title: Development and clinical application of a LC-MS/MS method for simultaneous determination of various tyrosine kinase inhibitors in human plasma.
abstract: BACKGROUND
  Increasing numbers of tyrosine kinase inhibitors (TKIs) were studied and approved for therapy of malignancies and other diseases. The aim of this study was to develop and validate a specific, simple and rapid quantification method for various TKIs in human plasma.
  
  
  METHODS
  A simultaneous test for six TKIs (erlotinib, imatinib, lapatinib, nilotinib, sorafenib, sunitinib) was developed using liquid chromatography tandem mass spectrometry in a multiple reaction monitoring mode. After protein precipitation the specimens were applied to the HPLC system and separated using a gradient of acetonitrile containing 1% formic acid with 10 mM ammoniumformiate on an analytic RP-C18 column.
  
  
  RESULTS
  The calibration range was 10-1000 ng/mL for sunitinib and 50-5000 ng/mL for the other TKIs with coefficients of determination ≥0.99 for all analytes. The intra- and inter day coefficients of variation were ≤15% and the chromatographic run time was 12 min. Plasma specimens were stable for measurement for at least 1 week at 4°C. Clinical applications of the assay are exemplarily discussed.
  
  
  CONCLUSIONS
  This novel high-throughput method is suitable for specific simultaneous determination of different TKIs in routine clinical practice.
authors.affiliation: Institute of Laboratory Medicine and Pathobiochemistry, Philipps-University Marburg, Marburg, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Götze
authors.forename: Axel
authors.initials: A
authors.lastname: Hegele
authors.forename: Stephan Klaus
authors.initials: SK
authors.lastname: Metzelder
authors.forename: Harald
authors.initials: H
authors.lastname: Renz
authors.forename: Wolfgang Andreas
authors.initials: WA
authors.lastname: Nockher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D047428:Protein Kinase Inhibitors / Q000097:blood*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D047428:Protein Kinase Inhibitors; D011505:Protein-Tyrosine Kinases