trials per year until 2003. Ongoing work is investigating treatment mechanisms of actions and evidence of preclinical efficacy among brain tumor studies.
 
 
 
 Low randomization rates and underpowered trial design may impede interpretability of efficacy. Increasing trends in COA use suggests cumulative influence of advocacy efforts to holistically evaluate net clinical benefit of interventions.
