Active Immunotherapy with Pox Vector Modified DC

使用 Pox 载体修饰 DC 进行主动免疫治疗

• 批准号: 7108677
• 负责人: MICHAEL A MORSE
• 金额: $ 21.36万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7108677
• 关键词: T lymphocyte; biotechnology; carcinoembryonal antigen; cell adhesion molecules; clinical research; clinical trials; colon neoplasms; dendritic cells; enzyme linked immunosorbent assay; human subject; immune response; leukocyte activation /transformation; leukocyte adhesion molecules; neoplasm /cancer immunotherapy; neoplasm /cancer vaccine; patient oriented research; transfection /expression vector; tumor antigens; vaccine development; vaccinia virus; vector vaccine

This revised project will test whether dendritic cells (DC) modified with pox vectors encoding the tumor antigen carcinoembryonic antigen (CEA) will induce a clinically-effective frequency of tumor antigen-specific T cells in patients with colon cancer. Antigen-specific T cell activation and proliferation are essential for clinically effective immune responses. Promising methods for activating antigen-specific T cells include the use of antigen loaded DC. During the initial period of funding, we administered DC loaded with mRNA encoding CEA to patients with minimal residual disease following resection of hepatic metastases of colon cancer. Although the DC were well-tolerated, we observed little augmentation of the CEA-specific immune response and no improvement in recurrence free survival. This can be explained partly by inadequate antigen expression and presentation within the DC, by poor T cell activation due to low levels of costimulatory molecules such as CD80 on the immature DC, and by limited immunogenicity of the native tumor antigen. To overcome these problems, we have modified DC with recombinant, replication-defective pox vectors (including vaccinia (rV) and fowlpox (rF)) that express a TRiad of COstimulatory Molecules (CD80, CD54, and CD58, designated TRICOM) as well as a modified tumor antigen CEA(6D), with an amino acid substitution that creates a more potent epitope. In a phase I study of patients with CEA-expressing malignancies who received ex vivo generated DC modified with rF-CEA(6D)-TRICOM, we detected antigen-specific T cell responses in the range of 0.1-0.5% of the peripheral blood mononuclear cells (PBMC). Clinical benefit was associated with the highest levels of immune response. Recently, it has been observed that greater levels of immune response to pox vector-encoded antigens occur with heterologous prime-boost immunizations. Priming with vaccinia encoding CEA followed by boosts with fowlpox encoding CEA has been suggested to improve survival in patients with advanced cancer. Nonetheless, the induced CEA-specific immune responses were 0.01% or less of the PBMC. We hypothesize that prime-boost strategies with pox vector-modified DC will achieve greater clinical benefit by increasing the level of CEA-specific T cell activity. Therefore, we propose a phase II study to choose between two immunization strategies, DC infected with rV-CEA(6D)-TRICOM followed by DC infected with rF-CEA(6D)-TRICOM or rV-CEA(6D)-TRICOM followed by rF-CEA(6D)-TRICOM, in terms of which is associated with a better rate of disease-free survival at 2 years following hepatic metastasis resection and adjuvant chemotherapy. We will also measure the rate and magnitude of the CEA-specific immune response by ELISPOT. IL-2 increases the magnitude of the CEA specific T cell responses to pox-vector immunizations. Therefore, we will subsequently explore the role of IL-2 in augmenting CEA-specific immunity when given with the optimal immunization strategy.

这个修订后的项目将测试用编码肿瘤抗原癌胚抗原（CEA）的痘载体修饰的树突状细胞（DC）是否会在结肠癌患者中诱导肿瘤抗原特异性T细胞的临床有效频率。抗原特异性T细胞活化和增殖对于临床有效的免疫应答是必不可少的。用于活化抗原特异性T细胞的有希望的方法包括使用负载抗原的DC。在最初的资助期间，我们将载有编码CEA的mRNA的DC给予患有轻微肿瘤的患者。 结肠癌肝转移切除术后的残留疾病。虽然DC耐受性良好，但我们观察到CEA特异性免疫应答几乎没有增强，无复发生存率也没有改善。这可以部分地解释为DC内抗原表达和呈递不足，由于未成熟DC上低水平的共刺激分子如CD 80导致的T细胞活化不良，以及由于未成熟DC上的免疫原性有限。 天然肿瘤抗原。为了克服这些问题，我们用重组的复制缺陷型痘载体（包括牛痘（rV）和鸡痘（rF））修饰DC，所述载体表达共刺激分子（CD 80、CD 54和CD 58，命名为TRICOM）的Triad以及修饰的肿瘤抗原CEA（6D），其具有产生更有效表位的氨基酸取代。在患有CEA表达恶性肿瘤的患者的I期研究中，这些患者接受了用rF-CEA（6D）-TRICOM修饰的离体产生的DC，我们检测到在外周血单核细胞（PBMC）的0.1-0.5%范围内的抗原特异性T细胞应答。临床获益与最高水平的免疫应答相关。最近，已经观察到对痘病毒载体编码的抗原的更高水平的免疫应答发生在异源初免-加强免疫中。已经提出用编码CEA的牛痘引发，随后用编码CEA的鸡痘加强，以提高晚期癌症患者的存活率。尽管如此，诱导的CEA特异性免疫应答为PBMC的0.01%或更少。我们假设，用痘病毒载体修饰的DC的初免-加强策略将通过增加CEA特异性T细胞活性的水平来实现更大的临床益处。因此，我们提出了一项II期研究以在两种免疫策略之间进行选择，用rV-CEA（6D）-TRICOM感染的DC随后用rF-CEA（6D）-TRICOM感染的DC或rV-CEA（6D）-TRICOM随后rF-CEA（6D）-TRICOM感染的DC，就其与肝转移切除术和辅助化疗后2年时更好的无病生存率相关而言。我们还将通过ELISPOT测量CEA特异性免疫应答的速率和幅度。IL-2增加了对痘病毒载体免疫的CEA特异性T细胞应答的幅度。因此，我们随后将探讨IL-2在增强CEA特异性免疫中的作用，当给予最佳免疫策略时。