Highly sensitive assessment of neuroblastoma minimal residual disease in ovarian tissue using RT-qPCR-A strategy for improving the safety of fertility restoration

Background: Ovarian tissue cryopreservation (OTC) is the only option available to preserve fertility in prepubertal females with neuroblastoma (NB), a childhood solid tumor that can spread to the ovaries, with a risk of reintroducingmalignant cells after an ovarian graft. Procedure: We set out to determine whether the analysis of TH (tyrosine hydroxylase), PHOX2B (paired-like homeobox 2b), and DCX (doublecortin) transcripts using quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) could be used to detect NB contamination in ovarian tissue. Analyses were performed on benign ovarian tissue from 20 healthy women between November 2014 and September 2015 at the University Hospital of Clermont-Ferrand. Pericystic benign ovarian tissues were collected and contaminated with increasing numbers of human NB cells (cell lines IMR-32 and SK-N-SH) before detection using RT-qPCR. Results: TH and DCX transcripts were detected in uncontaminated ovarian tissue from all the donors, hampering the detection of small numbers of tumor cells. By contrast, PHOX2B was not detected in any uncontaminated ovarian fragment. PHOX2B levels were significantly increased from 10 NB cells. Our study is the first to evaluate minimal residual disease detection using NB mRNAs in human ovarian tissue. Only PHOX2B was a reliable marker of NB cells contaminating ovarian tissue. Conclusions: These results are encouraging and offer hope in the near future for grafting ovarian tissue in women who survive cancer, whose fertility has been jeopardized by treatment, and who could benefit fromOTC without oncological risk.