Revolutionizing preclinical detection of risk factors for idiosyncratic drug-indu

描述（由申请人提供）：本项目涉及广泛的挑战领域（03）生物标志物发现和验证以及特定的挑战主题03-DK-104：“开发用于评估人类药物毒性的肾脏、肝脏和NIDDK感兴趣的其他器官的药物毒性生物标志物”。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，给医生、制药行业和监管机构带来了重大负担。通常，药物性肝损伤（DILI）表现为一种罕见的“特异质”事件，仅发生在罕见的易感患者中。该项目将评估一种新开发的小鼠模型群体（称为协作杂交）的使用，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手段，用于评估与易感患者中的药物相关的毒性风险，以及通过基因检测使其他有效药物仍能在公众中使用的手段。摘要药物性肝损伤（DILI）是导致药物监管行动的主要药物不良事件，包括批准失败、限制适应症和从市场上撤回。DILI最有问题的形式是“特异质”，这意味着药物对绝大多数治疗患者是安全的，但在罕见的易感患者中会造成灾难性的肝损伤。复杂性状的遗传易感性，如DILI，是由称为“数量性状基因座”（QTL）的基因内遗传变异的组合效应引起的。由于这些事件的罕见性，旨在检测人类群体中的因果风险等位基因的研究往往不够有力，从而阻碍了检测QTL的能力。然而，没有动物模型已被验证的能力，以检测这些遗传变异，赋予增加的风险，肝毒性的给定药物。该项目提出了一种新的临床前药物安全性范例，该范例使用新的小鼠群体协作交叉进行，该小鼠群体是专门为模拟遗传异质性人群而创建的。协作杂交是使用最大化品系之间遗传多样性的育种方案开发的，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杂交小鼠群体来鉴定使个体易患DILI的遗传变异。目标1 -确定在协作交叉的亲代小鼠品系中实现DILI应答所需的最佳药物和剂量-将使用已知引起特异质肝毒性的10种药物进行剂量递增研究。将进行肝损伤标志物的表型分析，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 -使用协作交叉小鼠品系确定调节特异质DILI敏感性的遗传基因座-将在150个协作交叉品系中进行。这些研究将利用在协作杂交小鼠群体中收集的肝损伤标志物来询问基因组内的遗传变异（即单核苷酸多态性; SNP）。目标2的结果将是与小鼠品系中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。将通过靶基因测序，然后对已鉴定的SNP进行相关性和风险比分析，确定单独或联合使用时导致DILI风险增加的特定遗传变异。这些研究为研究特异质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试验的执行方式。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，从而产生更安全的药物，并为仅在一部分患者人群中引起毒性的有效药物提供补救途径。 公共卫生相关性：该项目解决了药物开发过程中的一个重大挑战，该挑战极大地限制了药物的实用性和安全性。目前，由于肝毒性，大多数药物被从市场上撤下或未被批准用于临床。目前还没有平台对新药进行准确的临床前测试，以确定最有可能导致不良事件的药物或确定导致毒性敏感性的遗传因素。我们正在提出一种革命性的新模型，该模型基于专门开发用于模拟异质人群的小鼠资源。这种新资源的成功使用将大大改善药物开发，节省大量成本，并大大扩大制药行业。

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.