Treating pancreatic cancer with Listeria-32P

 描述(申请人提供)：胰腺导管腺癌是胰腺癌的同义词，是癌症死亡的第四大原因。“沉默的杀手”的特点是在原发肿瘤被发现之前就有转移行为，导致五年存活率只有4%，这突显了新的替代疗法的必要性。基于单核细胞增多性李斯特菌的癌症治疗可能是这样一种替代疗法。我们的实验室发现，李斯特菌展示了新的途径，对治疗转移性癌症特别有用。我们发现李斯特菌通过高水平的活性氧(ROS)感染转移和原发肿瘤并杀死肿瘤细胞，而髓系抑制细胞(MDSC)通过肿瘤细胞产生的化学/细胞因子选择性地将李斯特菌运送到肿瘤部位(S)，并在感染后通过其免疫抑制特性保护它们免受免疫清除。基于这些结果，我们现在使用李斯特菌作为一个平台，将抗癌药物输送到肿瘤微环境(TME)。一种新的应用是输送放射性同位素，它选择性地向肿瘤细胞发射杀伤性辐射，如偶联到李斯特菌的β粒子。这导致电离辐射协同摧毁肿瘤细胞，电离辐射通过β-粒子杀死细胞，并通过李斯特菌产生ROS。我们首次证明，在一个高度侵袭性的胰腺癌模型(PANC-02)中，李斯特菌的治疗将转移数量减少了50%，当与放射性同位素188-Re(188Re)结合时，转移数量减少了90%。这与放射性在转移瘤中的选择性积累有关，几乎没有副作用。这项研究发表在去年的PNAS上，其人类临床试验的潜力在PNAS的一篇评论中以及在《科学》、《自然》和《经济学人》和福布斯等非专业杂志上都有广泛的讨论。最近，我们探索了一种利用32P(32P)产生RL的全新方法，在李斯特菌(Listeria)培养过程中将32P掺入李斯特菌(Listeria-32P)的细胞壁中。事实证明，李斯特菌-32P不仅比李斯特菌-188Re更有效地对抗胰腺癌(很可能是因为32P的半衰期更长，为14天，而188Re为17小时)，而且更容易产生。这种新方法避免了对抗体的需要，而且比李斯特菌-188Re的产生要便宜得多，速度也快得多。用李斯特菌-32P治疗完全消除了80%的小鼠的转移性癌症。最重要的是，通过李斯特菌传递的~(32)P进入包括骨髓(BM)在内的正常组织中几乎检测不到，与仅有~(32)P进入骨髓形成鲜明对比。此外，李斯特菌-32P的副作用几乎检测不到。在这项赠款申请中，我们的主要目标是通过在人源化的胰腺导管腺癌小鼠模型(有条件地表达内源性Kras-G12D和P53-R172H突变等位基因的KPC小鼠)中的评估，探索李斯特菌-32P治疗胰腺癌的有效性和安全性。具体目的如下：(1)评价李斯特菌-32P在KPC小鼠体内的功能、稳定性、生物分布和安全性；(2)评价李斯特菌-32P对KPC小鼠的疗效和存活的影响。

 DESCRIPTION (provided by applicant): Pancreatic ductal adenocarcinoma, synonymous to pancreatic cancer, is the 4th leading cause of cancer deaths. The "silent killer" is characterized by its metastatic behavior before the primary tumor can be detected, resulting in a five-year survival rate of only 4%, underscoring the need for new alternative therapies. Listeria monocytogenes-based cancer therapy could be such an alternative therapy. Our laboratory discovered that Listeria exhibits novel pathways that are particularly useful against metastatic cancer. We found that Listeria infects metastases and primary tumors, and kills tumor cells through high levels of reactive oxygen species (ROS), and that myeloid-derived suppressor cells (MDSC) deliver Listeria selectively to the tumor site(s) through chemo/cytokines produced by the tumor cells, and by protecting them, after infection, from immune clearance through their immune suppressive character. Based on these results we now use Listeria as a platform for the delivery of anticancer agents to the tumor microenvironment (TME). One novel application is the delivery of radioisotopes, which emit cytocidal radiation such as beta-particles coupled to Listeria, selectively into the tumor cells. This leads to the synergistic destruction of tumor cell by ionizing radiation, which killed cells through beta-particles, and through ROS generation by Listeria. We were the first to demonstrate that in a highly aggressive model of pancreatic cancer (Panc-02), therapeutic treatment with Listeria reduced the number of metastases by 50%, and when coupled to radioisotope 188-Rhenium (188Re) by 90%. This correlated with a selective accumulation of radioactivity in the metastases with practically no side effects. This work was published in PNAS last year and its potential for human clinical trials was extensively discussed in a PNAS commentary, as well as in Science, Nature and lay magazines like The Economist and Forbes. Most recently, we explored a completely new method to RL generation using 32Phosphorus (32P), by incorporating 32P into the cell wall of Listeria (Listeria-32P) during culturing of Listeria. The Listeria-32P proved to be not only more effective against pancreatic cancer than Listeria-188Re (most likely as a result of the 32P longer half-life of 14 days vs 188Re of 17 hrs), but also much easier to generate. This novel approach avoids the need for antibodies and is much cheaper and faster than the generation of Listeria-188Re. Treatment with Listeria-32P completely eliminated the metastatic cancer in 80% of the mice. Most importantly, the incorporation of 32P delivered through Listeria into normal tissues including bone marrow (BM) was hardly detectable, in contrast to 32P alone, which strongly incorporated into the BM. Also, side effects of Listeria-32P were hardly detectable. In this grant application, our main goal is to explore the efficacy and safety of Listeria-32P for treatment of pancreatic cancer through evaluation in a humanized mouse model of pancreatic ductal adenocarcinoma (KPC mice, which conditionally express endogenous Kras-G12D and p53-R172H mutant alleles). The specific aims are as follows: (1) Evaluate function, stability, biodistribution, and safety of Listeria- 32P in KPC mice, and (2) Evaluate the effect of Listeria-32P on efficacy and survival in KPC mice.