Targeting FLT3 for the Treatment of Relapsed or Refractory Acute Myeloid Leukemia

项目总结 嵌合抗原受体(CAR)工程T细胞疗法使某些B细胞的治疗发生了革命性变化 恶性肿瘤，但类似的治疗急性髓系白血病(AML)的成功尚未显示，尽管是暂时的 早期临床试验的结果，包括我们自己的，是有希望的。我们造了一辆车，目标是 III型受体酪氨酸激酶(RTK)称为Flt3。利用患者来源的异种移植(PDX)模型 Flt3(+)人AML，我们发现输注人Flt3-CAR T细胞可延长AML的存活期。 在没有其他治疗方法的情况下生下老鼠。此外，Flt3-CAR T细胞不影响植入或存活 急性髓系白血病小鼠的造血干细胞(HSCs)。Flt3-CAR T细胞治疗急性髓系白血病的疗效观察 将取决于(1)AML原始细胞表面Flt3的抗原密度，包括与白血病干细胞(LSC)相关的 对于正常的HSC，以及(2)其他免疫效应细胞在体内消除AML的能力。 为此，我们发现，用RTK抑制剂(TKI)处理AML原始细胞后， Flt3在AML原始细胞和活体LSC上的表达，与正常HSC上Flt3表达的相关性。至 对AML进行了第二次细胞治疗干预，我们在人自然环境中表达了Flt3-CAR 杀伤(NK)细胞产生Flt3-CAR NK细胞，显示出强大的抗白血病活性 Flt3(+)AML。总而言之，这些发现使我们得出结论，针对Flt3(+)的程序 急性髓细胞白血病具有强大的理论基础，具有创新性，并可能导致急性髓细胞白血病子集的死亡率显著下降 病人。因此，这项建议的长期目标是同时进行临床前和临床研究。 这将最好地定义一种最佳策略，通过Flt3-car细胞疗法降低AML的死亡率 单独使用或与TKI结合使用。我们的中心假设是以复发/难治的Flt3(+)AML为靶点 联合应用Flt3-CAR T细胞或Flt3-CAR NK细胞联合TKIs将改善AML的预后。在这 我们将评估进行人类Flt3-CAR T第一阶段研究的可行性、安全性和毒性 针对Flt3(+)AML的细胞治疗(目标1)，我们将确定TKIs上调的机制 Flt3在LSCs和HSCs上的表面密度表达(Aim 2)，我们将优化Flt3-CAR NK细胞 平台并评估其针对反洗钱单独或与TKI结合的功能(目标3)。要实现这些目标 目的：我们已经开始临床生产Flt3-CAR T细胞，用于治疗符合条件的难治性或非霍奇金淋巴瘤患者。 复发性AML；我们将利用人AML细胞系和患者的AML细胞在体外和体内 使用我们的PDX模型进行相关和临床前研究，评估Flt3-CAR T和Flt3-CAR NK细胞 与TKI相结合。在结论中，我们将了解如何最好地优化细胞免疫治疗 治愈急性髓系白血病。对这一进程的进一步洞察，这将是执行和完成这项提案的结果 是有效的，因为它最终将导致部分急性髓细胞白血病患者的死亡率降低。

PROJECT SUMMARY Chimeric antigen receptor (CAR)-engineered T cell therapy has revolutionized treatment for certain B cell malignancies, but similar successes for acute myeloid leukemia (AML) have not yet been shown, although interim results of early phase clinical trials, including our own, are promising. We have constructed a CAR that targets the type III receptor tyrosine kinase (RTK) called FLT3. Utilizing a patient-derived xenograft (PDX) model of FLT3(+) human AML, we have shown that infusion of human FLT3-CAR T cells prolonged survival of AML- bearing mice in the absence of other therapies. Further, FLT3-CAR T cells did not affect engraftment or survival of hematopoietic stem cells (HSCs) in mice bearing AML. The effectiveness of FLT3-CAR T cell therapy in AML will depend on (1) surface antigen density of FLT3 on AML blasts, including leukemic stem cells (LSC) relative to normal HSCs, and (2) the ability of other immune effector cells to contribute to the eradication of AML in vivo. To this end, we have discovered that treatment of AML blasts with an RTK inhibitor (TKI) upregulates the expression of FLT3 on the AML blast and the LSC in vivo, relative to FLT3 expression on normal HSCs. To advance a second cellular therapeutic intervention for AML, we have expressed the FLT3-CAR in human natural killer (NK) cells to generate FLT3-CAR NK cells, which demonstrated potent anti-leukemic activity against FLT3(+) AML. Collectively, these discoveries have led us to conclude that a program directed against FLT3(+) AML has strong rationale, is innovative and could result in a significant decline in mortality for a subset of AML patients. Therefore, the long-term objective of this proposal is to perform both preclinical and clinical studies that will best define an optimal strategy to reduce mortality from AML with FLT3-CAR cellular therapy, either alone or in combination with TKIs. Our central hypothesis is that targeting relapsed/refractory FLT3(+) AML with FLT3-CAR T cells or FLT3-CAR NK cells in combination with TKIs will improve outcomes in AML. In this proposal, we will assess the feasibility, safety and toxicity of performing a phase I study of human FLT3-CAR T cell therapy directed against FLT3(+) AML (Aim 1), we will determine the mechanism by which TKIs upregulate the surface density expression of FLT3 on LSCs and HSCs (Aim 2), and we will optimize a FLT3-CAR NK cell platform and assess its functionality against AML alone or combined with TKI (Aim 3). To accomplish these objectives, we have begun clinical manufacturing of FLT3-CAR T cells to treat eligible patients with refractory or relapsed AML; we will utilize both human AML cell lines and patients' AML blasts in vitro as well as in vivo along with our PDX model for our correlative and preclinical studies evaluating FLT3-CAR T and FLT3-CAR NK cells in combination with TKI. Upon conclusion, we will understand how best to optimize cellular immune therapy to cure AML. Further insight into this process, as will result from the implementation and completion of this proposal is impactful as it will ultimately lead to a reduction in mortality for select patients suffering from AML.