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Erschienen in:
01.08.2011 | Original Article
Determination of 5-fluorouracil and dihydrofluorouracil levels by using a liquid chromatography–tandem mass spectrometry method for evaluation of dihydropyrimidine dehydrogenase enzyme activity
Erschienen in: Cancer Chemotherapy and Pharmacology | Ausgabe 2/2011
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Purpose
5-Fluorouracil (5-FU), acting as a pyrimidine antagonist, is a major chemotherapy drug used for the treatment of tumors such as gastrointestinal, breast, ovary, and head and neck cancers. The key and rate-limiting enzyme in 5-FU catabolism is dihydropyrimidine dehydrogenase (DHPDH), whose partial or complete deficiency exposes to a severe 5-FU toxicity in patients. The determination of DHPDH activity in patients before the treatment and setting up a personalized therapy for each patient receiving the drug can help us to prevent the possible risk of toxicity.
Methods
To isolate peripheral blood mononuclear cells (PBMCs), EDTA-anticoagulated blood samples were collected from randomly selected 47 patients and examined for 5-FU and its metabolite dihydrofluorouracil (FUH2) by using a liquid chromatography–tandem mass spectrometry (LC–MS/MS) to observe DHPDH activity at different intervals (0 and 4th hour) indirectly.
Results
Intra-assay and interassay CV % values of samples from the measurements of the modified methods are found 1.3–11.9, 2.3–9.4 for 5-FU and 3.1–14.4, 3.3–12.6 for FUH2, respectively. The reference values derived from 45 patients treated with 5-FU are 1.84 ± 0.34 ug/gr protein for 5-FU, 40.15 ± 11.43 ng/gr protein for FUH2, respectively. FUH2/5-FU ratio is 21.9 ± 3.72. In addition, the results determined from two patients, in which the lack of DHPDH is considered, were 3.24 and 4.16 ug/gr protein for 5-FU, 4.1 and 6.7 ng/gr protein for FUH2. FUH2/5-FU ratio is 1.26 and 1.61.
Conclusion
The measurements of 5-FU, FUH2, and especially their ratio (FUH2/5-FU) by the modified LC–MS/MS method could be used to determine DHPDH enzyme activity.