From the Journals

Proposed neuroblastoma classification scheme hinges on telomere maintenance mechanisms



Telomere maintenance mechanisms, RAS mutations, and p53 mutations can be used to mechanistically classify clinical phenotypes of neuroblastoma, according to investigators.

Genomic analysis of neuroblastomas showed that the aforementioned markers were strongly associated with outcome and other disease characteristics, reported Sandra Ackermann, MD, of the department of experimental pediatric oncology at the University Children’s Hospital of Cologne (Germany), and her colleagues.

Although previous studies have shown relationships between genetic alterations and behavior of neuroblastomas, “to date, these genomic data have not produced a coherent model of pathogenesis that can explain the extremely divergent clinical phenotypes of neuroblastoma,” the investigators wrote in Science.

The present study involved genomic sequencing of 416 pretreatment neuroblastomas, with tests for telomere maintenance mechanisms, RAS-pathway mutations, and p53-pathway mutations.

Based on existing data, the investigators first devised a panel based on 17 genes related to the RAS pathway (11 genes included ALK) and 6 related to the p53 pathway. In 198 cases, 28 tested positive for RAS- or p53-pathway abnormalities (17.8%). Positivity was more common in high-risk tumors than non–high-risk tumors (21.3% vs. 13.3%; P = .048), and in both risk groups, positivity was associated with poor outcome (hazard ratio, 2.056; P = .001).

However, because clinical courses varied widely among non–high-risk patients with RAS/p53 mutations, the investigators recognized that a piece of the puzzle was missing. They hypothesized that telomere maintenance mechanisms could also be playing a role. Following several intervening experiments, the investigators devised telomere maintenance mechanism testing, defined by MYCN amplification or TERT rearrangements, elevated TERT expression if negative for these abnormalities, or presence of ALT-associated promyelocytic leukemia nuclear bodies. Subsequent testing revealed that positivity for these parameters was associated with a HR of 5.184 (P less than .001), thereby confirming that telomere maintenance mechanisms could independently predict survival.

“Together, our findings demonstrate that the divergent clinical phenotypes of human neuroblastoma are driven by molecular alterations affecting telomere maintenance and RAS or p53 pathways, suggesting a mechanistic classification of this malignancy,” the authors concluded.

The proposed classification scheme also includes associations with other genetic features (tumor cell ploidy, segmental copy number alterations, MYCN/TERT/ATRX alterations, and gene expression favorability) and clinical characteristics (stage of disease and age at diagnosis).

The study was funded by the German Cancer Aid, the German Ministry of Science and Education, the MYC-NET, the Deutsche Forschungsgemeinschaft, the Berlin Institute of Health, the European Union, and others. One coauthor reported financial relationships with Biogazelle and pxlence, and another reported consulting fees from NEO New Oncology.

SOURCE: Ackermann S et al. Science. 2018 Dec 7. doi: 10.1126/science.aat6768.

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