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

 描述(申请人提供)：癌症干细胞(CSCs)或肿瘤启动细胞是一小部分恶性细胞，对化疗和放射治疗(RT)具有抵抗力，并能够在细胞毒治疗后重新填充肿瘤。正是这些静止的细胞可能导致癌症复发和转移，即使在治疗明显完全有效的情况下也是如此。与细胞毒疗法相比，免疫疗法为靶向CSCs提供了巨大的优势，因为免疫效应细胞不需要靶点积极增殖。因此，在非CSCs耗尽后，免疫介导的杀伤似乎是一个有吸引力的靶向CSCs的候选方法。自然杀伤(NK)细胞是一种细胞毒性淋巴细胞，在清除转化细胞方面发挥着重要作用。NK细胞不仅攻击恶性血液病和循环实体瘤细胞，而且具有自发识别和排斥异基因造血干细胞的独特能力。我们实验室有大量的初步数据表明，体外激活的NK细胞可以在多种实验模型中优先靶向CSCs，包括肿瘤细胞系、原代肿瘤样本和异种移植小鼠模型。同时，我们观察到，由于细胞毒治疗对非肿瘤干细胞的优先靶向，放疗和化疗对肿瘤干细胞有丰富的作用。此外，我们还发现RT使肿瘤细胞，尤其是CSCs对NK细胞的攻击和募集变得敏感。这一建议的中心假设是，RT和NK免疫治疗的结合将比标准的抗增殖治疗或单独的免疫治疗更有效，因为我们将能够同时针对非CSCs和CSCs。为了验证这一假设，我们提出了以下三个特定目标：第一个特定目标将决定NK细胞识别和杀伤CSCs的机制。这一目的还将检验RT对CSC对NK杀伤的增敏作用。具体目标1：证明在乳腺癌、胰腺癌和肉瘤中，激活的NK细胞识别和优先攻击CSC群体，而不是非CSC群体。我们假设，RT去除非CSCs将增强NK细胞破坏CSC群体的能力，从而产生最大的抗肿瘤效果。我们的第二个特定目标是测试NK联合局部放射治疗对包括原位乳腺、胰腺、肉瘤和患者来源的异种移植瘤模型的疗效。具体目的2：证明RT将通过减少肿瘤体积，丰富CSCs，使CSCs对NK攻击敏感，并将NK细胞招募到肿瘤部位，从而改善NK免疫治疗。我们的第三个具体目标是利用世界级的加州大学戴维斯分校兽医癌症中心在犬类伴侣动物身上建立临床试验。这项试验将涉及使用来自犬肉瘤患者的自体NK细胞，结合姑息性放疗或针对原发或转移性肿瘤的化疗。具体目的3：证明NK细胞放射免疫治疗将显示局部和全身针对CSCs和非CSCs的抗肿瘤效应，且毒性最小。这项研究的目的将阐明过继NK免疫疗法在靶向CSCs方面的作用，目的是将其转化为对实体癌患者有意义的临床益处。

 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.