Anti-melanoma Activity of Combined Lymphopenia and Immunotherapy

描述(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细胞无法介导巨大肿瘤的完全消退。扩增和激活这些T细胞的免疫治疗方法很少导致肿瘤的完全消退或治愈。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CD4+CD25+调节性T细胞和CD11b+Gr1+未成熟髓系细胞。在这些研究中，我们打算通过全身照射(TBI)来减少免疫介导的抑制，并删除荷瘤小鼠中无反应的宿主抗肿瘤T细胞。我们打算通过过继转移幼稚的T细胞，用“新的”T细胞重建免疫系统。我们将用多肽冲击的树突状细胞(DC)疫苗培养这些T细胞。初步研究表明，这种策略可以延缓肿瘤的生长，但不能提高黑色素瘤小鼠的存活率。为了改进这一模型，将检测两个已知的免疫抑制群体，即CD4+CD25+Foxp3+T细胞和CD11b+Gr1+未成熟髓系细胞的重建和活性。通过消耗这些群体，我们将确定这些抑制细胞对抗肿瘤免疫发展的影响。此外，还将探索发展抗肿瘤记忆T细胞和长期免疫的策略，包括过继转移肿瘤反应性T细胞。我们的实验室在使用肿瘤冲击的树突状细胞(DC)作为有效的抗原提呈细胞来诱导有效的抗肿瘤初级和记忆性T细胞反应方面拥有临床前的专业知识。我们已经证明，将肿瘤靶向于DC上的细胞表面受体可以导致增强的抗肿瘤T细胞反应，与细菌衍生的免疫佐剂联合治疗可以改善DC疫苗对肿瘤的免疫效果。我们假设黑色素瘤的消退将需要多种免疫治疗方法来诱导有效的抗肿瘤T细胞活性。具体地说，我们打算通过以下特定目的来实施诱导针对黑色素瘤的有效抗肿瘤T细胞反应的治疗：1.从实验上研究淋巴细胞减少后诱导免疫调节的机制；2.通过转移富含CD8+记忆T细胞的T细胞来检测DC疫苗在淋巴细胞减少症中的有效性；3.在小鼠黑色素瘤模型中确定树突状细胞疫苗和CpG辅助治疗与照射和过继T细胞转移相结合的疗效。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。这些发现可能会对人类临床免疫治疗试验产生重大影响。

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.