Publication
Population pharmacokinetics and pharmacodynamics of doxorubicin and cyclophosphamide in breast cancer patients: a study by the EORTC-PAMM-NDDG
Journal Paper/Review - Jan 1, 2007
Jörger Markus, Féty Régine, de Bruijn Ernst, Hempel Georg, Karlsson Mats, Tranchand Brigitte, Schrijvers Ad H G J, Twelves Chris, Beijnen Jos H, Schellens Jan H M, Jodrell Duncan I, Izquierdo Miguel A, Sleeboom Henk P, Huitema Alwin D R, Richel Dick J, Dittrich Christian, Pavlidis Nikolas, Briasoulis Evangelos, Vermorken Jan B, Strocchi Elena, Martoni Andrea, Sorio Roberto, EORTC-PAMM-NDDG
Units
PubMed
Citation
Type
Journal
Publication Date
Issn Print
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Brief description/objective
AIMS: To investigate the population pharmacokinetics and pharmacodynamics of doxorubicin and cyclophosphamide in breast cancer patients. PATIENTS AND METHODS: Sixty-five female patients with early or advanced breast cancer received doxorubicin 60 mg/m(2) over 15 minutes followed by cyclophosphamide 600 mg/m(2) over 15 minutes. The plasma concentration-time data of both drugs were measured, and the relationship between drug pharmacokinetics and neutrophil counts was evaluated using nonlinear mixed-effect modelling. Relationships were explored between drug exposure (the area under the plasma concentration-time curve [AUC]), toxicity and tumour response. RESULTS: Fifty-nine patients had complete pharmacokinetic and toxicity data. In 50 patients with measurable disease, the objective response rate was 60%, with complete responses in 6% of patients. Both doxorubicin and cyclophosphamide pharmacokinetics were associated with neutrophil toxicity. Cyclophosphamide exposure (the AUC) was significantly higher in patients with at least stable disease (n = 44) than in patients with progressive disease (n = 6; 945 micromol . h/L [95% CI 889, 1001] vs 602 micromol . h/L [95% CI 379, 825], p = 0.0002). No such correlation was found for doxorubicin. Body surface area was positively correlated with doxorubicin clearance; AST and patient age were negatively correlated with doxorubicin clearance; creatinine clearance was positively correlated with doxorubicinol clearance; and occasional concurrent use of carbamazepine was positively correlated with cyclophosphamide clearance. CONCLUSIONS: The proposed inhibitory population pharmacokinetic-pharmacodynamic model adequately described individual neutrophil counts after administration of doxorubicin and cyclophosphamide. In this patient population, exposure to cyclophosphamide, as assessed by the AUC, might have been a predictor of the treatment response, whereas exposure to doxorubicin was not. A prospective study should validate cyclophosphamide exposure as a predictive marker for the treatment response and clinical outcome in this patient group.