title: Cerebrospinal fluid asparagine concentrations after Escherichia coli asparaginase in children with acute lymphoblastic leukemia.
abstract: OBJECTIVE
  The CNS is an important sanctuary site in childhood acute lymphoblastic leukemia (ALL). CSF asparagine concentration reflects asparaginase systemic pharmacodynamics. We evaluated the time course of CSF asparagine depletion in children with ALL during and after a course of Escherichia coli asparaginase.
  
  
  METHODS
  Thirty-one children (24 newly diagnosed and seven at relapse) received E coli asparaginase 10,000 IU/m2 intramuscularly three times weekly for six and nine doses, respectively, as part of multiagent induction chemotherapy. CSF asparagine levels were measured before, during, and after asparaginase dosing.
  
  
  RESULTS
  The percentage of patients with undetectable (< 0.04 micromol/L) CSF asparagine was 3.2% (one of 31 patients) at baseline, 73.9% (17 of 23) during asparaginase therapy, and 56.3% (nine of 16) 1 to 5 days, 43.8% (seven of 16) 6 to 10 days, 20.0% (two of 10) 11 to 30 days and 0% (zero of 21) more than 30 days after asparaginase therapy. The proportion of patients with depleted CSF asparagine was higher during asparaginase therapy than at baseline (P < .001), 11 to 30 days (P = .003), and more than 30 days after asparaginase therapy (P < .001). Median CSF asparagine concentrations were 4.42 micromol/L before, less than 0.04 micromol/L during, and less than 0.04 micromol/L at 1 to 5 days, 1.63 micromol/L at 6 to 10 days, 1.70 micromol/L at 11 to 30 days, and 5.70 micromol/L at more than 30 days after asparaginase therapy, respectively. CSF depletion was more common in patients with low baseline CSF asparagine concentrations (P = .003).
  
  
  CONCLUSIONS
  CSF asparagine concentrations are depleted by conventional doses of E coli asparaginase in the majority of patients, but they rebound once asparaginase therapy is completed.
authors.affiliation: Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, and College of Pharmacy, University of Tennessee, Memphis 38105, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Woo
authors.forename: L J
authors.initials: LJ
authors.lastname: Hak
authors.forename: M C
authors.initials: MC
authors.lastname: Storm
authors.forename: A J
authors.initials: AJ
authors.lastname: Gajjar
authors.forename: J T
authors.initials: JT
authors.lastname: Sandlund
authors.forename: P L
authors.initials: PL
authors.lastname: Harrison
authors.forename: B
authors.initials: B
authors.lastname: Wang
authors.forename: C H
authors.initials: CH
authors.lastname: Pui
authors.forename: M V
authors.initials: MV
authors.lastname: Relling
mesh_terms: D000293:Adolescent; D000970:Antineoplastic Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001215:Asparaginase / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001216:Asparagine / Q000134:cerebrospinal fluid*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007273:Injections, Intramuscular; D016013:Likelihood Functions; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000134:cerebrospinal fluid* / Q000628:therapy; D012074:Remission Induction / Q000379:methods
chemical_list: D000970:Antineoplastic Agents; D001216:Asparagine; D001215:Asparaginase