Personalized Adoptive T-cell Therapy for AML

摘要/项目摘要 开发扩增和激活AML特异性T细胞的策略至关重要。我们有 开发了一种个性化的癌症疫苗，其中患者来源的肿瘤细胞与自体肿瘤细胞融合， 树突状细胞（DC），呈递广泛的抗原阵列，捕获白血病细胞的异质性 群体，包括共享抗原和新抗原。我们已经完成了一项II期临床试验， 在化疗后达到缓解的患者接受DC/AML融合体的系列疫苗接种。值得注意的是， 尽管中位年龄为63岁，但71%的患者在中位随访5年后仍无疾病。疫苗接种 与靶向自体AML细胞和白血病相关的T细胞扩增相关 抗原DC/AML疫苗可用作产生活化的白血病特异性T细胞的平台， 用于过继免疫治疗。以这种方式，可以产生白血病特异性的效应细胞， 捕获肿瘤异质性，并且离体活化以获得功能上有能力的表型。我们 已经证明，在IL-7/IL-15的背景下的疫苗刺激导致中枢神经系统的增强水平。 记忆细胞对于反应的长期持久性至关重要。虽然疫苗的产生刺激了 离体白血病特异性T细胞代表了在体内有效靶向AML细胞的有希望的策略， 肿瘤微环境的免疫抑制性质仍然是记忆发展的障碍 长期的保护和应对。我们在缓解期骨髓中进行了转录组分析， 与早期相比，确定可预测持久应答的生物标志物的疫苗接种时间 DC/AML融合疫苗接种后复发。值得注意的是，骨中TGF-β的表达减少， 骨髓微环境与持久缓解相关。这些结果与先前的结果一致。 有报道表明TGF-β是肿瘤免疫原性、T细胞活化和浸润的负调节剂 进入肿瘤床因此，靶向TGF β以增强疫苗效力是有充分理由的。在 目前的研究，我们将创建一个新的战略，过继T细胞治疗产生的疫苗介导的 刺激、选择抗原特异性T细胞和离体扩增。功能特性将是 在免疫活性鼠白血病模型中检查。然后我们将检查TGF-β抑制剂的作用， 对疫苗刺激的T细胞内的疫苗应答和TGF抑制的影响 效应器SMAD2。在第二个目的中，T细胞产物将关于靶向共享的免疫球蛋白来表征。 和新抗原靶点，库的寡克隆扩增和多样性， 活化、衰竭、衰老和迁移到肿瘤床所需的趋化因子。第三个目标， 我们将进行一项I期研究，在这项研究中，达到完全缓解的AML患者将接受 用疫苗刺激的T细胞进行过继治疗。

Abstract/Project Summary The development of strategies to expand and activate AML specific T cells is of critical importance. We have developed a personalized cancer vaccine in which patient derived tumor cells are fused with autologous dendritic cells (DCs), presenting a broad array of antigens that capture the heterogeneity of the leukemia cell population, including shared and neoantigens. We have completed a phase II clinical trial in which patients that achieve remission following chemotherapy undergo serial vaccination with DC/AML fusions. Remarkably, despite a median age of 63, 71% remained free of disease with a median follow up of 5 years. Vaccination was associated with the expansion of T cells targeting both autologous AML cells and leukemia associated antigens. The DC/AML vaccine can be used as a platform to generate activated leukemia-specific T cells ex- vivo for adoptive immunotherapy. In this way, effector cells may be generated that are leukemia specific, capture tumor heterogeneity, and are activated ex vivo to achieve a functionally competent phenotype. We have demonstrated that vaccine stimulation in the context of IL7/IL-15 results in enhanced levels of central memory cells critical for long term persistence of response. While the generation of vaccine stimulated leukemia specific T cells ex vivo represents a promising strategy to effectively target AML cells in vivo, the immunosuppressive nature of the tumor microenvironment remains a barrier to the development of a memory response and long-term protection. We performed transcriptome analysis in the remission bone marrow at time of vaccination to identify biomarkers that were predictive of durable response as compared to early relapse following vaccination with DC/AML fusions. Of note, decreased expression of TGF-β in the bone marrow microenvironment was associated with durable remission. These results are consistent with prior reports suggesting TGF-β as a negative regulator of tumor immunogenicity, T cell activation and infiltration into the tumor bed. As such there is strong rationale to target TGFβ to enhance vaccine efficacy. In the present study, we will create a novel strategy for adoptive T cell therapy generated by vaccine mediated stimulation, selection of antigen specific T cells and ex vivo expansion. Functional characteristics will be examined in an immunocompetent murine leukemia model. We will then examine the effect of TGF-β inhibition on vaccine response and TGF inhibition within vaccine stimulated T cells by silencing of the downstream effector SMAD2. In the second aim, the T cell product will be characterized with respect to targeting of shared and neo-antigen targets, oligoclonal expansion and diversity of the repertoire, expression of markers of activation, exhaustion, senescence, and chemokines needed for migration into the tumor bed. In the third aim, we will conduct a Phase I study in which patients with AML who achieve complete remission will undergo adoptive therapy with vaccine stimulated T cells.