Detection of plasma circulating GD2 ganglioside in patients with neuroblastoma and age-matched healthy children. Diagnostic and prognostic evaluation.

Background: GD2 ganglioside, a known specific marker for neuroblastoma (NB), exists in different lipoforms, including C18 and C20, which are distinguished by the length of their fatty acid chains. C18 and C20 GD2 lipoforms can be simultaneously measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We evaluated the diagnostic and prognostic performance of circulating GD2 levels in children with NB.

Methods: Thirty microliters of peripheral blood (PB) plasma samples from 83 children with NB at diagnosis and 83 age-matched healthy controls were analyzed by LC-MS/MS. From stage M patients, 29 additional PB plasma samples were collected after induction therapy, 7 before and after immunotherapy, and 6 at relapse. For 22 stage M patients, bone marrow (BM) plasma samples were also collected at diagnosis.

Results: C18 and C20 GD2 concentrations were significantly higher in children with NB than in controls. Receiver operating characteristic (ROC) analysis showed a cut-point of 44.1 and 0.47 nM for C18 and C20, respectively, able to discriminate with high specificity and sensitivity in patients with NB from controls. Circulating C18 and C20 levels in PB strongly correlated with those in BM. At diagnosis, C18 and C20 GD2 concentrations were significantly higher in stage M, deceased patients, and in those bearing tumors with MYCN amplification. ROC analysis identified prognostic cut points for the whole population, whereas only C20 concentrations above the cut points were significantly associated with a worse event-free survival of patients with stage M disease or with MYCN-amplified tumors. C18 and C20 plasma concentrations strongly decreased during treatment but increased at relapse.

Conclusions: Measurement of circulating GD2 seems to have prognostic power in the subsets of patients with stage M disease and with MYCN-amplified tumors, and be able to early detect relapse, thus its ability to monitor disease should be prospectively evaluated in future studies.