Xenograft-like rejection of tumors in a-gal glycolipids

描述（由申请人提供）：治疗难治性病变是实体瘤患者死亡的主要原因。尽管此类病变中的肿瘤细胞表达各种肿瘤相关抗原（TAA），但由于肿瘤内的免疫抑制微环境、调节性T （Treg）细胞的活性以及抗原呈递细胞（APC）缺乏适当的TAA呈递，它们通常被免疫系统“隐藏”。我们提出了一种新的免疫疗法，通过在肿瘤内注射含有a-gal表位（Gala1-3Galb1-4GlcNAc-R）的鞘糖脂胶束（命名为GSL?gal）来破坏这种病变并将其转化为内源性肿瘤疫苗。由于天然抗Gal抗体（人体免疫球蛋白的1%）与GSL? Gal的a- Gal表位结合，该注射剂可诱导强烈的肿瘤内炎症反应。在非灵长类哺乳动物（如猪）细胞中自然表达的a-gal表位与抗gal结合可诱导人类和猴子对异种移植物产生快速排斥反应。我们假设肿瘤内注射GSL？gal会导致病变的破坏，其机制类似于异种移植排斥反应，并会诱导对微转移的保护性免疫反应，足以克服Treg细胞的抑制作用。GSL的影响？Gal将通过以下机制介导：1。Anti-Gal/GSL激活补体产生趋化因子？加互动。2. 插入GSL？半乳糖进入细胞膜，导致抗半乳糖介导的肿瘤细胞破坏，如异种移植排斥反应。3. 通过anti-Gal对肿瘤细胞进行调控，使其被炎症募集到肿瘤中的APC有效摄取，从而将肿瘤转化为内源性疫苗。我们对缺乏a-gal表位并产生抗gal的敲除小鼠的初步研究表明，在很大比例的小鼠中，治疗过的黑色素瘤病变被破坏并转化为疫苗。我们的具体目标是：1。研究GSL的作用机制。gal诱导B16黑色素瘤病变内的炎症。2. 评估Treg细胞在约30%对GSL无反应的小鼠中防止诱导局部和全身保护性抗肿瘤免疫反应的作用？加治疗。3. 在自发性乳腺癌模型中确定瘤内GSL的保护作用？Gal注射在原发性病变的发展和诱导保护性免疫反应，防止额外的病变和转移。这些研究的成功将使我们能够建立GSL的临床试验。在癌症患者化疗顽固性病变。

DESCRIPTION (provided by applicant): Therapy refractory lesions are the main cause of death in solid tumor patients. Although the tumor cells in such lesions express various tumor associated antigens (TAA), they are usually "concealed" from the immune system because of immunosuppressive microenvironment within the tumor, activity of regulatory T (Treg) cells and lack of appropriate presentation of TAA by antigen presenting cells (APC). We propose a novel immunotherapy to destroy such lesions and convert them into endogenous tumor vaccines by intratumoral injection of micelles of glycosphingolipids bearing a-gal epitopes (Gala1-3Galb1-4GlcNAc-R) (designated GSL?gal). This injection induces a strong intratumoral inflammatory reaction due to binding of the natural anti- Gal antibody (1% of immunoglobulins in humans) to a-gal epitopes of GSL?gal. Anti-Gal binding to a-gal epitopes naturally expressed on cells of non-primate mammals (e.g. pigs) induces rapid rejection of xenografts in humans and monkeys. We hypothesize that intratumoral injection of GSL?gal will result in destruction of lesions in a mechanism similar to xenograft rejection and will induce a protective immune response against micrometastases, potent enough to overcome the suppressive effect of Treg cells. The effects of GSL?gal will be mediated by the following mechanisms: 1. Chemotactic factors generation due to complement activation by Anti-Gal/GSL?gal interaction. 2. Insertion of GSL?gal into cell membranes, resulting in anti-Gal mediated destruction of tumor cells as in xenograft rejection. 3. Opsonization of tumor cell by anti-Gal, targeting them for effective uptake by APC recruited into the tumor by the inflammation, thereby converting tumors into endogenous vaccines. Our preliminary studies in knockout mice lacking a-gal epitopes and producing anti-Gal, demonstrated destruction of treated melanoma lesions and their conversion into vaccine in a large proportion of mice. Our specific aims are: 1. To study the mechanisms by which GSL?gal induces inflammation within of B16 melanoma lesions. 2. To evaluate the role of Treg cells in preventing induction of a local and systemic protective anti-tumor immune response in the ~30% of mice that do not respond to GSL?gal treatment. 3. To determine in a model of spontaneous mammary carcinoma the protective effect of intratumoral GSL?gal injection in the development of the primary lesion and on induction of a protective immune response preventing additional lesions and metastases. Success in these studies will enable us to establish clinical trials with GSL?gal in cancer patients with chemotherapy refractory lesions. Our objective is to develop a novel method for treating cancer patients with recurrent chemotherapy refractory solid tumors, by injection into the lesion a substance called glycosphingolipids containing a carbohydrate structure called the a-gal epitope. This substance is referred to as GSL?gal. The treatment exploits the fact that all humans have a natural antibody called anti-Gal in very large amounts. This antibody interacts with a-gal epitopes on GSL?gal and induces local inflammation. Injection of GSL?gal into tumor lesions destroys the lesions with the assistance of anti-Gal and convert treated lesions into a self vaccine. This vaccine "educates" the immune system to recognize tumor cells in micrometastases (small groups of tumor cells in various organs) as cells that have to be destroyed. We will study this treatment in a unique mouse model that simulates the pertinent human immunological parameters. Success in the studies in the mouse model will enable us to apply this treatment to cancer patients.