SapC-DOPS nanovesicles for Treating Glioblastoma Multiforme

描述(由申请人提供)： 我们的目标是开发一种新的分子实体，具有新的作用机制，用于靶向和消除多形性胶质母细胞瘤(GBM，高级别胶质瘤)，这是一种致命的侵袭性脑瘤，目前还没有有效的治疗方法。预计今年将有1.2万名患者被诊断为GBM，其中大多数将在第一年内死亡。显然，人们迫切需要一种有效的抗胶质瘤药物。为了满足这一需求，我们正在开发一种新的治疗性蛋白脂纳米微囊，它可以靶向并摧毁胶质瘤肿瘤。由细小的溶酶体、鞘磷脂激活蛋白皂苷C(SapC，80aa)和磷脂二油酰磷脂酰丝氨酸(DOPS)组成；稳定的200 nm SapC-DOPS纳米胶囊对富含磷脂酰丝氨酸的膜表面具有异常高的亲和力，广泛存在于多种类型的肿瘤细胞和肿瘤新生血管中。在与鞘脂蛋白功能激活一致的机制中，SapC-DOPS似乎也选择性地诱导肿瘤细胞经历凋亡。在这项建议的第一阶段，我们证明了使用SapC-DOPS纳米微囊在小鼠模型中靶向和杀伤脑胶质瘤的可行性。在原位种植胶质瘤的小鼠体内注射SapC-DOPS导致了剂量依赖性的生存改善。在活体动物成像实验中，使用荧光标记的纳米微囊证明了SapC-DOPS对肿瘤块的特异性靶向性。我们还表明，与DOPS特异结合的皂苷C蛋白对于靶向是必不可少的。SapC-DOPS的抗癌活性在来自侵袭性和侵袭性胶质瘤系的第二个原位胶质瘤模型中得到证实。试点毒性数据表明，SapC-DOPS相对无毒，没有证据表明行为异常或病理损害。我们在第二阶段提案中的目标是确定和选择最优的SapC-DOPS配方和治疗方法，适合于推进计划中的人体试验。第二阶段的具体目标是：(1)优化蛋白质的表达和纯化，并开发临床适用的配方；(2)在动物模型中进行临床前药代动力学、稳定性以及脑和组织分布分析，以确定纳米微囊的体内处置；以及(3)在两个动物模型中进行毒性研究，以评估安全性，以便提交IND。在这些研究完成后，我们期望有令人信服的证据来推动SapC-DOPS纳米微囊作为一种有效的新的抗癌治疗方法的临床开发(在SBIR第三阶段)。这项研究具有创新性，因为SapC-DOPS纳米微囊为减缓肿瘤生长和消除深层脑瘤提供了一种独特的方法。最终，我们希望调整我们的技术，以针对不同类型的肿瘤，并开发针对肿瘤的诊断。 公共卫生相关性： 我们正在开发一种新的分子实体来治疗多形性胶质母细胞瘤，这是一种致命的脑瘤，90%以上的患者死亡。目前的治疗标准，包括手术、放射和化疗，在显著降低发病率方面并不有效。我们的策略包括使用新的蛋白脂纳米囊，这种纳米囊可以穿透肿瘤，在不损害正常细胞的情况下选择性地摧毁恶性肿瘤细胞。拟议中的动物模型的成功将使我们能够在人体上测试该产品。

DESCRIPTION (provided by applicant): Our goal is to develop a new molecular entity with a novel mechanism of action for targeting and eliminating glioblastoma multiforme (GBM, high grade glioma), a deadly and invasive brain tumor with no effective treatment. Of the 12,000 patients expected to be diagnosed with GBM this year, most will succumb within the first year. Clearly, there is an urgent demand for an efficacious anti-glioma drug. To address this need, we are developing a new class of therapeutic proteolipid nanovesicle that can target and destroy glioma tumors. Composed of the small lysosomal, sphingolipid activator protein saposin C (SapC, 80 aa) and the phospholipid dioleoylphosphatidylserine (DOPS); the stable 200 nm SapC-DOPS nanovesicles have unusually high affinity for phosphatidylserine-enriched membrane surfaces that occur widely in many types of tumor cells and tumor neovasculature. In a mechanism consistent with activation of sphingolipid protein function, SapC- DOPS also appears to selectively induce tumor cells to undergo apoptosis. In Phase I of this proposal, we demonstrated the feasibility of using SapC-DOPS nanovesicles to target and kill intracranial gliomas in mouse models. Injections of SapC-DOPS in mice with orthotopically implanted gliomas resulted in dose-dependent improvement in survival. Specific targeting of SapC-DOPS to the tumor mass was demonstrated using fluorescently-tagged nanovesicles in live animal imaging experiments. We also showed that saposin C protein, in specific association with DOPS is essential for targeting. Anticancer activity of SapC-DOPS was confirmed in a second orthotopic glioma model, derived from an aggressive and invasive glioma line. Pilot toxicity data indicated SapC-DOPS to be relatively nontoxic with no evidence of behavioral abnormalities or pathological lesions. Our objective in Phase II proposal is to identify and select optimized SapC-DOPS formulations and treatment methods suitable for advancing toward planned human testing. The specific aims of Phase II are: (1) optimize protein expression and purification, and develop clinically suitable formulation; (2) conduct preclinical pharmacokinetics, stability, and brain and tissue distribution analysis in animal models to determine in vivo disposition of the nanovesicles; and (3) carry out toxicity studies in two animal models to assess safety, towards filing of the IND. Upon the completion of these studies, we expect to have compelling evidence to progress clinical development of SapC-DOPS nanovesicles as a potent new anti-cancer therapeutic (during SBIR Phase III). This research is innovative because SapC-DOPS nanovesicles offer a unique approach for slowing tumor growth and eliminating deep-seated brain tumors. Ultimately, we expect to adapt our technology for targeting different types of tumors and for developing tumor-targeted diagnostics. PUBLIC HEALTH RELEVANCE: We are developing a new molecular entitity for treating glioblastoma multiforme, a deadly form of brain tumor that kills over 90% of afflicted patients. Current standards of treatment, consisting of surgery, radiation, and chemotherapy, have not been effective in significantly reducing morbidity. Our strategy involves using new proteolipid nanovesicles that can penetrate the tumors and selectively destroy malignant cells without harming normal cells. Success in the proposed animal models will enable us to test the product in humans.