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药物。我们已经证明，分泌肿瘤特异性抗原的重组单核细胞增生乳杆菌在移植到正常同基因小鼠体内后，不仅可以保护肿瘤免受肿瘤侵袭，还可以诱导肉眼可见的肿瘤消退。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具有不寻常的能力，可以逃离吞噬酶体，在细胞的细胞质中生存和生长。因此，单核增生乳杆菌分泌的抗原可以非常有效地靶向II类和I类限制性抗原递呈途径。因此，这种细菌可能是一种理想的疫苗载体，用于增强细胞介导的对肿瘤特异性抗原的免疫反应，作为一种癌症治疗方法。为了确定如何优化单核增生乳杆菌作为人类癌症疫苗的使用，我们将在FVB背景下使用HER-2/ new转基因乳腺癌小鼠模型来测试单核增生乳杆菌克服对自发产生的肿瘤的耐受性的能力。自从第一次提交这项拨款以来，我们已经完成了进行这些实验所需的Lm载体的构建，包括五个Lm- lo - HER-2/neu菌株，它们分泌HER-2蛋白的重叠片段，并发现它们在传递给正常和HER-2/neu转基因FVB小鼠时似乎揭示了HER-2/neu的隐表位。我们已经证实，这些表位是通过将抗原融合到LLO并由单核增生乳杆菌递送而不是通过将HER-2/neu作为蛋白片段递送而显示的。因此，该提案的一个新的子目标（特异性aim 1c）是全面绘制这些表位，以便我们可以在特异性aim 2中测量它们对整体免疫反应的贡献。特异性目的2的目的是将lm - lo - her -2/neu重组体的抗肿瘤有效性与B细胞和T细胞免疫的诱导联系起来。最后，在特异性目的3中，我们将比较HER-2/neu李斯特菌疫苗对HER-2/neu转基因小鼠移植和自发乳腺肿瘤的影响。自上次提交以来，我们发现五种lm - lo - HER-2/neu片段载体对自发肿瘤生长的影响能力不同，但对HER-2/neu转基因小鼠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.