Impact of Genetic Diversity on Human Xenograft Tumor Growth

项目摘要/摘要 患者来源的异种移植(PDX)小鼠模型是研究肿瘤生物学、生物标志物的重要工具 多人个性化药物策略的开发、药物筛选和临床前评估 癌症的类型。然而，由于宿主排斥而导致的异种移植失败率，即使在免疫功能低下的宿主中也是如此。 根据肿瘤类型的不同，大约在20%到100%之间。这样的失败常常导致样品丢失和丢失 获得该患者或肿瘤类型的临床相关数据的机会。新出现的证据表明 宿主遗传背景是异种移植物建立和肿瘤变异的主要原因 对药物的反应。为了提高PDX模型系统的临床相关性，一种创新的替代方案是 利用宿主PDX小鼠的遗传多样性作为一种工具来显著提高肿瘤的植入率。这个 协作杂交(CC)和分异远缘杂交(DO)是重组近交系和 分别来自8个亲本近交系的菌株，并将高遗传多样性与 平衡的种群结构是遗传特征图谱的理想选择。CC近交系提供了高度的 遗传变异性和潜在的在体内持续和可重复的PDX的遗传易操控平台 学习。DO在杂合性水平较高的近交系基因组中提供了最大的遗传变异性 对人类群体的影响，是表征宿主遗传的全部潜在影响的理想方法 肿瘤细胞扩增的背景变异。要建立PDX小鼠，宿主免疫系统必须 因接受异种移植而被抑制。拟议的研究中的挑战是抑制免疫 系统在具有不同遗传背景的个体免疫活性小鼠中。在《目标1》中，免疫 使用新的CRISPR-Cas9敲除Rag1基因将抑制CC小鼠的系统 基本编辑系统。在目标2中，基因独特的DO小鼠的免疫系统将受到抑制 使用一种新的口服免疫抑制药物。这项研究具有重要意义，因为它将提供 任何类型的肿瘤生长所必需的多样性，扩大了PDX平台以支持 以前不可能进行异种移植。这项研究在概念上是创新的，因为它将介绍 将遗传多样性引入PDX平台。这项研究在技术上是创新的，因为它将在 用最新的CRISPR-Cas9碱基编辑技术研究多个遗传差异小鼠的免疫系统 (目标1)或在饮用水中使用新型化学免疫抑制剂(目标2)。最先进的基地 AIM 1中的编辑系统将在所有小鼠中产生相同的突变，几乎没有或几乎没有伴随的基因改变。 这些新平台的开发具有风险，这些风险将随着PDX移植的产生而获得回报 对“疑难”肿瘤的研究，使人们能够更好地了解癌症生物学和开发新的治疗方法。 。

PROJECT SUMMARY/ABSTRACT Patient derived xenograft (PDX) mouse models are an essential tool for the study of cancer biology, biomarker development, drug screening, and the preclinical evaluation of personalized medicine strategies for many types of cancers. However, xenograft failure rates due to host rejection, even in immunocompromised hosts, is between ~20% and 100% depending on tumor type. Such failure often results in a lost sample and a lost opportunity to obtain clinically relevant data for that patient or tumor type. Emerging evidence suggests that host genetic background underlies much of this variability in xenograft establishment as well as tumor response to drugs. To advance the clinical relevance of the PDX model system, an innovative alternative is to utilize genetic diversity of the host PDX mice as a tool to substantially improve tumor engraftment. The Collaborative Cross (CC) and Diversity Outbred (DO) are complementary sets of recombinant inbred and strains, respectively, that derive from eight parental inbred strains, and combine high genetic diversity with balanced population structures ideal for genetic trait mapping. The CC inbred strains provide a high degree of genetic variability and potentially a genetically tractable platform for sustained and reproducible in vivo PDX studies. DO provides the most genetic variability in outbred genomes with high levels of heterozygosity similar to the human population, and is ideal for characterizing the full range of potential effects of host genetic background variation on tumor cell expansion. To establish a PDX mouse, the host immune system must be suppressed for xenograft acceptance. The challenge in the proposed studies is to suppress the immune system in individual immunocompetent mice with different genetic backgrounds. In Aim 1, the immune system will be suppressed in CC mice by knocking out the Rag1 gene using a novel CRISPR-Cas9 base editing system. In Aim 2, the immune system will be suppressed in genetically unique DO mice using a novel oral immunosuppressant drug. This study is significant because it will provide the genetic diversity necessary for the growth of any type of tumor, expanding the PDX platform to sustain cancers that have previously been impossible to xenograft. This study is conceptually innovative because it will introduce genetic diversity into the PDX platform. This study is technically innovative because it will compromise the immune system in multiple genetically diverse mice by state-of-the-art CRISPR-Cas9 Base Editor technology (Aim 1) or using a novel chemical immunosuppressant in the drinking water (Aim 2). The state-of-the-art Base Editor system in Aim 1 will produce identical mutations in all mice with little or no collateral genetic alterations. Development of these novel platforms has risks that will be rewarded with the generation of PDX engraftment of “difficult” tumors, enabling a greater understanding of cancer biology and development of novel therapeutics. .