Effects of UGT1A1*6, UGT1A1*28, and ABCB1-3435C>T polymorphisms on irinotecan induced toxicity in Chinese cancer patients.

OBJECT: The aim of this study was to investigate whether UGT1A1*6/*28 or ABCB1-3435C>T polymorphisms affect irinotecan-induced severe diarrhea and neutropenia in Chinese cancer patients. METHODS: A total of 157 cancer patients was enrolled in this study and the genotypes of UGT1A1*6/*28 and ABCB1-3435C>T polymorphisms were analyzed by PCRSanger sequence. The relationship between UGT1A1*6/*28 and ABCB1-3435C>T polymorphisms and irinotecan induced severe diarrhea and neutropenia were analyzed. RESULTS AND CONCLUSION: UGT1A1*6 and UGT1A1*28 polymorphisms were associated with severe neutropenia (p = 0.025, p = 0.022, respectively) but not diarrhea (p = 0.343, p = 0.185, respectively), and ABCB1- 3435C>T polymorphism was not associated with irinotecan induced severe toxicities (p = 0.457, p = 0.161, respectively).

Effect of CYP3A4*1G, CYP3A5*3, POR*28, and ABCB1 C3435T on the pharmacokinetics of nifedipine in healthy Chinese volunteers.

OBJECTIVE: Nifedipine is a calcium channel blocker that is widely used in the treatment of cardiovascular disease. However, significant individual variances in the disposition of nifedipine have been reported, and genetic factors are considered to play an important role. The aim of the present study was to investigate the effect of CYP3A4*1G, CYP3A5*3, ABCB1-C3435T, and POR*28 genetic polymorphisms on nifedipine pharmacokinetics in healthy Chinese volunteers. METHODS: 45 healthy Chinese volunteers enrolled in this study received a single oral dose of 90 mg nifedipine after providing written informed consent. Volunteers were genotyped for CYP3A4*1G, CYP3A5*3, POR*28, and ABCB1-C3435T. The blood concentrations of nifedipine were determined by high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method. RESULTS AND DISCUSSION: There were significant differences of AUC00-∞ and AUC0-48h in the different CYP3A5*3 genotype groups (p = 0.043 and p = 0.048, respectively). The CYP3A5*3 GG group and POR*28 CT/TT group were found to have lower AUC00-∞ and Cmax compared with the POR*28 CC group (p = 0.046 and p = 0.002, respectively). In addition, the POR*28 CT/TT group was found to have longer t1/2 but lower Cmax than the CYP3A4*1G GG group (p = 0.032 and p = 0.002, respectively) as well as the CYP3A4*1G GG and the CYP3A5*3 GG group (p = 0.038 and p = 0.036, respectively) compared with the POR*28 CC group. No significant associations were found between CYP3A4*1G/ABCB1-C3435T polymorphism and pharmacokinetics of nifedipine. CONCLUSION: Both CYP3A5*3 and POR*28 polymorphisms are found to be associated with the difference in disposition of nifedipine; POR*28 is considered to have an impact on CYP3A4 activity.