Anti-melanoma Activity of Combined Lymphopenia and Immunotherapy

描述（由申请人提供）：尽管在癌症患者的外周血和骨髓中检测到肿瘤特异性T细胞，但这些T细胞不能介导巨大肿瘤的完全消退。扩增和激活这些T细胞的免疫方法很少导致肿瘤完全消退或治愈。在癌症患者中，许多因素可能导致对肿瘤的无效免疫，包括调节性免疫细胞，如CD 4 + CD 25+调节性T细胞和CD 11b + Gr 1+未成熟骨髓细胞。在这些研究中，我们打算通过全身照射（TBI）治疗来减少荷瘤小鼠中免疫介导的抑制并删除无反应的宿主抗肿瘤T细胞。我们打算通过过继转移幼稚T细胞来用“新”T细胞重建免疫系统。我们将教育这些T细胞肽脉冲树突状细胞（DC）接种。初步研究表明，这种策略导致肿瘤生长延迟，但不会提高荷黑色素瘤小鼠的存活率。为了改进该模型，将检查两种已知的免疫抑制群体（CD 4 + CD 25 + foxp 3 + T细胞和CD 11b + Gr 1+未成熟骨髓细胞）的重建和活性。通过耗尽这些细胞群，我们将确定这些抑制性细胞对抗肿瘤免疫的发展的影响（如果有的话）。此外，将探索导致抗肿瘤记忆T细胞和长期免疫的发展的策略，包括肿瘤反应性T细胞的过继转移。我们的实验室在使用肿瘤脉冲树突状细胞（DC）作为有效的抗原呈递细胞诱导有效的抗肿瘤原发性和记忆性T细胞应答方面具有临床前专业知识。我们已经表明，将肿瘤靶向DC上的细胞表面受体可以导致增强的抗肿瘤T细胞应答，并且与细菌衍生的免疫佐剂的组合疗法可以改善针对肿瘤的DC疫苗接种。我们假设，建立黑色素瘤的消退将需要多种免疫方法来诱导有效的抗肿瘤T细胞活性。具体而言，我们打算通过以下具体目标实施用于诱导针对黑素瘤的有效抗肿瘤T细胞应答的疗法：1.实验研究淋巴细胞减少症后诱导的免疫调节机制; 2.通过转移富含CD 8+记忆T细胞的T细胞来检测DC疫苗在淋巴细胞减少症背景下的功效; 3.确定树突状细胞疫苗接种和CpG辅助治疗联合放疗和过继性T细胞转移在小鼠黑色素瘤模型中的疗效。本申请中概述的实验研究旨在继续我们成功的临床前努力，以产生针对黑色素瘤的免疫策略。这些发现可能对人类临床免疫试验具有重要意义。

DESCRIPTION (provided by applicant): Despite detection of tumor-specific T cells in the peripheral blood and bone marrow of cancer patients, these T cells are unable to mediate total regression of bulky tumors. Immunotherapeutic approaches to expand and activate these T cells rarely result in total tumor regressions or cures. In cancer patients, many factors may contribute to ineffective immunity against tumors including regulatory immune cells such as CD4+CD25+ regulatory T cells and CD11b+ Gr1+ immature myeloid cells. In these studies, we intend to decrease immune mediated suppression and delete unresponsive host anti-tumor T cells in tumor bearing mice by treatment with total body irradiation (TBI). We intend to reconstitute the immune system with "new" T cells by adoptive transfer of naive T cells. We will educate these T cells with peptide-pulsed dendritic cell (DC) vaccination. Initial studies have shown that this strategy leads to a delay in tumor growth but does not enhance survival in melanoma bearing mice. In order to improve this model, the reconstitution and activity of two known immune inhibitory populations, CD4+CD25+foxp3+ T cells and CD11b+Gr1+ immature myeloid cells, will be examined. By depleting these populations, we will determine the effects, if any, these inhibitory cells have on the development of anti-tumor immunity. In addition, strategies that lead to the development of anti-tumor memory T cells and long-term immunity will be explored, including adoptive transfer of tumor reactive T cells. Our laboratory has preclinical expertise in the use of tumor-pulsed dendritic cells (DC) as potent antigen presenting cells for the induction of effective anti-tumor primary and memory T cell responses. We have shown that targeting tumors to cell-surface receptors on DC can lead to enhanced anti-tumor T cell responses and combination therapy with bacterial derived immunoadjuvants can improve DC vaccination against tumors. We hypothesize that regression of established melanoma will require multiple immunotherapeutic approaches for the induction of effective anti-tumor T cell activity. Specifically, we intend to implement therapies for the induction of potent anti-tumor T cell responses against melanoma through the following Specific Aims: 1. To investigate experimentally the mechanisms of immune regulation induced after lymphopenia; 2.To examine the efficacy of DC-based vaccination in the setting of lymphopenia by transfer of T cells enriched in CD8+ memory T cells; 3. To determine the efficacy of dendritic cell vaccination and CpG adjuvant therapy in combination with irradiation and adoptive T cell transfer in a murine melanoma model. The experimental studies outlined in this application are designed to continue our successful preclinical efforts to generate immunization strategies against melanoma. These findings could have significant translation to human clinical immunotherapeutic trials.