Minimal residual disease in peripheral blood stem cell harvests from high-risk neuroblastoma patients.

Purpose We investigated whether detection of minimal residual disease (MRD) in peripheral blood stem cells (PBSC) by using tyrosine hydroxylase (TH) expression could predict outcome of patients with advanced neuroblastoma. Patients and Methods Quantitative real time polymerase chain reaction was performed for the detection of tumor contamination using TH messenger ribonucleic acid (mRNA) and correlated to clinical parameters and outcome in 45 high-risk neuroblastoma patients. Results High TH expression was detected in PBSC harvests obtained from 26 out of 45 (58%) patients. We did not find a significant correlation between MYCN status, DNA index or primary tumor site, and the TH mRNA level. Patients harboring high TH expression had reduced progression-free survival (PFS) (23%) versus those with low/negative TH expression (43%), although these results were not statistically significant. No significant correlation was observed between TH expression and overall survival. Conclusions The correlation between an unfavorable outcome and high TH expression in patients' PBSC harvests was not significant. This indicates a need to increase sample size in a long-term clinical outcome study to clarify the importance of TH mRNA contamination in PBSC.