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11.
Development and Validation of a High- Performance Liquid Chromatography– Tandem Mass Spectrometry Method for the Simultaneous Determination of Irinotecan and Its Main Metabolites in Human Plasma and Its Application in a Clinical Pharmacokinetic Study
Bianca Posocco, Elisa Mazzega, Elena Marangon, Giuseppe Toffoli, 2015, original scientific article

Abstract: Irinotecan is currently used in several cancer regimens mainly in colorectal cancer (CRC). This drug has a narrow therapeutic range and treatment can lead to side effects, mainly neutropenia and diarrhea, frequently requiring discontinuing or lowering the drug dose. A wide inter-individual variability in irinotecan pharmacokinetic parameters and pharmacodynamics has been reported and associated to patients’ genetic background. In particular, a polymorphism in the UGT1A1 gene (UGT1A1*28) has been linked to an impaired detoxification of SN-38 (irinotecan active metabolite) to SN-38 glucuronide (SN-38G) leading to increased toxicities. Therefore, therapeutic drug monitoring of irinotecan, SN-38 and SN-38G is recommended to personalize therapy. In order to quantify simultaneously irinotecan and its main metabolites in patients’ plasma, we developed and validated a new, sensitive and specific HPLC–MS/MS method applicable to all irinotecan dosages used in clinic. This method required a small plasma volume, addition of camptothecin as internal standard and simple protein precipitation. Chromatographic separation was done on a Gemini C18 column (3 μM, 100 mm x 2.0 mm) using 0.1% acetic acid/bidistilled water and 0.1% acetic acid/acetonitrile as mobile phases. The mass spectrometer worked with electrospray ionization in positive ion mode and selected reaction monitoring. The standard curves were linear (R20.9962) over the concentration ranges (10–10000 ng/mL for irinotecan, 1–500 ng/mL for SN-38 and SN-38G and 1–5000 ng/mL for APC) and had good back-calculated accuracy and precision. The intra- and inter-day precision and accuracy, determined on three quality control levels for all the analytes, were always <12.3% and between 89.4% and 113.0%, respectively. Moreover, we evaluated this bioanalytical method by re-analysis of incurred samples as an additional measure of assay reproducibility. This method wassuccessfully applied to a pharmacokinetic study in metastatic CRC patients enrolled in a genotype-guided phase Ib study of irinotecan administered in combination with 5-fluorouracil/ leucovorin and bevacizumab.
Keywords: Pharmacokinetic, pharmacodynamics, phase I clinical study, colorectal cancer, Mass spectrometry, pharmacogenetics
Published in RUNG: 21.03.2017; Views: 4513; Downloads: 0
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12.
SINGLE NUCLEOTIDE POLYMORPHISMS OF THE CHROMOSOME SEGREGATION GENES INVOLVED IN THE DEVELOPMENT OF GASTRIC CANCER
Marija Rogar, 2016, doctoral dissertation

Abstract: INTRODUCTION. Gastric cancer represents the fifth most frequently diagnosed cancer in the world. Despite numerous research studies, mechanisms leading to disease are poorly known and unclear. At the molecular level, many changes are involved in the development of gastric cancer, including malfunction of chromosome segregation genes. These abnormalities can lead to chromosomal instability (CIN). Segregation gene function can be affected by the low penetrance errors which include polymorphisms. AIM. The aim of this study is to examine the effect of selected polymorphisms in specific segregation genes on gastric cancer development. HYPOTHESIS. The study focused on exploring genotypes of selected polymorphisms in specific mitotic segregation genes. Those that differ significantly between the subjects and the healthy control population, may be associated with higher risk for developing gastric cancer or with certain clinical and histopathological characteristics, and may have effect on the survival of gastric cancer patients. METHODS. 30 polymorphisms in genes BUB1B, CASC5, ESPL1, PTTG1, SMC1A, TPX2, TTK and ZWINT were included in the study. Subjects were compared with the control group. Polymorphisms were determined using quantitative real-time PCR (qPCR), restriction fragment length polymorphism (RFLP) and DNA sequencing. RESULTS. The association between polymorphisms rs2277559 (BUB1B), rs2241666 (ZWINT), rs11858113 (CASC5) and rs11855334 (CASC5) and increased risk of developing gastric cancer in male population was determined. As concerning rs11855334, statistically significant difference was also observed in the genotype distribution between the whole population of subjects and controls. The association between the genotypes of polymorphisms (in gene BUB1B) rs2277559, rs2290551, rs1801376, rs1047130, rs1565866, rs2277560 and Lauren classification was recognized. Genotypes of polymorphisms rs1801376 (BUB1B), rs11855334 (CASC5), rs2241666 (ZWINT), rs2910101 (PTTG1) and rs1047130 (BUB1B) are linked to different tumour differentiation grades. Survival analysis revealed association between the lymph node involvement and perineural invasion. Statistically higher frequencies of haplotypes G-A-G-T-G-G-A, G-G-A-G-A-A-G and A-G-G-T-A-G-A in gene BUB1B and of haplotypes A-A-A-C and C-C-G-T in gene ESPL1 were observed in gastric cancer patients, whereas haplotypes A-C-A-T and C-A-G-T in gene ESPL1 were significantly more frequent in the control group. Association with gastric cancer was not noted with other polymorphisms. CONCLUSIONS. The association between specific polymorphisms of selected chromosome segregation genes and gastric cancer was recognized. Findings could provide guidelines for further research and polymorphisms linked to gastric cancer could serve as potential diagnostic and prognostic biomarkers.
Keywords: gastric cancer, chromosomal instability, polymorphisms, segregation genes
Published in RUNG: 27.07.2016; Views: 5983; Downloads: 347
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