Lessons Learned: Utilization of a Reference Laboratory for Targeted Sequencing of Pediatric Tumors at a Single Institution

Our study aims to report the prevalence of potentially actionable oncogenic variants in a sample of pediatric tumors from a single institution using a reference laboratory for tumor profiling. We investigated genomic alterations and immunotherapy biomarkers such a tumor mutation burden, microsatellite instability, and programmed death-ligand 1. Patients treated in the Cook Children's Health Care System who had tumor profiling performed by Foundation Medicine between January 1, 2013, and May 1, 2019, were included. Demographic variables, results of tumor profiling, and subsequent use of targeted therapies were captured. Eighty-one patients were in our final data set; patients had diagnoses of central nervous system tumors (n=5), leukemia and lymphoma (n=4), neuroblastoma (n=32), and other solid tumors (n=40). One or more genomic alterations were identified in 68 (84%) of patients, 34 of which had potential targeted therapies available. In all, 44/51 patients tested for tumor mutation burden had low tumor burden, and the rest had intermediate burden. All 41 patients tested for microsatellite instability status were microsatellite stable. Six of 34 patients tested for programmed death-ligand 1 status were positive. Twelve patients received targeted therapy. This study highlights a subset of pediatric tumors harboring targetable genetic alterations and describes the use of a reference laboratory for tumor profiling.