BACKGROUND: Recently, lung cancer has become the most common cause of cancer-related death, several studies indicate that the cytochrome P450 2A13 (CYP2A13) polymorphisms may be correlated with lung cancer susceptibility, but the results have been inconsistent and inconclusive. Therefore, the aim of this meta-analysis is to provide a precise conclusion on the potential association between CYP2A13 polymorphisms and the risk of lung cancer based on case-control studies.
METHODS: The PubMed, Embase, Cochrane Library, Web of Science, and China National Knowledge Infrastructure (CNKI) databases will be searched for case-control studies published up to September 2020. Odds ratio (OR) and 95% confidence interval (95% CI) were used to determine the effects of the CYP2A13 polymorphism on lung cancer risk, respectively.
RESULTS: The results of this meta-analysis will be submitted to a peer-reviewed journal for publication.
CONCLUSIONS: This meta-analysis will summarize the association between CYP2A13 polymorphisms and the risk of lung cancer.
UNASSIGNED: INPLASY202090102.

A systematic review was performed to describe the findings from 19 genetic association studies that have examined the genetic variants underlying four common treatment-induced chronic and late toxicities in breast cancer patients, and to evaluate the quality of reporting. Three out of 5 studies found an association between HER2 lle655Val polymorphisms and trastuzumab-induced cardiotoxicity. Two studies found a positive association between cognitive impairment and the Val allele of the COMT gene and the ε4 allele of the apolipoprotein E gene. Genetic associations were established between fatigue and the G/G genotype of IL6-174 and TNF-308, and the Met allele of the COMT gene in 4 studies. Among studies (N=8) that evaluated the genetic associations underlying peripheral neuropathy, CYP2C8∗3 variant is commonly reported as the associated gene. Most studies failed to conform to the major criteria listed in the STREGA guidelines, with a lack of transparent reporting of methods and results.

BACKGROUND: Genetic variability may influence methadone metabolism, dose requirements, and risk of relapse.
OBJECTIVE: To determine whether the CYP2B6*6 or ABCB1 (rs1045642) polymorphisms are associated with variation in methadone response (plasma concentration, dose, or response to treatment).
METHODS: Two independent reviewers searched Medline, EMBASE, CINAHL, PsycINFO, and Web of Science databases. We included studies that reported methadone plasma concentration, methadone response, or methadone dose in relation to the CYP2B6*6 or ABCB1 polymorphisms.
RESULTS: We screened 182 articles and extracted 7 articles for inclusion in the meta-analysis. Considerable agreement was observed between the two independent raters on the title (kappa, 0.82), abstract (kappa, 0.43), and full text screening (kappa, 0.43). Trough (R) methadone plasma concentration was significantly higher in CYP2B6*6 homozygous carriers when compared to non-carriers (standardized mean difference [SMD] = 0.53, 95% confidence interval [CI], 0.05-1.00, p = 0.03) with minimal heterogeneity (I(2) = 0%). Similarly, trough (S) methadone plasma concentration was higher in homozygous carriers of the *6 haplotype when compared to non-carriers, (SMD = 1.44, 95% CI 0.27-2.61, p = 0.02) however significant heterogeneity was observed (I(2) = 69%). Carriers of the CYP2B6*6 haplotype were not found to be significantly different from non-carriers with respect to dose or response to treatment. We found no significant association between the ABCB1 polymorphism and the trough (R), (S) plasma concentrations, methadone dose, or methadone response.
CONCLUSIONS: Although the number of studies included and sample size were modest, this is the first meta analysis to show participants homozygous for the CYP2B6*6 genotype have higher trough (R) and (S) methadone plasma concentrations, suggesting that methadone metabolism is significantly slower in *6 homozygous carriers.

BACKGROUND: The main challenge for warfarin anticoagulation is the risk for hemorrhagic complications. Although certain pharmacogenetic factors may explain the individual variabilities about the therapeutic warfarin dose requirement, the genetic factors to warfarin hemorrhagic complications due to over-anticoagulation are largely unknown. To interpret the potential role of warfarin-related genotypes on over-anticoagulation and hemorrhagic complications, we conducted a meta-analysis based on 22 published studies.
METHODS: A comprehensive search was applied to the reports on over-anticoagulation and hemorrhagic complications published prior to December 31, 2012 in PubMed and EMBASE. References were identified by strict inclusion and exclusion criteria, with additional information obtained by consulting with the authors of primary studies. The roles of genotypes in CYP2C9 and VKORC1 on over-anticoagulation (INR > 4) and hemorrhagic complications were analyzed by Revman 5.0.2 software.
RESULTS: A total of 6272 patients in 22 reports were included in the meta-analysis, including studies of 18 from Caucasians (3 from both Caucasian and African-American), 3 from Asians, and 1 from Brazilians. Compared to CYP2C9 wild genotype (CYP2C9*1), both CYP2C9*2 (rs 1799853, c. 430 C > T, p. Arg144Cys) and *3 (rs 1057910, c. 1075 A >C, p. Ile359Leu) confer significantly higher risk for warfarin over-anticoagulation and hemorrhagic complications. After stratification by CYP2C9 allele status, significantly higher risk for hemorrhagic complications was found only in carriers of at least 1 copy of CYP2C9*3 [For total hemorrhages: *1/*3 HR: 2.05 (1.36-3.10), p < 0.001; *3/*3 HR: 4.87 (1.38-17.14), p = 0.01; For major hemorrhages: *1/*3 HR: 2.43 (1.17-5.06), p = 0.02; *3/*3 HR: 4.81 (0.95-24.22), p = 0.06]. Furthermore, similar susceptibility of total hemorrhage by CYP2C9 genotypes was observed in Caucasians and Asians. After stratification by the occurrence time, both CYP2C9*2 and *3 are risk factors for over-anticoagulation within 30 days of warfarin treatment [*2 HR: 1.64 (1.11-2.43), p = 0.01; *3 HR: 2.48 (1.56-3.96), p < 0.001], and only CYP2C9*3 showed higher risk for over-anticoagulation after 30 days [HR: 1.86 (1.08-3.20), P = 0.03]. For VKORC1 c. -1639G > A (rs 9923231) genotypes, GA and AA contributed significantly higher risk for over-anticoagulation within 30 days [HR: 2.14 (1.75-2.62), p < 0.001], but not for over-anticoagulation after 30 days [HR:0.78 (0.46-1.33), p = 0.36]. No significant association was found between VKORC1 genotypes and hemorrhagic complications.
CONCLUSIONS: Both CYP2C9 and VKORC1 genotypes are associated with an increased risk for warfarin over-anticoagulation, with VKORC1 c. -1639G > A more sensitive early in the course of anticoagulation. CYP2C9*3 is the main genetic risk factor for warfarin hemorrhagic complications.

OBJECTIVE: To review the literature regarding the interaction among amiodarone therapy, thyroid hormone levels, and warfarin metabolism.
METHODS: A 73-year-old male with type 2 after describing an unusual case of amiodarone-induced thyrotoxicosis (AIT) who experienced a severe rise in international normalized ratio (INR) values after initiating warfarin therapy due to an unusual combination of excessive thyroid hormones, amiodarone therapy, and a genetic abnormality affecting warfarin metabolism.
RESULTS: Genetic analysis revealed that the patient was CYP2C9*2 wild-type, CYP2C9*3/*3 homozygous mutant, and VKORC1*3/*3 homozygous mutant. A review of the literature revealed that both mutations can independently affect warfarin metabolism. In addition, amiodarone therapy and the presence of thyrotoxicosis per se can affect warfarin metabolism and reduce the dose needed to maintain INR in the therapeutic range. The association of the 2 genetic polymorphisms in a patient with AIT is extremely rare and strongly impairs warfarin metabolism, exposing the patient to a high risk of overtreatment.
CONCLUSIONS: In patients with AIT, warfarin therapy should be gradually introduced, starting with a very low dose, because of the significant risk of warfarin overtreatment. Whether the genetic analysis of CYP2C9 and VKORC1 polymorphisms should be routinely performed in AIT patients remains conjectural.

The area of fruit juice-drug interaction has received wide attention with numerous scientific and clinical investigations performed and reported for scores of drugs metabolized by CYP3A4/CYP2C9. While grapefruit juice has been extensively studied with respect to its drug-drug interaction potential, numerous other fruit juices such as cranberry juice, orange juice, grape juice, pineapple juice and pomegranate juice have also been investigated for its potential to show drug-drug interaction of any clinical relevance. This review focuses on establishing any relevance for clinical drug-drug interaction potential with pomegranate juice, which has been shown to produce therapeutic benefits over a wide range of disease areas. The review collates and evaluates relevant published in vitro, preclinical and clinical evidence of the potential of pomegranate juice to be a perpetrator in drug-drug interactions mediated by CYP3A4 and CYP2C9. In vitro and animal pharmacokinetic data support the possibility of CYP3A4/CYP2C9 inhibition by pomegranate juice; however, the human relevance for drug-drug interaction was not established based on the limited case studies.

The purpose of our study was to characterise the CYP2C19*2 and CYP2C19*3 alleles in healthy Roma and Hungarian populations. DNA of 500 Roma and 370 Hungarian subjects were genotyped for CYP2C19*2 (G681A, rs4244285) and CYP2C19*3 (G636A, rs4986893) by PCR-RFLP assay and direct sequencing. Significant differences were found comparing the Roma and Hungarian populations in CYP2C19 681 GG (63.6 vs. 75.9%), GA (31.8 vs. 23.0%), AA (4.6 vs. 1.1%), GA+AA (36.4 vs. 24.1%) and A allele frequencies (0.205 vs. 0.125) (p<0.004). Striking differences were found between Roma and Hungarian samples in CYP2C19*1 (79.5 vs. 87.4%) and CYP2C19*2 (20.5 vs. 12.6%) alleles, respectively (p<0.001). None of the subjects was found to carry the CYP2C19*3 allele. Frequencies of the intermedier metabolizer phenotype defined by the *1/*2 genotype (0.318 vs. 0.230, p<0.005) and poor metabolizer predicted by the *2/*2 genotype (0.046 vs. 0.011, p<0.005) was significantly higher in Roma than in Hungarians, respectively. Genotype distribution of the Roma population was similar to those of the population of North India, however, a major difference was found in the frequency of the CYP2C19*2 allele, which is likely a result of admixture with European lineages. In conclusion, the frequencies of the CYP2C19 alleles, genotypes and corresponding extensive, intermediate and poor metabolizer phenotypes studied here in the Hungarian population are similar to those of other European Caucasian populations, but display clear differences when compared to the Roma population.

BACKGROUND: Clobazam was recently approved for Lennox-Gastaut syndrome in the United States. There is no published review article focused on clobazam therapeutic drug monitoring (TDM) in English.
METHODS: More than 200 clobazam articles identified by a PubMed search were carefully reviewed for information on clobazam pharmacokinetics. Clobazam is mainly metabolized by a cytochrome P450 (CYP) isoenzyme, CYP3A4, to its active metabolite, N-desmethylclobazam. Then, N-desmethylclobazam is mainly metabolized by CYP2C19 unless the individual has no CYP2C19 activity [poor metabolizer (PM)].
RESULTS: Using a mechanistic approach to reinterpret the published findings of steady-state TDM and single-dosing pharmacokinetic studies, 4 different serum clobazam concentration ratios were studied. The available limited steady-state TDM data suggest that the serum N-desmethylclobazam/clobazam ratio can be useful for clinicians, including identifying CYP2C19 PMs (ratio >25 in the absence of inhibitors). There are 3 possible concentration/dose (C/D) ratios. The clobazam C/D ratio has the potential to measure the contribution of CYP3A4 activity to the clearance of clobazam from the body. The N-desmethylclobazam C/D ratio does not seem to be a good measure of clobazam clearance and should be substituted with the total (clobazam + N-desmethylclobazam) C/D ratio.
CONCLUSIONS: Future clobazam TDM studies need to use trough concentrations after steady state has been reached (>3 weeks in normal individuals and several months in CYP2C19 PMs). These future studies need to explore the potential of clobazam and total C/D ratios. Better studies on the relative potency of N-desmethylclobazam compared with the parent compound are needed to provide weighted total serum concentrations that correct for the possible lower N-desmethylclobazam pharmacodynamic activity. Standardization and more studies of C/D ratios from clobazam and other drugs can be helpful to move TDM forward.

As the incidence of skin tumors has been steadily growing, there is an urgent need for the preventive measures as well as the improved therapeutic approaches. In the last two decades, natural plant derived polyphenols (PPs, resveratrol, silibinin, green tea polyphenols, flavonoids, anthocyanins, etc.) have been drawing particular interest as emerging active substances in dermatological/cosmeceutical compositions for the prevention, slowing, or reversion of skin tumorigenesis (chemoprevention). When chronically applied to the skin, they supposedly would not damage normal skin cells or negatively affect their functions while they would suppress tumorigenic cell transformation, inhibit tumor cell proliferation, and activate tumor cell apoptosis. PPs are also reported to synergize with conventional anti-cancer therapies. The major aim of this critical review is to provide recent updates on the molecular and cellular targets for the prevention and therapy of skin tumors with a special focus on the crossroad between inflammation and carcinogenesis as the most promising approach to chemoprevention. Novel therapeutic targets as different as epidermal stem cells, cellular senescence, epigenetic enzymes involved in carcinogenesis, epidermal growth factor and aryl hydrocarbon receptors, and metabolic CYP1 subfamily enzymes are highlighted. The mechanisms of PPs interaction with these molecular and cellular targets are reviewed. The feasibility of PPs to prevent/ cure specific cutaneous toxicity connected to anti-EGFR therapy and to reduce multidrug resistance of skin tumors is also discussed.

A systematic review and a meta-analysis were performed to quantify the accumulated information from genetic association studies investigating the impact of the CYP4F2 rs2108622 (p.V433M) polymorphism on coumarin dose requirement. An additional aim was to explore the contribution of the CYP4F2 variant in comparison with, as well as after stratification for, the VKORC1 and CYP2C9 variants. Thirty studies involving 9,470 participants met prespecified inclusion criteria. As compared with CC-homozygotes, T-allele carriers required an 8.3% (95% confidence interval (CI): 5.6-11.1%; P < 0.0001) higher mean daily coumarin dose than CC homozygotes to reach a stable international normalized ratio (INR). There was no evidence of publication bias. Heterogeneity among studies was present (I(2) = 43%). Our results show that the CYP4F2 p.V433M polymorphism is associated with interindividual variability in response to coumarin drugs, but with a low effect size that is confirmed to be lower than those contributed by VKORC1 and CYP2C9 polymorphisms.