Adoptive T cell Therapy for Pediatric Leukemia

在该项目的Aim 1下，启动临床试验测试cd22靶向CAR - T细胞作为复发或耐药前b ALL治疗的必要临床前工作已经完成。CD22在95%的前b细胞ALL中表达，儿科肿瘤科在使用免疫毒素结合抗体的CD22靶向治疗ALL方面有广泛的专业知识。临床前工作产生了许多重要的发现，这些发现大大简化了生成CAR - T细胞的过程。该试验目前处于开放状态，利用基于慢病毒的病毒载体对患者来源的扩增T细胞进行遗传修饰，以便在淋巴细胞耗尽化疗后重新输注。该试验的初步结果发表在Fry等人的杂志上。Nature Medicine 2018年的一项研究显示，活性剂量下的完全缓解率为70%，并且发现对CD19阴性/暗淡/阳性ALL有效。这项试验表明，CD19 CAR - T细胞疗法的成功可以扩展到ALL的其他靶点。此外，由于CD19 CAR治疗后观察到CD19阴性复发，第二个靶点将潜在地增加CAR治疗ALL的整体治疗潜力。该试验正在进行中，已经治疗了45名患者，随后的手稿描述了扩展的经验，毒性特征和细胞制造变化的影响，正在开发中。该试验正在探索新的科学目标，并有望继续开放以优化这种治疗策略。到目前为止，这是目前儿科中唯一高效的CD22 CAR试验。通过这项试验，我们还确定了抗原调节作为复发的机制。基于Fry实验室进行的临床前工作，确定了一种上调CD22的药物，未来评估增加CD22表达策略的试验正在计划阶段。在该项目的目标2下，我们开发了许多新颖的CAR结构，包括我们拥有专利的tslpr靶向CAR。这项研究已经发表在《血液》杂志上，我们正在准备进行临床试验。此外，我们还生成了一种具有出色体内活性的CD19/CD22双特异性CAR。这种结构可以防止体外系统中ALL靶缺失变体的出现。这种CAR目前正在积极地进行临床试验，迄今已有两名患者入组。这种相同的结构也在斯坦福大学用于治疗儿童ALL和弥漫性大B细胞淋巴瘤的临床试验中。我们进行了必要的临床前工作，纳入了一种可替代的、半自动的T细胞扩增和转导，这将进一步简化生产过程，该过程将在本试验中用于CAR制造。其次，我们正在开发新的急性髓性白血病CAR结构，可以降低与髓系抗原（如Flt3和CD33）相关的靶外肿瘤毒性。CD33 CAR试验正在积极开发中，计划于2019年进行临床转化。

Under Aim 1 of this project, the necessary preclinical work for the initiation of a clinical trial testing CD22-targeted CAR T cells as a therapy for relapsed or resistant pre-B ALL has been completed. CD22 is expressed on 95 % of pre-B cell ALL and there is extensive expertise in the Pediatric Oncology Branch in CD22-targeted therapy for ALL using immunotoxin conjugated antibodies. A number of important findings resulted from the pre-clinical work that have substantially streamlined the process of generating CAR T cells. This trial is currently open and utilizes lentiviral-based viral vectors for genetic modification of patient-derived expanded T cells to be reinfused after lymphodepleting chemotherapy. The initial experience from this trial was published in Fry et al. Nature Medicine 2018 and demonstrated 70% complete remission rate at an active dose and was found to be effective in CD19 negative/dim/positive ALL. This trial established that the success of CD19 CAR T cell therapy can be extended to other targets on ALL. Additionally, since CD19 negative relapse has been observed following CD19 CAR therapy, a second target will potentially increase the overall curative potential of CAR therapy for ALL. This trial is ongoing, has treated 45 patients and a subsequent manuscript describing the extended experience, toxicity profile and implications of cell manufacturing changes is in development. This trial is exploring new scientific aims and is anticipated to remain open to optimize this treatment strategy. To date, it is the only highly effective CD22 CAR trial in pediatrics at this point in time. Through this trial, we also identified antigen modulation as a mechanism of relapse. Based on preclinical work performed in the Fry lab, which identified an agent to upregulate CD22, a future trial evaluating strategies to increase CD22 expression is in the planning stages. Under Aim 2 of this project we have developed a number of novel CAR constructs including a TSLPR-targeted CAR for which we hold a patent. This work has been published in Blood and we are preparing for a clinical trial. In addition, we have generated a CD19/CD22 bispecific CAR with excellent in vivo activity. This construct can prevent the emergence of target-loss variants of ALL in an in vitro system. This CAR is now actively being tested in the clinic, with two patients enrolled to date. This identical construct is also in clinical trials at Stanford for the treatment of pediatric ALL and diffuse large B cell lymphoma. We performed necessary pre-clinical work for the incorporation of an alternative, semi-automated T cell expansion and transduction that will further streamline the production process, which is being used for CAR manufacturing in this trial. Second, we are developing novel acute myelogenous leukemia CAR constructs that may reduce the on-target off-tumor toxicity associated with myeloid antigens such as Flt3 and CD33. The CD33 CAR trial is under active development with plans for clinical translation in 2019.