Bone Marrow Transplantation for Hematologic Malignancies using Novel Radioimmunot

急性髓性白血病（AML）和骨髓增生异常综合征（MDS）目前杀死了大多数患者，尽管联合化疗和造血细胞移植（HCT）治疗。对于急性白血病的潜在治疗，HCT的选择必须进一步扩展到那些没有现成的hla匹配供体的患者，例如少数民族患者。放射标记的抗cd45单克隆抗体（Ab）已被证明可以改善HCT环境下AML和MDS的预后，但毒性仍然很高，治愈率也不理想。本研究计划的目的是开发一种策略，以提高AML和MDS的治愈率，使用预先靶向CD45细胞抗原的放射免疫疗法（RIT）。在Aim 1中，我们将通过比较90Y-和177Lu标记的生物素在比较生物分布、剂量学和治疗实验中的相对优点来优化预靶向RIT方法的治疗效果和毒性，以确定177Lu较短的路径长度b发射是否比90Y可实现的更有利的肿瘤-正常器官比率。在目标2中，我们将评估使用mhc单倍体相同干细胞的HCT的相对优点，使用具有抗cd45 Ab (30F11)-链亲和素（SA）偶联物的清骨髓预靶向RIT，然后使用90Y或177lu标记的dota生物素（根据目标1确定，将使用最佳放射性核素）。在临床相关的弥散性AML小鼠白血病模型中，白血病细胞和正常造血细胞均表达CD45，与使用直接放射标记的抗CD45 Ab （30F11）的传统RIT进行比较。我们预计，这一目标的结果将证明，预先靶向的RIT优于传统的RIT，并将使我们能够提高单倍体同源BMT的治疗效果，具有可耐受的毒性。在Aim 3中，我们将在采用环磷酰胺（CY）移植后移植物抗宿主病预防的临床前小鼠单倍体HCT模型中，通过90Y或177lu标记的生物素（由Aim 1确定）与优化补充剂量的全身照射（TBI）和氟达拉滨（FLU）联合向淋巴造血组织传递辐射的骨髓抑制和免疫抑制作用进行表征和最大化。减少TBI和FLU剂量，同时给予高剂量的预先靶向90Y-或177lu -生物素作为骨髓HCT准备方案的一部分，将取决于证明这种方法的能力：1)消融骨髓空间，2)产生足够的免疫抑制。因此，在目的3中，我们还将在小鼠白血病模型中使用抗mcd45抗体- sa偶联物（30F11抗体- sa）和放射性生物素评估造血和免疫细胞重建的动力学和持久性，随后使用减少剂量的TBI和/或FLU和输注mhc -单倍体相同的BM和移植后CY。我们假设，与常规RIT联合标准调理试剂相比，本提案中定义的预靶向RIT策略将增加传递给白血病细胞的辐射量，减少传递给肝脏、肺部和其他正常器官的辐射，提高缓解率和治愈率，延长生存期，并显着减弱毒性。因此，我们期望将优化的有希望的预靶向RIT快速转化为AML和MDS的临床RIT HCT项目。

Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) currently kill the majority of afflicted patients despite treatment with combination chemotherapy and hematopoietic cell transplantation (HCT). The option of HCT for potential therapy of acute leukemias must be further extended to patients who do not have a readily available HLA-matched donor, such as patients in ethnic minority groups. Radiolabeled anti-CD45 monoclonal antibodies (Ab) have been shown to improve outcomes for AML and MDS in the setting of HCT, but toxicity remains high and cure rates are suboptimal. The objective of this research proposal is to develop a strategy to improve the cure rate of AML and MDS using radioimmunotherapy (RIT) pretargeted to the CD45 cell antigen. In Aim 1 we will optimize the therapeutic efficacy and toxicities of the pretargeted RIT approach by comparing the relative merits of 90Y- and 177Lu-labeled biotin in comparative biodistribution, dosimetry and therapy experiments to determine if the shorter path length b emissions of 177Lu afford more favorable tumor-to-normal organ ratios than those achievable with 90Y. In Aim 2 we will assess the relative merits of HCT employing MHC-haploidentical stem cells utilizing myeloablative pretargeted RIT with an anti-CD45 Ab (30F11)-streptavidin (SA) conjugate followed by either 90Y- or 177Lu-labeled DOTA-biotin (as determined from aim 1 the best radionuclide will be used), compared to conventional RIT using a directly radiolabeled anti-CD45 Ab (30F11) in clinically relevant disseminated AML murine leukemia model in which both leukemic cells and normal hematopoietic cells express CD45. We anticipate that the results from this aim will demonstrate that pretargeted RIT is superior to conventional RIT and will allow us to improve the therapeutic efficacy of haploidentical BMT, with tolerable toxicity. In Aim 3 we will characterize and maximize the myelosuppressive and immunosuppressive effects of radiation delivered to lymphohematopoietic tissues via either 90Y- or 177Lu-labeled biotin (as determined from aim 1) in combination with optimized supplemental doses of total body irradiation (TBI) and Fludarabine (FLU) in a preclinical murine haploidentical HCT model employing cyclophosphamide (CY) post-transplant graft-vs-host disease prophylaxis. Reducing the TBI and FLU doses, while administering high doses of pretargeted 90Y- or 177Lu-biotin as part of a preparative regimen for marrow HCT, would depend upon the demonstration of the ability of such an approach to: 1) ablate the marrow space, and 2) produce adequate immunosuppression. Thus, in aim 3 we will also evaluate the kinetics and durability of hematopoietic and immune cell reconstitution using an anti-mCD45 Ab-SA conjugate (30F11 Ab-SA) and radiobiotin, followed by reduced doses of TBI and/or FLU and infusion of MHC-haploidentical BM and post-transplantation CY in a murine leukemia model. We hypothesize that the pretargeted RIT strategy defined in this proposal will amplify the amount of radiation delivered to leukemia cells, decrease the radiation delivered to the liver, lungs, and other normal organs, improve remission and cure rates, prolong survival, and markedly attenuate toxicities compared to conventional RIT combined with standard conditioning reagents. We therefore anticipate rapid translation of the optimized promising pretargeted RIT into our clinical RIT HCT program for AML and MDS.