Droplet digital PCR as an alternative to FISH for MYCN amplification detection in human neuroblastoma FFPE samples

Background: MYCN amplification directly correlates with the clinical course of neuroblastoma and poor patient survival, and serves as the most critical negative prognostic marker. Although fluorescence in situ hybridization (FISH) remains the gold standard for clinical diagnosis of MYCN status in neuroblastoma, its limitations warrant the identification of rapid, reliable, less technically challenging, and inexpensive alternate approaches. Methods: In the present study, we examined the concordance of droplet digital PCR (ddPCR, in combination with immunohistochemistry, IHC) with FISH for MYCN detection in a panel of formalin-fixed paraffin-embedded (FFPE) human neuroblastoma samples. Results: In 112 neuroblastoma cases, ddPCR analysis demonstrated a 96-100% concordance with FISH. Consistently, IHC grading revealed 92-100% concordance with FISH. Comparing ddPCR with IHC, we observed a concordance of 95-98%. Conclusions: The results demonstrate that MYCN amplification status in NB cases can be assessed with ddPCR, and suggest that ddPCR could be a technically less challenging method of detecting MYCN status in FFPE specimens. More importantly, these findings illustrate the concordance between FISH and ddPCR in the detection of MYCN status. Together, the results suggest that rapid, less technically demanding, and inexpensive ddPCR in conjunction with IHC could serve as an alternate approach to detect MYCN status in NB cases, with near-identical sensitivity to that of FISH.