Project 2: Minimal-Intensity Conditioning with Antibody-Targeted Alpha Radiation

摘要--项目2 这项临床前项目使用非恶性血液疾病的犬模型来开发条件调节方案。 用于异体造血细胞移植(HCT；项目1)和基因治疗(项目3) 最小的毒性，是安全的，避免了短期和长期的毒性，如生长障碍、不孕和晚期 癌症，同时实现高水平供者多血统植入。我们寻求实现 这些目标与单抗(MAb)靶向放射免疫治疗(RIT)使用强大的阿尔法- 发射放射性核素-211(211 At)。阿尔法发射器的特点是高效地杀死细胞，因为它们的 极短的路径长度(40-70μm)和高的线性能量传递。靶向照射将避免短路和 到目前为止使用的全身调理疗法的长期毒性。 具体目标1：开发DLA相合和DLA半相合红细胞移植的调节方案 211AT标记的抗CD45单抗在犬红细胞疾病模型中的应用在这里，我们打算克服 靶向照射联合应用于常规调理的植入问题和毒性 211At标记的全血细胞抗CD45单抗。丙酮酸激酶(PK)缺陷犬作为一种 血红蛋白病。我们将优化DLA相合和DLA半相合HCT的~(211)At剂量。 具体目标2：用~(211)At标记的抗-Hct建立DLA-单倍体相合的HCT预适应方案 犬X连锁严重联合免疫缺陷(SCID-X1)模型中的CD45单抗血细胞比容最低或无 在SCID-X1患者中，条件化常常导致B细胞植入和功能缺陷。谦虚的 长期治愈还需要稳定的供体骨髓植入程度。我们建议一种养生法 掺入~(211)At标记的抗CD45单抗将实现多系植入，毒性最小 SCID-X1患者。 具体目标3：评价211At标记的抗CD45单抗在克服输血诱导中的作用 已建立的DLA相合的HCT模型中的致敏和随后的移植物排斥反应。研究将会是 以确定靶向靶向211At标记的抗CD45单抗的最佳剂量 负责移植排斥反应的免疫细胞和始终如一地建立供者造血细胞的植入 毒性最小。 特定目标4：体外扩增DLA相合的造血干细胞，以促进 用211At进行非清髓性预适应。在移植物抗宿主病的发展中没有好处 患有非恶性疾病的患者。这个目标将探索使用RIT来嫁接非常高的数字的能力 扩大的干细胞(在项目3中开发)作为T细胞耗竭的同种异体红细胞移植的模型。

ABSTRACT – PROJECT 2 This preclinical project uses canine models of nonmalignant blood disorders to develop conditioning regimens for allogeneic hematopoietic cell transplantation (HCT; Project 1) and gene therapy (Project 3) that have minimal toxicity, are safe, avert the short- and long-term toxicities such as growth failure, infertility, and late cancers, while at the same time achieving high-level donor multi-lineage engraftment. We seek to accomplish these goals with monoclonal antibody (MAb) targeted radioimmunotherapy (RIT) using a powerful alpha- emitting radionuclide, astatine-211 (211At). Alpha-emitters are characterized by efficient cell killing due to their very short path length (40-70 μm) and high linear energy transfer. Targeted irradiation will avoid the short- and long-term toxicities of systemic conditioning regimens used up to now. Specific Aim 1: Develop conditioning regimens for DLA-identical and DLA-haploidentical HCT using 211At-labeled anti-CD45 MAb in a dog model of red blood cell disorders. Here we intend to overcome engraftment problems and toxicities of conventional conditioning by using targeted irradiation with an 211At-labeled panhematopoietic anti-CD45 MAb. Pyruvate kinase (PK) deficient dogs serve as a model of hemoglobinopathy. We will optimize 211At dosing for both DLA-identical and DLA-haploidentical HCT. Specific Aim 2: Develop conditioning regimens for DLA-haploidentical HCT using 211At-labeled anti- CD45 MAb in a dog model of X-linked severe combined immunodeficiency (SCID-X1). HCT with minimal or no conditioning often results in deficient B-cell engraftment and function in patients with SCID-X1. A modest degree of stable donor marrow engraftment is also required for long-term cure. We propose that a regimen incorporating 211At-labeled anti-CD45 MAb will achieve multi-lineage engraftment, with minimal toxicity in patients with SCID-X1. Specific Aim 3: Evaluate the use of 211At-labeled anti-CD45 MAb to overcome transfusion-induced sensitization and subsequent graft rejection in a well-established DLA-identical HCT model. Studies will be conducted to determine the optimal doses of 211At-labeled anti-CD45 MAb that are needed to target the immune cells responsible for graft rejection and consistently establish engraftment of donor hematopoietic cells with minimal toxicity. Specific Aim 4: Ex vivo expanded DLA-identical hematopoietic stem cells to facilitate engraftment after nonmyeloablative conditioning with 211At. There is no benefit in the development of graft versus host disease in patients with nonmalignant disorders. This aim will explore the ability to use RIT to engraft very high numbers of expanded stem cells (developed in Project 3) as a model of T-cell-depleted allogeneic HCT.