Expression of Five Neuroblastoma Genes in Bone Marrow or Blood of Patients with Relapsed/Refractory Neuroblastoma Provides a New Biomarker for Disease and Prognosis.

Abstract

<b>Purpose:</b> We determined whether quantifying neuroblastoma-associated mRNAs (NB-mRNAs) in bone marrow and blood improves assessment of disease and prediction of disease progression in patients with relapsed/refractory neuroblastoma.<b>Experimental Design:</b> mRNA for CHGA, DCX, DDC, PHOX2B, and TH was quantified in bone marrow and blood from 101 patients concurrently with clinical disease evaluations. Correlation between NB-mRNA (delta cycle threshold, Δ<i>C</i>_t, for the geometric mean of genes from the TaqMan Low Density Array NB5 assay) and morphologically defined tumor cell percentage in bone marrow, ¹²³I-meta-iodobenzylguanidine (MIBG) Curie score, and CT/MRI-defined tumor longest diameter was determined. Time-dependent covariate Cox regression was used to analyze the relationship between Δ<i>C</i>_t and progression-free survival (PFS).<b>Results:</b> NB-mRNA was detectable in 83% of bone marrow (185/223) and 63% (89/142) of blood specimens, and their Δ<i>C</i>_t values were correlated (Spearman <i>r</i> = 0.67, <i>P</i> < 0.0001), although bone marrow <i>C</i>_t was 7.9 ± 0.5 <i>C</i>_t stronger than blood <i>C</i>_t When bone marrow morphology, MIBG, or CT/MRI were positive, NB-mRNA was detected in 99% (99/100), 88% (100/113), and 81% (82/101) of bone marrow samples. When all three were negative, NB-mRNA was detected in 55% (11/20) of bone marrow samples. Bone marrow NB-mRNA correlated with bone marrow morphology or MIBG positivity (<i>P</i> < 0.0001 and <i>P</i> = 0.007). Bone marrow and blood Δ<i>C</i>_t values correlated with PFS (<i>P</i> < 0.001; <i>P</i> = 0.001) even when bone marrow was morphologically negative (<i>P</i> = 0.001; <i>P</i> = 0.014). Multivariate analysis showed that bone marrow and blood Δ<i>C</i>_t values were associated with PFS independently of clinical disease and <i>MYCN</i> gene status (<i>P</i> < 0.001; <i>P</i> = 0.055).<b>Conclusions:</b> This five-gene NB5 assay for NB-mRNA improves definition of disease status and correlates independently with PFS in relapsed/refractory neuroblastoma. <i>Clin Cancer Res; 23(18); 5374-83. ©2017 AACR</i>.