PITTSBURGH – Genetic analysis of circulating free DNA (cfDNA) from pediatric solid tumors can noninvasively identify somatic mutations and copy number alterations that could be used to identify therapeutic targets, investigators reported.
An analysis of tumor specimens and plasma samples from children with neuroblastoma, osteosarcoma, and Wilms tumor revealed in cfDNA both somatic mutations and copy number alterations that had already been detected in the solid tumors, and new, potentially targetable mutations, reported Prachi Kothari, DO, and her colleagues from Memorial Sloan Kettering Cancer Center in New York.
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Dr. Prachi Kothari
“Circulating free DNA is much less invasive than a tumor biopsy, and you can do it throughout the patient’s entire timeline of treatment, so you get real-time information or after they relapse to see what’s going on if you’re not able to get a tumor biopsy,” Dr. Kothari said at annual meeting of the American Society of Pediatric Hematology/Oncology.
So-called “liquid biopsy” using cfDNA has been used for molecular profiling of adults malignancies, but there are few data on its use in pediatric tumors, Dr. Kothari said.
To see whether the technique could provide useful clinical information for the management of pediatric tumors, the investigators examined tumor samples taken at diagnosis or at the time of disease progression from 15 patients with neuroblastoma, 10 with osteosarcoma, and 5 with Wilms tumor. They analyzed the tumor samples using targeted next-generation sequencing (NGS), and cfDNA using three different genomic analysis techniques, including NGS, MSK-IMPACT (Integrated Mutation Profiling of Actionable Cancer Targets), and shallow whole genome sequencing.
For each of the tumor types studies, cfDNA analysis with the MSK-IMPACT platform identified key drivers of malignancy, including MYCN, ALK, and ATRX in neuroblastoma; CDKN2A and MDM2 in osteosarcoma; and DICER1 and AMER1 in Wilms tumor.
The cfDNA samples also revealed somatic mutations and copy number alterations previously reported in the tumors of 8 of the 15 patients with neuroblastoma, as well as potentially targetable new mutations in 6 of the 15 patients, including NRAS, MLL2, ARID1B, and IDH2.