Immunotherapeutic strategies for breast cancer

描述（由申请人提供）：我们建议开发单核细胞增生李斯特菌，作为表达HER-2/neu的乳腺肿瘤的癌症治疗剂。我们已经证明重组L.分泌肿瘤特异性抗原的单核细胞增多症不仅可以保护免受肿瘤攻击，而且还可以在移植到正常同基因小鼠中后诱导肉眼可见的已建立肿瘤的消退。这种令人印象深刻的抗肿瘤反应可能是由于这种兼性细胞内细菌逃避吞噬溶酶体并在细胞质中生存和生长的不寻常能力。L.因此，单核细胞增多症非常有效地靶向II类和I类限制性的抗原呈递途径。因此，这种细菌可能是理想的疫苗载体，用于加强对肿瘤特异性抗原的细胞介导的免疫应答，作为癌症治疗剂。确定如何优化L.为了研究单核细胞增多症作为人类癌症疫苗，我们将使用FVB背景下的乳腺癌HER-2/neu转基因小鼠模型来测试单核细胞增多症的能力。单核细胞增多症，以克服耐受自发产生的肿瘤。自从首次提交该授权以来，我们已经完成了进行这些实验所需的Lm载体的构建，包括5个Lm-LLO-Her-2/neu菌株，其分泌HER-2蛋白的重叠片段，并发现当递送至正常和HER-2/neu转基因FVB小鼠时，它们似乎揭示HER-2/neu中的隐蔽表位。我们已经证实，这些表位是通过将抗原融合到LLO并通过L.因此，该提议的新的子目标（特异性目标1c）是完全定位这些表位，使得我们可以测量它们对特异性目标2中的总体免疫应答的贡献。具体目标2的目标是将Lm-LLO-HER-2/neu重组体的抗肿瘤有效性与B和T细胞免疫的诱导相关联。最后，在具体目标3中，我们将比较李斯特菌HER-2/neu疫苗对HER-2/neu转基因小鼠中移植和自发性乳腺肿瘤的影响。自上次提交以来，我们发现五种Lm-LLO-Her-2/neu片段载体对自发性肿瘤生长具有不同的影响能力，但对HER-2/neu转基因小鼠中的可移植肿瘤具有相似的影响，并增加了探索这一发现背后机制的新目标。

DESCRIPTION (provided by applicant): We propose to develop Listeria monocytogenes, as a cancer therapeutic for HER-2/neu expressing breast tumors. We have shown that recombinant L. monocytogenes that secretes a tumor specific antigen can not only protect against tumor challenge but can also induce regression of macroscopic established tumors after transplantation into normal syngeneic mice. This impressive anti-tumor response is probably due to the unusual ability of this facultative intracellular bacterium to escape the phagolysosome and live and grow in the cytoplasm of cells. Antigens secreted by L. monocytogenes, therefore, are very effectively targeted to both the class II and class I restricted pathways for antigen presentation. Thus this bacterium may be the ideal vaccine vector for boosting the cell mediated immune response to tumor specific antigens as a cancer therapeutic. To determine how to optimize the use of L. monocytogenes as a cancer vaccine in humans we will use a HER-2/neu transgenic mouse model of breast cancer on the FVB background to test the ability of L. monocytogenes to overcome tolerance to spontaneously arising tumors. Since the first submission of this grant we have completed the construction of Lm vectors rquired to perform these experiments, including five Lm-LLO-Her-2/neu strains that secrete overalpping fragments of the HER-2 protein and discovered that they appear to reveal cryptic epitopes in HER-2/neu when delivered to the normal and HER-2/neu transgenic FVB mouse. We have verified that these epitopes are revealed by fusing the antigen to LLO and delivery by L. monocytogenes and not by delivering HER-2/neu as protein fragments.Thus a new sub- aim of this proposal (Specific Aim 1c) is to fully map these epitopes so that we can measure their contribution to the overall immune response in Specific Aim 2. The goal of Specific Aim 2 is to correlate the anti-tumor effectiveness of the Lm-LLO-HER-2/neu recombinants with the induction of B and T cell immunity. Finally, in Specific Aim 3, we will compare the efficacy of the Listeria HER-2/neu vaccines to impact on transplanted and spontaneously arising breast tumors in mice transgenic for HER-2/neu. Since the last submission we have found that the five Lm-LLO-Her-2/neu fragment vectors have different abilities to impact on sponataneous tumor growth but have similar impacts on the tranplantable tumor in the HER-2/neu trangenic mouse and have added new aims that explore the mechanism behind this finding.