Development of a new immunotherapeutic approach for the treatment of pancreatic adenocarcinoma by combining tumor-specific CAR-T cells with tumour-persistent immunostimulating bacteria.

胰腺癌的诊断对大多数受影响的人来说意味着没有治愈的可能性和极其不利的相对五年生存率。在常规疗法的帮助下，治愈的可能性往往受到诊断时疾病晚期的限制。因此，开发针对这种恶性肿瘤疾病的新治疗方案具有重要的社会意义。免疫性T细胞治疗是一种有前景的靶向治疗肿瘤的策略。嵌合抗原受体（CAR）的表达赋予T细胞针对肿瘤细胞表面上表达的肿瘤相关抗原（TAA）的新特异性。这种CAR的结合导致受影响的肿瘤细胞的T细胞介导的裂解。虽然CAR T细胞介导的免疫疗法在治疗恶性血液病方面取得了巨大成功，但在治疗实体瘤方面尚未实现其所带来的希望。这项研究旨在将CAR T细胞疗法扩展到实体瘤的治疗，特别是胰腺癌。这一目标将通过开发CAR T细胞和免疫调节细菌的新组合疗法来实现。转基因革兰氏阴性E.大肠杆菌菌株Nissle 1917，在表面上具有免疫激活细胞因子的诱导型表达，将其口服给予携带胰腺肿瘤的免疫活性小鼠。通常，健康组织中的这种细菌会被内源性免疫系统完全清除。然而，胰腺肿瘤代表了一个免疫特权区域，这些细菌可以在其中存活并长期存在。目的是通过限制于肿瘤组织的促炎细胞因子的诱导型表达来积极利用这种现象，以便永久地调节肿瘤基质，从而募集CAR T细胞以及内源性免疫细胞，特别是肿瘤相关巨噬细胞（TAM）、自然杀伤细胞（NK）、NK T细胞（NKT），用于消除肿瘤。预期检测以下候选物：TNF-α、IFN-γ、IL-18、IL-21和GM-CSF。计划在肿瘤持久性细菌表面上的诱导型细胞因子表达将在胰腺肿瘤区域中建立急性炎症。在这种联合治疗的第二部分，肿瘤特异性CAR T细胞将被静脉注射，以完全消除肿瘤微环境的细菌介导的免疫调节所支持的肿瘤。我们期望通过这种联合治疗，通常无法治愈的胰腺肿瘤疾病将获得具有治愈前景的新的免疫选择。

The diagnosis of pancreatic carcinoma means for most of the affected persons no possibility of a cure and an extremely unfavorable relative five-year survival rate. The curative possibilities with the help of conventional forms of therapy are often limited by the advanced stage of the disease at the time of diagnosis. Therefore, it is of great social importance to develop new treatment options against this malignant tumor disease. Adoptive T-cell therapy is a promising, targeted strategy in the treatment of tumor diseases. The expression of a chimeric antigen receptor (CAR) gives T cells new specificity against tumor-associated antigens (TAA) expressed on the surface of tumor cells. The binding of such a CAR leads to T-cell-mediated lysis of the affected tumor cells. While CAR T-cell mediated immunotherapy has enjoyed great success in the treatment of malignant hematological diseases, the hopes raised in it have not yet been fulfilled in the treatment of solid tumors. This research aims to extend CAR T-cell therapy to the treatment of solid tumors, in particular pancreatic cancer. This goal is to be achieved by developing a new combination therapy of CAR T cells and immunomodulating bacteria. Genetically modified gram-negative E. coli bacteria of the strain Nissle1917 with inducible expression of an immune-activating cytokine on the surface, will be administered orally to pancreas tumor-bearing, immunocompetent mice. As a rule, such bacteria in healthy tissue will be completely eliminated by the endogenous immune system. However, the pancreatic tumor represents an immune-privileged area where such bacteria can survive and persist in the long term. The aim is to actively exploit this phenomenon through the inducible expression of a proinflammatory cytokine limited to tumor tissue in order to modulate the tumor stroma permanently and thus recruit CAR T cells as well as endogenous immune cells, in particular tumor-associated macrophages (TAMs), natural killer cells (NK), NK T cells (NKT) for the elimination of the tumor. The testing of the following candidates is intended: TNF-ɑ, IFN-γ, IL-18, IL-21 and GM-CSF. It is planned that inducible cytokine expression on the surface of tumor-persistent bacteria will establish an acute inflammation in the area of the pancreatic tumor. In the second part of this combination therapy, tumor-specific CAR T cells will be injected intravenously to completely eliminate the tumors favored by bacterial-mediated immune modulation of the tumor microenvironment. We expect from this combination therapy that the often incurable pancreatic tumor disease will receive a new immunotherapeutic option with the prospect of cure.