Mixed-Ligand Targeting of a Nano-Pharmaceutical Against GBM Stem Cells

描述（由申请人提供）：在本I期SBIR项目中，Parabon NanoLabs，Inc. (PNL)将产生一种新型的纳米药物化合物，优先选择和破坏脑肿瘤干细胞（BTSC），以帮助治疗多形性胶质母细胞瘤（GBM），这是最致命的脑癌之一。GBM中的BTSC已被鉴定为促进肿瘤血管生成和治疗抗性的高度致瘤性细胞亚群。例如，只有100个BTSC可以在小鼠模型中启动肿瘤生长，而来自同一肿瘤的100万个非干细胞则不能。目前的标准治疗无法消除足够的BTSC可能是GBM复发率>90%及其预后不良的原因。使用Parabon的“药物开发平台”，将在称为PNL 24的专有“分子试验板”上开发先导化合物及其实验变体，该分子试验板可以用不同的靶向配体和细胞毒性有效载荷以“即插即用”方式进行功能化。这些化合物将用于检验混合配体、低亲和力靶向与单配体替代物相比可以实现上级BTSC靶向特异性的假设。为了测试BTSC特异性，将通过用两种不同靶向配体之一和两者的组合官能化PNL 24来产生三种靶向化合物。每种化合物的染料标记将用于测试体外靶向特异性，通过荧光共聚焦显微镜测量，针对BTSC和作为对照的正常人细胞系，特别是神经干细胞、神经元和星形胶质细胞。三种靶向结构中最具选择性的（假设为混合配体构建体）将进一步用聚乙二醇官能化。 白喉毒素衍生物，并通过标准细胞毒性测定测试针对BTSC的功效和针对三种正常细胞系的安全性。最后，将在hBTSC颅内异种移植小鼠模型中通过对流增强递送（CED）测试该化合物的抗BTSC功效。如果发现安全有效，该化合物将成为后续II期项目中未来研究的主要化合物，该项目将检查系统毒性，PK和生物分布，为最终的IND申请做准备。 公共卫生相关性：该第一阶段SBIR项目将生产一种新型纳米药物化合物，该化合物可主动靶向和破坏多形性胶质母细胞瘤（GBM）的脑肿瘤干细胞（BTSC），GBM是最致命的脑癌形式之一。将使用“药物开发平台”（该平台实现了首个“即插即用”分子工程），生产一种具有不同靶向成分的主动靶向纳米化合物和实验变体。这些化合物将针对代表性细胞系和小鼠模型进行测试，以证明BTSC的选择性靶向和破坏，以及对正常脑细胞的可忽略毒性。

DESCRIPTION (provided by applicant): In this Phase I SBIR project, Parabon NanoLabs, Inc. (PNL) will produce a novel, nano- pharmaceutical compound that preferentially selects and destroys brain tumor stem cells (BTSCs) to aid the treatment of glioblastoma multiforme (GBM), one of the most lethal brain cancers. BTSCs in GBM have been identified as a highly tumorigenic cell subpopulation that promotes tumor angiogenesis and therapeutic resistance. For example, as few as 100 BTSCs can initiate tumor growth in a mouse model, whereas 1 million non-stem cells from the same tumor cannot. The inability to eliminate sufficient BTSCs with the current standard of care may account for the >90% recurrence rate of GBM and its poor prognosis. Using Parabon's Essemblix" Drug Development Platform, the lead compound and its experimental variants will be developed upon a proprietary "molecular breadboard," called PNL24, that can be functionalized with different targeting ligands and cytotoxic payloads in "plug and play" fashion. These compounds will be used to test the hypothesis that mixed-ligand, low-affinity targeting can achieve superior BTSC targeting specificity versus single-ligand alternatives. To test BTSC specificity, three targeting compounds will be created by functionalizing PNL24 with one of two different targeting ligands and a combination of both. Dye-labeling of each compound will be used to test in vitro targeting specificity, measured via fluorescent confocal microscopy, against BTSC and normal human cell lines serving as controls, specifically, neural stem cells, neurons and astrocytes. The most selective of the three targeting structures (hypothetically the mix-ligand construct) wil be further functionalized with a diphtheria toxin derivative and the result tested for efficacy against BTSC and safety against three normal cell lines via standard cytotoxicity assay. Finally, the anti-BTSC efficacy of this compound will be tested in a hBTSC intracranial xenograft mouse model via convection-enhanced delivery (CED). If found to be both safe and effective, this compound will be the lead compound for future studies in a subsequent Phase II project that examines systematic toxicity, PK and biodistribution in preparation for an eventual IND application. PUBLIC HEALTH RELEVANCE: This Phase I SBIR project will produce a novel nano-pharmaceutical compound that actively targets and destroys brain tumor stem cells (BTSCs) from glioblastoma multiforme (GBM), one of the most lethal forms of brain cancer. Built using the Essemblix" Drug Development Platform, which enables first-of-its-kind "plug and play" molecular engineering, an actively targeted nano-compound and experimental variants with different targeting components, will be produced. The compounds will be tested against representative cell lines and a mouse model to demonstrate selective targeting and destruction of BTSCs, and negligible toxicity to normal brain cells.