Chimeric Antigen Receptor T Cell Therapies Clinical Trials in Pediatric Oncology: A Retrospective Analysis from Clinicaltrials.Gov
Authors: Vargas Cely Fabio Samir , Martinez David A. , Garcia Robledo Juan , Franco-Fuquen Pedro , Hans Rhea , Moreno-Cortes Eider , Castro Martinez Daniela A , Castro Januario E. 
Published: December 2023

Background:
Chimeric Antigen Receptor (CAR) T-cell clinical trials are growing exponentially. Database analysis can help identify scientific trends and generate projections regarding potential approvals before the results of the studies are completed or published. This is particularly interesting in pediatric oncology, where available analyses from repository databases are scarce or not available. Because of that reason, we sought to analyze the clinical trial public records from entries related to CAR T-cell clinical studies in pediatric patients (18 years or younger) uploaded to the clinicaltrials.gov database.
Methods:
We query the available data from clinicaltrials.gov using the following keywords: “CAR T cell in pediatrics”, “CAR T cell and cancer”, “chimeric antigen receptor”, “CAR T AND tumor antigen”, 'CAR T cell antigens“, ”Tumor antigens targeted by CAR T cells“, ”engineered T cells“, ”modified T cell“, ”CAR T cells in Cancer“, ”CAR T cell therapy“, ”CAR T cell therapy AND Cancer“ (data cut off July-2023). The data were tabulated, and the trials that did not meet the search criteria were excluded manually. Data cleansing was performed using published scientific data, web search-based information, and patent databases.
Results:
We found 4297 results in the Clinicaltrials.gov platform; we excluded 3978 clinical trials that did not involve the pediatric population (&lt;18 years) or CAR T-cell intervention. The final analysis included 319 clinical trials posted on the clinicaltrials.gov website by the cut-off date. 207 (64.9%) were conducted in China, 74 (23.2%) in the US, and 21 (6.5%) in Europe. Most CAR T-cell trials focused on hematological cancer (89%), followed by non-CNS solid tumors 8%, and CNS tumors 3%. The most frequent targets were CD19 (46%), CD7 (7%), followed by GD2, CD22, CD123, CD19 + CD22 and CD30.
Most clinical trials did not report the construct generation used in their CAR T cell product (58%). Among the trials with that information, second-generation constructs (2G) were used in 32% of the studies, followed by 3G and 4G constructs (5% of studies each). Most clinical trials were in early stages of development, Phase 1 or 2 (75%). We observed a continuous increase in the number of clinical trials registered yearly, except for a small reduction in 2022 and 2021, probably related to COVID restrictions and challenges. Overall, the general trend predicts at least a 50% yearly increase in registered studies ( Figure 1). Similarly, to what is observed in adult clinical trials, the most common signaling domains are 2G CAR constructs expressing either CD28 or 4-1BB as costimulatory domains. Among those, 4-1BB being is the most popular choice.
Conclusion:
Our findings indicate a growing interest in the clinical development of CAR T-cell therapies applied to pediatric oncology. Most of these studies are in early phase I and II and focus primarily on hematological cancers using second-generation constructs targeting CD19. The is a steady increase in the number of studies registered each year that predicts future FDA approvals using CAR T-cell products.