Mechanisms of action of a TCR-like antibody to WT1

WT1 类 TCR 抗体的作用机制

• 批准号: 8989076
• 负责人: DAVID A SCHEINBERG
• 金额: $ 38.47万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-09-26 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8989076
• 关键词: Animal Model; Antibodies; Antibody Specificity; Antibody Therapy; Antigen Presentation; Binding; Binding Sites; Biological Assay; Biotin; CD8B1 gene; Cancer Etiology; Cancer Model; Cell Surface Proteins; Cell surface; Cells; Clinic; Collaborations; Complex; Data; Drug Kinetics; Effector Cell; Epitopes; Event; Floor; Goals; HLA-A2 Antigen; Hand; Health; Hospitals; Human; Immune; Immune system; Immunobiology; Immunology; In Vitro; Knowledge; Lead; Malignant Neoplasms; Marketing; Mediating; Modality; Modeling; Monoclonal Antibody Therapy; Mus; Mutate; New Agents; Oncogenes; Organ; Patients; Peptides; Performance; Pharmaceutical Preparations; Proteins; Radioimmunoconjugate; Recruitment Activity; Relapse; Research Design; Research Personnel; Resistance; Site; Solid Neoplasm; Specificity; Surface Antigens; T-Lymphocyte; Testing; Therapeutic; Therapeutic Agents; Toxic effect; Translating; Translations; Vaccines; WT1 gene; Work; anti-cancer therapeutic; base; cancer cell; cancer type; cytotoxic; cytotoxicity; design; drug candidate; effective therapy; expectation; extracellular; human monoclonal antibodies; immunodeficient mouse model; in vitro activity; in vivo; killings; leukemia; leukemia treatment; mouse model; neoplastic cell; novel; novel strategies; pre-clinical; preclinical study; selective expression; tool; tumor

DESCRIPTION (provided by applicant): This proposal builds on the 20 years of this R01 discovering naked and radiolabeled antibodies for the treatment of leukemia and translating them into the clinic. Here we have advanced our goals to a more difficult and intriguing target for a mAb: the intracellular oncoprotein Wilms' tumor 1 (WT1), which is selectively expressed in neoplastic cells of most leukemias, and many other cancer types. We, and others, had previously identified peptides derived from the WT1 protein that induce HLA-A0201-restricted cytotoxic CD8 T cells, capable of killing tumor cells via TCR recognition. We hypothesized that a mAb specific for the WT1 peptide/HLA-A2 complex (mimicking a TCR) would be a novel and useful tool to study the immunobiology of WT1 and possibly an effective therapeutic agent. We discovered a human, cytotoxic mAb (ESK1) directed to a WT1 peptide that is presented on cell surface HLA-A0201. We have proposed a new approach to the treatment of patients with cancers by targeting an otherwise "un-druggable" intracellular oncoprotein. The preclinical performance of the mAb we discovered, more than exceeded our expectations as a possible therapeutic lead drug, but we need to fully understand its mechanism of action and host/cellular resistance in order to exploit its activity in humans. This approach would also provide a proof of concept for other tumor-specific, intracellular targets. Here, in a collaboration of two complementary labs across the street from each other (Scheinberg and Ravetch), we seek to understand in great detail the mechanisms of action of this new agent and to use the antibody as a highly specific tool to probe some aspects of the relationship between antigen presentation and effector function. AIM 1: To determine the mechanisms of possible resistance to ESK action in current mouse models of human leukemia and solid tumors. ESK1 therapeutic activity in vitro and in vivo is Fc-dependent, and ADCC dominates this activity. We will explore how the therapeutic activity is evaded causing relapse including possible target cell, agent and host pharmacokinetic, and host effector cell causes. AIM 2: By use of a tagged WT1 peptide- biotin probe, to understand the importance of epitope site number on the function of ESK1 in vivo and in vitro. We ask: How can therapy be achieved with so few epitopes (our target cells display 0.1-1.0% of typical mAb epitopes)? Is there a floor to this epitope number? Based on our preliminary data, we hypothesize that the number of mAb binding events required to recruit immune effector cells for ADCC (now unknown) will be far lower (<100/cell) than previously expected. If this is true, it would have profound implications for antibody specificity, activity ad therapy. We will also explore the minimal floor of epitope sites needed for therapy with an alpha emitting form (which requires only 1 hit to kill). AIM 3: To create a new, humanized Fc?R mouse as a model of cancer and characterize within it, ESK1 therapeutic activity. Can we create a more relevant mouse model to test human mAb? This tool will be critical to many investigators for the preclinical design and study of naked human mAb therapies. Within the model, the key FcR bearing effector cells will be determined.

描述（由申请人提供）：该提案建立在此R01的20年中，发现裸露的放射性标记抗体用于治疗白血病并将其转化为诊所。在这里，我们将目标提高到了一个更加困难和有趣的目标 mAb：细胞内癌蛋白Wilms的肿瘤1（WT1），它在大多数白血病的肿瘤细胞和许多其他癌症类型中有选择地表达。我们和其他人先前已经鉴定出从WT1蛋白衍生的肽，该肽诱导HLA-A0201限制的细胞毒性CD8 T细胞，能够通过TCR识别杀死肿瘤细胞。我们假设对WT1肽/HLA-A2复合物（模仿TCR）的MAB特异性是研究WT1免疫生物学以及可能是有效的治疗剂的新型且有用的工具。我们发现了一个针对细胞表面HLA-A0201上呈现的WT1肽的人类细胞毒性mAb（ESK1）。我们已经提出了一种新的方法来治疗癌症患者，通过靶向其他“不可驱动”的细胞内癌蛋白。我们发现的MAB的临床前性能超出了我们作为一种可能的治疗铅药物的期望，但是我们需要充分理解其作用机理和宿主/细胞抗性的机理，以利用其在人类中的活性。这种方法还将为其他肿瘤特异性的细胞内靶标提供概念证明。在这里，在彼此之间的两个互补实验室的合作（Scheinberg and Ravetch）中，我们试图详细了解该新药物的作用机理，并将抗体用作探测抗原表现和效应功能之间关系的某些方面的高度特定工具。目标1：确定当前人类白血病和实体瘤的小鼠模型中可能抗ESK作用的机制。 ESK1在体外和体内的治疗活性是FC依赖性的，ADCC主导了这一活性。我们将探索如何探测治疗活性，从而导致复发，包括可能的靶细胞，药物和宿主药代动力学以及宿主效应细胞原因。 AIM 2：通过使用标记的WT1肽 - 生物素探针，以了解表位点数对ESK1在体内和体外功能的重要性。我们问：如何使用如此少的表位（我们的目标细胞显示0.1-1.0％的典型mAb表位）来实现治疗？这个表位号有地板吗？根据我们的初步数据，我们假设募集ADCC免疫效应细胞所需的MAB结合事件数量（现在未知）将比以前预期的要低得多（<100/cell）。如果这是真的，它将对抗体特异性，活动AD疗法产生深远的影响。我们还将探索使用Alpha发射形式进行治疗所需的表位地板的最小地板（仅需要1次杀死）。目标3：创建一种新的人源化FC？r小鼠作为癌症模型，并在其中表征ESK1治疗活性。我们可以创建一个更相关的鼠标模型来测试人物mAB吗？对于许多研究人员而言，该工具将至关重要。在模型中，将确定关键的FCR轴承效应细胞。