Combination strategies to enhance therapy for Ph-like B-ALL

 描述（由申请人提供）：该提案侧重于B细胞急性淋巴细胞白血病（B-ALL）。尽管在过去的几十年中治愈率急剧增加，但B-ALL儿童的一个子集仍然具有不可接受的高复发率。在这个“高风险”组中的白血病包括由BCR-ABL酪氨酸激酶驱动的费城染色体阳性（Ph+）病例，但大多数是Ph阴性。许多高风险的Ph阴性B-ALL病例由于相似的基因表达和酪氨酸激酶的激活，现在可以被指定为“Ph样”B-ALL。新出现的数据表明，Ph样B-ALL在青少年和年轻成人患者中也很普遍。重要的是，在体外用酪氨酸激酶抑制剂（TKI）治疗后，Ph样白血病显示激酶信号传导减少，并且TKI治疗抑制异种移植模型中的疾病。这些发现为与Ph样B-ALL患者特异性基因组病变匹配的TKI的临床检测奠定了坚实的基础。然而，TKI耐药性在许多癌症中发展，强调需要靶向其他生存机制。使用成人Ph+ B-ALL的异种移植模型，我们报告了mTOR的第二代ATP竞争性抑制剂与靶向BCR-ABL癌基因的TKI协同作用。mTOR激酶抑制剂（TOR-KIs）与TKI联合使用比单独使用TKI或TKI加雷帕霉素更能导致白血病消退，即使在对BCR-ABL激酶抑制剂具有内在耐药性的肿瘤中也是如此。mTOR激酶抑制剂在治疗剂量下耐受良好。由于TKI/TOR-KI联合治疗Ph+ B-ALL异种移植物效果良好，我们认为类似的联合治疗对Ph样B-ALL也有效。本项目将检验这一假设，目的是获得支持TKI + TOR-KI治疗儿童、青少年和年轻人Ph样B-ALL的临床试验的概念验证数据。我们将使用来自合作者提供的已建立的Ph样B-ALL异种移植物的细胞来实现这一目标。第一个具体目的是评价双途径抑制对异种移植的Ph样白血病样品的功效。终点将是骨髓中白血病细胞的百分比，以及白血病与正常骨髓细胞群中循环细胞的分数。第二个具体目标是测试组合治疗是否比单一治疗更深刻地抑制B-ALL细胞中的存活信号。我们将通过对从异种移植小鼠骨髓中获得的细胞进行磷酸流分析来部分解决这一问题。我们还将验证一种新兴的技术，CYTOF，用于多参数分析治疗小鼠骨髓中B-ALL细胞的磷酸化蛋白质组。这些研究可能会导致新的方法来预防高危B-ALL的复发和生物标志物来监测治疗反应。

 DESCRIPTION (provided by applicant): This proposal focuses on B-cell acute lymphoblastic leukemia (B-ALL). Despite a dramatic increase in cure rates over the past decades, a subset of children with B-ALL continues to have unacceptably high rates of relapse. Leukemias in this "high-risk" group include Philadelphia chromosome positive (Ph+) cases driven by the BCR-ABL tyrosine kinase, but the majority are Ph- negative. Many high-risk Ph-negative B-ALL cases can now be designated as "Ph-like" B-ALL due to similar gene expression and activation of tyrosine kinases. Emerging data indicate that Ph-like B-ALL is also prevalent in adolescent and young adult patients. Importantly, Ph-like leukemias show decreased kinase signaling upon treatment with tyrosine kinase inhibitors (TKIs) in vitro and TKI treatment suppresses disease in xenograft models. These findings establish strong rationale for clinical testing of TKIs matched to patient-specific genomic lesions in Ph-like B-ALL. However, TKI resistance develops in many cancers, emphasizing the need to target additional survival mechanisms. Using xenograft models of adult Ph+ B-ALL we have reported that second generation, ATP- competitive inhibitors of mTOR work in synergy with TKIs targeting the BCR-ABL oncogene. Combining mTOR kinase inhibitors (TOR-KIs) with TKIs causes regression of leukemia to a greater extent than TKI alone or TKI plus rapamycin, even in tumors with intrinsic resistance to BCR-ABL kinase inhibitors. mTOR kinase inhibitors are well tolerated at therapeutic doses. Because the TKI/TOR-KI combination works well in Ph+ B-ALL xenografts, we believe similar combinations will be effective in Ph-like B-ALL. This project will test this hypothesis, with the goal of obtaining proof-of- concept data supporting clinical trials of TKI plus TOR-KIs in children, adolescents and young adults with Ph-like B-ALL. We will accomplish this objective using cells from established Ph-like B-ALL xenografts, provided by collaborators. The first specific aim is to evaluate the efficacy of dual pathway inhibition on xenografted Ph-like leukemia samples. Endpoints will be percent leukemia cells in the bone marrow, and fraction of cycling cells in the leukemia versus normal bone marrow cell populations. The second specific aim is to test whether the combination treatments suppress survival signaling in B-ALL cells more profoundly than single treatments. We will address this in part through phosphoflow analysis of cells obtained from bone marrow of xenografted mice. We will also validate an emerging technology, CYTOF, for multiparameter analysis of the phosphoproteome in B-ALL cells from bone marrow of treated mice. These studies may lead to new approaches to prevent relapse in high-risk B-ALL and biomarkers to monitor response to therapy.