Application of pharmacokinetic (PK)-guided 5-fluorouracil (FU) in clinical practice.

2595 Background: Body surface area (BSA)-based dosing of FU results in up to 100-fold inter-individual PK variability. PK-guided FU compared to BSA-based dosing resulted in higher response rates and decreased rate of toxicities in two randomized clinical trials. A paucity of data exists on PK-guided FU dosing in the clinical setting. Methods: A total of 70 colorectal cancer (CRC) patients (pts) from 6 academic and community sites received mFOLFOX6 (FU 2,400 mg/m2over 46 h every 2 wks) +/- bevacizumab. Peripheral blood was obtained 2-44 h after start of FU infusion and AUCs were estimated using an immunoassay at Myriad Genetics. FU doses for cycles 2-4 (C2-4) were adjusted algorithmically to target an area under the concentration-time curve (AUC) of 20-25 mg*h/L. The primary outcome was the % of pts within target AUC by C4, with a secondary outcome of toxicity rates compared to historical data. Comparisons between cycles were made using generalized linear models, accounting for repeated observations within...