Combined Detection of Copy Number Variations of MYCN and ALK using Droplet Digital Polymerase Chain Reaction to Identify High-Risk Patients with Neuroblastoma

Abstract

The current study sought to explore the significance of copy number variations (CNVs) of MYCN (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived [avian]) and ALK (anaplastic lymphoma kinase) genes individually as well as their combined impact on clinical outcome and overall survival of patients with neuroblastoma (NB). A total 71 individuals including healthy controls (n= 11), circulating DNA (n= 11), and primary tumors (n= 49) were evaluated to detect CNVs of MYCN and ALK genes using droplet digital polymerase chain reaction. Data were correlated with univariate and multivariate survival analysis. CNVs of MYCN and ALK were detected in 27% and 18.2% from circulating DNA samples. A statistically significant difference in CNVs was noted between healthy controls and circulating DNA samples for MYCN (P=0.001) and ALK (P= 0.004) genes. Further, we noted >70% concordance in CNVs of MYCN (P= 0.030) and ALK (P= 0.040) from primary tumors and concordant plasma samples of patients with NB. Multivariate survival analysis for disease-free survival (P= 0.031) and overall survival (P= 0.011) showed that CNVs of both genes emerged at step 1 and thus remained as significant markers for predicting early recurrence and shorter survival, respectively, for patients with NB. Our study showed that the analysis of circulating DNA by droplet digital polymerase chain reaction is a helpful technique to identify high-risk patients for aggressive therapy at an early stage of disease. We also concluded that codetection of MYCN and ALK is a more powerful tool for identifying high-risk patients with NB. Thus, this study showed a novel coordinately significant prognostic role of MYCN and ALK CNVs.