Background/objectives

Standard supportive care during induction therapy for high-risk neuroblastoma (HR-NBL) includes primary prophylactic granulocyte colony-stimulating factor (G-CSF) aimed at limiting duration of neutropenia, reducing infection risk, and minimizing treatment delays. Preclinical models suggest that G-CSF promotes maintenance of neuroblastoma cancer stem cells and may reduce the efficacy of chemotherapy. This study's objective was to determine the safety and feasibility of administering induction chemotherapy without routine use of prophylactic G-CSF.

Design/methods

Children with newly diagnosed HR-NBL received six-cycle induction chemotherapy regimen without prophylactic G-CSF in four cycles. G-CSF was administered for stem cell mobilization after cycle 3 and granulocyte-monocyte colony-stimulating factor after cycle 5 prior to surgical resection of primary disease. The primary outcome measure was the incidence of grade 3 or higher infection. We hypothesized that the per patient infection rate would be comparable to our institutional baseline rate of 58% in patients with HR-NBL receiving induction chemotherapy with prophylactic growth factor support. The trial used an A'Hern single-stage design.

Results

Twelve patients with HR-NBL received 58 cycles of chemotherapy on study. Three patients completed the entire six-cycle regimen with no infections. Nine patients experienced grade 3 infections (bacteremia four, urinary tract infection two, skin/soft tissue infection three). No patients experienced grade 4 infections or required intensive care treatment for infection.

Conclusion

A greater than expected number of serious bacterial infections were observed during administration of induction chemotherapy for HR-NBL without primary prophylactic G-CSF. These results support continued prophylactic administration growth factor during induction chemotherapy.

Microarray-based molecular signatures have not been widely integrated into neuroblastoma diagnostic classification systems due to the complexities of the assay and requirement for high-quality RNA. New digital technologies that accurately quantify gene expression using RNA isolated from formalin-fixed paraffin embedded (FFPE) tissues are now available. In this study, we describe the first use of a high-throughput digital system to assay the expression of genes in an "ultra-high risk" microarray classifier in FFPE high-risk neuroblastoma tumors. Customized probes corresponding to the 42 genes in a published multi-gene neuroblastoma signature were hybridized to RNA isolated from 107 FFPE high-risk neuroblastoma samples using the NanoString nCounter™ Analysis System. For classification of each patient, the Pearson's correlation coefficient was calculated between the standardized nCounter™ data and the molecular signature from the microarray data. We demonstrate that the nCounter™ 42-gene panel sub-stratified the high-risk cohort into two subsets with statistically significantly different overall survival (p = 0.0027) and event-free survival (p = 0.028). In contrast, none of the established prognostic risk markers (age, stage, tumor histology, MYCN status, and ploidy) were significantly associated with survival. We conclude that the nCounter™ System can reproducibly quantify expression levels of signature genes in FFPE tumor samples. Validation of this microarray signature in our high-risk patient cohort using a completely different technology emphasizes the prognostic relevance of this classifier. Prospective studies testing the prognostic value of molecular signatures in high-risk neuroblastoma patients using FFPE tumor samples and the nCounter™ System are warranted.