Treating pancreatic cancer with Listeria-32P

 描述（由申请人提供）：胰腺导管腺癌，胰腺癌的同义词，是癌症死亡的第四大原因。这种“沉默杀手”的特点是在原发肿瘤被发现之前就已经转移，导致五年生存率仅为4%，这凸显了对新的替代疗法的需求。 基于单核细胞增生李斯特菌的癌症疗法可能是这样一种替代疗法。我们的实验室发现，李斯特菌表现出对转移性癌症特别有用的新途径。我们发现李斯特菌感染转移瘤和原发性肿瘤，并通过高水平的活性氧（ROS）杀死肿瘤细胞，并且髓源性抑制细胞（MDSC）通过肿瘤细胞产生的化疗/细胞因子选择性地将李斯特菌递送到肿瘤部位，并且在感染后通过其免疫抑制特性保护它们免于免疫清除。基于这些结果，我们现在使用李斯特菌作为将抗癌剂递送到肿瘤微环境（TME）的平台。一种新的应用是将放射性同位素选择性地递送到肿瘤细胞中，所述放射性同位素发射杀细胞辐射，例如与李斯特菌偶联的β-粒子。这导致了电离辐射对肿瘤细胞的协同破坏，电离辐射通过β粒子和李斯特菌产生的ROS杀死细胞。我们是第一个证明在高度侵袭性的胰腺癌模型（Panc-02）中，用李斯特菌进行治疗性治疗可将转移灶的数量减少50%，当与放射性同位素188-铼（188 Re）结合时，减少90%。这与转移灶中放射性的选择性蓄积相关，几乎没有副作用。这项工作发表在去年的PNAS上，它在人体临床试验中的潜力在PNAS评论中得到了广泛的讨论，以及在科学，自然和外行杂志，如经济学家和福布斯。最近，我们探索了一种全新的方法，利用32磷（32 P），通过将32 P掺入李斯特菌的细胞壁（李斯特菌-32 P）在培养李斯特菌。李斯特菌-32P被证明不仅比李斯特菌-188Re更有效地对抗胰腺癌（最可能是由于32 P的半衰期为14天，而188 Re的半衰期为17小时），而且更容易产生。这种新方法避免了对抗体的需要，并且比李斯特菌-188Re的产生更便宜和更快。用李斯特菌-32P治疗完全消除了80%小鼠的转移性癌症。最重要的是，通过李斯特菌递送的32 P掺入正常组织（包括骨髓（BM））中几乎检测不到，与单独的32 P相反，32 P强烈地掺入BM中。此外，李斯特菌-32P的副作用几乎检测不到。在这项资助申请中，我们的主要目标是通过在胰腺导管腺癌的人源化小鼠模型（KPC小鼠，条件性表达内源性Kras-G12 D和p53-R172 H突变等位基因）中进行评估，探索李斯特菌-32 P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-32 P在KPC小鼠中的功能、稳定性、生物分布和安全性;（2）评价李斯特菌-32 P对KPC小鼠的疗效和存活率的影响。

 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.