CELL BASED TUMOR VACCINES TARGETING CD4+ T LUMPHOCYTES

我们正在开发疫苗策略，以诱导对眼黑色素瘤的免疫，这是眼睛最常见的恶性肿瘤。虽然原发肿瘤可以治疗，但50%的患者会发展为转移性疾病，目前尚无成功的治疗方法。我们假设产生肿瘤特异性的长期免疫可能是一种有效的治疗原发性和转移性疾病的方法。在过去的8年中，我们开发了一种独特的免疫疗法，使用转基因肿瘤细胞疫苗来增强肿瘤抗原的抗原呈递。我们的策略侧重于激活肿瘤特异性CD4+ T辅助淋巴细胞。CD4+ T细胞在抗肿瘤免疫中特别重要，因为它们为最佳的CD8+活性提供必要的“帮助”，并且因为它们对长期记忆至关重要。我们在3个小鼠模型中表明，转染了同源MHC II类、CD80和超抗原基因的肿瘤细胞是有效的免疫治疗剂。考虑到有希望的动物实验结果，我们想在病人身上测试我们的方法。动物实验使用自体肿瘤细胞作为“基础”疫苗。然而，自体的人类肿瘤材料并不总是可用的，并且为个体患者定制既不符合成本效益也不可行。作为一种替代方法，我们将使用已建立的人类眼部黑色素瘤肿瘤细胞系作为“基础”疫苗。我们相信，如果我们了解了疫苗刺激抗肿瘤免疫的机制，就可以达到最佳的疫苗效果。因此，我们将不仅评估疫苗的有效性，还将通过执行以下具体目标来验证疫苗策略所基于的几个假设：1)确定人类眼黑色素瘤细胞系是疫苗的“基础”系，并将CD80， HLA-DR和超抗原基因转染它们。2)确定转染物刺激肿瘤特异性HLA-DR限制性CD4+ T细胞反应的能力。3)确定疾病的分期或程度是否影响患者对疫苗的反应能力。4)确定肿瘤患者是否对其肿瘤抗原具有“耐受性”，因此不太可能产生反应；5)确定疫苗是否作为肿瘤编码的内源性合成抗原的抗原提呈细胞。这些研究的完成将为进行临床试验提供框架，并将为进一步改进疫苗提供机制信息。

We are developing vaccine strategies for inducing immunity to ocular melanoma, the most common malignancy of the eye. Although primary tumor can be treated, 50% of patients develop metastatic disease for which there is no successful therapy. We hypothesize that the generation of tumor-specific, long-term immunity may be a useful therapy for established primary and metastatic disease. During the past 8 years we have developed a unique immunization therapy using genetically modified tumor cell-based vaccines for enhancing antigen presentation of tumor antigens. Our strategy focuses on activating tumor-specific CD4+ T helper lymphocytes. CD4+ T cells are particularly important in anti- tumor immunity because they provide the requisite "help" for optimal CD8+ activity, and because they are critical for long-term memory. We have shown in 3 mouse models that tumor cells transfected with syngeneic MHC class II, CD80 and superantigen genes are potent immunotherapeutic agents. Given the promising animal results, we would like to test our approaches in patients. The animal studies used autologous tumor cells for the "base" vaccine. Autologous human tumor material, however, is not always available, and customization for individual patients is neither cost effective nor feasible. As an alternative approach we will use established human ocular melanoma tumor cell lines as the "base" vaccine. We believe that optimal vaccine efficacy can be achieved if we understand the mechanism by which the vaccines stimulate anti- tumor immunity. We will, therefore, not only assess vaccine efficacy, but also test several hypothesis on which the vaccine strategy is based by performing the following Specific Aims: 1) Identify human ocular melanoma cell lines are the "base" lines for the vaccine, and transfect them with CD80, HLA-DR, and superantigen genes. 2) Determine the ability of the transfectants to stimulate tumor-specific HLA-DR restricted CD4+ T cell responses. 3) Determine if the stage or extent of disease affects patients' ability to respond to the vaccine. 4) Determine if individuals with tumor are "tolerant" to their tumor antigens and hence less likely to respond; and 5) Determine if the vaccines function as antigen presenting cells for tumor-encoded endogenously synthesized antigens. Completion of these studies will provide the framework for conducting a clinical trial, and will provide mechanistic information for further improvement of the vaccines.