title: Quantitative method for the determination of iso-fludelone (KOS-1803) in human plasma by LC-MS/MS.
abstract: Epothilones are relatively new tubulin-poison anticancer drugs. Iso-fludelone (KOS-1803) is a synthetic third generation epothilone drug discovered at Memorial Sloan Kettering Cancer Center, and currently in phase I clinical trials. We report an LC-MS/MS assay for the sensitive, accurate and precise quantitation of iso-fludelone in 0.2mL of human plasma. Validation was performed according to FDA guidance. The assay comprised of KOS-1724 as the internal standard and an MTBE liquid-liquid extraction with a water wash step. Separation was achieved with an YMC-Pack ODS-AQ column and an isocratic mobile phase of 0.1% formic acid in acetonitrile and water (70:30, v/v) at 0.3mL/min for 4min. Chromatographic separation was followed by electrospray, positive-mode ionization tandem mass spectrometric detection in the multiple reaction monitoring (MRM) mode. The assay was linear from 0.1 to 300ng/mL and was accurate (-9.41 to -7.07%) and precise (1.03-13.7%) which fulfilled FDA criteria for validation. Recovery from plasma was 73.9-79.7% and ion suppression was negligible (-22.8 to -31.3%). Plasma freeze-thaw stability (99.97-105.7%), stability for 11 months at -80°C (94.93-107.9%), and stability for 6h at room temperature (94.75-105.5%) were all acceptable. This assay is currently being applied to quantitate iso-fludelone in clinical samples.
authors.affiliation: Molecular Therapeutics/Drug Discovery Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Christner
authors.affiliation: Molecular Therapeutics/Drug Discovery Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Parise
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Erica D
authors.initials: ED
authors.lastname: Levine
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Naiyer A
authors.initials: NA
authors.lastname: Rizvi
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Mrinal M
authors.initials: MM
authors.lastname: Gounder
authors.affiliation: Molecular Therapeutics/Drug Discovery Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA; Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA 15213, USA. Electronic address: beumerj@gmail.com.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Beumer
mesh_terms: D000970:Antineoplastic Agents / Q000097:blood*; D002138:Calibration; D002853:Chromatography, Liquid / Q000592:standards; D003080:Cold Temperature; D004355:Drug Stability; D034261:Epothilones / Q000097:blood*; D006801:Humans; D059625:Liquid-Liquid Extraction; D012015:Reference Standards; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000592:standards; D053719:Tandem Mass Spectrometry / Q000592:standards; D013997:Time Factors; D050257:Tubulin Modulators / Q000097:blood*
chemical_list: D000970:Antineoplastic Agents; D034261:Epothilones; D050257:Tubulin Modulators; C506241:fludelone
keywords: Assay; Epothilone; KOS-1803 (iso-fludelone); LC–MS/MS; Validation