基因多型性與臨床因素對於使用tacrolimus的腎臟移植病人臨床結果之影響

Abstract

研究背景與目的： tacrolimus（TAC）是腎臟移植後維持治療的重要基石，但即使使用相同劑量的TAC，個體間血中濃度差異很大。研究發現基因多型性與多種臨床因素會影響到TAC藥動學（pharmacokinetics，PK），但對於病人臨床結果（clinical outcomes）的影響還沒有定論，更沒有臺灣人相關的研究。 本研究目的為探討七種基因多型性（CYP3A5*3、CYP3A4*1G、POR*28、CYP3A4*18B、ABCB1 1236C>T、ABCB1 2677G>T/A、ABCB1 3435C>T）以及臨床因素，包括肝功能、白蛋白（albumin，Alb）、血紅素（hemoglobin，Hb）與血比容（hematocrit，Hct）、免疫抑制劑療法、免疫抑制劑血中濃度、藥品交互作用等對於臺灣腎臟移植病人臨床結果的影響。主要指標包括移植器官存活、移植後一年內發生活檢證實之急性排斥（biopsy proven acute rejection，BPAR）；次要指標包括病人存活、移植後腎功能與TAC相關不良反應。 方法： 本研究為回溯性研究，利用臺大醫療體系醫療整合資料庫，分析本團隊過去研究中已納入由2008年1月1日至2015年7月31日進行腎臟移植之98位臺灣病人，於移植前一個月至2017年12月31日之臨床資料。本研究有五個時間點：移植後1、3、5、7、9年。若資料為連續性數據，作為依變項於迴歸分析前會先用Kolmogorov-Smirnov test或Shapiro-Wilk test檢測是否符合常態分布，若不符合常態分布會將資料取自然對數轉換，並再進行一次常態分布檢定以確保資料符合常態分布。 統計方法部分，類別性數據分析使用Chi-square test或Fisher’s exact test；連續性數據分析使用Student’s t-test或Mann-Whitney U test。在迴歸分析中，依變項若為連續性數據，則使用線性迴歸（linear regression）分析；依變項若為二元類別性數據，則使用羅吉斯迴歸（logistic regression）分析；若依變項為納入時間考量之存活數據，則使用cox迴歸（cox regression）分析。本研究使用估算之腎絲球過濾率（estimated glomerular filtration rate，eGFR）來預測病人的腎功能。 結果： 本研究的可追蹤人數隨時間減少，在五個時間點分別為，移植後1年為98人；3年為89人；5年為65人；7年為45人；9年為12人。 主要指標包括移植器官存活以及移植後一年內發生BPAR。本研究未發現任何基因或臨床因素對於移植器官存活有顯著影響。CYP3A5非表現者以及帶有ABCB1 3435C>T變異會減少移植後一年內發生BPAR的風險（odds ratio, OR = 0.17 and 0.29, p < 0.05），整體模型解釋力為11 %（R2 = 0.11）。 次要指標包括病人存活、移植後腎功能以及TAC相關不良反應。本研究未發現任何基因或臨床因素對於病人存活有顯著影響。在腎功能部分，我們發現捐贈者年齡越高，移植後第一、三、五、七年的eGFR會顯著下降；移植後一年內沒有發生BPAR以及帶有POR*28變異，移植後第一年及第三年的eGFR會顯著上升；帶有ABCB1 3435C>T變異，移植後第三年及第七年的eGFR會顯著下降。在TAC相關不良反應的部分，我們發現身體質量指數（body mass index，BMI）越高，移植後糖尿病（post-transplant diabetes mellitus，PTDM）的風險越高（OR = 2.35, p < 0.05）；第五年sirolimus（SRL）谷濃度（trough concentration，C0）越高，移植後血脂異常的風險越高（hazard ratio, HR = 1.99, p < 0.05）；接受活體腎移植，移植後血脂異常的風險較低（OR = 0.04, p < 0.05）；第三年SRL C0越高，移植後發生感染的風險越高（OR = 3.51, p < 0.05）；移植後第一年TAC C0越高，移植後發生癌症的風險越高（OR = 8.10, p < 0.05），捐贈者年齡越高和帶有ABCB1 2677G>T/A變異，移植後發生癌症的風險越低（OR = 0.82 and 0.01, p < 0.05）。 本研究另外使用傾向分數匹配（propensity score matching，PSM）的方式以1：1配對出移植後一年內未發生BPAR的病人（N=14）作為移植後一年內有發生BPAR（N=14）的病人的對照組，來探討控制基因型、性別與年齡等因素後，移植後至事件發生期間兩組在TAC C0或臨床因素是否有差異。經過匹配後兩組在所有病人特性的分布皆沒有顯著差異。TAC C0與臨床因素在兩組之間皆沒有顯著差異，移植後一年內有發生BPAR的病人組無論是移植後至事件發生期間的平均TAC C0或BPAR發生前的TAC C0皆比沒有發生BPAR的病人組還高。 結論： 本研究是目前第一個同時探討基因與臨床因素對於使用TAC的腎臟移植病人短期臨床結果（移植後一年內發生BPAR）以及長期臨床結果（移植器官存活、病人存活、移植後腎功能、TAC相關不良反應）之影響的研究。 腎臟移植病人移植後一年內，影響是否會發生BPAR的重要因素為受贈者的CYP3A5基因型與ABCB1 C3435T基因型，CYP3A5非表現者以及帶有ABCB1 3435C>T變異會減少移植後一年內發生BPAR的風險（OR = 0.17 and 0.29），整體模型解釋力為11 %（R2 = 0.11）。但本研究未發現BPAR與TAC C0的關係，因此無法將基因型的影響與TAC C0去做連結。我們發現帶有POR*28變異在移植後三年內有較好的腎功能；帶有ABCB1 2677G>T/A變異，移植後發生癌症的風險較低，但上述兩個基因多型性與臨床結果的關係，在之前並沒有相關的研究。除此之外，在移植器官存活、病人存活及除癌症以外的TAC相關不良反應，基因多型性皆沒有顯著的影響。對於長期的臨床結果，基因因素並沒有顯著的影響，但或許對於短期的臨床結果，基因因素還是其有影響力存在，建議在評估有使用TAC的腎臟移植病人於移植後一年內發生BPAR的風險時，應將CYP3A5與ABCB1 C3435T基因型納入考量。 臨床因素的部分，本研究發現移植後第一年TAC C0越高，移植後發生癌症的風險越高；此外，SRL C0越高，移植後血脂異常及感染的風險會較高。免疫抑制劑療法、藥品交互作用以及對於TAC PK可能有影響的臨床因素如肝功能、Alb、Hb與Hct等，皆未對任何臨床結果有顯著的影響。

Background: Tacrolimus (TAC) is the cornerstone of maintenance therapy after kidney transplant. Due to large variance of TAC pharmacokinetics (PK), patients may have different trough concentration (C0) even receiving same dose. Many genetic polymorphisms and clinical factors have been reported to affect TAC PK, whether these factor can affect clinical outcomes is still controversial and there is no related study in Taiwanese. The purpose of this study is to investigate the effects of genetic polymorphisms and clinical factors, including liver function, albumin (Alb), hemoglobin (Hb) and hematocrit (Hct), immunosuppressive regimen, drug concentration and drug-drug interaction, on clinical outcomes in Taiwanese kidney transplant recipients. The primary endpoints are graft survival and biopsy proven acute rejection (BPAR) within 1 year post-transplant (post-Tx). The secondary endpoints are patient survival, post-Tx renal function and TAC-related adverse drug reactions (ADR). Method: This is a retrospective study. Integrated medical database of National Taiwan University Hospital were used to collect the clinical data of 98 kidney transplant recipients, who underwent kidney transplant during Jan 1, 2008 to Jul 31, 2015 and were included in our previous study, from 1 months before transplant to Dec 31, 2017. The time points in this study were 1st year, 3rd year, 5th year, 7th year and 9th year post-Tx. This study use Chi-square test or Fisher’s exact test to analysis categorical data, and use Student’s t-test or Mann-Whitney U test to analysis continuous data. For regression analysis, we use linear regression when dependent variables are continuous data; logistic regression when dependent variables are binary data; cox regression when dependent variables are time-related survival data. We use eGFR to predict renal function. Results: There were 98, 89, 65, 45 and 12 patients at 1st year, 3rd year, 5th year, 7th year and 9th year post-Tx, respectively. For primary endpoints, we found the risk of BPAR within 1 year was lower in CYP3A5 nonexpressers (odds ratio, OR = 0.17) and patients with ABCB1 3435C>T variant (OR = 0.29). The coefficient of determination (R2) of the model was 11 %. There was no factor affecting graft survival. For secondary endpoints, there was no factor affecting patient survival. For recipient renal function, older donor age significantly decreased eGFR at time points of 1st, 3rd, 5th and 7th year post-Tx. Recipients without BPAR within 1 year post-Tx and recipients with POR*28 variant had significantly higher eGFR at time points of 1st and 3rd year post-Tx. Recipients with ABCB1 3435C<T variant had significantly lower eGFR at time points of 3rd and 7th year post-Tx. For TAC-related ADRs, we found higher body mass index (BMI) increased the risk of post-transplant diabetes mellitus (PTDM, OR = 2.35); higher sirolimus (SRL) trough concentration (C0) at 5th year increased the risk of post-Tx dyslipidemia (HR = 1.99) and living donor decreased the risk of post-Tx dyslipidemia (OR = 0.04); higher SRL C0 at 3rd year increased the risk of post-Tx infection (OR = 3.51); higher TAC C0 at 1st year increased the risk of post-Tx cancer (OR = 8.10), older donor age and recipients with ABCB1 2677G>T/A variant decreased the risk of post-Tx cancer (OR = 0.82 and 0.01). This study also compare BPAR group (N = 14) and control group (N = 14) paired by propensity score matching (PSM) to investigate TAC C0 and clinical factors during the time to event period after controlling baseline characteristics. After matching, there was no difference between two groups in baseline characteristics. The two groups had no significant difference in TAC C0 and clinical factors. Conclusion: To our knowledge, this is the first study to investigate the influence of many genetic and clinical factors on short-term clinical outcome including BPAR, and long-term clinical outcomes including graft and patient survival, renal function and TAC-related ADRs of Taiwanese kidney transplant patients with TAC-based immunosuppression. After transplant, recipient’s CYP3A5 and ABCB1 C3435T genotypes influenced BPAR within 1 year post-Tx. CYP3A5 nonexpressers and recipients with ABCB1 3435C>T variant had lower risk of BPAR (OR = 0.17 and 0.29). But we did not find the correlation between BPAR and TAC C0 and could not attribute the effect of genotypes to drug concentration. We also found recipients with POR*28 variant had better renal function within 3 years post-Tx and recipients with ABCB1 2677G>T/A variant had lower risk of post-Tx cancer. However, there was no relevant results from previous studies. Regarding to kidney transplant, genetic factors which affect TAC PK may not have sufficient influence on long-term outcomes. According to our results, genetic factors may have an effect on short-term clinical outcomes. To assess the risk of acute rejection within 1 year post-Tx for kidney transplant recipients with TAC-based immunosuppression, recipient’s CYP3A5 and ABCB1 C3435T genotypes could be considered. As for the influence of clinical factors, our study found that recipients with higher TAC C0 in 1st year may have higher risk of post-Tx cancer. Recipients with higher SRL C0 may have higher risk of post-Tx dyslipidemia and infection. Immunosuppressive regimen, drug-drug interaction and clinical factors which may affect TAC PK including liver function, Alb, Hb and Hct, did not affect any clinical outcome.