Hepatic cytochrome P450 3A drug metabolism is reduced in cancer patients who have an acute-phase response

Inflammatory disease states (infection, arthritis) are associated with reduced drug oxidation by the cytochrome P450 3A system, Many chemotherapy agents are metabolised through this pathway, and disease may therefore influence inter-individual differences in drug pharmacokinetics. The purpose of this study was to assess cytochrome P450 3A function in patients with advanced cancer, and its relation to the acute-phase response. We evaluated hepatic cytochrome P450 3A function in 40 patients with advanced cancer using the erythromycin breath test. Both the traditional C-20min measure and the recently proposed I/T-MAX values were estimated. The marker of acute-phase response, C-reactive protein and the pro-inflammatory cytokines IL-6, IL-1beta, TNFalpha and IL-8 were measured in serum or plasma at baseline. Cancer patients with an acute phase response (C-reactive protein > 10 mg l(-1), n=26) had reduced metabolism as measured with the erythromycin breath test I/T-MAX (Kruskal-Wallis Anova, P=0.0062) as compared to controls (C-reactive protein less than or equal to 10 mg l(-1), n= 14). Indeed, metabolism was significantly associated with C-reactive protein over the whole concentration range of this acute-phase marker (r=-0.64, Spearman Rank Correlation, P < 0.00001). C-reactive protein serum levels were significantly correlated with those of IL-6 (Spearman coefficient=0.58, P<0.0003). The reduction in cytochrome P450 3A function with acute-phase reaction was independent of the tumour type and C-reactive protein elevation was associated with poor performance status. This indicates that the sub-group of cancer patients with significant acute-phase response have compromised drug metabolism, which may have implications for the safety of chemotherapy in this population. (C) 2002 Cancer Research UK.