Genomic Profiling of Pediatric Tumors: A Single Institution Experience

Purpose The goal of this project is to study the prevalence of potentially actionable oncogenic variants in a sample of pediatric tumors, to identify agents that may target those variants, and to highlight the potential utility of targeted therapies in pediatric cancers. This study will also describe the tumor mutation burden (TMB), microsatellite instability (MSI), and programmed death-ligand 1 (PD-L1) status of the included samples. Methods Retrospective chart review was conducted on 82 patients treated for cancer who underwent molecular sequencing from 2013 to 2019 at Cook Children's Medical Center. Tumor samples were sent to Foundation Medicine, Inc. for sequencing, which identified genetic variants and available approved or experimental targeted therapies. When requested, reports included TMB, MSI, and PD-L1 status. Results There were 5 patients with central nervous system tumors, 4 patients with leukemia and lymphoma, 33 patients with neuroblastoma, and 40 patients with other solid tumors. Thirty-five (43%) patients were identified as having actionable genetic alterations, and 13 (16%) patients received targeted therapy. Thirty-four patients were tested for PD-L1 status and 6 (18%) were positive. TMB was determined for 51 patients: 44 (86%) were low burden, 7 (14%) intermediate burden, and none were high burden. MSI status was determined for 41 patients and all were MSI-stable. Conclusion Whole genome sequencing has emerged as a tool to identify driver genetic alterations in various tumors. This study highlights how tumor profiling can be utilized to identify potential molecular targets and biomarkers in pediatric cancers.