Mechanistic Insights into ALK Fusion Biology Through Investigation of the Fusion Partner

摘要 涉及间变性淋巴瘤激酶(ALK)的基因重排代表了一类独特的 在许多上皮细胞中越来越多地检测到具有治疗靶向的癌基因， 间叶性、造血性和神经性恶性肿瘤1。重要的是，ALK融合已经在多达 8%的非小细胞肺癌(NSCLC)和50%的炎性肌纤维母细胞瘤(IMT)2，3. ALK融合的流行突出了了解融合激酶生物学以便发展的重要性 最有效的治疗策略。 虽然ALK易位导致的致癌融合蛋白是癌症治疗的有效靶点，但我们的 与其他致癌基因相比，人们对如何最有效地靶向这些融合缺乏了解 司机。例如，在EGFR突变的非小细胞肺癌中，不同的EGFR改变赋予不同程度的敏感性 或对EGFR定向治疗的耐药性4-8。此外，对于其他致癌融合，如维甲酸 受体α(RARα)融合在白血病亚型中发现，已知该特定基因融合到 RARα不仅影响治疗反应，而且本身也可以成为治疗的靶点。尽管有许多不同 ALK融合的5‘配对基因已被报道，ALK融合阳性癌症的治疗已被决定 而不考虑哪一个5‘伙伴在场。例如，在NSCLC中，患有EML4-ALK、KIF5B-ALK或 TFG-ALK融合都可以用ALK酪氨酸激酶抑制剂(TKI)Crizotinib治疗。 临床上，ALK TKIs对ALK融合阳性肿瘤是有效的；然而，几乎没有数据来说明 不同的融合伙伴如何影响治疗前的临床特征、疾病 对靶向治疗的反应，或获得性抵抗力。此外，每个5‘伙伴的角色并没有 进行了系统的调查。总体而言，我们假设5‘伴侣影响内在属性 以及影响整体致癌潜力的细胞功能，导致 疾病表型和对靶向治疗的反应的变异性。为了检验我们的假设，我们将进行 使用在NSCLC和IMT中检测到的已知ALK融合的实验：1)确定5‘伴侣是否改变 2)决定ALK融合的5‘端伴侣是否影响致癌 细胞功能，并探索可能赋予不同致瘤性的机制。因为更复杂的 下一代测序技术正走在临床诊断的前沿，临床医生不会 只知道存在酪氨酸激酶融合，而且还知道该激酶与哪个特定的5‘端伴侣融合。 因此，这些研究的发现有望改进ALK融合阳性癌症的治疗 以便更有效地抑制肿瘤生长，了解潜在的治疗耐药机制。 此外，由于在许多恶性肿瘤中发现了激酶融合，这些研究也可能具有潜力。 对其他由激酶驱动的癌症的影响。

ABSTRACT Gene rearrangements involving the anaplastic lymphoma kinase (ALK) represent a unique class of therapeutically targetable oncogenes that are increasingly being detected in numerous epithelial, mesenchymal, hematopoietic, and neural malignancies1. Importantly, ALK fusions have been identified in up to 8% of non-small cell lung cancer (NSCLC) and 50% of inflammatory myofibroblastic tumor (IMT)2,3. The prevalence of ALK fusions highlights the importance of understanding fusion kinase biology in order to develop the most effective therapeutic strategies. While the oncogenic fusion proteins resulting from ALK translocations are valid targets for cancer therapy, our understanding of how to most effectively target these fusions is lacking in comparison to other oncogenic drivers. For example, in EGFR-mutant NSCLC, different EGFR alterations confer varying degrees of sensitivity or resistance to EGFR directed therapies4-8. In addition, for other oncogenic fusions, such as the retinoic acid receptor alpha (RARα) fusions found in subtypes of leukemia, it is known that the particular gene fused to RARα not only affects response to therapy but also can be a therapeutic target itself8. Although many different 5' partner genes have been reported for ALK fusions, treatment of ALK fusion positive cancers is decided without regard to which 5' partner is present. For example, in NSCLC, patients with EML4-ALK, KIF5B-ALK, or TFG-ALK fusions are all treated with the ALK tyrosine kinase inhibitor (TKI), crizotinib. Clinically, ALK TKIs are effective for ALK fusion positive tumors; however, there is little data to address the question of how a different fusion partner may affect pretreatment clinical characteristics, disease responsiveness to targeted therapies, or acquired resistance. Additionally, the role of each 5' partner has not been systematically investigated. Overall, we hypothesize that the 5' partner influences the intrinsic properties of the ALK fusion protein as well as the cellular functions that impact overall oncogenic potential, resulting in variability in disease phenotypes and response to targeted therapies. To test our hypothesis, we will carry out experiments using known ALK fusions detected in NSCLC and IMT to: 1) determine if the 5' partner alters kinase activity and efficacy of ALK TKIs, and 2) determine if the 5' partner of ALK fusions affects oncogenic cellular functions and explore mechanisms that may confer differential oncogenicity. Since more sophisticated next-generation sequencing technologies are coming to the forefront of clinical diagnostics, clinicians will not only know that a tyrosine kinase fusion is present, but also to which specific 5' partner the kinase is fused. Therefore, the findings from these studies are expected to refine the treatment of ALK fusion positive cancers in order to more effectively inhibit tumor growth and understand potential therapeutic resistance mechanisms. Furthermore, as kinase fusions are found in numerous malignancies, these studies may also have potential implications for other kinase-driven cancers.