Novel Biologically Targeted Therapy Against the Mer and Axl Receptor Tyrosine Kin

描述(申请人提供)：癌症是1至14岁儿童疾病相关死亡的主要原因，白血病是儿童最常见的恶性肿瘤。每年，被诊断为急性白血病的儿童中约有20%被诊断为急性髓系白血病(AML)。虽然AML在儿童白血病中所占的比例比急性淋巴细胞白血病(ALL)小，但AML的预后较差。与过去20-30年来所有治愈率的提高(目前总存活率约为80%)相比，儿童AML的总存活率为50%-60%，化疗强度大，需要频繁住院。复发的AML单用化疗的存活率为20%至30%。这种不理想的预后表明需要更多的研究来改善儿童急性髓细胞白血病的预后。此外，目前的化疗药物产生显著的短期和长期毒性。因此，需要新的治疗方法来继续提高疗效和减少与治疗相关的毒性。我的实验室研究了受体酪氨酸激酶蛋白Mer和Axl在儿童急性髓系白血病中的异常表达和激活。Mer和Axl具有多种与细胞周期、生存和增殖相关的功能。在目前的拨款方案中，我们将评估使用我实验室开发的新型生物抑制剂抑制儿童髓系白血病细胞Mer和/或Axl后的白血病细胞死亡。我们还将在细胞培养中为我们令人兴奋的初步结果提供更多证据，即抑制Mer使白血病细胞对标准白血病化疗药物更敏感。此外，MER和抑制将在人类白血病的小鼠动物模型中进行疗效测试。这些实验将有助于建立相关的Mer和Axl受体作为儿童AML治疗的新靶点。拟议的研究还可能为儿科肿瘤学家提供一种高效且毒性小得多的替代方案，以取代目前用于治疗儿童AML的化疗药物。

DESCRIPTION (provided by applicant): Cancer is the leading cause of disease-related deaths among children 1 to 14 years of age, and leukemia is the most common malignancy in children. Every year, approximately 20% of children diagnosed with acute leukemia are diagnosed with acute myelogenous leukemia (AML). Though AML constitutes a smaller percentage of childhood leukemia than acute lymphoblastic leukemia (ALL), AML carries an inferior prognosis. In contrast to the improvements in ALL cure rates over the past 20-30 years (now ~80% overall survival), the overall survival for pediatric AML is 50-60% and the chemotherapy is intensive with frequent required hospitalization. Relapsed AML carries survival rate with chemotherapy alone of 20% to 30%. This suboptimal prognosis demonstrates the need for more research into improvement in the outcome of pediatric AML. Furthermore, current chemotherapeutics produce significant short-term and long-term toxicities. Thus, new therapies are needed to continue to improve efficacy and decrease treatment related toxicity. My lab studies Mer and Axl, receptor tyrosine kinase proteins abnormally expressed and activated in childhood acute myeloid leukemia. Mer and Axl have multiple functions pertaining to cell cycling, survival, and proliferation. In the current grant proposal, we will evaluate leukemia cell death after inhibition of Mer and/or Axl in childhood myeloid leukemia cells using novel biologic inhibitors developed in my lab. We will also provide additional evidence in cell culture for our exciting preliminary results that Mer inhibition makes leukemia cells more sensitive to standard leukemia chemotherapy drugs. Additionally, Mer and inhibition will be tested for efficacy in mouse animal models of human leukemia. These experiments will help establish the related Mer and Axl receptors as novel targets for childhood AML therapy. The proposed studies will also potentially provide pediatric oncologists with a highly effective and much less toxic alternative to the currently used chemotherapy drugs in the treatment of childhood AML.