降血脂藥引發肌肉性不良反應與基因多型性之研究

Abstract

研究背景 心血管疾病(Cardiovascular disease, CVD)為全球十大死因之一，降脂藥物(Lipid-lowering drugs)除了良好的降血脂功能，同時具多效作用(pleiotropic effect)，減緩血管粥狀硬化，降低心血管事件發生率，因而被全球廣泛使用。降脂藥物引發的肌肉病變雖然發生機率低，卻是危險性相當高的藥物不良反應。截至目前，僅對於帶有SLCO1B1 rs4149056T>C變異會增加史達汀血中濃度與肌肉性不良反應(myopathy)的風險達到共識，CPIC (The Clinical Pharmacogenetics Implementation Consortium)對此於2014年提出治療建議總結，其他可能致病基因則沒有顯著的相關性。然而從降脂藥物的作用機制來思考，肌肉毒性可能和mevalonate pathway受到抑制有直接關係。Isoprenoids負責蛋白質的轉譯後修飾(prenylation)，經修飾後的蛋白質(prenylated protein)又稱小GTP結合蛋白(small GTPases protein)，在細胞中擔任重要角色，負責調控細胞死亡與訊息傳遞。Isoprenoids pathway上GGPP、FPP、GGTase I、GGTase II、Rab、Ras/Rap對降脂藥物引發肌肉毒性的可能性，值得進一步探討。 研究方法 本研究回溯性納入17位國際診斷碼ICD-9-CM: 728.88-728.89為發病組；另回溯性及前瞻性收集74位使用Atorvastatin或Rosuvastatin大於四週並未有肌肉性藥物不良反應者為控制組。利用iPLEX SNP Genotyping鑑定94位受試者18個基因：GGPS1、RABGGTA、RABGGTB、RAB1A、RAB1B、RAB2A、RAB6A、RAB7A、RAB33B、RAP1A、GATM、RYR2、ATP2B1、DMPK、HTR3B、HTR7、SLCO1B1、COQ1，共57個SNP。統計分析基因多型性與降脂藥物引發肌肉毒性之相關性。

研究結果 本研究除了rs16832568 (GGPS1)、rs2930041 (RAB2A)、rs1880643 (RAB6A)鑑定失敗外，其餘皆可鑑定出基因型，鑑定結果有8個SNPs頻率集中於同一基因型。發病組與控制組平均年齡分別為59.9歲、60.0歲。發病組中女性佔的比例比男性高(女性：58.8%，男性：41.2%)。發病組17人平均發病時間為8.4個月，其中4人(23.5%)合併用藥，進一步分析單一/合併用藥與發病年齡、發病時間、檢驗生化值，皆無顯著關係(p > 0.05)。94位研究案例，在0.05顯著水準下，9個單一SNP與疾病發生具有相關性：RAB2A： rs2875968、rs2326562、rs2875967、rs2981277、rs41420549、rs2930040、rs671275；RAP1A rs565522；COQ1 rs10829053。將這9個單一SNP與發病時間、檢驗生化值進一步做相關性分析，在0.05顯著水準下，COQ1 rs10829053的AA基因型發病時間會比AG基因型高出10.27(月)。RAB2A SNP rs16926265(T>C)與RAB2A rs41420549(A>T)組成的單套型T-A與疾病發生有相關性(p -value =0.0302)。 結論 本研究發現某些基因型與受試者疾病發生具有相關性，顯示先天遺傳在降脂藥物引發肌肉毒性方面有其重要性。以往多著重於藥物動力學與藥效學可能致病基因上作探討，本研究可提供不同面向：Isoprenoids pathway上高血脂病患在肌肉毒性之預防上作為參考。結果是否可於更大的台灣人族群中得到驗證，需未來更多進一步之研究。

Introduction Cardiovascular disease (CVD) is one of the major causes of death globally. Hypercholesterolemia with elevated low-density lipoprotein cholesterol (LDL-C) is one of the major risk factor of CVD and stroke. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor also known as statins are the most widely used drugs for hypercholesterolemia. Statins successfully lower plasma LDL-C concentrations, reduce CVD risk and also improve health status in people with CVD. Unfortunately, rare but severe muscle toxicity such as rhabdomyolysis can be fatal by usage of statins or fibrates. The incidence of muscle toxicity is relatively uncertain, ranging from 1.5% to 5% in randomized controlled trials. There are many studies regarding the effects of polymorphic genes on muscle toxicity. However, only the variants in SLCO1B1 is the consensus. The mechanism that underlies statin toxicity is likely to be related to be a direct consequence of the inhibition of mevalonate pathway since mevalonate supplementation prevents toxicity in vitro and in vivo. Statin-induced muscle cell damage is consequently suppressed by depleting GGPP and FPP, which reduce prenylated proteins and intracellular vesicle traffic. Normal cell growth and differentiation may be altered by statins through the control of the cell cycle and entry into apoptosis. However, there are limited data in humans. Therefore, the thesis is aimed to study the risk factors which are possibly involved in severe adverse drug reactions and their genotype-phenotype relations. Methods The research subjects are in two groups: myopathy group and control group. Subjects in myopathy group was retrospectively collected in National Taiwan University Hospital from August 1997 to August 2007 with records of rhabdomyolysis upon lipid-lowering drugs monotherapy or combined therapy. Subjects treated with ATV 10 mg/day or RSV 10 mg/day with no diagnosis of myopathy were designated as control group, which were retrospectively or prospectively collected in National Taiwan University Hospital from January 2006 to December 2006. The DNA of 94 individuals were extracted for detection of 57 SNPs in the genes related to muscle toxicity. They includes GGPS1、RABGGTA、RABGGTB、RAB1A、RAB1B、RAB2A、RAB6A、RAB7A、RAB33B、RAP1A、GATM、RYR2、ATP2B1、DMPK、HTR3B、HTR7、SLCO1B1 and COQ1. Analysis was focused on the association between the incidence of muscle toxicity and genetic variations in patients receiving statins or fibrates. Results There were 94 patients in total enrolled in this study. Amon them, 17 patients were enrolled as the myopathy group and 74 patients were as the control group. Monotherapy or combined therapy are not associated with patients suffering from rhabdomyolysis. Nine SNPs (RAB2A： rs2875968、rs2326562、rs2875967、rs2981277、rs41420549、rs2930040、rs671275；RAP1A rs565522；COQ1 rs10829053) are correlated with the incidence of rhabdomyolysis (p < 0.05), in specific genetic models. In haplotype analysis, incidence of toxicity was shown in the individuals with haplotype T-A (frequency: 55.5%) of RAB2A. Individuals with AG genotype of COQ1 res10829053 showed faster onset compared to AA genotype (p < 0.05). Conclusion Results demonstrate the risk factors of myotoxicity in use of statins or fibrates in NTUH patients. Statins-induced depletion of isoprenoids and inactivation of small GTPases such as Rab may be involved in lipid lowering drugs-related myotoxicity. Further study is needed.