Trends in Immunotherapy Clinical Trials to Treat Glioblastoma: A Look at Progress and Challenges

-PURPOSE: We aimed to catalog past and present clinical trials on immunotherapy treatments for glioblastoma (GBM) and discover relevant trends in this field. -METHODS: Former and ongoing clinical trials involving the use of immunotherapy to treat GBM were queried in July 2022 within the clinicaltrials.gov registry (https:// clinicaltrials.gov/). Pertinent trials were categorized by variables including immunotherapy classification, tumor type (newly diagnosed versus recurrent), country of origin, start date, clinical phase, study completion status, esti-mated subject enrollment, design, publication status, and funding source. -RESULTS: A list of 173 trials was identified in total. The -umber of immunotherapy clinical trials to treat GBM has increased over time. The largest proportion of trials were gene therapies (97 studies; 56.1%) and viral therapies (37 studies; 21.4%). Studies were designated as a biologic (45.1%), drug (43.9%), genetic (2.3%), or procedure (1.2%). Trials spanned 19 countries; China, the second largest contributor (5.8%) after the United States (70.0%), has increased clinical trial development in the past years. The average time to completion was 52.3 months. Trials were primarily funded by academic centers; however, one-fourth of the trials were funded by industry and 2 were funded by foundations. One-t of the trials were active and over one-third were linked to publications. -CONCLUSIONS: Our findings provide a comprehensive summary of the state of immunotherapy clinical trials for GBM, highlighting the evolving nature and growing scope of this field.