Relationship between UGT1A1*6/*28 polymorphisms and severe toxicities in Chinese patients with pancreatic or biliary tract cancer treated with irinotecan-containing regimens

Effect of drug metabolizing enzymes and transporters in Thai colorectal cancer patients treated with irinotecan-based chemotherapy

Genetic polymorphisms in drug metabolizing enzymes and drug transporters may affect irinotecan toxicity. Although genetic polymorphisms have been shown to influence the irinotecan toxicity, data are limited in Thai population. Thus, the aim of this study was to assess the allele and genotype frequencies and the relationship between CYP3A4/5, DPYD, UGT1A1, ABCB1, and ABCC2 genetic variations and irinotecan-induced toxicity in Thai colorectal cancer patients. One hundred and thirty-two patients were genotyped, and the effect of genetic variations on irinotecan-induced toxicity was assessed in 66 patients who received irinotecan-based chemotherapy. Allele frequencies of ABCB1 c.1236C > T, ABCB1 c.3435C > T, ABCC2 c.3972C > T, ABCG2 c.421C > A, CYP3A4*1B, CYP3A4*18, CYP3A5*3, DPYD*5, UGT1A1*28, and UGT1A1*6 were 0.67, 0.43, 0.23, 0.27, 0.01, 0.02, 0.64, 0.19, 0.16, and 0.09, respectively. DPYD*2A and DPYD c.1774C > T variants were not detected in our study population. The ABCC2 c.3972C > T was significantly associated with grade 1–4 neutropenia (P < 0.012) at the first cycle. Patients carrying both UGT1A1*28 and *6 were significantly associated with severe neutropenia at the first (P < 0.001) and second (P = 0.017) cycles. In addition, patients carrying UG1A1*28 and *6 had significantly lower absolute neutrophil count (ANC) nadir at first (P < 0.001) and second (P = 0.001) cycles. This finding suggests that UGT1A1*28, *6, and ABCC2 c.3972C > T might be an important predictor for irinotecan-induced severe neutropenia.

The Ontogeny of UDP-glucuronosyltransferase Enzymes, Recommendations for Future Profiling Studies and Application Through Physiologically Based Pharmacokinetic Modelling

Limited understanding of drug pharmacokinetics in children is one of the major challenges in paediatric drug development. This is most critical in neonates and infants owing to rapid changes in physiological functions, especially in the activity of drug-metabolising enzymes. Paediatric physiologically based pharmacokinetic models that integrate ontogeny functions for cytochrome P450 enzymes have aided our understanding of drug exposure in children, including those under the age of 2 years. Paediatric physiologically based pharmacokinetic models have consequently been recognised by the European Medicines Agency and the US Food and Drug Administration as innovative tools in paediatric drug development and regulatory decision making. However, little is currently known about age-related changes in UDP-glucuronosyltransferase-mediated metabolism, which represents the most important conjugation reaction for xenobiotics. Therefore, the objective of the review was to conduct a thorough literature survey to summarise our current understanding of age-related changes in UDP-glucuronosyltransferases as well as associated clinical and experimental sources of variance. Our findings indicate that there are distinct differences in UDP-glucuronosyltransferase expression and activity between isoforms for different age groups. In addition, there is substantial variability between individuals and laboratories reported for human liver microsomes, which results in part from a lack of standardised experimental conditions. Therefore, we provide a number of best practice recommendations for experimental conditions, which ultimately may help improve the quality of data used for quantitative clinical pharmacology approaches, and thus for safe and effective pharmacotherapy in children.

Impact of UGT1A1 genetic polymorphism on toxicity in unresectable pancreatic cancer patients undergoing FOLFIRINOX

Studies have indicated an association between UDP‐glucuronosyltransferase‐1A1 (UGT1A1) genetic polymorphisms and irinotecan‐induced toxicity. We undertook this study to investigate the association between UGT1A1 genetic polymorphisms and toxicity in patients treated with the FOLFIRINOX (comprising oxaliplatin, irinotecan, fluorouracil, and leucovorin) chemotherapy regimen in the JASPAC 06 study. Patients screened for UGT1A1*6 and UGT1A1*28, and treated with either the original FOLFIRINOX (oxaliplatin 85 mg/m², irinotecan 180 mg/m², leucovorin 200 mg/m², bolus 5‐fluorouracil [5‐FU] 400 mg/m², and continuous 5‐FU 2400 mg/m²) or a modified FOLFIRINOX (oxaliplatin 85 mg/m², irinotecan 150 mg/m², leucovorin 200 mg/m², and continuous 5‐FU 2400 mg/m²) as first‐line chemotherapy were included. Of 199 patients eligible for this analysis, 79 patients were treated with the original FOLFIRINOX regimen and 120 patients were treated with the modified FOLFIRINOX regimen. In the original FOLFIRINOX group, 54 were UGT1A1 WT, and 25 were UGT1A1 heterozygous type (−/*6, 12 patients; −/*28, 13 patients). In the modified FOLFIRINOX group, 64 were UGT1A1 WT and 56 were UGT1A1 heterozygous type (−/*6, 33 patients; −/*28, 23 patients).

In the original FOLFIRINOX group, the incidence of diarrhea was significantly higher among patients with UGT1A1 heterozygous type than among those with UGT1A1 WT and the incidence of leukopenia and diarrhea was significantly higher among patients with UGT1A1 −/*6 than among those with UGT1A1 −/*28. Patients with UGT1A1 heterozygous type, especially those with UGT1A1 −/*6, tended to show a higher incidence rate of severe adverse events, but this was not statistically significant. However, for patients who received the modified FOLFIRINOX, there was no difference in the frequency of adverse events due to UGT1A1 status. In conclusion, patients with heterozygous UGT1A1 polymorphisms treated with the original FOLFIRINOX regimen experienced severe toxicity more frequently than patients with WT UGT1A1.

Uridine 5'-diphospho-glucronosyltrasferase: Its role in pharmacogenomics and human disease

Biotransformation is an enzyme-catalyzed process in which the body converts endogenous compounds, xenobiotics and toxic substances into harmless or easily excreted metabolites. The biotransformation reactions are classified as phase I and II reactions. Uridine 5'-diphospho (UDP)-glucuronosyltransferases (UGTs) are a superfamily of phase II enzymes which have roles in the conjugation of xenobiotics or endogenous compounds, including drugs and bilirubin, with glucuronic acid to make them easier to excrete. The method the human body uses to achieve glucuronidation may be affected by a large interindividual variation due to changes in the sequences of the genes encoding these enzymes. In the last five years, the study of the genetic variants of the UGTs at a molecular level has become important due to its association with several diseases and the ability to predict adverse events due to drug metabolism. In the present review, the structure and the prominent genetic variants of the UGT1A subfamily and their metabolic and clinical implications are described.

Hepatic expression of transcription factors affecting developmental regulation of UGT1A1 in the Han Chinese population

PURPOSE

Complete or partial inactivity of UGT1A1, the unique enzyme responsible for bilirubin glucuronidation, is commonly associated with hyperbilirubinemia. We investigated the dynamic expression of UGT1A1, and that of the transcription factors (TFs) involved in its developmental regulation, during human hepatic growth in Han Chinese individuals.

METHODS

Eighty-eight prenatal, pediatric, and adult liver samples were obtained from Han Chinese individuals. Quantitative real-time polymerase chain reaction was used to evaluate mRNA expression of UGT1A1 and TFs including PXR, CAR, HNF1A, HNF4A, PPARA, etc. UGT1A1 protein levels and metabolic activity were determined by western blotting and high-performance liquid chromatography. Direct sequencing was employed to genotype UGT1A1*6 (211G˃A) and UGT1A1*28 (TA6˃TA7) polymorphisms.

RESULTS

UGT1A1 expression was minimal in prenatal samples, but significantly elevated during pediatric and adult stages. mRNA and protein levels and metabolic activity were prominently increased (120-, 20-, and 10-fold, respectively) in pediatric and adult livers compared to prenatal samples. Furthermore, expression did not differ appreciably between pediatric and adult periods. Dynamic expression of TFs, including PXR, CAR, HNF1A, HNF4A, and PPARA, was consistent with UGT1A1 levels at each developmental stage. A pronounced correlation between expression of these TFs and that of UGT1A1 (P < 0.001) was observed. Moreover, UGT1A1*6 and UGT1A1*28 polymorphisms reduced levels of UGT1A1 by up to 40-60 %.

CONCLUSIONS

Hepatic expression of transcription factors is associated with developmental regulation of UGT1A1 in the Han Chinese population. Moreover, UGT1A1 polymorphisms are associated with reduced expression of UGT1A1 mRNA and protein, as well as enzyme activity.

MMP-2 gene polymorphisms are associated with type A aortic dissection and aortic diameters in patients

Matrix metalloproteinases-2 (MMP-2) plays an important role in the pathogenesis of type A aortic dissection (AD). The aim of this study was to evaluate the association of 3 single nucleotide polymorphisms (SNPs) in the MMP-2 gene with type A AD risk and aortic diameters in patients. We performed a case-control study with 172 unrelated type A AD patients and 439 controls. Three SNPs rs11644561, rs11643630, and rs243865 were genotyped through the MassARRAY platform. Allelic associations of SNPs and SNP haplotypes with type A AD and aortic diameters in patients were evaluated. The frequency of the G allele of the rs11643630 polymorphism was significantly lower in type A AD patients than in control subjects (odds ratio 0.705, 95% confidence interval 0.545-0.912, P = 0.008). The association remained significant after adjusting for clinical covariates (P = 0.008). Carriers of the GG genotype of the rs11643630 polymorphism had significantly smaller aortic diameters than those with GT genotype or TT genotype (P = 0.02). Further haplotype analysis identified 1 protective haplotype (GC; P = 0.008) for development of type A AD. Again, a significant correlation was observed between haplotype GC and AD size (P = 0.020). Our results suggest that MMP-2 gene polymorphisms contribute to type A AD susceptibility. In addition, MMP-2 gene SNPs are associated with AD size, which could be used as a target for the development of new drug therapy.

Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use

During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.

Nanovectors for anti-cancer drug delivery in the treatment of advanced pancreatic adenocarcinoma

Liposome, albumin and polymer polyethylene glycol are nanovector formulations successfully developed for anti-cancer drug delivery. There are significant differences in pharmacokinetics, efficacy and toxicity between pre- and post-nanovector modification. The alteration in clinical pharmacology is instrumental for the future development of nanovector-based anticancer therapeutics. We have reviewed the results of clinical studies and translational research in nanovector-based anti-cancer therapeutics in advanced pancreatic adenocarcinoma, including nanoparticle albumin-bound paclitaxel and nanoliposomal irinotecan. Furthermore, we have appraised the ongoing studies incorporating novel agents with nanomedicines in the treatment of pancreatic adenocarcinoma.

A novel genetic score model of UGT1A1 and TGFB pathway as predictor of severe irinotecan-related diarrhea in metastatic colorectal cancer patients

PURPOSE

UGT1A1*28/*6 as predictors of severe irinotecan-related diarrhea (SIRD) were duplicated by many studies. However, some patients of lower risk genotype (UGT1A1*1/*1) still suffered SIRD and the extremely low frequency of UGT1A1*6/*6 limited its clinical usage. Previous studies proved that the transforming growth factor (TGFB) family may have some effect on MTX-induced mucositis. However, the associations between TGFB gene variants and SIRD have never been reported so far. Our aim was to improve the predictive value of UGT1A1 gene variants on SIRD.

METHODS

Six SNPs (TGFB1 rs1800469; TGFBR1 rs10733710, rs334354 and rs6478974; TGFBR2 rs3087465; UGT1A1*6) and UGT1A1*28 were selected for genotyping in 160 metastatic colorectal cancer patients treated with irinotecan in a prospective multicenter trial (NCT01282658).

RESULTS

UGT1A1*6, UGT1A1*28, rs1800469 and rs3087465 were all associated with SIRD (p = 0.026, 0.014, 0.047 and 0.045 respectively). A novel genetic score model (with a cut off value of 1.5) based on them was created to predict SIRD (OR = 11.718; 95 % CI 2.489-55.157, p = 0.002). In patients of gene score > 1.5, the risk of SIRD was much higher (23.5 vs. 2.8 %, p = 2.24E-04) and continued in the first 6 cycles of chemotherapy, while in patients with gene score ≤1.5, the risk was much lower and none of them suffered SIRD after the first cycle of chemotherapy (p = 0.0003).

CONCLUSIONS

The novel genetic score model improved the predictive value of UGT1A1 on SIRD. If validated, it will provide valuable information for clinical use of irinotecan.