Trimetrexate, an investigational antifol, has been associated with marked variability in drug tolerance among patients. The agent is extensively protein bound, and hepatic biotransformation plays a major role in its elimination. In early phase II testing, nine of 15 patients who experienced life-threatening or fatal toxic effects from trimetrexate had albumin levels ≤3.5 g/dL prior to treatment. This prompted a review of the data base on 272 patients entered in phase I clinical trials. The incidence of severe or life-threatening anemia, leukopenia, neutropenia, thrombocytopenia, mucositis, and hepatic toxic effects during the first course of trimetrexate was analyzed according to dose, schedule, prior treatment, and baseline protein and albumin levels. The schedules using doses given by short infusions of 30-60 minutes daily for 5 days or weekly for 3 weeks were generally associated with higher incidence of toxic effects than the schedules using doses given every other week by short infusions or those using continuous infusion. The occurrence of leukopenia and mucositis was dose related. Patients with baseline albumin levels ≤3.5 g/dL had higher incidence of all types of severe or life-threatening toxic effects than those with albumin levels ≥3.6 g/dL, and the differences were significant for the development of anemia, thrombocytopenia, and mucositis. Similar correlations were noted for pretreatment protein levels ≤6.0 g/dL. The small cohort of patients with leukemia experienced substantial toxic effects and tended to have low protein and albumin levels. Performance status and prior therapy dit not emerge as strong predictors of severe toxic effects in the univariate analysis. Multivariate analysis confirmed that the type of cancer (leukemia vs. solid tumor), does, schedule, and baseline albumin level were significant and independent predictors of severe and life-threatening toxic effects in the phase I patient population. Multivariate analysis including only patients with solid tumors indicated that albumin level, dose, and schedule remained significant predictors of toxic effects. Since normal liver function as reflected by bilirubin and transaminase values were a requirement for eligibility, the results suggest that albumin and protein levels may provide a more sensitive index of hepatic function. Patients with hypoalbuminemia and hypoproteinemia are at increased risk of experiencing severe or life-threatening toxic effects from trimetrexate and should be treated cautiously.
ASJC Scopus subject areas
- Cancer Research