Oral Presentation Advances in Neuroblastoma Research Congress 2016

Identification of somatic mutations determining the neuroblastoma phenotype (#54)

Matthias Fischer 1 , Frank Westermann 2 , Johannes H Schulte 3 , Alexander Schramm 4 , Jo Vandesompele 5 , Falk Hertwig 1 , Sandra Ackermann 1 , Daniel Dreidax 2 , Moritz Gartlgruber 2 , Frederik Roels 1 , Bram De Wilde 5 , Fakhera Ikram 1 , Roopika Menon 6 , Johannes M Heuckmann 6 , Janine Altmüller 7 , Peter Nürnberg 7 , Frederik Sand 1 , Ruth Volland 1 , Sven Perner 8 , Franki Speleman 5 , Angelika Eggert 3 , Frank Berthold 1 , Carl Herrmann 2 , Roderick J O'Sullivan 9 , Barbara Hero 1 , Roman K Thomas 10 , Martin Peifer 10
  1. University Children's Hospital of Cologne, Cologne, Germany
  2. German Cancer Research Center, Heidelberg, Germany
  3. Charité University Medical Center, Berlin, Germany
  4. University Children’s Hospital of Essen, Essen, Germany
  5. Center for Medical Genetics, Ghent University, Ghent, Belgium
  6. NEO New Oncology AG, Cologne, Germany
  7. Cologne Center for Genomics, University of Cologne, Cologne, Germany
  8. Institute of Pathology, University of Bonn, Bonn, Germany
  9. University of Pittsburgh Cancer Institute (UPCI), Pittsburgh, USA
  10. Department of Translational Genomics, University of Cologne, Cologne, Germany

Background: The molecular mechanisms driving the contrasting clinical courses of neuroblastoma have remained largely enigmatic to date. We therefore aimed to determine the genetic alterations underlying the distinct neuroblastoma phenotypes by massively parallel sequencing.

Methods: Mutation patterns of 416 diagnostic neuroblastoma specimens were determined by massively parallel sequencing (whole-genome sequencing, n=56; whole-exome sequencing, n=162; targeted sequencing, n=198).

Results: We discovered genomic rearrangements of the TERT locus in 12/56 neuroblastomas by whole-genome sequencing. TERT rearrangements affected exclusively high-risk tumors, in mutually exclusive fashion with MYCN amplification and ATRX mutations. In an extended cohort (n=217), TERT rearrangements were detected in 24% of high-risk neuroblastomas, and were associated with particularly poor patient outcome. We demonstrated that such rearrangements led to massive induction of TERT expression and telomerase activation caused by translocation of strong enhancer elements. Similarly, we observed upregulation of TERT and telomerase in MYCN-amplified tumors, while activation of the Alternative Lengthening of Telomeres pathway was detected in high-risk tumors lacking these alterations. In addition, we identified mutations in ALK and other RAS/MAPK pathway-acting genes as well as p53/MDM2 pathway genes in 36/402 (9.0%), 25/402 (6.2%) and 18/402 (4.5%) neuroblastomas, respectively. Such mutations affected predominantly high-risk tumors (51/227 cases, 22.5%) but occurred also in non-high-risk tumors (22/173 cases, 12.7%). Notably, survival of patients whose tumors harbored mutations in these cancer genes was significantly worse than those without such mutations in the entire cohort, and in both the high-risk and the non-high-risk subgroups (p<0.001 each).

Conclusion: Our data demonstrate that activation of telomere maintenance mechanisms is a hallmark of high-risk neuroblastoma, while low-risk tumors lack such mechanisms, which may explain their capacity of spontaneous regression. Furthermore, the clinical course of the disease is strongly influenced by the presence of mutations in RAS/MAPK and p53/MDM2 pathway genes at diagnosis. Together, our data strongly suggest that the clinical phenotype of neuroblastoma is driven by specific patterns of somatic mutations.