Bypassing the vaccine factory: creating a lymphoma vaccine in the tumor.In situ vaccination combining intratumoral Flt3L, cytotoxic therapy, and TLR agonists.

淋巴瘤是10种最常见的癌症之一，大多数类型都是无法治愈的标准疗法。现有疗法仅诱导暂时缓解，患者变得更加虚弱，并且疾病随着随后的每次迭代疗法变得更具侵袭性。在该提案中，我们将进一步开发一种肿瘤靶向疫苗方法，该方法已经在我们中心的早期临床试验中证明了疗效-原位疫苗接种-其包括1）肿瘤内施用FMS相关酪氨酸激酶3配体（Flt 3L），以将树突状细胞（DC）募集到肿瘤，2）细胞毒性治疗以释放肿瘤抗原用于DC摄取和呈递，和3）肿瘤内施用Toll样受体（TLR）激动剂以活化负载抗原的DC。本研究的总体目的是了解淋巴瘤肿瘤的免疫微环境如何从致耐受性状态操纵到免疫原性状态，以及什么样的细胞和分子机制允许或阻止这种情况。初步数据表明，Flt 3L更有效地招募时，肿瘤内，而不是全身施用DC。我们将评估哪些DC亚群最有效地内吞和呈递肿瘤抗原，以及已知诱导免疫原性细胞死亡的不同抗肿瘤细胞毒性疗法以及已知激活这些DC亚群的不同TLR激动剂的影响。随后，我们将确定这种Flt 3L引发的原位疫苗是否比我们先前单独使用TLR激动剂的方法更有效，以及哪些效应T细胞亚群介导抗肿瘤作用。最后，我们将评估疫苗与我们实验室正在研究的全身免疫调节剂的合理组合，包括T细胞刺激剂（例如常见的γ链细胞因子）和检查点阻断抗体（例如抗CTLA-4，抗PD 1，抗LAG 3）。这些研究的结果将有助于确定最佳的原位疫苗接种程序，从而产生有效的抗肿瘤免疫应答和肿瘤消退。

Lymphoma ranges among the 10 most common cancers and most types are incurable with standard therapies. Existing therapies induce only temporary remissions with patients becoming more debilitated and the disease becoming more aggressive with each subsequent iteration of therapy. In this proposal we will further develop a tumor-targeted vaccine approach already demonstrating efficacy in an early phase clinical trial at our center - in situ vaccination - which consists of 1) intratumoral administration of FMS-related tyrosine kinase 3 ligand (Flt3L), to recruit dendritic cells (DC) to the tumor, 2) cytotoxic therapy to release tumor antigens for DC uptake and presentation, and 3) intratumoral administration of Toll-like Receptor (TLR) agonists to activate antigen-loaded DC. The overall aim of this study is to understand how the immune microenvironment of lymphoma tumors can be manipulated from a tolerogenic to an immunogenic state and what cellular and molecular mechanisms allow or prevent this. Preliminary data demonstrate that Flt3L more effectively recruits DC when administered intratumorally rather than systemically. We will assess which DC subsets most effectively endocytose and present tumor antigens and the impact of different anti-tumor cytotoxic therapies known to induce immunogenic cell death as well as different TLR agonists known to activate these DC subsets. Subsequently, we will determine whether this Flt3L-primed in situ vaccine is even more effective than our previous approach using the TLR agonist alone and which effector T cell subsets mediate the anti-tumor effect. Finally, we will assess rational combinations of the vaccine with systemic immunomodulators being studied in our lab, including T cell stimulants (e.g. common gamma chain cytokines) and checkpoint blockade antibodies (e.g. anti-CTLA-4, anti-PD1, anti-LAG3). The results of these studies will help to identify the optimal in situ vaccination procedure leading to an effective anti-tumoral immune response and regression of the tumors.