Patient characteristics associated with high-risk methotrexate concentrations and toxicity

J Clin Oncol. 1994 Aug;12(8):1667-72. doi: 10.1200/JCO.1994.12.8.1667.


Purpose: Following high-dose methotrexate (HD-MTX) treatment, delayed MTX elimination is an important problem because it necessitates increased leucovorin rescue and additional hospitalization for hydration and urinary alkalinization. Our purpose was to identify factors associated with high-risk MTX plasma concentrations (defined by plasma concentration > or = 1.0 mumol/L at 42 hours from the start of MTX) and with toxicity.

Patients and methods: Variables associated with MTX concentrations and toxicity were assessed in 134 children treated with one to five courses of HD-MTX (900 to 3,700 mg/m2 intravenously [i.v.] over 24 hours for a total of 481 courses) for acute lymphoblastic leukemia (ALL).

Results: High-risk MTX concentrations, toxicity (usually mild mucositis), and delay in resuming continuation chemotherapy occurred in 106 (22%), 123 (26%), and 66 (14%) of 481 courses, respectively. Using a mixed effects model for repeated measures, high-risk MTX concentrations were significantly associated with a higher MTX area-under-the-concentration-time curve (AUC), low urine pH, emesis, low MTX clearance, low urine output relative to intake, use of antiemetics during the MTX infusion, and concurrent intrathecal therapy (all p values < .01). Clinical toxicities and delay in resumption of continuation chemotherapy due to myelosuppression were more common in those with high 42-hour MTX concentrations, despite increased leucovorin rescue for all patients with high-risk MTX concentrations. However, with individualized rescue, no patient developed life-threatening toxicity. A more aggressive hydration and alkalinization regimen for subsequent courses reduced the frequency of high-risk MTX concentrations to 7% of courses (13 of 183) (P = .0001), and the frequency of toxicity decreased to 11% of courses (P = .0074).

Conclusion: This study identified several clinical variables that influence MTX disposition that, when modified, can reduce the frequency of high-risk MTX concentrations and toxicity.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Child
  • Child, Preschool
  • Female
  • Fluid Therapy
  • Humans
  • Hydrogen-Ion Concentration
  • Infusions, Intravenous
  • Leucovorin / administration & dosage
  • Male
  • Methotrexate / administration & dosage
  • Methotrexate / adverse effects*
  • Methotrexate / blood*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / blood*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / drug therapy
  • Risk Factors
  • Urine
  • Vomiting / blood


  • Leucovorin
  • Methotrexate