Genetic Improvements of Tumor-Targeted Salmonella

描述（由申请方提供）：沙门氏菌正在开发中，可作为抗癌载体。在小鼠中，静脉内或瘤内注射减毒沙门氏菌优先在肿瘤内繁殖，抑制肿瘤生长并延长存活期。其中一个菌株VNP20009目前正在进行人体I期临床试验。VNP20009中的一个关键突变，msbB基因的部分缺失，使细菌内毒素实际上不能引起脓毒性休克，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。先前分离了具有补偿突变的自发产生的菌株，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，但它们的功效范围从一种菌株中几乎没有或没有抗肿瘤活性到具有高度抗肿瘤活性的那些，如VNP20009。因此，这些补偿突变是多样的，并且对于抗肿瘤菌株的功效是重要的。最近，通过应用交替选择技术和更广泛的生理测定，分离出了更广泛多样的自发补偿突变，这些突变恢复了对部分或全部这些敏感性的抗性。因此，由于补偿突变的广谱性只是最近才被认识到的，因此迄今为止，只有少数这些突变被测试了抗肿瘤活性。在这里，我们建议使用转座子诱变分离出这种广谱的补偿突变体，并将这些插入转移到肿瘤选择性菌株中，从而产生具有改善特性潜力的新的抗肿瘤菌株。将对这些具有补偿突变的沙门氏菌新菌株进行抗肿瘤活性测试。 拟议的商业应用： 高度选择性的细菌载体直接作用于全身的患病部位，提供了根除患病组织的潜力，同时大大减少了由于非特异性毒性引起的副作用。我们预计，患有无法治疗和无法获得的转移性肿瘤和实体肿瘤的患者将成为主要市场。第一个沙门氏菌载体VNP20009已经在人体I期临床试验中用于治疗实体瘤。

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.