title: A pharmacokinetic/pharmacodynamic model of tumor lysis syndrome in chronic lymphocytic leukemia patients treated with flavopiridol.
abstract: OBJECTIVE
  Flavopiridol, the first clinically evaluated cyclin-dependent kinase inhibitor, shows activity in patients with refractory chronic lymphocytic leukemia, but prevalent and unpredictable tumor lysis syndrome (TLS) presents a major barrier to its broad clinical use. The purpose of this study was to investigate the relationships between pretreatment risk factors, drug pharmacokinetics, and TLS.
  
  
  METHODS
  A population pharmacokinetic/pharmacodynamic model linking drug exposure and TLS was developed. Plasma data of flavopiridol and its glucuronide metabolite (flavo-G) were obtained from 111 patients treated in early-phase trials with frequent sampling following initial and/or escalated doses. TLS grading was modeled with logistic regression as a pharmacodynamic endpoint. Demographics, baseline disease status, and blood chemistry variables were evaluated as covariates.
  
  
  RESULTS
  Gender was the most significant pharmacokinetic covariate, with females displaying higher flavo-G exposure than males. Glucuronide metabolite exposure was predictive of TLS occurrence, and bulky lymphadenopathy was identified as a significant covariate on TLS probability. The estimated probability of TLS occurrence in patients with baseline bulky lymphadenopathy less than 10 cm or 10 cm or more during the first 2 treatments was 0.111 (SE% 13.0%) and 0.265 (SE% 17.9%), respectively, when flavo-G area under the plasma concentration versus time curve was at its median value in whole-patient group.
  
  
  CONCLUSIONS
  This is the first population pharmacokinetic/pharmacodynamic model of TLS. Further work is needed to explore potential mechanisms and to determine whether the associations between TLS, gender, and glucuronide metabolites are relevant in patients with chronic lymphocytic leukemia treated with other cyclin-dependent kinase inhibitors.
authors.affiliation: The Comprehensive Cancer Center, College of Pharmacy, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Ji
authors.forename: Diane R
authors.initials: DR
authors.lastname: Mould
authors.forename: Kristie A
authors.initials: KA
authors.lastname: Blum
authors.forename: Amy S
authors.initials: AS
authors.lastname: Ruppert
authors.forename: Ming
authors.initials: M
authors.lastname: Poi
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Johnson
authors.forename: John C
authors.initials: JC
authors.lastname: Byrd
authors.forename: Michael R
authors.initials: MR
authors.lastname: Grever
authors.forename: Mitch A
authors.initials: MA
authors.lastname: Phelps
mesh_terms: D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D005260:Female; D005419:Flavonoids / Q000493:pharmacokinetics / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000150:complications / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D020714:Maximum Tolerated Dose; D008954:Models, Biological; D009364:Neoplasm Recurrence, Local; D010880:Piperidines / Q000493:pharmacokinetics / Q000627:therapeutic use*; D015995:Prevalence; D011379:Prognosis; D014018:Tissue Distribution; D015275:Tumor Lysis Syndrome / Q000453:epidemiology* / Q000209:etiology; D014481:United States / Q000453:epidemiology
chemical_list: D000970:Antineoplastic Agents; D005419:Flavonoids; D010880:Piperidines; C077990:alvocidib