Genetic Improvements of Tumor-Targeted Salmonella

描述（由申请人提供）：沙门氏菌是正在开发的抗癌载体。在小鼠中，经静脉注射或瘤内注射的减毒沙门氏菌在肿瘤内优先繁殖，抑制肿瘤生长并延长生存期。其中一种毒株VNP20009目前正在人体I期临床试验中。VNP20009的一个关键突变，即msbB基因的部分缺失，使细菌内毒素几乎无法引发感染性休克，也使细菌对各种盐和螯合剂敏感，通常在某些条件下限制细菌的生长。先前已分离出具有代偿性突变的自发产生的菌株，其中包括VNP20009，并测定了它们的抗肿瘤活性。这些菌株的生长特性得到部分恢复，但它们的抗肿瘤活性从一个菌株几乎没有或没有抗肿瘤活性到VNP20009等具有高度抗肿瘤活性的菌株。因此，这些代偿性突变是多种多样的，对抗肿瘤菌株的疗效也很重要。最近，通过应用替代选择技术和更广泛的生理分析，分离出了更广泛的自发代偿突变，这些突变恢复了对部分或全部这些敏感性的抗性。因此，由于代偿性突变的广谱性直到最近才被发现，到目前为止，只有少数的代偿性突变进行了抗肿瘤活性测试。在这里，我们建议使用转座子诱变分离这种广谱的代偿突变体，并将这些插入物转移到肿瘤选择性菌株中，从而产生具有改进性能潜力的新抗肿瘤菌株。这些具有补偿性突变的沙门氏菌新菌株将用于抗肿瘤活性测试。

DESCRIPTION (provided by applicant): Salmonella are under development as anticancer vectors. In mice, attenuated Salmonella injected intravenously or intratumorally multiply preferentially within tumors, suppress tumor growth and prolong survival. One strain, VNP20009, is currently in human Phase I clinical trials. A key mutation in VNP20009, a partial deletion of the msbB gene which renders the bacterial endotoxin virtually incapable of eliciting septic shock, also makes the bacteria sensitive to a variety of salt and chelating agents, generally limiting the growth of the bacteria under certain conditions. Spontaneously arising strains with compensatory mutations were previously isolated which included VNP20009, and their antitumor activity determined. Growth properties of these strains were partially restored, but their efficacy ranged from little or no antitumor activity in one strain, to those such as VNP20009 with a high degree of antitumor activity. Thus, these compensatory mutations are both diverse and important for efficacy of antitumor strains. Recently, by applying alternate selection techniques and a broader spectrum of physiological assays, a much wider diversity of spontaneous compensatory mutations which restore resistance to part or all of these sensitivities were isolated. Thus, because the broad spectrum of compensatory mutations was only recently recognized, only a few of these have been tested for antitumor activity thus far. Here, we propose to isolate this broad spectrum of compensatory mutants using transposon mutagenesis and to move these insertions into tumor-selective strains, thereby generating new antitumor strains with the potential for improved properties. These new strains of Salmonella with compensatory mutations will be tested for antitumor activity. PROPOSED COMMERCIAL APPLICATIONS: Highly selectie bacterial vectors working directly at diseased sites throughout the body offer the potential to eradicate diseased tissue with substantially reduced side effects due to non-specific toxicity. We anticipate that patients with untreatable and inaccessible metastatic and solid tumors will be the primary markets. The first Salmonella vector, VNP20009, is already in human phase I clinical trials for treatment of solid tumors.