Revolutionizing preclinical detection of risk factors for idiosyncratic drug-indu

描述（由申请人提供）：该项目涉及广泛的挑战领域（03）生物标志物的发现和验证以及特定的挑战主题03- dk -104：“开发用于NIDDK感兴趣的肾脏、肝脏和其他器官的药物毒性生物标志物，用于评估人类药物毒性”。药物毒性引起的肝损伤是与药物开发相关的严重安全风险，对医生、制药行业和监管机构构成了重大负担。通常，药物性肝损伤（DILI）表现为一种罕见的“特异性”事件，仅发生在罕见的易感患者中。该项目将评估新开发的小鼠模型种群（称为协作交叉）的使用情况，以检测导致个体易患DILI的遗传变异。一旦得到验证，该研究工具将提供一种独特的方法来评估易感患者中与药物制剂相关的毒性风险，并通过基因检测提供一种方法，使其他有效的药物制剂可以继续在公众中使用。药物性肝损伤（drug -induced liver injury， DILI）是导致药物监管部门采取措施的主要药物不良事件，包括未获批准、限制适应症和退出市场。DILI最有问题的形式是“特殊的”，这意味着这种药物对绝大多数接受治疗的患者是安全的，但对罕见的易感患者却会造成灾难性的肝损伤。复杂性状（如DILI）的遗传易感性是被称为“数量性状位点”（QTL）的基因内遗传变异的综合效应。由于这些事件的罕见性，旨在检测人群中因果风险等位基因的研究往往缺乏动力，从而阻碍了检测QTL的能力。然而，目前还没有动物模型被证实能够检测出那些会增加给定药物肝毒性风险的基因变异。该项目提出了一种临床前药物安全性的新范例，该范例使用了一种新的可用小鼠种群，协作交叉，这是专门为遗传异质人类种群建模而创建的。协作杂交是利用一种育种方案开发的，该方案最大限度地提高了品系之间的遗传多样性，允许捕获小鼠中90%的已知遗传变异。在三个具体目标中，我们的目标是利用协作交叉小鼠种群来识别易患DILI的个体的遗传变异。目的1 -确定在协作交叉的亲本小鼠品系中实现DILI反应所需的最佳药物和剂量-将使用已知引起特异性肝毒性的十种药物进行剂量递增研究。将对肝损伤标志物进行表型分析，以确定QTL分析所需的最佳药物和剂量。使用最佳药物和剂量，目标2 -确定使用协作杂交小鼠品系调节特异性DILI易感性的遗传位点-将在150个协作杂交品系中进行。这些研究将利用在协作杂交小鼠群体中收集的肝损伤标记物来询问基因组内的遗传变异（即单核苷酸多态性；snp）。Aim 2的结果将是在小鼠品系中与肝损伤风险显著相关的基因组区域。为了跟进这些研究，将进行目标3 -确定候选基因区域内毒性易感性的风险等位基因。将通过对目标基因进行测序，然后对已鉴定的snp进行相关性和风险比分析，确定单独或联合增加DILI风险的特定遗传变异。这些研究为研究特异性DILI易感性的遗传结构提供了一个独特的机会，并有可能彻底改变临床前药物安全性测试的执行方式。拟议研究的成功完成将为改进药物安全性测试提供路线图，从而导致更安全的药物和挽救仅在一小部分患者群体中引起毒性的有效药物的途径

DESCRIPTION (provided by applicant): This project addresses broad Challenge Area (03) Biomarker Discovery and Validation and specific challenge topic 03-DK-104: "Development of drug toxicity biomarkers for kidney, liver, and other organs of NIDDK interest for use in assessing human drug toxicity". Liver injury due to drug toxicity is a serious safety risk associated with drug development and poses a significant burden to physicians, the pharmaceutical industry, and regulatory agencies. Often, drug-induced liver injury (DILI) manifests as a rare, "idiosyncratic" event that occurs only in the rare, susceptible patient. This project will evaluate the use of a newly developed mouse model population, called the Collaborative Cross, to detect genetic variants that cause individuals to be susceptible to DILI. Once validated, this research tool will provide a unique means for evaluating the toxicity risk associated with pharmaceutical agents in susceptible patients as well as a means for which otherwise efficacious pharmaceutical agents may remain in public use, enabled by genetic testing. ABSTRACT Drug-induced liver injury (DILI) is the major adverse drug event that leads to regulatory actions on drugs, including failure to approve, restricted indications, and withdrawal from the marketplace. The most problematic form of DILI is "idiosyncratic", meaning the drug is safe for the vast majority of treated patients while causing catastrophic liver injury in the rare, susceptible patient. Genetic predisposition for complex traits, such as DILI, results from the combined effects of genetic variations within genes termed "quantitative trait loci" (QTL). Due to the rarity of these events, studies aimed at detection of causal risk alleles in human populations are often under-powered, thus hampering the ability to detect QTL. However, there are no animal models that have been validated for the ability to detect those genetic variants that confer an increased risk for liver toxicity for a given pharmaceutical. The project proposes a new paradigm for preclinical drug safety that is performed using a newly available mouse population, the Collaborative Cross, which was created specifically to model the genetically heterogeneous human population. The Collaborative Cross was developed using a breeding scheme that maximizes the genetic diversity between strains, allowing capture of 90% of the known genetic variation in mice. In three specific aims, our goal is to utilize the Collaborative Cross mouse population to identify genetic variants that predispose individuals for DILI. In Aim 1 - Determine the optimal drug and dose necessary to achieve a DILI response within the parental mouse strains of the Collaborative Cross - a dose- escalation study will be performed with ten drugs known to cause idiosyncratic hepatotoxicity. Phenotyping of liver injury markers will be performed to determine the optimal drug and dose needed for QTL analysis. Using the optimal drug and dose, Aim 2 - Determine genetic loci that modulate susceptibility to idiosyncratic DILI using the Collaborative Cross mouse strains - will be performed in 150 Collaborative Cross lines. These studies will utilize liver injury markers collected across the Collaborative Cross mouse population to interrogate genetic variations within the genome (i.e. single nucleotide polymorphisms; SNPs). The outcome of Aim 2 will be regions of the genome that are significantly associated with liver injury risk across mouse strains. To follow up on these studies, Aim 3 - Identify risk alleles for toxicity susceptibility within candidate gene regions - will be performed. Specific genetic variants that confer an increased risk of DILI, alone or in combination, will be identified by sequencing of target genes followed by correlation and risk ratio analysis of identified SNPs. These studies offer a unique opportunity to study the genetic architecture of predisposition to idiosyncratic DILI and have the potential to revolutionize how preclinical drug safety testing is performed. Successful completion of the proposed studies will provide a roadmap for improved drug safety testing, leading to safer drugs and a route to rescue efficacious drugs that cause toxicity in only a subset of the patient population PUBLIC HEALTH RELEVANCE: This project addresses a major challenge in the drug development process that greatly limits the utility and safety of drugs. Currently, most drugs are removed from the marketplace or are not approved for clinical use because of liver toxicity. No current platform exists to perform accurate preclinical testing of new drugs to identify those most likely to result in adverse events or to identify genetic factors that contribute to toxicity susceptibility. We are proposing a revolutionary new model based upon a mouse resource that was specifically developed to model the heterogeneous human population. The successful use of this new resource will dramatically improve drug develop, saving significant costs and greatly expanding the pharmaceutical industry.