A validated HPLC-MS/MS method for estimating the concentration of the ganglioside, G_D2, in human plasma or serum

G_D2 is a ganglioside found in the plasma membrane of the neural crest-derived cancer, neuroblastoma. G_D2 is shed into the circulation of patients with neuroblastoma and could serve as a tumor biomarker to monitor tumor burden or response to treatment. We developed and validated a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method to quantify the D18:1-18:0 (C18) and the D18:1-20:0 (C20) lipoforms of G_D2 in human plasma and serum. Human brain derived G_D2 containing a mixture of C18 and C20 was used as the analytical standard. Samples were extracted with methanol containing dueterated-G_M1 (internal standard), and analytes were separated on a Phenomenex Kinetex C₁₈ column eluted with a gradient mobile phase composed of ammonium acetate buffer, methanol and isopropanol. An AB Sciex 4500 QTRAP mass spectrometer in negative ion mode was used to quantify the doubly charged G_D2 C18 and C20 lipoform precursor ions (m/z 836.8 and m/z 850.8) that both yield a product ion of m/z 290.0. The calibration curves were linear from 4-1000 ng/mL and 6-1500 ng/mL for G_D2 C18 and C20 lipoforms respectively. Inter-day and intra-day accuracy were within the acceptable validation range in plasma and serum.