Generation and characterization of a mouse model for ALK-positive anaplastic thyroid carcinoma

甲状腺癌是一种常见的恶性肿瘤，也是一种常见的恶性肿瘤。中位生存期仅为6个月。在转移性ATC中，使用积极的方法，例如联合放疗/化疗，不能改善生存率，迫切需要新的治疗策略。促进ATC发生和发展的主要机制是由于致癌突变导致细胞信号通路，特别是PI 3 K和MAPK通路的过度激活。更好地了解甲状腺癌的分子发病机制可能为开发甲状腺未分化癌的新临床策略提供前所未有的机会。可能，ATC不应该被视为一种统一的疾病，而是根据驱动突变进行区分。例如，在ATC患者中报告了间变性淋巴瘤激酶（ALK）的突变，并将其视为驱动突变。然而，这还没有得到实验证明。如果得到证实，ALK阳性ATC患者可以接受FDA批准的ALK抑制剂的靶向治疗。因此，本项目的目的是建立ALK阳性未分化甲状腺癌小鼠模型，以确定激活ALK突变在ATC发展和进展中的作用，并研究该ATC亚组的新治疗选择，特别是ALK抑制剂。为了实现这一目标，我们将使用一种新的条件性基因敲入小鼠模型，其中甲状腺特异性表达组成型活性ALK突变体（F1174 L）。在这个小鼠模型中，我们将通过一系列体内生物发光成像和甲状腺组织学研究ALK阳性ATC的发展和进展（去分化，转移的时间和程度）。此外，我们将研究ALK阳性ATC的功能和分子特征，特别是信号通路激活、放射性碘摄取、血管生成以及免疫微环境（例如PD-L1表达和肿瘤相关巨噬细胞的密度和类型）。该项目的主要目标是用ALK抑制剂（TAE-684）治疗这些ATC小鼠，以确定ALK抑制是否会减缓这些小鼠的肿瘤进展和肿瘤存活，因此，这是ALK阳性ATC的一种有前景的治疗选择。这些结果具有直接的临床意义，因为成功证明ALK抑制剂的疗效将改变ALK阳性ATC患者的治疗模式。此外，该项目还将提供一种具有免疫活性的ATC小鼠模型，以研究进一步的创新治疗方法，例如使用检查点抑制剂进行免疫治疗。

Anaplastic thyroid cancer (ATC) is a rare but highly lethal form of thyroid cancer. Median survival is only 6 months. In metastatic ATC, the use of aggressive approaches, e.g. combined radio-/chemotherapy, does not improve survival and new therapeutic strategies are urgently needed. The primary mechanism that promotes development and progression of ATC is overactivation of cellular signaling pathways, especially the PI3K and MAPK pathways, due to oncogenic mutations. Better understanding the molecular pathogenesis of thyroid cancer may open unprecedented opportunities for the development of novel clinical strategies for anaplastic thyroid cancer. Possibly, ATC should not be seen as a uniform disease, but rather be distinguished depending on the driver mutation. For example, mutations in the anaplastic lymphoma kinase (ALK) have been reported in ATC patients and are considered driver mutations. However, this has not yet been proven experimentally. If proven, patients with ALK-positive ATCs could receive targeted therapy with available FDA-approved ALK-inhibitors. Therefore, aim of this project is to establish a mouse model for ALK-positive anaplastic thyroid carcinoma to determine the role of activating ALK mutations in ATC development and progress and to study new treatment options for this ATC subgroup, especially ALK inhibitors. To achieve this aim, we will use a novel conditional knock-in mouse model with thyroid-specific expression of a constitutively active ALK mutant (F1174L). In this mouse model, we will study the development and progress of ALK-positive ATC (dedifferentiation, timing and extent of metastasis) with serial in vivo bioluminescence imaging and thyroid histology. Furthermore, we will study the functional and molecular characteristics of ALK-positive ATC, especially signaling pathway activation, radioiodine uptake, angiogenesis as well as the immunological microenvironment (e.g. PD-L1 expression and density and type of tumor associated macrophages). Major goal of this project is to treat these ATC mice with an ALK inhibitor (TAE-684) to determine if ALK inhibition slows tumor progress and prolongs survival in these mice and, thus, represents a promising treatment option for ALK-positive ATC. These results are of immediate clinical relevance, because successful demonstration of efficacy of ALK inhibitors will change the treatment paradigm for ALK-positive ATC patients. In addition, this project will provide an immunocompetent ATC mouse model to study further innovative treatments, e.g. immunotherapy with checkpoint inhibitors.