Genomic Profiling of Pediatric Acute Myeloid Leukemia Reveals a Changing Mutational Landscape from Disease Diagnosis to Relapse.

The genomic and clinical information used to develop and implement therapeutic approaches for acute myelogenous leukemia (AML) originated primarily from adult patients and has been generalized to patients with pediatric AML. However, age-specific molecular alterations are becoming more evident and may signify the need to age-stratify treatment regimens. The NCI/COG TARGET-AML initiative used whole exome capture sequencing (WXS) to interrogate the genomic landscape of matched trios representing specimens collected upon diagnosis, remission, and relapse from 20 cases of de novo childhood AML. One hundred forty-five somatic variants at diagnosis (median 6 mutations/patient) and 149 variants at relapse (median 6.5 mutations) were identified and verified by orthogonal methodologies. Recurrent somatic variants [in (greater than or equal to) 2 patients] were identified for 10 genes (FLT3, NRAS, PTPN11, WT1, TET2, DHX15, DHX30, KIT, ETV6, KRAS), with variable persistence at relapse. The variant allele fraction (VAF), used to measure the prevalence of somatic mutations, varied widely at diagnosis. Mutations that persisted from diagnosis to relapse had a significantly higher diagnostic VAF compared with those that resolved at relapse (median VAF 0.43 vs. 0.24, P < 0.001). Further analysis revealed that 90% of the diagnostic variants with VAF >0.4 persisted to relapse compared with 28% with VAF <0.2 (P < 0.001). This study demonstrates significant variability in the mutational profile and clonal evolution of pediatric AML from diagnosis to relapse. Furthermore, mutations with high VAF at diagnosis, representing variants shared across a leukemic clonal structure, may constrain the genomic landscape at relapse and help to define key pathways for therapeutic targeting. Cancer Res; 76(8); 2197-205. ©2016 AACR.

Somatic characterization of pediatric acute myeloid leukemia using next-generation sequencing.

Acute myeloid leukemia (AML) is a complex and heterogeneous disease with distinct age-associated genomic and epigenomic alterations. A large number of somatic karyotypic and molecular alterations have been identified in AML to date; however, very few predict outcome or identify potential therapeutic targets. Here we describe the current state of known molecular and genetic alterations in pediatric AML. Further, as recent advances in sequencing technologies have revolutionized our ability to interrogate cancer genome, transcriptome, and epigenome, we will also review the emerging genomic data identified by next-generation sequencing and discuss their potential impact as tools for therapeutic interventions in the near future. In coming years, a wealth of data from large-scale discovery phase projects such as the Children's Oncology Group/ National Cancer Institute (COG/NCI) TARGET AML initiative will be available to researchers to discover new biomarkers for risk and target identification in pediatric AML.