Minimal Residual Disease Detection in Peripheral Blood of Patients With High-Risk Neuroblastoma Correlates With Outcome in the International GPOH-DCOG Prospective Validation Study.

Abstract

About 60% of patients with high-risk neuroblastoma relapse. Specific mRNA detection in bone marrow (BM) by reverse transcriptase quantitative PCR (RT-qPCR) is associated with survival outcomes. Peripheral blood (PB) sampling is less invasive. Therefore, we prospectively validated an RT-qPCR panel of neuroblastoma mRNA in PB of patients with high-risk neuroblastoma, treated in NB2004-HR (GPOH) and NBL2009 (DCOG). From 312 patients, 634 PB samples were prospectively collected (2009-2017) at diagnosis, after two cycles and end-of-induction therapy. RT-qPCR was performed using our panel of neuroblastoma mRNA markers: <i>PHOX2B</i>, <i>TH</i>, <i>DDC</i>, <i>CHRNA3</i>, and <i>DBH</i>. Results were compared with paired BM samples. The association between neuroblastoma detection and event-free survival (EFS) and overall survival (OS) was estimated using Kaplan-Meier's methodology and multivariable Cox regression model. Clear correlation between calculated infiltration by neuroblastoma mRNA expression in PB and BM was seen at diagnosis (<i>r</i>_s 0.70 [95% CI, 0.62 to 0.76]), and heterogeneity was seen after two cycles (0.37 [95% CI, 0.12 to 0.58]) and end of induction (0.61 [95% CI, 0.10 to 0.87]). mRNA expression was significantly lower in PB compared with BM. At diagnosis, PB infiltration ≥1% was a prognostic factor for survival: adjusted hazard ratio (HR) was 2.37 [95% CI, 1.56 to 3.60] for EFS and 2.60 [1.65-4.08] for OS. At the end of induction, <i>PHOX2B</i> positivity in PB samples (n = 11) was associated with poor outcomes: HR 3.06 [1.51-6.20] for EFS and 2.88 [1.36-6.11] for OS. In patients with ≥10% BM infiltration at diagnosis, detection of the mRNA panel in PB samples could significantly distinguish between survival groups; the adjusted HR of PB infiltration ≥1% was 2.09 [1.01-4.30] for OS. PB infiltration is associated with EFS and OS at diagnosis; it is also significantly associated with survival outcomes of patients with ≥10% BM infiltration at diagnosis. During follow-up, neuroblastoma mRNA detection in PB can be of added value, when BM analysis is not possible.