Combination therapy using tumor-targeting synthetic dsRNA and gemcitabine

描述(申请人提供)：癌症是美国主要的死亡原因之一。化疗仍然是一种重要的癌症治疗方式。传统上，使用的是只激活一种肿瘤杀伤机制的细胞毒分子。联合化疗现在是一种常见的做法，它涉及用几种不同的药物治疗患者，这些药物的杀伤机制不同。吉西他滨被批准用于治疗各种癌症：胰腺癌、乳腺癌、肺癌和膀胱癌。虽然吉西他滨在培养的肿瘤细胞中非常有效，但在患者中的临床结果相当有限，最近的临床前数据表明，吉西他滨脂质体配方有助于提高吉西他滨的疗效。最近的一个新进展是将合成的双链RNA(DsRNA)用作潜在的化疗药物。某些dsRNA分子具有多种直接和间接的促凋亡、抗增殖和抗血管生成活性。有趣的是，我们最近的数据显示，当局部注射的合成dsRNA与系统剂量的吉西他滨联合使用时，其抗肿瘤活性显著增强，这表明使用吉西他滨和dsRNA的联合治疗代表了一种有前景的肿瘤治疗方法。然而，对于大多数肿瘤，局部瘤周注射在临床上是不可行的。我们建议开发表皮生长因子(EGF)偶联的、长循环的纳米级脂质体dsRNA制剂和吉西他滨制剂，以便在静脉注射后将其靶向EGF受体高表达的肿瘤细胞，并在小鼠或人类癌症模型中验证所产生的抗肿瘤活性。为了实现我们的总体目标，我们提出了以下三个具体目标：(I)为合成dsRNA和吉西他滨设计EGF包衣的长循环脂质体载体，并验证其体外活性；(Ii)评估脂质体载体在静脉注射后将dsRNA和/或吉西他滨运送到小鼠模型肿瘤中的程度；以及(Iii)评估使用肿瘤靶向脂质体dsRNA和吉西他滨的联合治疗将在多大程度上抑制体内肿瘤的生长。这项申请的完成将为我们制定策略，改善未来对dsRNA和吉西他滨敏感的癌症的临床结果奠定坚实的科学基础。也可以采用类似的策略将dsRNA与其他化疗药物结合起来对抗其他肿瘤。公共卫生相关性：许多肿瘤细胞过度表达EGF受体。EGF偶联的长循环脂质体合成dsRNA和脂质体吉西他滨的成功工程及其联合给药的抗肿瘤活性的验证，将为未来改善对吉西他滨和dsRNA敏感的肿瘤的临床结果奠定坚实的科学基础。通过将dsRNA与其他化疗药物相结合，类似的策略也可以用于对抗其他癌症。

DESCRIPTION (provided by applicant): Cancer is one of the leading causes of death in the US. Chemotherapy remains an important cancer treatment modality. Traditionally, cytotoxic molecules that activate only a single tumor-killing mechanism are used. Combination chemotherapy is now a common practice, which involves treating patients with several medicines that differ in their killing mechanisms. Gemcitabine is approved for the treatment of various carcinomas: pancreatic, breast, lung, and bladder cancers. Although it is extremely potent in tumor cells in culture, the clinical outcomes of gemcitabine in patients is rather modest, and recent pre-clinical data indicated that a gemcitabine-in-liposome formulation helped improve the efficacy of gemcitabine. A recent new development is the use of synthetic double-stranded RNA (dsRNA) as a potential chemotherapy agent. Certain dsRNA molecules have multiple direct and indirect pro-apoptotic, anti-proliferative, and anti-angiogenic activities. Interestingly, our recent data showed that the anti-tumor activity of a locally injected synthetic dsRNA was significantly enhanced when the dsRNA was dosed in combination with systemically dosed gemcitabine, indicating that a combination therapy using gemcitabine and dsRNA represents a promising tumor therapy approach. However, local peritumoral injection is clinically impractical for the majority of tumors. We propose to develop epidermal growth factor (EGF)-conjugated, long-circulating, nanometer-scale liposomal dsRNA formulation and gemcitabine formulation to target them into EGF receptor-over-expressing tumor cells after intravenous injection and to validate the resultant anti-tumor activity in mouse models of mouse or human cancers. To accomplish our overall goal, we propose the following three specific aims: (i) to engineer EGF-coated, long-circulating liposomal carriers for a synthetic dsRNA and for gemcitabine and to validate their activities in vitro, (ii) to evaluate the extent to which the liposomal carriers will deliver the dsRNA and/or the gemcitabine into model tumors in mice after intravenous injection, and (iii) to evaluate the extent to which a combination therapy using tumor-targeting liposomal dsRNA and gemcitabine will inhibit the tumor growth in vivo. The completion of this application will lay a solid scientific foundation for us to devise strategies to improve the clinical outcome of cancers sensitive to dsRNA and gemcitabine in the future. A similar strategy can also be adopted to combine dsRNA with other chemotherapy agents to fight other tumors. PUBLIC HEALTH RELEVANCE: Many tumor cells over-express the EGF receptor. The successful engineering of EGF-conjugated, long- circulating liposomal synthetic dsRNA and liposomal gemcitabine and the validation of their anti-tumor activities when given in combination will lay a sound scientific foundation for future improvement of the clinical outcomes of tumors sensitive to both gemcitabine and dsRNA. A similar strategy can also be utilized to fight other cancers by combining dsRNA with other chemotherapy agents.