Uncovering the potential of circulating tumor DNA for pediatric precision oncology

Pediatric solid high-risk malignancies mostly lack molecular biomarkers for early tumor detection, assessment of minimal residual disease or therapy monitoring. Small patient numbers, limited sample volumes, low tumor mutational burden, and few recurrent alterations in pediatric tumors pose further challenges to liquid biopsy analyses for this patient population. Within the prospective, multinational molecular profiling program INFORM, we collected liquid biopsies from 130 children patients followed by optimized isolation of cell-free DNA (cfDNA). CfDNA was subjected to whole-genome, whole-exome, and targeted panel sequencing applying liquid biopsy-adapted protocols. Integration with tissue-derived molecular information and orthogonal comparison revealed low-coverage whole genome sequencing (lcWGS) as a reliable method for tumor detection. In silico integration of fragment length with differentially weighted genome segment alterations into a ctDNA estimation score (CES) significantly increased sensitivity and specificity to 95% and allowed for plasma-based tumor detection in 93% of patients. Performance of whole exome sequencing (WES) and panel sequencing for detection of molecular targets being predictive for matched treatment responses varied between groups of high-risk entities and cumulative evidence for presence of cancer by all three methods was found in 92% of patients. In-depth analyses for selected patients also demonstrated great the potential of liquid biopsies to decipher temporal and spatial tumor evolution. This study establishes improved methods for liquid biopsy analyses in pediatric oncology and provides the rationale for well-informed implementation of these approaches in future clinical trials to improve the clinical management of high-risk pediatric cancer patients.

• Type: Cancer Genomics
• Archiver: European Genome-phenome Archive (EGA)