title: Bioanalytical method requirements and statistical considerations in incurred sample reanalysis for macromolecules.
abstract: BACKGROUND
  Incurred sample reanalysis (ISR) is the most recent in-study validation parameter that regulatory agencies have mandated to ensure reproducibility of bioanalytical methods supporting pharmacokinetic/toxicokinetic and clinical studies. The present analysis describes five representative case studies for macromolecule therapeutics.
  
  
  METHODS
  Single ISR acceptance criteria (within 30% of the averaged or original concentration) and a modified Bland-Altman (BA) approach were used to assess accuracy and precision of ISR results. General concordance between the two criteria was examined using simulation studies.
  
  
  RESULTS
  All five methods met the ISR criteria. The results indicated that thorough method development and prestudy validation were prerequisites for a successful ISR. The overall agreement between the original and reanalyzed results as determined by BA was within 20%. Simulation studies indicated that concordance between the ISR criteria and BA was observed in 95% of the cases. Dilution factors had no significant impact on the ISR, even for C(max) samples where 1:100 or higher dilutions were used.
  
  
  CONCLUSIONS
  The current ISR acceptance criteria for macromolecules was scientifically and statistically meaningful for methods with a total error of 25% or less.
authors.affiliation: Department of Pharmacokinetics & Drug Metabolism, Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA 91320, USA. theingi.thway@amgen.com
authors.forename: Theingi M
authors.initials: TM
authors.lastname: Thway
authors.forename: Chris R
authors.initials: CR
authors.lastname: Macaraeg
authors.forename: Dominador
authors.initials: D
authors.lastname: Calamba
authors.forename: Laura A
authors.initials: LA
authors.lastname: Brunner
authors.forename: Michael
authors.initials: M
authors.lastname: Eschenberg
authors.forename: Ramak
authors.initials: R
authors.lastname: Pourvasei
authors.forename: Liana
authors.initials: L
authors.lastname: Zhang
authors.forename: Mark
authors.initials: M
authors.lastname: Ma
authors.forename: Binodh
authors.initials: B
authors.lastname: Desilva
mesh_terms: D000818:Animals; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D017321:Clinical Trials, Phase I as Topic; D006801:Humans; D046911:Macromolecular Substances / Q000032:analysis* / Q000097:blood; D004364:Pharmaceutical Preparations / Q000378:metabolism; D051381:Rats; D015203:Reproducibility of Results; D013810:Therapeutic Equivalency
chemical_list: D046911:Macromolecular Substances; D004364:Pharmaceutical Preparations