Leveraging in vivo models to identify epigenetic vulnerabilities in leukemia

 描述(由申请人提供)：小鼠癌症模型是基础实验室发现和人类临床试验转化之间的关键纽带。用于体内靶向验证 模型往往是有效性的最终仲裁者(例如，对于出版)，以及在药物开发中 没有利用体内模型的有效性证据，任何新的化学实体都不会取得进展。尽管小鼠癌症模型的预测价值仍有争议，但体内模型确实概括了非生理细胞培养条件下体外细胞系模型所缺乏的癌症生物学的许多方面。然而，出于实用的原因，尽管体外模型存在明显的局限性，但大多数大规模的目标识别努力严格使用基于细胞系的筛选方法。我们假设，将体内模型整合到初级靶点筛选将有助于临床相关靶点的识别，并可能识别仅使用体外细胞系筛选方法不明显的靶点。鉴于人们对表观遗传疗法的兴趣激增，在这项建议中，我们将使用汇集shRNA的方法来全面识别T细胞急性淋巴细胞白血病(T-ALL)和混合血统白血病(MLL)的表观遗传易感性。使用针对449个已知和假定的表观遗传调节蛋白的3,040个shRNA文库，我们将同时使用体外细胞系模型和体内原位白血病模型评估相关性。在第一个目标中，我们将通过获得代表T-ALL和MLL的高白血病亚系来克服体内筛查的主要障碍之一。对于这些预后较差的白血病亚型，对更好的治疗方法的需求尚未得到满足。在第二个目标中，我们将使用同时在体外和体内进行的汇集shRNA分析来识别这两类白血病的表观遗传易感性。最后，在第三个目标中，我们将充分验证关键的脆弱性，包括实现治疗靶向的体内概念验证。总之，这些研究利用创新和新兴技术的融合来识别白血病的表观遗传脆弱性。这些研究的成功将建立一个新的目标发现范式，在发现运动开始时利用体内模型。除了快速消除假阳性，这种方法还可以识别对标准体外筛选方法不透明的新靶类。

 DESCRIPTION (provided by applicant): Mouse models of cancer are a critical link between basic laboratory discovery and translation to human clinical trials. For target validation, in vivo models are often the ultimate arbiters of validity (e.g., for publication), and in drug development no new chemical entity advances without evidence of efficacy utilizing in vivo models. Although the predictive value of mouse cancer models is subject to debate, in vivo models do recapitulate many aspects of cancer biology that are absent from in vitro cell line models under non-physiological cell culture conditions. For pragmatic reasons, however, most large-scale target identification efforts strictly utilize cell line-based screening methods despite the clear limitatons of in vitro models. We hypothesize that incorporating in vivo models into primary target identification screens will facilitate the identification of clinically relevant targets, and may identify targets that would not be evident using only in vitro cell line screening approaches. Given the explosion of interest in epigenetic therapies, in this proposal we will use a pooled shRNA approach to comprehensively identify epigenetic vulnerabilities in T-cell acute lymphoblastic leukemia (T- ALL) and mixed lineage leukemia (MLL). Using a library of 3,040 shRNAs targeting 449 known and putative epigenetic regulatory proteins, we will simultaneously assess for dependencies using in vitro cell line models and in vivo orthotopic leukemia models. In the first Aim, we will surmount one of the major impediments to in vivo screening by deriving highly leukemogenic sub-lines representing T-ALL and MLL. There is an unmet need for better therapies for these poor prognosis leukemia subclasses. In the second Aim, we will use pooled shRNA assays, performed simultaneously in vitro and in vivo, to identify epigenetic vulnerabilities in these two subclasses of leukemia. Finally, in the third Aim, we will fully validte critical vulnerabilities, including achieving in vivo proof-of-concept for therapeutic targeting. Together, these studies utilize a convergence of innovative and emerging technologies to identify epigenetic vulnerabilities in leukemia. Success in these studies would establish a new paradigm for target discovery leveraging in vivo models at the inception of discovery campaigns. In addition to rapid elimination of false positive hits, this approach may identify new target classes that are opaque to standard in vitro screening methods.