Optimizing the Efficacy and Safety of CD33-Targeted Immunotherapy for Acute Myeloid Leukemia and Other CD33+ Disorders

摘要 长期以来，针对CD33的治疗一直被用来改善急性髓系白血病(AML)的预后。 使用CD33单抗(MAb)-药物结合物getuzumab ozogamicin(GO)可延长生存期 验证了该方法的有效性。然而，CD33是一个具有挑战性的靶点：几种药物在临床上失败了，并受益于 WITH GO仅限于AML患者亚群。作为一个可能的缺点，几乎所有CD33导向的药物， 包括GO，识别CD33的膜-远端V-set结构域。作为新疗法的基础，实验室 单位主任(罗兰·B·沃尔特，医学博士，医学博士，硕士)提出了新的，完全人类的单抗，不仅针对V- CD33的SET结构域和膜近端的C2-SET结构域；后者显示增强的效应细胞 功能和以所有自然产生的CD33变体为靶标(即“CD33PAN”单抗)。现在有了这些单抗 沃尔特实验室将进行良好控制的体外和体内机制研究，以优化 CD33靶向治疗的有效性和安全性，明确的患者应用目标。我们将主要专注于 我们在放射免疫治疗(RIT)方面所做的努力：发射放射性同位素Astatine-211(211 At)的阿尔法粒子， 利用AML细胞对辐射的高度敏感性、211At的高效和靶细胞选择性，以及我们的 将基于211At的RIT从替补席引入诊所的机构基础设施和专业知识。因为CD33 也显示在正常血细胞上，CD33靶向药物会导致显著的“靶上、非AML细胞”毒性， 最值得注意的是长期严重的骨髓抑制。因此，在我们最大限度地提高 在CD33靶向治疗的有效性的同时，我们还在开发新的基因编辑方法来保护正常 从这些药物中提取造血干细胞和造血祖细胞以拓宽其治疗窗口并加以利用 更安全。研究专家乔治·S·拉兹洛博士自沃尔特实验室成立以来一直是该实验室的成员 在2010年。他负责所有技术人员的培训、指导和监督，以及 开发和验证所有实验方法、方法、分析和生成所有 这些工具/试剂共同为NCI支持的CD33优化研究计划奠定了基础 定向治疗以及沃尔特实验室参与的其他几个由美国国立卫生研究院资助的研究项目。一个 Laszlo博士和Walter博士共发表了22篇同行评议的联合出版物(9篇，Laszlo博士是第一作者) 记录他们卓有成效的工作关系。在接下来的5年里，Laszlo博士将是我们 本申请中描述的研究，以及在生成、生产、纯化和 重组单抗及其衍生疗法的鉴定和基因工程细胞的发展 基于直线的药物测试工具，以及对人类急性髓系白血病细胞的体内药物疗效评估。使用 Laszlo博士的技能和专业知识对于我们开发新的、有效的CD33靶向将是不可或缺的 用于AML和其他CD33+疾病患者的流水线过程中的药物，目前对他们来说 治疗方法往往是无效的。

ABSTRACT Therapies targeting CD33 have long been pursued to improve outcomes in acute myeloid leukemia (AML). Longer survival with the CD33 monoclonal antibody (mAb)-drug conjugate gemtuzumab ozogamicin (GO) validates this approach. However, CD33 is a challenging target: several drugs have failed clinically, and benefit with GO is restricted to AML patient subsets. As one possible shortcoming, almost all CD33-directed drugs, including GO, recognize the membrane-distal V-set domain of CD33. As a basis for new therapies, the laboratory of the Unit Director (Roland B. Walter, MD PhD MS) has raised new, fully human mAbs not only against the V- set domain but also the membrane-proximal C2-set domain of CD33; the latter show enhanced effector cell functions and target all naturally occurring CD33 variants (i.e., are “CD33PAN” mAbs). With these mAbs now available, the Walter Lab will conduct well-controlled mechanistic in vitro and in vivo studies to optimize the efficacy and safety of CD33-targeted therapy, with the explicit goal of patient application. We will primarily focus our efforts on radioimmunotherapy (RIT) with the alpha particle emitting radioisotope astatine-211 (211At), leveraging the exquisite radiosensitivity of AML cells, the high potency and target cell selectivity of 211At, and our institutional infrastructure and expertise in bringing 211At-based RIT from the bench to the clinic. Because CD33 is also displayed on normal blood cells, CD33-targeted drugs cause significant “on-target, off-AML cell” toxicity, most notably prolonged, profound myelosuppression. Therefore, in parallel to our work on maximizing the efficacy of CD33-targeted therapy, we are also developing novel gene editing approaches to protect normal hematopoietic stem and progenitor cells from these drugs to widen their therapeutic window and make their use safer. The Research Specialist, George S. Laszlo, PhD, has been a member of the Walter Lab since its inception in 2010. He has been responsible for the training, guidance, and supervision of all technicians as well as the development and validation of all experimental methodologies, approaches, assays, and generation of all tools/reagents that, together, built the foundation for the NCI-supported research program on optimizing CD33- directed therapy as well as several other NIH-supported research projects that the Walter Lab is involved in. A total of 22 peer-reviewed joint publications between Drs. Laszlo and Walter (9 with Dr. Laszlo as first author) document their fruitful work relationship. Over the next 5 years, Dr. Laszlo will be essential for the conduct of our studies described in this application, with key roles in the generation, production, purification, and characterization of recombinant mAbs and derived therapeutics, the development of genetically engineered cell line-based tools for drug testing, and the in vivo assessment of drug efficacies against human AML cells. With his skills and expertise, Dr. Laszlo will be indispensable for our efforts to develop new, efficacious CD33-targeted drugs in a stream-lined process for the benefit of patients with AML and other CD33+ disorders, for whom current therapies are often ineffective.