Pharmacokinetics of the disialoganglioside, G, a circulating tumor biomarker for neuroblastoma, in nonhuman primates.

BACKGROUND

: The ganglioside G is a potential circulating tumor biomarker for the childhood cancer neuroblastoma. Interpreting the levels of a circulating tumor biomarker depends in part on a knowledge of the biomarker’s clinical pharmacology.

METHODS

: We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of the C lipoform of G in two nonhuman primates with indwelling subcutaneous CSF lateral ventricular reservoir systems. G was quantified with a validated high-performance liquid chromatography (HPLC)/tandem mass spectrometry assay. G was administered as a short intravenous infusion and frequent plasma and CSF samples were drawn over 72 hours.

RESULTS

: G plasma concentration declined monoexponentially with a half-life of 16 hours. Clearance was 0.0136 and 0.0131 L/h and volume of distribution (V) was 0.035 and 0.038 L/kg in the two animals. V was equivalent to plasma volume. Greater than 98% of G in plasma is in a bound form consistent with its known association with lipoproteins and accounting for its limited volume of distribution. G did not cross over from plasma into the CSF.

CONCLUSIONS

: The pharmacokinetic profile of G is favorable for a circulating tumor biomarker. This study demonstrates the value of characterizing the clinical pharmacology of circulating biomarkers to better understand their clinical behavior.