Radio-immunotherapy to Target Cancer Stem Cells in Solid Tumor Malignancies

 描述（由申请人提供）：癌症干细胞（CSC）或肿瘤起始细胞是一小部分恶性细胞，对化疗和放疗（RT）具有抗性，并且能够在细胞毒性治疗后重新填充肿瘤。正是这些静止细胞可以播种癌症复发和转移，即使在对治疗明显完全反应的情况下。免疫疗法相对于靶向CSC的细胞毒性疗法提供了巨大的优势，因为免疫效应细胞不需要靶标积极增殖。因此，免疫介导的杀伤似乎是在消耗非CSC后靶向CSC的有吸引力的候选者。自然杀伤（NK）细胞是细胞毒性淋巴细胞，其在消除转化细胞中起主要作用。NK细胞不仅攻击恶性血液病和循环实体瘤细胞，而且似乎还具有自发识别和排斥异基因造血干细胞的独特能力。我们的实验室有大量的初步数据表明，离体激活的NK细胞可以优先靶向多种实验模型中的CSC，包括肿瘤细胞系，原发性肿瘤样本和异种移植小鼠模型。同时，我们观察到RT和化疗由于细胞毒性疗法优先靶向非CSC而富集CSC。此外，我们已经表明RT使肿瘤细胞，特别是CSC对NK细胞攻击和募集敏感。该提议的中心假设是RT和NK免疫疗法的组合将比标准抗增殖疗法或单独的免疫疗法更有效，因为我们将能够同时靶向非CSC和CSC。为了验证这一假设，我们提出了以下3个具体目标：第一个具体目标将确定NK细胞识别和杀死CSC的机制。该目的还将检查RT对CSC对NK杀伤的致敏作用的影响。具体目标1：证明在乳腺癌、胰腺癌和恶性肉瘤中，活化的NK细胞识别并优先攻击CSC群体，而非CSC。我们假设非CSC的RT减积将增强NK细胞破坏CSC群体的能力，从而产生最大的抗肿瘤作用。我们的第二个具体目标将测试NK和局部RT的组合针对异种移植肿瘤模型（包括原位乳腺、胰腺和肉瘤以及患者来源的异种移植物）的功效。具体目标二：证明RT将通过减少肿瘤体积、富集CSC、使CSC对NK攻击敏感以及将NK细胞募集至肿瘤部位来改善NK免疫治疗。我们的第三个具体目标将利用世界级的加州大学戴维斯分校兽医癌症中心建立犬伴侣动物的临床试验。该试验将涉及使用来自犬肉瘤患者的自体NK细胞与针对原发性或转移性肿瘤的姑息性RT或化疗组合。具体目标3：证明NK细胞放射免疫治疗将在犬患者中显示靶向CSC和非CSCS的局部和全身抗肿瘤作用，毒性最小。本研究的目的是阐明过继性NK免疫疗法对靶向CSC的作用，目的是为实体癌患者带来有意义的临床益处。

 DESCRIPTION (provided by applicant): Cancer stem cells (CSCs) or tumor-initiating cells are a small subset of malignant cells which are resistant to chemotherapy and radiotherapy (RT) and are able to repopulate a tumor after cytotoxic treatment. It is these quiescent cells which can seed cancer relapse and metastasis, even in cases of apparent complete response to treatment. Immunotherapy offers a tremendous advantage over cytotoxic therapies to target CSCs because immune effector cells do not require targets to be actively proliferating. Therefore, immune-mediated killing appears to be an attractive candidate for targeting CSCs following the depletion of non-CSCs. Natural killer (NK) cells are cytotoxic lymphocytes which play a major role in eliminating transformed cells. NK cells not only attack hematologic malignancies and circulating solid tumor cells, but they also appear to have the unique ability to spontaneously recognize and reject allogeneic hematopoietic stem cells. Our laboratory has extensive preliminary data demonstrating that ex vivo activated NK cells can preferentially target CSCs in multiple experimental models, including tumor cell lines, primary tumor samples, and xenograft mouse models. In parallel, we have observed that RT and chemotherapy enrich for CSCs due to preferential targeting of non-CSCs by cytotoxic therapy. In addition, we have shown that RT sensitizes tumor cells, especially CSCs, to NK cell attack and recruitment. The central hypothesis of this proposal is that the combination of RT and NK immunotherapy will be more effective than standard anti-proliferative therapy or immunotherapy alone because we will be able to simultaneously target both non-CSCs and CSCs. To test this hypothesis, we propose the following 3 Specific Aims: The first specific aim will determine the mechanism by which NK cells recognize and kill CSCs. This aim will also examine the effects of RT on the sensitization of the CSC to NK killing. Specific Aim 1: To demonstrate that activated NK cells recognize and preferentially attack CSC populations compared with non-CSC in breast, pancreatic, and sarcoma malignancies. We hypothesize that RT debulking of non-CSCs will augment the ability of NK cells to destroy the CSC population resulting in the greatest anti-tumor effects. Our second specific aim will test the efficacy of combination of NK and local RT against xenograft tumor models including both orthotopic breast, pancreatic, and sarcomas and patient-derived xenografts. Specific Aim 2: To demonstrate that RT will improve NK immunotherapy by decreasing tumor bulk, enriching CSCs, sensitizing CSCs to NK attack, and recruiting NK cells to the tumor site. Our third specific aim will utilize the world-class UC Davis Veterinary Cancer Center to establish a clinical trial in canine companion animals. This trial will involve the use o autologous NK cells from canine sarcoma patients in combination with palliative RT or chemotherapy directed towards either primary or metastatic tumors. Specific Aim 3: To demonstrate that NK cell radio-immunotherapy will show local and systemic anti-tumor effects targeting CSCs and non-CSCS with minimal toxicities in canine patients. The aims of this research will elucidate the role of adoptive NK immunotherapy to target CSCs with the goal of translation to meaningful clinical benefit for patients with solid cancers.