DIRECT INTRATUMORAL ADMINISTRATION OF DENDRITIC CELLS

树突状细胞（DC）在人实体瘤块原位增加的外观已间接与更好的预后。 未成熟DC可有效地从凋亡细胞体获得抗原并诱导MHC I类限制性抗原特异性细胞毒性T淋巴细胞。 这一发现增加了额外的支持的概念，DC可能发挥主导作用，在“交叉引发”事件，在体内的免疫应答的启发。 我们以前的研究表明，早期培养的DC在体外摄取高分子量葡聚糖颗粒以及整个肿瘤裂解物方面具有高度活性。由于这些发现，可以想象DC可以提供用于触发肿瘤内的免疫应答的有效手段，特别是在含有显著基线水平的凋亡细胞体的那些团块中。 事实上，我们已经发现，直接瘤内（IT）注射“未脉冲的”（即，未负载肿瘤抗原或未脉冲的）DC可以介导小鼠中已建立的乳腺肿瘤结节的消退。 这种抗肿瘤作用似乎与局部递送DC之前在肿瘤块内测量的基线细胞凋亡水平直接相关。 重要的是，远离DC注射肿瘤结节的部位的肿瘤结节也经历了消退。 在该鼠乳腺肿瘤模型中，通过IT注射DC引起的免疫抑制作用严重依赖于宿主来源的T细胞（CD 8+）免疫应答的激活，包括局部和全身。 驱动这种RO 1应用的假设是，在体内引发增强的肿瘤细胞凋亡的方法将增强DC的治疗功效和免疫刺激能力。 我们建议开发新的实验和临床策略，用于治疗乳腺癌，利用有效的抗原呈递DC结合剂，可以选择性地引发肿瘤细胞凋亡在体内。 我们的基本原理是基于我们在小鼠和人肿瘤系统中开发的实验数据和方法。 我们建议的具体目标是：1。实验研究在相关小鼠乳腺（MT-901）肿瘤模型中单独和与肿瘤细胞增殖诱导剂组合的DC的直接IT施用; 2.在II期临床试验中研究DC在晚期乳腺癌患者中的直接IT施用。 我们的转化研究工作的总体目标将是开发一种新的，创新的治疗晚期乳腺癌的策略，采用肿瘤增殖诱导剂与DC相结合。

Increased appearance of dendritic cells (DC) within human solid tumor masses in situ has been associated indirectly with better prognosis. Immature DC can efficiently acquire antigen from apoptotic cell bodies and induce MHC class I-restricted, antigen- specific cytotoxic T lymphocytes. This finding adds additional support to the concept that DC may play the predominant role in "cross-priming" events for the elicitation of an immune response in vivo. Our previous studies demonstrated that DC in early culture are highly active at uptaking high molecular weight dextran particles as well as whole tumor lysates in vitro. Because of these findings, it is conceivable that DC may offer an efficient means for triggering immune responses within tumors, particularly in those masses containing a significant baseline level of apoptotic cell bodies. Indeed, we have found that direct intratumoral (IT) injections of "unpulsed" (i.e. not tumor antigen-loaded or pulsed) DC can mediate the regression of established breast tumor nodules in mice. This antitumor effect appears to be directly correlated with the level of baseline apoptosis measured within the tumor mass before the local delivery of DC. Of importance, tumor nodules at distant sites from the DC-injected tumor nodule also underwent regression. The immunotherapeutic effect elicited by IT injections of DC in this murine breast tumor model is critically dependent upon activation of a host-derived T cell (CD8+) immune response, both locally and systemically. The hypothesis driving this RO1 application is that approaches that elicit enhanced apoptosis of tumors in vivo will augment both the therapeutic efficacy and immune stimulatory capacity of DC. We propose to develop new experimental and clinical strategies for the treatment of breast cancer that utilize potent antigen presenting DC combined with agents that can selectively elicit tumor apoptosis in vivo. Our rationale is based on experimental data and methodologies that we have developed in both murine and human tumor systems. The Specific Aims of our proposal are to: 1. Investigate experimentally the direct IT administration of DC alone and combined with tumor cell apoptosis-inducing agents in a relevant murine breast (MT-901) tumor model; 2. Investigate clinically in phase II trials the direct IT administration of DC in patients with advanced breast cancer. The overall goal of our translational research effort will be to develop a new, innovative strategy for the treatment of advanced breast cancer that employs tumor apoptosis-inducing agents combined with DC.