Project 4: Enhancing the Efficacy of Chimeric Antigen Receptor Therapy for B-ALL and DLBCL

项目4：项目概要/摘要 骨髓移植提供了第一个无可辩驳的证据，表明细胞疗法可以介导有效的， 持久的抗癌效果。基于这些开创性的观察，该领域一直在努力工作， 了解和增强细胞介导的移植物抗肿瘤（GVT）效应，在同种异体和 自体干细胞移植尽管有这些努力，GVT在B细胞恶性肿瘤中的临床获益 仍然主要限于接受剂量密集型移植预处理的低负担疾病患者 随后输注自体或同种异体干细胞拯救。自2011年首次观测以来， 越来越清楚的是，经遗传工程改造以表达嵌合抗原受体（汽车）的T细胞可以 介导针对B细胞恶性肿瘤的有效且持久的作用，将癌症细胞疗法确立为可行的方法 治疗方式，即使是对于化疗难治性，高负担疾病的患者。CAR-T的出现 细胞疗法是利用基于细胞的抗肿瘤免疫的努力的自然延伸， 在干细胞移植的研究中占主导地位。简单地说，该项目旨在改善短期- 以及基于CAR的治疗对B细胞恶性肿瘤的长期益处。B-ALL的经验确定了两个 CAR抗性的主要机制，这似乎在很大程度上是相互排斥的：由于丢失而导致的肿瘤逃逸 或靶向抗原的表达减少（这通常在存在持续性CAR-T的情况下发生 细胞）和T细胞衰竭（其通常随着靶抗原的持续表达而发生）。目标1将测试 假设抗原水平是影响CD 19-CAR后应答和复发的重要因素， CD 22-CAR用于DLBCL，并将测试第一个进入临床的双特异性CAR的疗效，目标是 降低B-ALL和DLBCL中由于抗原neg/lo变异体而复发的风险。目标2测试 假设“T细胞耗竭”是与T细胞衰竭相关的复发的主要原因。我们将寻求 识别可以区分CAR T细胞容易衰竭的患者的预测性生物标志物， 并进行最先进的单细胞TCR/RNA测序，以绘制持久性CAR T细胞的命运图，作为第一个 朝着“抗衰竭”移植工程的长期目标迈进。目标3开始解决一个主要问题 临床医生用CD 19-CAR T细胞治疗DLBCL患者面临的实际挑战，即“哪些患者 是否应该接受自体或异体HSCT的CAR后巩固？"以先前达成 在这项计划项目资助中的成功证明了循环肿瘤DNA（ctDNA）在 预测B细胞恶性肿瘤的临床结果，我们将测试ctDNA是否可以预测以下结果： CD 19-CAR治疗DLBCL，作为CAR后巩固个性化分层的第一步 疗法

Project 4: Project Summary/Abstract Bone marrow transplantation provided the first irrefutable evidence that cell therapy can mediate potent and long-lasting anti-cancer effects. Based upon these seminal observations, the field has worked diligently to understand and enhance cell mediated graft-versus-tumor (GVT) effects in the context of allogeneic and autologous stem cell transplantation. Despite these efforts, clinical benefit from GVT in B cell malignancies remains largely limited to patients with low burden disease who undergo dose intensive transplant conditioning following by infusion of autologous or allogeneic stem cell rescue. Since the first observation in 2011, it has become increasingly clear that T cells genetically engineered to express chimeric antigen receptors (CARs) can mediate potent and durable effects against B cell malignancies, establishing cell therapy for cancer as a viable therapeutic modality, even for patients with chemorefractory, high burden disease. Thus, emergence of CAR-T cell therapies is a natural extension of the efforts to harness cell based anti-tumor immunity that has long dominated research in the context of stem cell transplantation. Very simply, this Project seeks to improve short- and long-term benefit of CAR based therapies for B cell malignancies. Experience in B-ALL has identified two major mechanisms of CAR resistance, which appear to be largely mutually exclusive: tumor escape due to loss or diminished expression of the targeted antigen (which typically occurs in the presence of persistent CAR-T cells) and T cell failure (which typically occurs with continued expression of the targeted antigen). Aim 1 will test the hypothesis that antigen level is an important factor impacting response and relapse following CD19-CAR and CD22-CAR for DLBCL, and will test the efficacy of the first bispecific CAR to enter the clinic, with the goal of diminishing the risk of relapse due to antigen neg/lo variants in both B-ALL and DLBCL. Aim 2 tests the hypothesis that “T cell exhaustion” is the major cause of relapse associated with T cell failure. We will seek to identify predictive biomarkers that can distinguish patients whose CAR T cells are predisposed to exhaustion, and undertake state-of-the-art single cell TCR/RNA sequencing to fate map persistent CAR T cells, as a first step toward a long-term goal of engineering grafts for “exhaustion resistance”. Aim 3 begins to address a major practical challenge facing clinicians treating patients with CD19-CAR T cells for DLBCL, namely “which patients should undergo post-CAR consolidation with autologous or allogeneic HSCT?”. Building upon previous successes in this Program Project Grant in demonstrating the utility of circulating tumor DNA (ctDNA) in predicting clinical outcomes for B cell malignancies, we will test whether ctDNA can predict outcomes following CD19-CAR therapy for DLBCL, as a first step toward personalized stratification of post-CAR consolidation therapy.