Poster Presentation Advances in Neuroblastoma Research Congress 2016

Clinical relevance of genomic and epigenomic classification of MYCN-non-amplified neuroblastoma (#194)

Miki Ohira 1 , Yohko Nakamura 2 , Yasutoshi Tatsumi 2 , Kenji Tatsuno 3 , Shuichi Tsutsumi 3 , Shogo Yamamoto 3 , Genta Nagae 3 , Claire Renard-Guillet 3 , Ryuichi P Sugino 1 , Masayuki Haruta 1 , Hisanori Takenobu 1 , Hiroki Nagase 2 , Takehiko Kamijo 1 , Hiroyuki Aburatani 3 , Akira Nakagawara 4
  1. Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan
  2. Chiba Cancer Center Research Institute, Chiba
  3. RCAST, University of Tokyo, Tokyo
  4. Saga Medical Center Koseikan, Saga

Neuroblastoma is known to exhibit a wide range of clinical phenotypes, from spontaneous regression to highly resistant to chemotherapy. One of the challenges in the clinic is to develop adequate therapeutic strategies for the intermediate risk-type of patients (stage 3 or 4 without MYCN amplification) whose prognosis still tends to be poor in terms of long-term follow-up (10 years survival rate was 51%, n=161). To identify key therapeutic targets involved in the patient group with unfavorable phenotypes, we have analyzed 63 primary tumors (dead:32, alive:31) without MYCN amplification nor ALK alteration by integrated genomic analyses such as array CGH, whole exome sequencing (SureSelect XT Human All Exon V4, average read depth:157), RNA sequencing, as well as Methylome profiling (Infinium HumanMethylation450 BeadChip). We found so far 816 non-synonymous somatic single nucleotide variations (SNVs) in coding exons in total (approximately 20 per tumor in average) and number of alterations in each tumor strongly correlated with age at diagnosis (p<0.0001) and patient prognosis (p=0.0077). Recurrent somatic SNVs (n=2 to n=5) were found in 66 genes, 19 of those were involved only in the tumors from the patients with fatal outcome. Gene Ontology and pathway analysis using the 66 genes showed that mutations occurred in the features including cytoskeleton, ion channel and extracellular matrix were significantly correlated with patient survival of the 63 tumors with logrank p-values of 0.0039, 0.0482 and 0.0011, respectively. ATRX mutations were observed in four tumors (6.3%), all of them were occurred in patients with unfavorable phenotypes (3 dead, 1 alive but relapsed twice). Methylome signature subdivided the 63 tumors into at least three clusters, which also showed strong correlation with patient prognosis (cluster-1 vs. cluster-2 and -3, p=0.0368). Unfavorable cluster-2 and -3 exhibited hyper-methylation in CpG islands and the former was quite similar to that of MYCN-amplified tumors. These genomic features could be useful markers for risk classification and help understanding molecular mechanism for aggressive phenotypes of MYCN–non-amplified neuroblastomas.