Pharmacokinetic (Pk)-Guided Optimization Of 5-Fluorouracil (5fu) Exposure In Colorectal Cancer (Crc) Patients: Usbased Clinical Practices Experience.

3574 Background: Multiple studies have demonstrated how PK-guided dosing to optimize infusional 5FU exposure improves both response rates and toxicities. With 5FU PK testing now available using a rapid, reliable immunoassay, we present US-based oncologists’ experience with individualizing 5FU dosing based on PK in patients with adjuvant or metastatic CRC. Methods: Between June 5, 2013 and January 17, 2014, Saladax Biomedical Laboratories (a CLIA-certified lab) determined 5FU plasma levels (My5-FU assay) in 631 samples collected ~24+6Hr after the start of 5FU continuous infusion from 240 CRC patients (n=250 therapy lines). Systemic 5FU exposure (calculated as area under the curve [AUC]) and dose adjustment recommendations to achieve target range (AUC = 20 – 30 mg*hr/L) were reported to physicians. Evaluable cycle pairs were defined as two consecutive cycles with AUC results. Actual vs. target AUC, recommended vs. actual dose adjustment, and ability to adjust exposure to target range were evaluated. Results...