Targeted next-generation sequencing of pediatric neuro-oncology patients improves diagnosis, identifies pathogenic germline mutations, and directs targeted therapy.

BACKGROUND: Molecular profiling is revolutionizing cancer diagnostics and leading to personalized therapeutic approaches. Herein we describe our clinical experience performing targeted sequencing for 31 pediatric neuro-oncology patients.

METHODS: We sequenced 510 cancer-associated genes from tumor and peripheral blood to identify germline and somatic mutations, structural variants, and copy number changes.

RESULTS: Genomic profiling was performed on 31 patients with tumors including 11 high-grade gliomas, 8 medulloblastomas, 6 low-grade gliomas, 1 embryonal tumor with multilayered rosettes, 1 pineoblastoma, 1 uveal ganglioneuroma, 1 choroid plexus carcinoma, 1 chordoma, and 1 high-grade neuroepithelial tumor. In 25 cases (81%), results impacted patient management by: (i) clarifying diagnosis, (ii) identifying pathogenic germline mutations, or (iii) detecting potentially targetable alterations. The pathologic diagnosis was amended after genomic profiling for 6 patients (19%), including a high-grade glioma to pilocytic astrocytoma, medulloblastoma to pineoblastoma, ependymoma to high-grade glioma, and medulloblastoma to CNS high-grade neuroepithelial tumor with BCOR alteration. Multiple patients had pathogenic germline mutations, many of which were previously unsuspected. Potentially targetable alterations were identified in 19 patients (61%). Additionally, novel likely pathogenic alterations were identified in 3 cases: an in-frame RAF1 fusion in a BRAF wild-type pleomorphic xanthoastrocytoma, an inactivating ASXL1 mutation in a histone H3 wild-type diffuse pontine glioma, and an in-frame deletion within exon 2 of MAP2K1 in a low-grade astrocytic neoplasm.

CONCLUSIONS: Our experience demonstrates the significant impact of molecular profiling on diagnosis and treatment of pediatric brain tumors and confirms its feasibility for use at the time of diagnosis or recurrence.