Fate and efficacy of targeted therapies for metastatic tumors

摘要 晚期乳腺癌患者有很高的倾向转移到大脑与人类表皮 生长因子受体（EGFR）阳性和三阴性乳腺癌（TNBC;雌激素受体，孕酮 受体和Her 2阴性）亚型显示脑转移的最高发病率。大多数患者有 在诊断时有多个转移病灶，使得手术本身不是一个适当的治疗选择。 此外，全脑放射治疗（WBRT）和紧血脑（TBI）引起的认知功能下降也是一个重要的因素。 脑屏障（BBB）阻止全身性治疗在脑中的脑渗透性，这对治疗的成功提出了挑战。 现有的治疗方法，并导致未能改善患者的总体生存率。为了有效治疗多发性高血压， 侵袭性乳腺脑转移灶，迫切需要开发肿瘤特异性多靶向 同时靶向TNBC中的多种异常信号传导途径并利用 专门寻找脑内的转移灶在我们以前发表的初步研究中，我们有1） 广泛证明了工程化的人类和小鼠神经干细胞（NSC）和间充质干细胞 (MSC)广泛地归巢于脑中的原发性和转移性肿瘤，并提供现场手段来递送新的 肿瘤特异性试剂;和2）工程化EGFR特异性纳米抗体（ENb）及其促凋亡变体，双- 功能性ENb-TRAIL，并显示其在一种机制中靶向细胞增殖和死亡途径的潜力 在广谱肿瘤细胞的基础上。本提案的长期目标是测试基于 全身递送的NSC-ENb-TRAIL在TNBC衍生的乳腺至脑的小鼠模型中的治疗功效 模拟乳腺转移性肿瘤生长和进展的临床情况的转移。我们将初步 筛选建立的和患者来源的TNBC细胞系对EGFR和DR 4/5靶向治疗的反应， 评估他们转移到大脑的倾向TNBC对NSC-ENb-TRAIL的基于机制的应答和 NSC-ENb-TRAIL在脑转移小鼠模型中的转归和治疗效果 将评估寻求患者来源的TNBC系。我们假设同时靶向EGFR和 DR 4/5对上皮-间质转化（EMT）和肿瘤的生长、发展有重要影响。基于 我们关于联合使用BBB渗透性组蛋白去乙酰化酶抑制剂（HDACi）CN 147的令人兴奋的初步数据 和ENb-TRAIL以及之前的研究结果，即HDACi与DR 4/5激动剂和EGFR抑制剂同时使用， 将评估NSC-ENb-TRAIL和CN 147的组合治疗功效。我们假设ENB- TRAIL和HDACi将在具有更广泛遗传背景的转移性TNBC中具有治疗功效 并且在体内对ENb-TRAIL具有不同的敏感性。本申请中提出的研究可能会解开 基于机制的靶向干细胞介导的转移性乳腺肿瘤治疗。我们设想设计一个 动脉内注射NSC-ENb-TRAIL以靶向脑中的转移性肿瘤沉积的策略 转移性乳腺癌患者。这将对挽救许多癌症患者的生命产生重大影响。

ABSTRACT Patients with advanced breast cancer have a high propensity to metastasize to the brain with human epidermal growth factor receptor (EGFR) positive and triple-negative breast cancer (TNBC; estrogen receptor, progesterone receptor and Her2 negative) subtypes showing the highest incidence of brain metastases. Most patients have multiple metastatic lesions at the time of diagnosis making surgery an inadequate therapeutic option on its own. Furthermore, impaired cognitive decline induced by whole-brain radiation therapy (WBRT) and the tight blood brain barrier (BBB) preventing the brain permeability of systemic therapies in the brain pose challenges for the success of existing therapies and result in failure to improve overall patient survival. To effectively treat multiple highly aggressive breast metastatic foci in the brain, there is an urgent need to develop tumor specific multi-targeting agents that simultaneously target multiple aberrant signaling pathways in TNBC and utilize delivery vehicles which specifically seek metastatic foci in the brain. In our previously published and preliminary studies, we have 1) extensively demonstrated that engineered human and mouse neural stem cells (NSC) and mesenchymal stem cells (MSC) home extensively to primary and metastatic tumors in the brain and provide on-site means to deliver novel tumor specific agents; and 2) engineered EGFR-specific nanobodies (ENb) and their pro-apoptotic variant, bi- functional ENb-TRAIL and shown its potential to target both cell proliferation and death pathways in a mechanism based manner in broad spectrum of tumor cells. The long term goal of this proposal is to test the mechanism based therapeutic efficacy of systemically delivered NSC-ENb-TRAIL in TNBC derived mouse models of breast to brain metastasis that mimic the clinical scenario of breast metastatic tumor growth and progression. We will initially screen established and patient derived TNBC lines for their response to EGFR and DR4/5 targeted therapies and assess their propensity to metastasize to brain. The mechanism based response of TNBC to NSC-ENb-TRAIL and the fate and therapeutic efficacy of NSC-ENb-TRAIL in brain metastasis mouse models generated from brain seeking patient derived TNBC lines will be assessed. We hypothesize that simultaneous targeting of EGFR and DR4/5 will significantly influence epithelial-mesenchymal transition (EMT) and tumor growth and progression. Based on our exciting preliminary data on the combined use BBB permeable histone deacetylase inhibitor (HDACi), CN147 and ENb-TRAIL and the previous findings that concomitant use of HDACi with DR4/5 agonists and EGFR inhibitors, the combined therapeutic efficacy of NSC-ENb-TRAIL and CN147 will be assessed. We hypothesize that ENb- TRAIL and HDACi will have therapeutic efficacy in metastatic TNBC with a broader range of genetic backgrounds and with varying sensitivity to ENb-TRAIL in vivo. The proposed studies in this application are likely to unravel the mechanism-based, targeted stem cell mediated therapies for metastatic breast tumors. We envision designing a strategy in which NSC-ENb-TRAIL will be injected intra-arterially to target the metastatic tumor deposits in the brain of metastatic breast cancer patients. This will have a major impact in saving the lives of many cancer patients.