Single Blood Test Detects Various Tumor Types Less Invasively Than Tissue Biopsy

Around 40% of childhood cancers are pediatric solid tumors. Although pediatric cancer is uncommon, children can develop various tumor types in different body parts, making differential diagnosis difficult. Now, a newly developed liquid biopsy for solid tumors could be highly beneficial in cases where surgery or a tissue biopsy is not possible, potentially enabling more targeted diagnoses.

Pediatric tumors and adult tumors exhibit different genetic makeups, necessitating the development of specific tests for the former. Adult tumors usually result from mutations or sequence-based changes in a gene, resulting in the development of liquid biopsy tests that specifically identify such mutations. However, pediatric tumors caused by mutations are less common. Instead, children's tumors tend to be characterized by copy number changes- having extra or losing copies of one or more genes- or rearrangements of genes resulting in gene fusions. For their research study, investigators at Children’s Hospital Los Angeles (Los Angeles, CA, USA) combined a technique known as Low-Pass Whole Genome Sequencing (LP-WGS) with targeted sequencing of cell-free DNA from plasma to detect copy number changes, as well as mutations and gene fusions, which are typical of pediatric solid tumors. Importantly, the study required a much smaller volume of sample as compared to that required for liquid biopsy studies in adults. The smaller blood volume in an infant or young child required the assays to be scaled down in order to adjust for this difference.

In November 2022, the initial version of the test was released, enabling the evaluation of chromosomal copy number changes in blood samples, cerebrospinal fluid, and the aqueous humor of the eye to support clinical diagnoses of patients with solid tumors, retinoblastoma, and brain tumors, respectively. The upcoming version of the clinical assay, estimated for release in approximately six months, will include the detection of gene fusions and mutations. These liquid biopsy-based genetic tests will add to the CHLA-developed OncoKids cancer panel, a next-generation sequencing-based assay to detect changes in DNA or RNA related to pediatric leukemias, brain and solid tumors; the CHLA Cancer Predisposition Panel; RNAseq for cancer, a transcriptome-based assay using RNA sequencing; VMD4Kids, a panel for vascular and mosaic disorders; as well as methylation array-based profiling for pediatric brain tumors.

“This is one of the first clinically validated liquid biopsy tests to be launched at a pediatric academic medical center,” said Jaclyn Biegel, PhD, Chief of Genomic Medicine and Director of the Center for Personalized Medicine at CHLA.

“We created a test that may be helpful in making a diagnosis, determining prognosis, and potentially identifying an effective therapy for children with solid tumors,” added Fariba Navid, MD, Medical Director of Clinical Research in the Cancer and Blood Disease Institute at CHLA.

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Children’s Hospital Los Angeles