Optimization of Tumor Vaccines for the Aged

描述（由申请人提供）：考虑到超过50%的癌症发生在老年人中，老年人的免疫系统与反应性的急剧降低有关，我们小组和其他人的研究表明，在年轻人中有效的免疫疗法不一定在老年人中有效。为了有效地开发免疫策略并能够将这种方法转化为老年癌症的治疗，有必要：1）使用密切反映癌症患者的相关模型，其中自我耐受和衰老同时存在; 2）识别和理解老年免疫系统的内在缺陷。我们已经通过将FVB-Her-2/neu小鼠与HLA-A2小鼠（A2 xneu）杂交建立了肿瘤模型。这些动物对Her-2/neu抗原具有耐受性，并且在22-27月龄时出现自发性肿瘤。因此，A2 xneu小鼠模型代表了一种独特的模型，其中衰老和耐受性同时存在，使我们能够评估在老年耐受环境中的免疫和抗肿瘤反应。我们的初步结果表明，治疗与肿瘤内注射的CpG-ODN加上肽疫苗接种和消耗的TCLN诱导免疫应答，拒绝原发性肿瘤在100%的年轻A2 xneu小鼠和所有年轻的动物发展了保护性记忆反应。相比之下，老年A2 xneu小鼠仅延迟肿瘤生长。尽管我们能够克服年轻A2 xneu小鼠的耐受性，但这些结果表明老年A2 xneu小鼠中可能存在其他缺陷，阻碍了这些动物免疫反应的最佳激活。对年轻和老年树突状细胞（DCs）的功能分析表明，与年轻DCs相比，老年DCs在CpG-ODN刺激后被次优地激活。但用CpG-ODN和抗CD 40抗体刺激老年DCs后，老年DCs的功能可得到恢复。此外，我们的结果表明，更多数量的老年幼稚CD 8 + T细胞表达B7-H1。由于B7-H1负调节T细胞应答，我们假设B7-H1在旧的CD 8 + T细胞中的表达可以限制或减少这些细胞的免疫功能。事实上，我们的研究结果表明，在旧的CD 8 + T细胞中阻断B7- H1可以恢复这些细胞的功能。基于这些结果，我们假设CpG-ODN、抗-CD 40、TcB耗竭和抗-B7-H1的组合将诱导能够控制老年耐受性A2 xneu小鼠中肿瘤生长的更强的抗肿瘤免疫应答。初步结果表明情况确实如此。在我们的疫苗接种方案中加入抗-CD 40和抗-B7-H1是重要的，因为：1）将抗-CD 40加入到CpG-ODN疫苗接种方案中将恢复DC的功能，导致更强的免疫应答;和2）阻断B7-H1将恢复旧的CD 8 T细胞的功能，允许这些细胞的最佳活化和扩增。目的1将评估阻断B7-H1如何恢复老年CD 8 T细胞的功能以及CpG+抗CD 40的组合如何增强老年DC的功能。目的2优化并评价CpG-ODN、抗CD 40、TdR去除和抗B7-H1免疫老年耐受宿主（老年A2 xneu小鼠）后对免疫应答的生物学效应。目的3探讨最佳免疫治疗条件下的抗肿瘤效应。这些研究的信息将揭示控制和操纵免疫系统的新策略，以在旧的耐受宿主中开发更有效的癌症免疫疗法。

DESCRIPTION (provided by applicant): Considering that more than 50% of cancer occurs in the elderly and the immune system of the old is associated with a dramatic reduction in responsiveness, studies from our group and others indicate that immunotherapies that are effective in the young are not necessarily effective in the old. To effectively develop an immunotherapeutic strategy and be able to translate this approach for the treatment of cancers in the old, it is necessary to: 1) use relevant models that closely reflect those of cancer patients where self-tolerance and aging are present simultaneously; and 2) identify and understand the intrinsic defects of the old immune system. We have developed a tumor model by crossing the FVB-Her-2/neu mice with HLA-A2 mice (A2xneu). These animals are tolerant to Her-2/neu antigens and spontaneous tumors appear when they are 22-27 months old. Therefore, the A2xneu mouse model represents a unique model where aging and tolerance are present simultaneously allowing us to evaluate the immune and antitumor responses in an old-tolerant environment. Our preliminary results indicate that treatment with intratumoral injections of CpG-ODN plus peptide vaccination and depletion of Tregs induce an immune response that reject the primary tumors in 100% of young A2xneu mice and all young animals developed a protective memory response. In contrast, old A2xneu mice only delay the tumor growth. Although we were able to overcome tolerance in young A2xneu mice, these results suggest that other deficiencies may exist in old A2xneu mice preventing the optimal activation of an immune response in these animals. Analysis of the function of young and old dendritic cells (DCs) indicates that old DCs were suboptimally activated after CpG-ODN stimulation when compared to young DCs. However, the function of old DCs could be restored if old DCs were stimulated with CpG-ODN plus anti-CD40. Additionally, our results indicate that a higher number of old naive CD8+ T cells express B7-H1. Since B7-H1 negatively regulates T cell responses, we hypothesized that the expression of B7-H1 in old CD8+ T cells could restrict or diminish the immune function of these cells. Indeed, our results indicate that blockade of B7- H1 in old CD8+ T cells restore the function of these cells. Based on these results, we hypothesized that the combination of CpG-ODN, anti-CD40, Tregs depletion and anti-B7-H1, will induce stronger antitumor immune responses capable of controlling the tumor growth in old tolerant A2xneu mice. Preliminary results indicate that this is the case. The incorporation of anti-CD40 and anti-B7-H1 in our vaccination protocol is important because: 1) the addition of anti-CD40 into the CpG-ODN vaccination protocol will restore the function of DC resulting in stronger immune responses; and 2) blockade of B7-H1 will restore the function of old CD8 T cells permitting the optimal activation and expansion of these cells. Aim 1 will evaluate how blockade of B7-H1 restore the function of old CD8 T cells and how the combination of CpG+anti-CD40 enhances the function of old DCs. Aim 2 will optimize and evaluate the biological effects on the immune responses following immunization with CpG-ODN, anti-CD40, Tregs depletion and anti-B7-H1 in old tolerant hosts (old A2xneu mice). Aim 3 will evaluate the antitumor responses using the optimal immunotherapy condition. The information of these studies will reveal new strategies for controlling and manipulating the immune system to develop more effective cancer-immunotherapies in old tolerant hosts.