基因多态性对他莫昔芬治疗乳腺癌的影响与个体化用药进展

他莫昔芬(Tamoxifen)为人工合成的非胆固醇类抗雌激素药物,被广泛用于临床的雌激素受体(estrogen receptor,ER)阳性乳腺癌患者防治,有显著的个体差异。他莫昔芬经肝药酶CYP2D6、CYP3A4/5和SULT1A1等调节,这些基因的多态性现象是,导致临床治疗个体化差异的重要原因。该文就近年来药物基因多态性对他莫昔芬在乳腺癌治疗的作用与个体化用药进展情况综述。     

CYP2D6＊10基因型与接受他莫昔芬治疗乳腺癌患者的生存率的相关性研究

目的研究CYP2D6＊10基因型对接受他莫昔芬（tamoxifen,TAM）治疗乳腺癌患者的生存率相关性的影响。方法选择该院乳腺外科2008—2003年收治的257名接受TAM治疗乳腺癌患者。调查TAM使用情况和生存状态等相关资料;采集患者外周静脉血5 mL或石蜡切片用于DNA提取;用PCR技术检测CYP2D6＊10基因多态性;查明CYP2D6＊10基因多态性与患者的生存率相关性的关系。结果该次研究中,携带CYP2D6＊10/＊10患者占15%（38/257）,CYP2D6野生型（Wt）/＊10患者占41%（105/257）和CYP2D6Wt/Wt占44%（114/257）。各CYP2D6＊10基因型的临床病理参数之间没有相关性差异。在中国CYP2D6＊10/＊10基因型对接受TAM治疗乳腺癌患者的DFS和OS的影响CYP2D6Wt/Wt和CYP2D6Wt/＊10基因型是类似（P＆gt;0.05）,不存在相关性。结论研究结果显示,CYP2D6＊10基因型与接受TAM治疗乳腺癌患者的生存率之间没有相关性。     

乳腺癌患者CYP2D6基因多态性对他莫昔芬疗效影响的系统评价

目的 系统评价CYP2D6基因多态性对他莫昔芬(Tam)参与治疗乳腺癌患者的无病生存期(DFS)和总生存期(OS)的影响,评价其作为Tam疗效预测指标及指导个体化用药的可行性。方法 计算机检索Cochrane Library、Pub Med、Embase、中国知网、中国生物医学文献数据库、维普全文数据库、万方等数据库,并手工检索相关文献,查找关于CYP2D6基因型及Tam治疗乳腺癌患者以DFS、OS为结局指标的文献。检索时间为1995年1月至2016年10月。采用Rev Man5.3软件进行Meta分析。结果 共纳入文献26篇,其中22篇为英文文献,4篇为中文文献,共包含12 602例患者。Meta分析结果显示,与未携带CYP2D6突变基因患者相比,携带CYP2D6突变基因的患者具有更短的DFS[HR=1.44,95%CI(1.18~1.76),P=0.000 3]和OS[HR=1.20,95%CI(1.07~1.35),P=0.002]。结论 乳腺癌患者经Tam治疗后,携带CYP2D6突变基因患者比未携带CYP2D6突变基因的患者具有更短的DFS和OS,可在临床使用Tam治疗前测定CYP2D6基因多态性,促进个体化给药。     

CYP2D6*10和CYP2C19*2基因型多态性与接受他莫昔芬治疗乳腺癌患者生存率的相关性研究

目的:研究CYP2D6*10和CYP2C19*2基因型多态性与接受他莫昔芬(tamoxifen,TAM)治疗乳腺癌患者生存率的相关性研究.方法:选择2009至2004年本院甲乳外科和肿瘤内科收治的171名术后服用TAM治疗的雌激素阳性乳腺癌患者,调查TAM使用情况和生存状态等相关资料;收集相关的石蜡组织切片用于DNA提取;用PCR技术检测CYP2D6*10和CYP2C19*2基因型多态性;查明CYP2D6*10和CYP2C19*2基因型多态性与患者生存率的相关性.结果:本次研究中,CYP2D6Wt/Wt、CYP2D6Wt/*10 和CYP2D6*10/*10基因型的总生存率(overall survival,OS)类似,差异无统计学意义(P＞0.05).CYP2C19*2/*2基因型的5年OS明显优于CYP2C19 Wt/Wt,差异具有统计学意义(P＜0.05);CYP2C19*2/*2基因型的10年OS明显优于CYP2C19 Wt/Wt和CYP2C19 Wt/*2,差异具有统计学意义(P＜0.05);但是CYP2C19Wt/Wt与CYP2C19 Wt/*2的5、10年OS差异无统计学意义(P＞0.05).结论:研究结果显示,CYP2D6*10基因型多态性与服用TAM治疗乳腺癌患者的生存率之间不存在相关性;CYP2C19*2基因型多态性与接受TAM治疗乳腺癌患者的生存率之间存在相关性,CYP2C19*2/*2接受TAM治疗乳腺癌患者的生存率最高,CYP2C19 Wt/*2生存率较高,CYP2C19 Wt/Wt较低.     

CYP2D6基因多态性与阿立哌唑及其代谢物血药浓度的相关性研究

目的 研究CYP2D6基因多态性与精神分裂症患者阿立哌唑及其活性代谢物脱氢阿立哌唑血药浓度的相关性。方法 纳入200例经阿立哌唑治疗的精神分裂症患者,采集清晨服药前空腹血,采用LC-MS/MS法测定阿立哌唑及其代谢物脱氢阿立哌唑稳态谷浓度。通过Axiom基因芯片分析技术检测CYP2D6(*2、*5、*10、*41)4个SNP位点的基因型,比较不同基因型患者阿立哌唑及其代谢物的浓度剂量比（C/D）及代谢物与阿立哌唑血药浓度比值（CDARI/CARI）的差异。结果 200例精神分裂症患者CYP2D6正常代谢型与中代谢型患者脱氢阿立哌唑C/D值差异存在统计学意义（P <0.05）;CYP2D6正常代谢型与慢代谢型患者脱氢阿立哌唑C/D值差异存在高度统计学意义（P <0.01）;CYP2D6正常代谢型与慢代谢型患者阿立哌唑及其代谢物总浓度C/D值差异存在统计学意义（P <0.05）。结论 CYP2D6基因多态性可影响阿立哌唑体内药动学过程,建议临床根据患者CYP2D6基因型制定个体化治疗方案。     

CYP3A4和CYP3A5基因多态性对汉族肾移植患者他克莫司血药浓度的影响

目的:研究CYP3A4* 18B (rs2242480)、CYP3 A5 6989 A/G(rs776746)两个位点的基因多态性对肾移植术后他克莫司血药浓度/校正剂量比值(C/D)的影响,对肾移植患者基因导向的他克莫司个体化给药提供有意义的信息和数据.方法:101名健康志愿者和56例亲体肾移植且随访超过6个月的患者参加本研究,应用基因芯片法检测2个位点的基因型.用均相酶扩大免疫分析法(EMIT)测定术后7d、14 d、1个月、3个月和6个月时血药浓度.比较不同基因型间他克莫司C/D值之间的差异.结果:在101例汉族人群中,CYP3A4、CYP3A5的等位基因频率分别为:23.75％、73.80％.移植术后6个月内,CYP3A5 GG型(*3/*3)的C/D值显著高于AA型(*1/*1)和AG型(*1/*3)(P＜0.05).CYP3A5 AA型与AG型相比较,差异无统计学意义(P＞0.05).CYP3A4 CC型(*1/*1)的C/D值显著高于CT型(*1/*18B)和TT型(*18B/* 18B)(P＜0.05),其中CT型与TT型比较,C/D值差异无统计学意义(P＞0.05) 结论:肾移植患者术后服用他克莫司C/D值与CYP3A4、CYP3A5基因多态性具有显著相关性.     

CYP3A4与CYP3A5基因多态性与中国汉族急性白血病易感性的相关性研究

目的检测中国汉族急性白血病(AL)患者和健康受试者中CYP3A4*18和CYP3A5*3基因型分布特征,探讨CYP3A4和CYP3A5基因多态性与中国汉族AL易感性的相关性。方法病例对照研究,用聚合酶链反应(PCR)后直接测序的方法,检测中国汉族AL患者91例,健康受试者200例的CYP3A4*18B和CYP3A5*3位点的基因型分布及等位基因频率。结果中国汉族AL患者和健康受试者CYP3A4*18B和CYP3A5*3基因型分布均符合Hardy-Weinberg平衡。与健康受试者比较,AL患者CYP3A4*18B基因型及等位基因频率差异均无统计学意义(P>0.05),CYP3A5*3基因型及等位基因分布频率差异均有统计学意义(P<0.05)。结论 CYP3A4*18B多态性与中国汉族AL的易感性可能无关,CYP3A5*3多态性与中国汉族AL的易感性可能相关。     

CYP1A2、CYP2D6和CYP2C19基因多态性与氯氮平及其代谢物血药浓度的相关性研究

目的：研究CYP1A2、CYP2D6和CYP2C19基因多态性与精神分裂症患者氯氮平（clozapine,CLZ）及其活性代谢物去甲氯氮平（N-desmethy clozapine,N-CLZ）血药浓度的相关性。方法：纳入156例经CLZ单药治疗1个月以上的精神分裂症患者,采集清晨服药前空腹血,采用液相色谱-串联质谱（LC-MS/MS）法测定CLZ及N-CLZ稳态谷浓度。通过Axiom基因芯片分析技术检测CYP1A2（*1C、*1F）、CYP2D6（*2、*10）、CYP2C19（*2、*3）等6个SNP位点的基因型,比较不同基因型患者CLZ及其代谢物的浓度剂量比（C/D）及代谢物与CLZ血药浓度比值（C_N-CLZ/C_CLZ）的差异。结果：CYP2D6*10基因多态性与N-CLZ C/D具有相关性（P<0.01）。CYP1A2*1C、CYP2D6（*2、*10）基因多态性与C_N-CLZ/C_CLZ具有相关性（P<0.05,P<0.01,P<0.01）。CYP1A2*1F、CYP2C19*2、CYP2C19*3基因多态性与C/D及C_N-CLZ/C_CLZ无相关性（P>0.05）。结论：CYP1A2*1C和CYP2D6（*2、*10）基因多态性对CLZ代谢存在影响,建议临床在使用CLZ治疗前检测患者CYP1A2*1C和CYP2D6（*2、*10）基因型,为CLZ个体化治疗提供参考。     

CYP2D6基因多态性及其临床意义

CYP2D6是CYP酶系中重要的一种氧化代谢酶,参与多种药物的代谢.CYP2D6具有基因多态性,使药物代谢在不同种族之间,甚至在同种族不同人群中产生较大的差异,从而影响药物的疗效.因此,深入了解CYP2D6基因的多态性以及对药物代谢的影响,对指导临床合理用药和调整用药方案具有重大意义.     

异基因造血干细胞移植受者CYP3A4及CYP3A5基因多态性对他克莫司血药浓度及疗效的影响

目的 研究P4503A4*18B(CYP3A4*18B)及3A5*3(CYP3A5*3)突变频率,探讨基因多态性与异基因造血干细胞移植受者他克莫司(Tac)血药浓度的关系.方法 采用原位杂交荧光染色脱氧核糖核酸测序技术检测CYP3A4、CYP3A5基因型,酶联免疫吸附技术测定受者Tac浓度.比较术后7、15、30 d不同基因型受者间Tac浓度/剂量(C0/D)的差异.结果 16例中,CYP3A4*18B、CYP3A5*3突变等位基因发生的频率分别是25％和75％.CYP3A5纯合突变型受者中,CYP3A4野生纯合型者的浓度剂量比高于CYP3A4突变型.结论 异基因造血干细胞移植受者CYP3A4*18B和CYP3A5*3基因多态性对TAC药代动力学的影响显著,可以考虑应用临床.     

服用卡马西平癫痫患者CYP3A4基因多态性的研究

目的:研究服用卡马西平癫痫患者细胞色素P4503A4(CYP3A4)的基因多态性,为临床制定卡马西平个体化给药方案提供依据。方法:收集临床服用卡马西平癫痫患者的血标本,用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)法检测CYP3A4的突变。结果:141例患者中存在CYP3A4*4、CYP3A4*6的突变,个体突变率均为0.71%;未见CYP3A4*5的突变。结论:2例突变型标本与其他标本的血药浓度与临床疗效比较无显著性差异,不能说明CYP3A4*4、CYP3A4*6的突变对其表达的药物代谢酶的活性有影响。     

Polymorphisms in CYP2C8 and CYP3A5 genes in the Nigerian population

Polymorphisms in CYP2C8 and CYP3A5 genes have implications for responses elicited by the ingestion of some xenobiotics, the metabolism of which are mediated by these enzymes. CYP2C8*2, CYP2C8*3, CYP3A5*3, CYP3A5*6 and CYP3A5*7 are a few functionally-relevant variants of these genes which this study provides data for, in the Nigerian population. Blood samples were processed for genomic DNA from 178 unrelated subjects spread across Nigerian ethnicities and screened for these polymorphism through the Sequenom iPLEX MassARRAY platform. Results obtained were further validated with Sanger sequencing of a few samples and thereafter, the genotype data were statistically processed. All alleles were in Hardy–Weinberg equilibrium and CYP2C8*2 occurred at a frequency (95% CI) of 0.194 (0.154, 0.239), while CYP3A5*3, CYP3A5*6 and CYP3A5*7 were found at frequencies (95% CI) of 0.160 (0.124, 0.202), 0.096 (0.067, 0.131) and 0.126 (0.094, 0.166), respectively. However, CYP2C8*3 was not detected in the population. The study observed a 60% prevalence of carriers of at least a CYP3A5 polymorphism in the population, suggesting the probable existence of huge variability in CYP3A5 activity which may prove significant in the administration of drugs with narrow therapeutic windows and whose metabolism is largely mediated by CYP3A5.     

The potent mechanism-based inactivation of CYP2D6 and CYP3A4 with fusidic acid in in vivo bioaccumulation

1.?The accumulation of fusidic acid (FA) after multiple doses of FA has been reported on in previous studies but the related mechanisms have not been clarified fully. In the present study, we explain the mechanisms related to the mechanism-based inactivation of CYP2D6 and CYP3A4.

2.?The irreversible inhibitory effects of FA on CYP2D6 and CYP3A4 were examined via a series of experiments, including: (a) time-, concentration- and NADPH-dependent inactivation, (b) substrate protection in enzyme inactivation and (c) partition ratio with recombinant human CYP enzymes. Metoprolol α-hydroxylation and midazolam 1′-hydroxylation were used as marker reactions for CYP2D6 and CYP3A4 activities, and HPLC-MS/MS measurement was also utilised.

3.?FA caused to the time- and concentration-dependent inactivation of CYP2D6 and CYP3A4. About 55.8% of the activity of CYP2D6 and 75.8% of the activity of CYP3A4 were suppressed after incubation with 10?μM FA for 15?min. K_I and k_inact were found to be 2.87?μM and 0.033?min^?1, respectively, for CYP2D6, while they were 1.95?μM and 0.029?min^?1, respectively, for CYP3A4. Inhibition of CYP2D6 and CYP3A4 activity was found to require the presence of NADPH. Substrates of CYP2D6 and CYP3A4 showed that the enzymes were protected against the inactivation induced by FA. The estimated partition ratio for the inactivation was 7 for CYP2D6 and 12 for CYP3A4.

4.?FA is a potent mechanism-based inhibitor of CYP2D6 and CYP3A4, which may explain the accumulation of FA in vivo.     

The human hepatic metabolism of simvastatin hydroxy acid is mediated primarily by CYP3A,and not CYP2D6

AIMS: To identify the cytochrome P450 (CYP) isoforms responsible for the metabolism of simvastatin hydroxy acid (SVA), the most potent metabolite of simvastatin (SV). METHODS: The metabolism of SVA was characterized in vitro using human liver microsomes and recombinant CYPs. The effects of selective chemical inhibitors and CYP antibodies on SVA metabolism were assessed in human liver microsomes. RESULTS: In human liver microsomes, SVA underwent oxidative metabolism to three major oxidative products, with values for Km and Vmax ranging from about 50 to 80 microM and 0.6 to 1.9 nmol x min(-1) x mg(-1) protein, respectively. Recombinant CYP3A4, CYP3A5 and CYP2C8 all catalysed the formation of the three SVA metabolites, but CYP3A4 was the most active. CYP2D6 as well as CYP2C19, CYP2C9, CYP2A6, CYP1A2 did not metabolize SVA. Whereas inhibitors that are selective for CYP2D6, CYP2C9 or CYP1A2 did not significantly inhibit the oxidative metabolism of SVA, the CYP3A4/5 inhibitor troleandomycin markedly (about 90%) inhibited SVA metabolism. Quercetin, a known inhibitor of CYP2C8, inhibited the microsomal formation of SVA metabolites by about 25-30%. Immunoinhibition studies revealed 80-95% inhibition by anti-CYP3A antibody, less than 20% inhibition by anti-CYP2C19 antibody, which cross-reacted with CYP2C8 and CYP2C9, and no inhibition by anti-CYP2D6 antibody. CONCLUSIONS: The metabolism of SVA in human liver microsomes is catalysed primarily (> or = 80%) by CYP3A4/5, with a minor contribution (< or = 20%) from CYP2C8. CYP2D6 and other major CYP isoforms are not involved in the hepatic metabolism of SVA.     

Modulation of CYP2D6 and CYP3A4 metabolic activities by Ferula asafetida resin

Present study investigated the potential effects of Ferula asafetida resin on metabolic activities of human drug metabolizing enzymes: CYP2D6 and CYP3A4. Dextromethorphan (DEX) was used as a marker to assess metabolic activities of these enzymes, based on its CYP2D6 and CYP3A4 mediated metabolism to dextrorphan (DOR) and 3-methoxymorphinan (3-MM), respectively. In vitro study was conducted by incubating DEX with human liver microsomes and NADPH in the presence or absence of Asafetida alcoholic extract. For clinical study, healthy human volunteers received a single dose of DEX alone (phase-I) and repeated the same dose after a washout period and four-day Asafetida treatment (phase-II). Asafetida showed a concentration dependent inhibition on DOR formation (in vitro) and a 33% increase in DEX/DOR urinary metabolic ratio in clinical study. For CYP3A4, formation of 3-MM in microsomes was increased at low Asafetida concentrations (10, 25 and 50 μg/ml) but slightly inhibited at the concentration of 100 μg/ml. On the other hand, in vivo observations revealed that Asafetida significantly increased DEX/3-MM urinary metabolic ratio. The findings of this study suggest that Asafetida may have a significant effect on CYP3A4 metabolic activity. Therefore, using Ferula asafetida with CYP3A4 drug substrates should be cautioned especially those with narrow therapeutic index such as cyclosporine, tacrolimus and carbamazepine.     

CYP3A5、ABCB1基因多态性对中国肾移植患者服用他克莫司剂量和血药浓度的影响

目的：研究肾移植患者CYP3A5、ABCB1基因多态性对肾移植术后患者他克莫司（TAC）血药浓度及给药剂量的影响。方法：采集83例中国肾移植患者术后3个月内TAC的常规监测的谷浓度（C0）。测定受试者CYP3A5*3（rs776746）、ABCB1 1236C＞ T（rs1128503）、2677G＞ T/A（rs2032582）、3435C＞ T（rs1045642）位点的基因型,分析基因多态性对TAC的C0、剂量的影响。结果：患者CYP3A5、ABCB1基因型频率均符合Hardy-Weinberg平衡（P ＞ 0.05）。在移植后3个月期间,CYP3A5*3/*3型患者相较于携带*1等位基因患者,具有更高的C0和更低的剂量（P ＜ 0.05）。ABCB1 2677GG基因型的C0显著低于GT、GA、AA、TT、AT型（P ＜ 0.05）;3435CT型的C0显著高于CC、TT型（P ＜ 0.05）。根据ABCB1的单倍型进行分组,并与CYP3A5进行了联合分析,结果发现,发现CYP3A5*1/*1与*1/*3组与*3/*3组中,不同ABCB1单倍型对TAC血药浓度影响的差异无统计学意义。术后随时间延长,CYP3A5*3/*3型患者的TAC剂量逐步降低,而携带*1基因患者的剂量则呈增加趋势。结论：CYP3A5比ABCB1基因多态性对肾移植受者TAC血药浓度的影响更显著,若达到相同的血药浓度,CYP3A5*3/*3型患者每日所服用的剂量更低。根据CYP3A5基因型制定给药方案,有助于尽早达到浓度标准,达到精准治疗的目标。     

Impact of CYP2D6, CYP3A5, CYP2C9 and CYP2C19 polymorphisms on tamoxifen pharmacokinetics in Asian breast cancer patients

AIM

To investigate the impact of genetic polymorphisms in CYP2D6, CYP3A5, CYP2C9 and CYP2C19 on the pharmacokinetics of tamoxifen and its metabolites in Asian breast cancer patients.

METHODS

A total of 165 Asian breast cancer patients receiving 20 mg tamoxifen daily and 228 healthy Asian subjects (Chinese, Malay and Indian; n = 76 each) were recruited. The steady-state plasma concentrations of tamoxifen and its metabolites were quantified using high-performance liquid chromatography. The CYP2D6 polymorphisms were genotyped using the INFINITI™ CYP450 2D6I assay, while the polymorphisms in CYP3A5, CYP2C9 and CYP2C19 were determined via direct sequencing.

RESULTS

The polymorphisms, CYP2D6*5 and *10, were significantly associated with lower endoxifen and higher N-desmethyltamoxifen (NDM) concentrations. Patients who were *1/*1 carriers exhibited 2.4- to 2.6-fold higher endoxifen concentrations and 1.9- to 2.1-fold lower NDM concentrations than either *10/*10 or *5/*10 carriers (P < 0.001). Similarly, the endoxifen concentrations were found to be 1.8- to 2.6-times higher in *1/*5 or *1/*10 carriers compared with *10/*10 and *5/*10 carriers (P≤ 0.001). Similar relationships were observed between the CYP2D6 polymorphisms and metabolic ratios of tamoxifen and its metabolites. No significant associations were observed with regards to the polymorphisms in CYP3A5, CYP2C9 and CYP2C19.

CONCLUSIONS

The present study in Asian breast cancer patients showed that CYP2D6*5/*10 and *10/*10 genotypes are associated with significantly lower concentrations of the active metabolite of tamoxifen, endoxifen. Identifying such patients before the start of treatment may be useful in optimizing therapy with tamoxifen. The role of CYP3A5, CYP2C9 and CYP2C19 seem to be minor.     

Influences of cytochrome b5 expression and its genetic variant on the activity of CYP2C9, CYP2C19 and CYP3A4

The objective of the present study was to investigate the effects of cytochrome b5 (cytb5) on the drug metabolism catalyzed by CYP2C9, CYP2C19 and CYP3A4. Activities of CYP2C9, CYP2C19, and CYP3A4 were determined by using the prototypical substrates tolbutamide, omeprazole and midazolam, respectively. Cytb5 protein and mRNA contents showed large inter-individual variations with 11- and 6-fold range, respectively. All of three P450s showed an increased activity in proportion to the amount of cytb5 expression. Particularly, CYP3A4 showed the strongest correlation between cytb5 protein amount and the activity, followed by CYP2C9 and CYP2C19. The putative splicing variant, c.288G>A (rs7238987) was identified and was screened in 36 liver tissues by direct DNA sequencing. Liver tissues having a splicing variant exhibited unexpected sizes of cytb5 mRNA and a decreased expression tendency of cytb5 protein compared to the wild-type. A decreased activity in the metabolism of the CYP2C19 substrate omeprazole was observed in liver tissues carrying the splicing variant when compared to the wild-type Cytb5 (P < 0.05). The present results propose that different expression of cytb5 can cause variations in CYP mediated drug metabolism, which may explain, at least in part, the inter-individual difference in drug responses in addition to the CYP genetic polymorphisms.