Event‐free survival of infants and toddlers enrolled in the HR‐NBL‐1/SIOPEN trial is associated with the level of neuroblastoma mRNAs at diagnosis

1 Background: The purpose of this study was to evaluate whether levels of neuroblastoma mRNAs in bone marrow and peripheral blood from stage M infants (≤12 months of age at diagnosis, MYCN amplified) and toddlers (between 12 and 18 months, any MYCN status) predict event‐free survival (EFS).

2 Methods: Bone marrow aspirates and peripheral blood samples from 97 infants/toddlers enrolled in the European High‐Risk Neuroblastoma trial were collected at diagnosis in PAXgene™ blood RNA tubes. Samples were analyzed by reverse transcription quantitative polymerase chain reaction according to standardized procedures.

3 Results: Bone marrow tyrosine hydroxylase (TH) or paired‐like homeobox 2b (PHOX2B) levels in the highest tertile were associated with worse EFS; hazard ratios, adjusted for age and MYCN status, were 1.5 and 1.8 respectively. Expression of both TH and PHOX2B in the highest tertile predicted worse outcome (p = 0.015), and identified 20 (23%) infants/toddlers with 5‐year EFS of 20% (95%CI: 4%–44%). Prognostic significance was maintained after adjusting for over‐fitting bias (p = 0.038), age and MYCN status. In peripheral blood, PHOX2B levels in the highest tertile predicted a two‐fold increased risk of an event (p = 0.032), and identified 23 (34%) infants/toddlers with 5‐year EFS of 29% (95%CI: 12%–48%). Time‐dependent receiver operating characteristic analysis confirmed the prognostic value of combined TH and PHOX2B in bone marrow and of PHOX2B in peripheral blood during the first year of follow‐up.

4 Conclusions: High levels of bone marrow TH and PHOX2B and of peripheral blood PHOX2B at diagnosis allow early identification of a group of high‐risk infant and toddlers with neuroblastoma who may be candidates for alternative treatments. Integration with additional biomarkers, as well as validation in additional international trials is warranted.