Quantitative analysis of imetelstat in plasma with LC-MS/MS using solid-phase or hybridization extraction

Aim: Imetelstat, a 13-mer oligonucleotide with a lipid tail is being evaluated for treating hematologic myeloid malignancies. This report describes the development of extraction and quantification methods for imetelstat. Methodology & results: Imetelstat was extracted using SPE (rat plasma) or by hybridization using a biotinylated capture probe (human plasma) and was quantified by LC-MS/MS. Calibration curves were established (0.1-50 mu g/ml). Stability of imetelstat in plasma was demonstrated. Concentrations of imetelstat extracted using either of the methods and quantified with LC-MS/MS were comparable with a validated ELISA. Conclusion: Two extraction methods (solid phase and hybridization) were developed for quantifying imetelstat in plasma using LC-MS/MS. The hybridization extraction in combination with LC-MS/ MS is a novel extraction approach.